# Let's talk about making Naturally Aspirated horsepower



## Jettaboy1884 (Jan 20, 2004)

Hello,
I have this posted up in the fabrication forum, but I'm an 8v guy at heart. Also, considering that we have the underdog of VW motors, I know that the people in here that race really know how to get the most out of them.
Link:
http://forums.vwvortex.com/zerothread?id=3472422
Thanks,
Mike.


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## Jettaboy1884 (Jan 20, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (Jettaboy1884)*

Bump


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## setaus (Apr 29, 2006)

*Re: Let's talk about making Naturally Aspirated horsepower (Jettaboy1884)*

I'm watching.


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## ny_fam (Apr 3, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (setaus)*

some conversation was taking place on he thread link above.


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## Jettaboy1884 (Jan 20, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (ny_fam)*

Yup. But I'm looking for more! http://****************.com/smile/emthup.gif


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## VWCR8ZY (May 10, 2006)

*Re: Let's talk about making Naturally Aspirated horsepower (Jettaboy1884)*

another 8v junkie eagerly awaiting http://****************.com/smile/emthup.gif


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## Andrew Stauffer (Oct 2, 2000)

*Re: Let's talk about making Naturally Aspirated horsepower (VWCR8ZY)*

Sky is the limit but you've got to know when to say when and when to take it "further". 
Most give up around 130whp when it comes to 8v. Seems to be the limit of bolt ons. Though we've already seen 12 second quarters out of 180whp 8v in these forums. It''s been a few years, however. 
8v is hard. But doable. Never the winner of the #s game (whp or 1320) but way more capable than most give it credit for...


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## SWMurnau (Jun 10, 2005)

*Re: Let's talk about making Naturally Aspirated horsepower (Andrew Stauffer)*

Awesome thread Mike.


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## MkIIRoc (Feb 20, 2005)

*Re: Let's talk about making Naturally Aspirated horsepower (Andrew Stauffer)*


_Quote, originally posted by *Andrew Stauffer* »_ but way more capable than most give it credit for... 

I see the old "get rid of your 8v and just buy a 16v" argument all the time. Give the 8v some more credit! I hope to be in the 12's soon. I run into weather, bad tuning, traction and poor driving problems all the time(not to make excuses







) But take a look at the all motor FWD list in the drag racing section. How many 16v's are in the 12 second range? How many 8v's? There is a "limit" for NA, but I don't think it has been hit just yet. Financially, that limit can be hit very quick. I think romero or kossob could have hit 11's with their 8v's, they were both very close.
http://forums.vwvortex.com/zerothread?id=3299439
And I saw someone post in the other thread that a NA motor can't hit 100% VE. I disagree. VERY much so.



_Modified by MkIIRoc at 8:54 AM 10-11-2007_


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## Jettaboy1884 (Jan 20, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (MkIIRoc)*


_Quote, originally posted by *MkIIRoc* »_
I see the old "get rid of your 8v and just buy a 16v" argument all the time. Give the 8v some more credit! 

X2. The 8v is a great motor that people just don't give any credit to...

_Quote, originally posted by *MkIIRoc* »_
And I saw someone post in the other thread that a NA motor can't hit 100% VE. I disagree. VERY much so.


Agreed. It is possible to tune a naturally aspirated engine to be more than 100% VE within a certain RPM band. http://****************.com/smile/emthup.gif 
Mike.


_Modified by Jettaboy1884 at 1:03 AM 10-31-2008_


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## VWralley (Mar 30, 2002)

*Re: Let's talk about making Naturally Aspirated horsepower (Jettaboy1884)*

NA 8v's pretty much cost a million dollars to make what a stock 16v with good management will make, thats why that argument pops up all the time.
8v's do have their place, and its in racing where rules dictate stock engines, with update/backdate rules in place most can go to the 1.8 in all early dubs in most cases...
it basically takes a stout bottom end (forged rods, pistons, hardware, lightening/balancing) and a heavily ported and cam'd head. the further you push the envelope the less life the engine will have. the lighter the bottom, the more wear on the bearings etc...
as stated, 130whp ish is about the most you are going to get out of a built up 8v. you can do alot more to them, but it pretty much makes them un-streetable on a daily basis.


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## Diggatron (Sep 4, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (VWralley)*


_Quote, originally posted by *VWralley* »_
as stated, 130whp ish is about the most you are going to get out of a built up 8v. you can do alot more to them, but it pretty much makes them un-streetable on a daily basis. 

....You've just given me the impetus to go further. 
I just have a really hard time wrapping my head around the "fact" that a VW 8v can only do 130. I'm not calling you out and saying that you are wrong, I just want to try it out for myself. Has anyone REALLY pulled out all of the stops and recorded a result (Dyno)?


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## Jettaboy1884 (Jan 20, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (Diggatron)*


_Quote, originally posted by *Diggatron* »_
....You've just given me the impetus to go further. 
I just have a really hard time wrapping my head around the "fact" that a VW 8v can only do 130. I'm not calling you out and saying that you are wrong, I just want to try it out for myself. Has anyone REALLY pulled out all of the stops and recorded a result (Dyno)?

Honestly, I also think the 8v can do a lot better. I think that 99% of people just toss them to the side and take the easier route by going with a motor that has more power allready. (I don't have anything against doing that, but I feel that sometimes it's more fun to take the road less travelled)
Does anyone have any specs on Collins' 8v Rabbit motor? IIRC, it was running stock CIS injection, and had all internal mods...


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## VWralley (Mar 30, 2002)

*Re: Let's talk about making Naturally Aspirated horsepower (Diggatron)*

do eet! there is def more to be made no doubt. im speaking only by what i have seen and experiance. my roomate has a race car with a wicked 8v, its by far the most built one i have ever come across and it made 136whp on a mustang dyno (read low supposidly) on an un-tuned carb setup. 
his setup is essentially what i mentioned above, he is going to fuel injection and ITB's when the $$ is there as well as going w/ a smaller dia valve stem and a few other mods to the head. the road race car i crew for is making 148whp out of a 1.8 16v bottom with a worked 8v head on MS and race gas...
roomates race car


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## Northern RD (Mar 16, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (VWralley)*

For Gawd sake, please DON`T put a 4bbl on it, like the mentioned in the carb column,...


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## Holden McNeil (Jul 26, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (VWralley)*


_Quote, originally posted by *VWralley* »_
roomates race car









I really love this picture and have stared at it in the past for quite some time.... he's doing some neat things like redundant ignitions, Miata alternator (looks like one) with a tooth'd pulley and run off the timing belt, the electric water pump, etc... http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif Very cool


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## VWralley (Mar 30, 2002)

*Re: Let's talk about making Naturally Aspirated horsepower (Holden McNeil)*

he is my teacher of pretty much everything VW







dudes got some awesome ideas and knows how to squeeze every micro hp out of motors....epjetta is his SN on here if anyone wants to ask him specific ?'s about his setup








i get to drive that car from time to time...it is freakin insane, i love it


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## Diggatron (Sep 4, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (Jettaboy1884)*


_Quote, originally posted by *Jettaboy1884* »_
Honestly, I also think the 8v can do a lot better. I think that 99% of people just toss them to the side and take the easier route by going with a motor that has more power allready. (I don't have anything against doing that, but I feel that sometimes it's more fun to take the road less travelled)
Does anyone have any specs on Collins' 8v Rabbit motor? IIRC, it was running stock CIS injection, and had all internal mods...

I had Collin's specs located at one point, but can't seem to find them in this labrynth I call a computer.
I guess that I look at this 8v thing a bit different than some. I am a dubber from back when the 8v was all that we had, the 16v was too expensive, and the G60 was a wet dream







I hate the thought of tossing an engine to the side, I'd much rather work with what I got. I tend to agree with the statements that you and Andrew S. have already made..............let the games begin! http://****************.com/smile/emthup.gif


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## MkIIRoc (Feb 20, 2005)

I talked to collin a few weeks ago. From what I gathered, they threw carbs on it later on and went faster than the 12.8 on CIS. Don't know why they don't advertise those times.
What made that car fast was the fact it weighed around 1400 lbs w/o driver, and a highly worked 8v. I think better times could have been had out of the CIS setup. I would like to have seen the timeslip. I don't know how good of a driver he was.
Kossob never dynoed his rabbit, but to put down a 12.2, it had to have around 200 at the crank.


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## Diggatron (Sep 4, 2004)

*Re: (MkIIRoc)*

Talking about the same topic from two different angles, on two different Vortex threads is driving my A.D.D. over the brink!


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## stntman (Sep 19, 2002)

*Re: (Diggatron)*

I am having a hard time believing that 130 is about the top of the line for a daily. 
My mkII has a basemap with its MSnS andit has a RV/ABA set-up in it.
Its at 121whp and 118ftlbs.
I would like to imagine that with some tunining and a few other goodies that 150whp is an opptomistic goal. 
May justbe me but I agree with what people are saying, people get discouraged about their 8v and give into other swaps that already have more power.


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## Jettaboy1884 (Jan 20, 2004)

*Re: (stntman)*


_Quote, originally posted by *stntman* »_
May justbe me but I agree with what people are saying, people get discouraged about their 8v and give into other swaps that already have more power.

Yup. The other swaps are fairly easy, so people see quick gains for little effort. I don't have a problem with that, I just hate to see a good motor get no recognition.

_Quote, originally posted by *Diggatron* »_Talking about the same topic from two different angles, on two different Vortex threads is driving my A.D.D. over the brink!









The other thread has gotten very interesting the past couple days, with some great discussion of cranks, rods and pistons. http://****************.com/smile/emthup.gif


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## jerrymic (Apr 19, 2007)

*Re: (Jettaboy1884)*

a friend has a 78 scirocco with a 1.8... dual carbs and a 288 cam and is laying down 141 whp...


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## Diggatron (Sep 4, 2004)

*Re: (jerrymic)*


_Quote, originally posted by *jerrymic* »_a friend has a 78 scirocco with a 1.8... dual carbs and a 288 cam and is laying down 141 whp...

Headwork?


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## MkIIRoc (Feb 20, 2005)

stock 1.6 small valve!
haha
I put down a [email protected] mph yesterday. 12's are an impenetrable wall








I'm in the middle of buying some lash caps to shim up my 340*, .560" lift cam. I think I'm going to get it dynoed this winter during the off season just to see what it puts down.


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## jerrymic (Apr 19, 2007)

*Re: (Diggatron)*

ported/polished and decked a bit... set to -4* 
he has to slip the clutch a bit if stopped on a hill but its his daily driver...


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## ny_fam (Apr 3, 2004)

*Re: (MkIIRoc)*


_Quote, originally posted by *MkIIRoc* »_stock 1.6 small valve!
haha
I put down a [email protected] mph yesterday. 12's are an impenetrable wall










Waite - your saying that your race scirocco has a stock 1.6 small valve head?


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## eurotrashrabbit (Oct 25, 2001)

*Re: Let's talk about making Naturally Aspirated horsepower (Jettaboy1884)*

I just want to say that comparing dyno #'s are pretty much pointless unless you are testing all the same vehicles on the same dyno in the same conditions. Not all dynos are the same. Dynos are good for making adjustments and comparison to acheive maximum power







That is just my uneducated opinion with out any facts to substatiate it


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## Wraith04 (Jun 24, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (eurotrashrabbit)*

Actually we need to quantify this experiment with crank hp or wheel hp. Easier to achieve consistent results and not play the "which dyno did you use" game. And of course altitude needs to be accounted for.


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## MkIIRoc (Feb 20, 2005)

no they asked about the 78 above me. I was just making a joke


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## Jettaboy1884 (Jan 20, 2004)

*Re: (MkIIRoc)*

Bump this back up...
So in the other thread, we're talking about setting up an Oversquare engine that has a larger bore than stroke... The problem with running a short stroke and large bore in a VW engine is that you end up with a lot of room above the piston when it's at TDC. We've talked about running longer rods, and decking the engine block to make up for this space...
So, I wanted to know if anyone has tried this:
ABA block at stock 82.5mm bore
2.0L 16v pistons at 82.5mm 
ABA Rods (I don't know the length)
1.6L crank at 80mm
This would create an Oversquare setup (bore larger than stroke) and the 16v pistons would help raise the compression back up while not having to deck the block/head a whole lot.
Anyone have any thoughts on this? Would everything bolt together?


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## Diggatron (Sep 4, 2004)

*Re: (Jettaboy1884)*


_Quote, originally posted by *Jettaboy1884* »_
ABA Rods (I don't know the length)


159mm


_Modified by Diggatron at 5:31 PM 10-22-2007_


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## Jettaboy1884 (Jan 20, 2004)

*Re: (Diggatron)*

Thanks http://****************.com/smile/emthup.gif


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## setaus (Apr 29, 2006)

*Re: (Jettaboy1884)*

Decreasing displacement will not gain you power, and you will lose torque. In fact you are likely to lose power by doing this because of the frictional losses at the higher engine speeds required to pump the same amount of air. The only reason you would decrease the stroke is to move to (or stay in) a lower displacement class. Squaring up an engine by increasing the bore is good, and you are gaining displacement too. Squaring it up by decreasing stroke is bad unless specific output is your goal.
That said, I am still interested to know if someone has done this to see the results.

_Quote, originally posted by *Jettaboy1884* »_Bump this back up...
So in the other thread, we're talking about setting up an Oversquare engine that has a larger bore than stroke... The problem with running a short stroke and large bore in a VW engine is that you end up with a lot of room above the piston when it's at TDC. We've talked about running longer rods, and decking the engine block to make up for this space...


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## chois (May 12, 2000)

There is some tradeoff of mass for the components as well. When you build the bottom end light and well balanced, and spin it to 9, the short stroke 1.5 (basically a 1.6 with a short crank) does pretty well, with stock dia valves and stock TB. As noted this pays off in racing due to weight breaks or class changes. In the end there ain't no replacement for displacement, but you can minmize the gap by turning it faster.
Honestly, there is more to be had in doing a true full build on these motors than people realize. By that I mean rebore for next size piston (with a torque plate) to be sure all is straight and tight, new pistons, rings (cast/malleable iron), blueprint/balance rotating assy-pistons-rods, small compression bump, proper tuning. Do all these little things - even the oft questioned underdrive pullys, and it adds up. To the tune of 15-20% improvement with stock intake, cam, head on a 1.8.


_Modified by chois at 8:46 PM 10-22-2007_


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## Mk2doorgolf (Aug 17, 2007)

*Re: (chois)*

I love my 8v its running CIS and it seems pretty reliable but damn coming out of a durango and driving my 58 beetle with the stock 36 horse and then into my 8v its like the best of both works its peppy and fast and it gets damn good gas mileage No complaints here ****a 16v for now


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## Jettaboy1884 (Jan 20, 2004)

*Re: (Mk2doorgolf)*

I just found this article that I saved on my computer a while back. It may be hellpful, although old...








































Mike.


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## JUS_GT_EYEZ (Nov 12, 2001)

*Re: Let's talk about making Naturally Aspirated horsepower (Holden McNeil)*


_Quote, originally posted by *Holden McNeil* »_
I really love this picture and have stared at it in the past for quite some time.... he's doing some neat things like redundant ignitions, Miata alternator (looks like one) with a tooth'd pulley and run off the timing belt, the electric water pump, etc... http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif Very cool









i was just staring at that pic too.. hmm miata alternator? got me thinking... http://****************.com/smile/emthup.gif


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## Jettaboy1884 (Jan 20, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (JUS_GT_EYEZ)*

Can anyone tell me how much a 1.8L block can be bored out to? Could you fit ABA pistons (82.5mm) in a bored 1.8L?


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## Diggatron (Sep 4, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (Jettaboy1884)*


_Quote, originally posted by *Jettaboy1884* »_Can anyone tell me how much a 1.8L block can be bored out to? Could you fit ABA pistons (82.5mm) in a bored 1.8L?

Yes, the will fit. IIRC, you can fit up to an 83.5mm piston in a 1.8 block.


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## Jettaboy1884 (Jan 20, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (Diggatron)*


_Quote, originally posted by *Diggatron* »_
Yes, the will fit. IIRC, you can fit up to an 83.5mm piston in a 1.8 block.

Thank You,
So I've decided that I want to try and build a high revving bottom end using the following OEM parts. I have two different Bottom ends in mind:
1.
1.8L block, bored to fit 82.5mm ABA pistons
1.6L Crankshaft and Connecting rods. (Lighten and balance crank - Shot Peen and balance rods)
I have an ABA and a 1.8L 16v block laying around. So I can use the ABA pistons, and the 16v block. All I would need is the 1.6 crank/rods 
2.
1.7L block bored to fit 81.0mm pistons (or a refreshed 1.8L block)
1.8L 16v pistons (they would raise the compression ratio back up after using a 1.6L crank/connecting rods)
1.6L crank/rods balanced, etc.
I would top it off with a 1.8L JH head, P&P, HD springs, etc.
So, can anyone help me figure out the compression ratio for the above motors? I figure the 1.8L 16v pistons would give a higher compression ratio than the ABA pistons, but on the other hand, the ABA pistons would increase displacement by a little bit. Both setups would provide for an oversquare bottom end. 80mm stroke with either 81mm or 82.5mm pistons.
Can anyone offer suggestions/comments on either setup above?
Thanks,
Mike.


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## chois (May 12, 2000)

*Re: Let's talk about making Naturally Aspirated horsepower (JUS_GT_EYEZ)*


_Quote, originally posted by *JUS_GT_EYEZ* »_
i was just staring at that pic too.. hmm miata alternator? got me thinking... http://****************.com/smile/emthup.gif 

We have run Toyota alternators on 8v cars as well.


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## chois (May 12, 2000)

*Re: Let's talk about making Naturally Aspirated horsepower (Holden McNeil)*


_Quote, originally posted by *Holden McNeil* »_
I really love this picture and have stared at it in the past for quite some time.... he's doing some neat things like redundant ignitions, Miata alternator (looks like one) with a tooth'd pulley and run off the timing belt, the electric water pump, etc... http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif Very cool









I don't see any redundant ignition. He is running two coil packs, each firing two cylinders, and fires each one wiith an ignition module. http://****************.com/smile/emthup.gif 
Not sure I would EVER want something else running off my timing belt. Why introduce another potential failure point to a critical system?








The electric water pump is a good idea http://****************.com/smile/emthup.gif


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## Jettaboy1884 (Jan 20, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (chois)*


_Quote, originally posted by *chois* »_
I don't see any redundant ignition. He is running two coil packs, each firing two cylinders, and fires each one wiith an ignition module. http://****************.com/smile/emthup.gif 

He may be reffering to the fact that there are two Ignition control Modules (?) in the raintray.

_Quote, originally posted by *Jettaboy1884* »_
1.
1.8L block, bored to fit 82.5mm ABA pistons
1.6L Crankshaft and Connecting rods. (Lighten and balance crank - Shot Peen and balance rods)
I have an ABA and a 1.8L 16v block laying around. So I can use the ABA pistons, and the 16v block. All I would need is the 1.6 crank/rods 
2.
1.7L block bored to fit 81.0mm pistons (or a refreshed 1.8L block)
1.8L 16v pistons (they would raise the compression ratio back up after using a 1.6L crank/connecting rods)
1.6L crank/rods balanced, etc.


Could anyone tell me if either of the above motors would or would not work? 
My buddy and I were talking today, and we're pretty sure that both motors would require custom rods... I'd like to stick with OEM parts for cost sakes...


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## chois (May 12, 2000)

The ignition modules are each firing one of the ignition coils. They are not redundant because they are firing different cylinders.
Our engine builder feels comfortable taking a 1.8 up to 9k. We may end up doing this next year, depending on how some rule changes fall out.


_Modified by chois at 12:24 PM 11-1-2007_


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## Jettaboy1884 (Jan 20, 2004)

*Re: (chois)*


_Quote, originally posted by *chois* »_
Our engine builder feels comfortable taking a 1.8 up to 9k. We may end up doing this next year, depending on how some rule changes fall out.


Cool. What specs?


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## chois (May 12, 2000)

Pretty much like the 1.5 is now. Lightened/balanced internals, lots of headwork, shim under bucket lifters, Ti retainers, might need Ti valves with the larger 1.8 valve size, custom cam, all the little details. The only real change is the bigger valves, and the crank (well the pistons and rods change, but not structurally), and the crank looks like it will handle the situation to us.


_Modified by chois at 2:38 PM 11-1-2007_


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## MkIIRoc (Feb 20, 2005)

*Re: (chois)*

I had my 8v dynoed last week. 144 whp on a really bad tune, as evident by the A/F plot. I got my new webers in, and I'm going to hit the dyno again with these 45's. More 8v powah to come.


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## JW-VW (Feb 13, 2003)

*Re: (MkIIRoc)*

Counterflow or cross flow head? Any pics of the engine? -Jacob-


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## MkIIRoc (Feb 20, 2005)

*Re: (JW-VW)*

counterflow


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## Diggatron (Sep 4, 2004)

*Re: (MkIIRoc)*

......is that valvecover any indication of what lies beneath?







http://****************.com/smile/emthup.gif


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## Jettaboy1884 (Jan 20, 2004)

*Re: (Diggatron)*

I dunno, but It's pretty cool that a Seat can run without the spark plug wires hooked up. Maybe that's why you had a bad air/fuel ratio!


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## ABA Scirocco (May 30, 2001)

*Re: Let's talk about making Naturally Aspirated horsepower (MkIIRoc)*


_Quote, originally posted by *MkIIRoc* »_
And I saw someone post in the other thread that a NA motor can't hit 100% VE. I disagree. VERY much so.



_Quote, originally posted by *Jettaboy1884* »_
Read some of the articles that I posted. Specifically the Intake tuning article from GrapeApeRacing, and the article about exhaust system design. Both articles state that it is possible to tune a naturally aspirated engine to be more than 100% VE within a certain RPM band. 

You are both correct, to put that in perspective, 100% VE on a 2.0L @ 7000rpm would corresponds to somewhere in the neighbourhood of 175hp at the crank. Admittedly, it's not easy to get ther with an 8v but I've personally seen it done a few times and have reliable second hand reports of several others.


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## MkIIRoc (Feb 20, 2005)

*Re: (Diggatron)*

Nah, it just looks cool.
Wrinkly valve covers are intimidating


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## stereosubstance (Apr 11, 2006)

im glad to see that chois went the extra lenth to do the suspension right as well. i assume its not your daily? it brings a tear of joy to my eye to see so many VW lovers actually know what there doing. now i only wish i had the money to do this stuff to my jetta


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## 1badimport (Aug 27, 2006)

*Re: (stereosubstance)*

i built an a2 gti about 2 years ago with an 11.5-1 forged piston bottom end ,scat rods a counter flow head flowing in the low 180cfm @28 range and a tt 276 cam it made 145 whp on a dyno jet off the bottle and 262 whp with the nos dual intake fogger 
the car was a streeter and weighed in at 2400 lbs or so and only went 15.2 -14.9 on motor and went 12.9 on the bottle on a drag radial ..
the more displacement the better it had 83.5 mm pistons and crappy stock digi management with a 300z mass air meter ..i had to lose tye origional digi mass air meeter it sucked ..and tt burned me a no revlimiter chip ,it had a full lenth race header tt jet hot caoted and 2 1/2 " exaust ....ill post a pic ..
pic 








motor on the stand 

















_Modified by 1badimport at 4:17 PM 11-3-2007_


_Modified by 1badimport at 4:20 PM 11-3-2007_


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## Jettaboy1884 (Jan 20, 2004)

*Re: (1badimport)*


_Quote, originally posted by *1badimport* »_...a counter flow head flowing in the low 180cfm @28 range and a tt 276 cam it made 145 whp on a dyno jet off the bottle and 262 whp with the nos dual intake fogger ... and crappy stock digi management with a 300z mass air meter 

That's pretty cool that you ran Nitrous. Most VW people shy away from nitrous, even though it is a very legitimate power-adder. I suppose it's becuase it has a "street racer" or "*****" stigma...








It looks like you got rid of the Digi setup (the pic of the motor in the stand) How is it doing now that you're not running Digi?
Your car looks great in all other respects. It's nice to see people still running built 8v's http://****************.com/smile/emthup.gif


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## ramdmc (Jul 25, 2005)

*A good example of 8V power*

Just found this cruising ebay.de and thought of this thread. 
http://cgi.ebay.ca/ws/eBayISAP...:1123
218hp from a 1945 counterflow 8v, not too shabby








ghah, wish I had 2500 euro
RC


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## Jettaboy1884 (Jan 20, 2004)

*Re: A good example of 8V power (ramdmc)*


_Quote, originally posted by *ramdmc* »_Just found this cruising ebay.de and thought of this thread. 
218hp from a 1945 counterflow 8v, not too shabby








RC

Man, that's awesome. Thanks for the link. I'd love to see the real specs on that motor to see how it makes so much power!
On that note:
It looks like he had a 3 year old draw the dyno plot with a pen:


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## 1badimport (Aug 27, 2006)

i wound up running the digi set up it worked out better for me .
i have a v8 sbc race car that i run spray on and ive had tons of cars in the past with the bottle it was cheap and easy ..
the old turbo dubs reqired more tuning and are way more expensive ..not a good option w/o stand alone


----------



## Jettaboy1884 (Jan 20, 2004)

*Re: (1badimport)*

Bump.
Here's another good thread:
http://forums.vwvortex.com/zerothread?id=3536643


----------



## Diggatron (Sep 4, 2004)

*Re: (Jettaboy1884)*

Sorry for the hiatus, guys.........I just had another child! Well, I didn't, I just sat back and watched the doctors take it out.........anyway......
has this been broached?: An Audi 3A with the Cross-flow head? Gimme your thoughts...........


----------



## Jettaboy1884 (Jan 20, 2004)

*Re: (Diggatron)*


_Quote, originally posted by *Diggatron* »_Sorry for the hiatus, guys.........I just had another child! Well, I didn't, I just sat back and watched the doctors take it out.........anyway......
has this been broached?: An Audi 3A with the Cross-flow head? Gimme your thoughts...........

Awesome! Congratulations!
As for a crossflow 3A: Why crossflow? IIRC, the crossflow head only flows better than a counterflow because it has thinner valvestems. I also believe the crossflow head will lower the compression ratio a little when compared to a counterflow.
Don't get me wrong, I like the crossflow; especially for ease of maintenance, and how much more room it makes for a turbo setup...


----------



## ABA Scirocco (May 30, 2001)

*Re: (Jettaboy1884)*

The crossflow is nicer for carbs too, there's more up front and they're away from the heat of the exhaust.


----------



## Diggatron (Sep 4, 2004)

*Re: (Jettaboy1884)*


_Quote, originally posted by *Jettaboy1884* »_
Awesome! Congratulations!
As for a crossflow 3A: Why crossflow? IIRC, the crossflow head only flows better than a counterflow because it has thinner valvestems. I also believe the crossflow head will lower the compression ratio a little when compared to a counterflow.
Don't get me wrong, I like the crossflow; especially for ease of maintenance, and how much more room it makes for a turbo setup...

I suppose I just have an affinity towards heads that don't eat-n-crap on the same side








Of course, at this stage in the game, compression issues can be solved very easily (i.e. pistons). I am unsure of what the maximum piston is that can be put into that block, but it may also prove to be a good basis for our "over-square" project. Maybe, de-stroke it to a 1.9....add the largest piston, and let 'er rip...........


----------



## Jettaboy1884 (Jan 20, 2004)

*Re: (Diggatron)*

I posted this question in the other thread, so I want to try it in here as well:
Boost gauges typically show a vaccum reading. Is there any potential in using a vaccum gauge to see at what RPM your engine is pulling air most efficiently? For example: I would think that when the intake tract is supplying the perfect amount of air to each cylinder, the vaccum in the intake would be very low... Is this true?
I would think that with an intake setup using a plenum, you could put a vaccum gauge in every runner and find out how effectively the air is distributed under actual conditions. On the other hand, I don't see how this can be useful for tuning unless you can constantly remove the head and intake to tune them...
Mike.


----------



## Holden McNeil (Jul 26, 2004)

*Re: (Jettaboy1884)*

Mike - Here is a rather inexpensive Autometer Vaccum Gauge - I'm sure you could use one of the existing ports on the intake as your hook up...
http://www.egauges.com/vdo_ind...-4384


----------



## MkIIRoc (Feb 20, 2005)

*Re: (Jettaboy1884)*

No. Under WOT, there should be none to next to none intake manifold vacuum sensed. If there is, you have restrictions up stream, toward the throttle body. Once you close the throttle, and the engine is trying to pull the same volume of air in, but is limited by the throttle plate, you now have a high vacuum area.


----------



## Jettaboy1884 (Jan 20, 2004)

*Re: (MkIIRoc)*


_Quote, originally posted by *MkIIRoc* »_No. Under WOT, there should be none to next to none intake manifold vacuum sensed. If there is, you have restrictions up stream, toward the throttle body. Once you close the throttle, and the engine is trying to pull the same volume of air in, but is limited by the throttle plate, you now have a high vacuum area.

Ok, that is what I was thinking. However, just for clarification: In my head, I envision the vaccum sensors for each gauge placed as close to the intake valve 
as possible, (like somewhere near the fuel injectors) so that they could measure the vaccum for each intake runner 
(By doing this, one could tell if one port is getting more air than another.) My idea is that if the engine is not flowing air efficiently, 
the Vaccum gauge will show at what RPM's there is resistance in the intake manifold/plenum/tract...

I have another question:
What are the steps for determining the length of the intake runners for Helmholtz and resonation tuning:
I would think that the best way to go about doing this would be to first port & polish the cylinder head and determine the peak CFM. 
Then, Given the displacement of the motor, figure out at what RPM the motor sucking in that quantity of air. 
*Given no other losses in the intake tract, Would this be the point where the motor can reach 100% Volumetric Efficiency?*
I would assume that as as the RPM's demand more CFM than the head can flow, the motor will quickly drop from 100% Volumetric Efficiency...
So now I wonder: Is this the peak RPM that you'd want to single out for Helmholtz tuning, since the motor should theoretically be at 100% VE at this point? 
If not, How do you determine what RPM to tune the intake and exhaust tract for optimal pulse tuning and scavenging?
Thanks,
Mike.

Edited to make it easier to read.


_Modified by Jettaboy1884 at 8:23 PM 12-3-2007_


----------



## eurotrashrabbit (Oct 25, 2001)

*Re: (Jettaboy1884)*

Throttle bodies and carbs are your friend


























_Modified by eurotrashrabbit at 11:03 PM 12-3-2007_


----------



## Jettaboy1884 (Jan 20, 2004)

*Re: (eurotrashrabbit)*


_Quote, originally posted by *eurotrashrabbit* »_Throttle bodies and carbs are your friend










From what I've read, I have to wonder though: Isn't it better to run a plenum type intake, so that one can utilize resonance and helmholtz tuning? I understand that you can use different velocity stacks to resonance tune the individual runners, but beyond the stacks, there is open air, and no plenum to contain the pulses...
On the other hand, maybe it is possible to get the best of both worlds.
By using ITB's in the runner, and drawing air thru a plenum and intake tube, at full throttle the entire intake will be not be much different than if one were to use a single throttle body feeding a plenum/runners...
Yay/Nay?


----------



## eurotrashrabbit (Oct 25, 2001)

*Re: (Jettaboy1884)*

That is what most air boxes do for throttle bodies or carbs. They are a closed type box. All I know is my car is fun to drive.


----------



## VWralley (Mar 30, 2002)

*Re: (Jettaboy1884)*


_Quote, originally posted by *Jettaboy1884* »_
Yay/Nay?

either, both will make damn near the same horsepower


----------



## Diggatron (Sep 4, 2004)

*Re: (Jettaboy1884)*


_Quote, originally posted by *Jettaboy1884* »_
From what I've read, I have to wonder though: Isn't it better to run a plenum type intake, so that one can utilize resonance and helmholtz tuning? I understand that you can use different velocity stacks to resonance tune the individual runners, but beyond the stacks, there is open air, and no plenum to contain the pulses...
On the other hand, maybe it is possible to get the best of both worlds.
By using ITB's in the runner, and drawing air thru a plenum and intake tube, at full throttle the entire intake will be not be much different than if one were to use a single throttle body feeding a plenum/runners...
Yay/Nay?

Please remember the fact that we are looking into large cams on this build and (according to Collin at TT) carbs/ITB's are gonna be more idle friendly (than a plenum) when it comes to larger cams. I, for one, think that the plenum will provide yet another restriction to max hp in this case. No scientific proof, just my .02.


----------



## ABA Scirocco (May 30, 2001)

*Re: (Diggatron)*

Very good power can be made with a plenum even with really big cams but the plenum adds an extra variable so getting the set-up right is a lot tougher. Setting up a carb with a plenum is completely different than it is with individual runners. Varying the plenum size will effect the performance characteristics of the engine, matching that to the characteristics of the cam etc. can require a fair bit of experimentation. Most people don't have the time, knowledge or resources to really make a plenum set-up work for their application, individual runners are much easier.


----------



## set_au2 (Jun 12, 2007)

*Re: (ABA Scirocco)*

I agree. Plenums add a whole lot of extra tunable parameters to the mix, making a consistent torque curve more difficult to achieve. Even changing the inlet duct length will move a very strong, narrow peak around the RPM band - I've experimented with this.
ITBs or carbs with what is effectively an infinite plenum (even a large air shroud falls into this category) will ultimately generate more power than a single TB plenum arrangement with a typical plenum volume. Of course you could max out the plenum volume with a single TB to achieve the same ultimate power but throttle response would be terrible.


----------



## ABA Scirocco (May 30, 2001)

*Re: (set_au2)*

I can across THIS Excel spreadsheet (right click Save As), a few minutes ago, I haven't had much time to look at it yet but it seems pretty cool and relates directly to some of the stuff talked about in this thread.


----------



## tdogg74 (Mar 1, 2002)

*Re: (ABA Scirocco)*


_Quote, originally posted by *ABA Scirocco* »_I can across THIS Excel spreadsheet (right click Save As), a few minutes ago, I haven't had much time to look at it yet but it seems pretty cool and relates directly to some of the stuff talked about in this thread.

WHOA!!!







That spread sheet is amazing!


----------



## Jettaboy1884 (Jan 20, 2004)

*Re: (tdogg74)*


_Quote, originally posted by *tdogg74* »_
WHOA!!!







That spread sheet is amazing!


Going to have to download that on my work PC... No excel on my home computer.
This gives me a reason to look forward to work tomorrow!


----------



## pwnt by pat (Oct 21, 2005)

*Re: (Jettaboy1884)*

spreadsheet is down.
anyone have a copy?


----------



## ABA Scirocco (May 30, 2001)

*Re: (pwnt by pat)*

The author of that spreadsheet has a lousy server very limited bandwidth, try again later, I do know however, he plans to copy to somewhere better.


----------



## ny_fam (Apr 3, 2004)

*Re: (Jettaboy1884)*

If you don't have MS excel just down load the free office software
openoffice.org 
http://www.openoffice.org
it can read and work with MS office files, worked for me.


----------



## ny_fam (Apr 3, 2004)

*Re: (ny_fam)*

Another good reference site:
http://www.ftlracing.com/tech/engine/intake.html

_Quote, originally posted by *ny_fam* »_Throttle Body
The size of throttle body effects engine response and peak hp. Here are some simple rules.
Large cross-sectional area increases throttle response.
Large cross-sectional area increased high rpm torque.
Small cross-sectional area decreased throttle response.
Large cross-sectional area increased low rpm torque.
Note: that “required” cross-sectional area is Dependant on HP. 
The following equation is a good rule of thumb for throttle body diameter (~ +/- 5%)

D (“) = sqrt[(WHP x 4)/(AP x CR)]
sqrt = square root
D = diameter of throttle body (single)
WHP = wheel horse power
AP = Atmospheric Pressure (14psi)
CR = Engine compression ratio
Cross Sectional Area = 3.14 x (D/2) 

(150WHP x 4)/( 14 x 9.5) = 600/133 = sqrt (4.51) = 2.12" Diameter single plate throttle body


----------



## Jettaboy1884 (Jan 20, 2004)

*Re: (ny_fam)*


_Quote, originally posted by *ny_fam* »_Another good reference site:
http://www.ftlracing.com/tech/engine/intake.html

(150WHP x 4)/( 14 x 9.5) = 600/133 = sqrt (4.51) = 2.12" Diameter single plate throttle body









Well, that is pretty interesting. I would consider a 2.12" throttle body (about 54mm) to be very small. Is engine RPM not important when sizing the throttle body? 
That's a nice brief writeup as well. Lots of formulas in there that I will have to go back and figure out how to use. 
Thanks! http://****************.com/smile/emthup.gif 
On a side note: My wife got me an early Christmas present. I've been blabbering on and on for a year or so about how cool Taurus SHO motors are... So last night, we went up to Connecticut and picked up a '91 SHO with 160k miles... It needs a clutch, and I'll be taking the motor out to do the 60k maintenance... I'm super excited! 


_Modified by Jettaboy1884 at 10:12 PM 12-15-2007_


----------



## ABA Scirocco (May 30, 2001)

*Re: (Jettaboy1884)*


_Quote, originally posted by *Jettaboy1884* »_
Is engine RPM not important when sizing the throttle body? 

No, it's power output that's the key factor. For a well tuned engine, it takes more or less the the same amount of fuel flow to make a given amount power whether it's being made at 3000 rpm or 8000 rpm and in either case, it takes more or less the same amount of air to burn that fuel. 
BTW, I was recently looking at the specs for VW new F3 race engine, it's breathing through a 26mm restrictor and makes peak power of 210hp @5800 rpm, I know it's sort of comparing apples and oranges but by that standard, 2.12" or 53.8mm is huge.


----------



## Jettaboy1884 (Jan 20, 2004)

*Re: (ABA Scirocco)*

That's a good point. I've always wondered if it is necessary to go with a huge throttle body, as a lot of people seem to do... I guess that is not always a good thing. 

So, this isn't related to 8v's, but I think it's worth cross-posting from the thread in the Fabrication forum:
To follow-up my last post, I was lurking in an SHO forum that I like, and came across this very cool thread:
http://www.shoforum.com/showthread.php?t=83786
In the thread are a lot of links to Patent pages regarding intake manifolds with variable runners, or variable plenum volume... One of the patent pages has links to a lot of other similar patents.
Have a look, and check out the other patents listed along the lower-left side. Check out the drawings -> Definitely some very interesting stuff. http://****************.com/smile/emthup.gif 
http://www.google.com/patents?...90464


----------



## ny_fam (Apr 3, 2004)

*Re: (Jettaboy1884)*

Yea when I grow up I want to build and race formula cars








Some of older 1.8 Super Vee rabbit engine powered cars made 235 HP.
The current F3 rules most be quite restrictive.
Great article on the super vee history
http://www.grmotorsports.com/b...e.php


----------



## ABA Scirocco (May 30, 2001)

*Re: (ny_fam)*

Here are the rules that I'm aware of, the F3 engine must be based on a stock block and head with a minimum production of 2500, no titanium rods or valves, no variable valve timing or variable runner length or plenum volume, a maximum displacement of 2000cc (the VW F3 is 1997cc), 102 octane fuel bosch Motronic 3.1 management, a limited array of engine sensors, no radio telemetry and the real kick, the air box must breathe through a 26mm restrictor, 3mm thick.


----------



## ny_fam (Apr 3, 2004)

*Re: (ABA Scirocco)*

Do you have a link to the specs for the F3 engine?
2 valve engine? What type of head work is allowed?
Depending on if diffusers on either side of the restriction are allowed you can get quite a bit more air through a small hole that way. Google SAE intake and you'll see lots of them. think SAE teams have a 20mm restriction to deal with. My snow blower has a 20mm intake








SV rules were 40MM valves, (not sure about if 8mm stems were spec'ed)
1.8.
I've had a SV head in my shop for testing. Sweet stuff. few pictures on my site.
http://scientificrabbit.com/in...mid=1


----------



## ABA Scirocco (May 30, 2001)

*Re: (ny_fam)*

They're 16v engines, I've been trying to figure out exactly which production engine it's based on. Click Here for more details.
BTW, This used to be a Brabham super vee head.


----------



## ny_fam (Apr 3, 2004)

*Re: (ABA Scirocco)*

Here are some specs
http://www.volkswagen-motorspo...=1369
This is what gets delivered 210hp, but with team modifications I bet they go up from there,
The SV head I had, looked like the valves went where they were not intended to be. But it was fixable.


----------



## Jettaboy1884 (Jan 20, 2004)

*Re: (ny_fam)*

Bump...
I was reading recently about using a degree wheel to check the timing of all the components. It is quite interesting to know that some parts such as cams can be timed quite inaccurately from the factory or aftermarket tuning companies...
My wife got me some books for Christmas. One of them is "How to get horsepower out of any engine" by David Vizard. Although more oriented towards V8's it has some good info in it...
Between all the day-to-day stuff in life, I always find myself looking to learn more about engines. I can't get enough!


----------



## ny_fam (Apr 3, 2004)

*Re: (Jettaboy1884)*

David Vizard has done some very good work over the years. Including a 175 CFM VW 1.6 counter flow big valve head work for the street, that I've modeled my head porting work after. Its seems that the books that have the secrets are in the books that cost like $800.


----------



## Jettaboy1884 (Jan 20, 2004)

*Re: (ny_fam)*


_Quote, originally posted by *ny_fam* »_ David Vizard has done some very good work over the years. Including a 175 CFM VW 1.6 counter flow big valve head work for the street, that I've modeled my head porting work after. Its seems that the books that have the secrets are in the books that cost like $800. 


I recently stumbled upon Vizard's writings and have since been on the lookout for anything written by him, as he seems to be very knowledgable and well-spoken on engines of all types...
I'd be interested in learning more about that 1.6L motor. I recently got a 1.6 motor that was supposedly built by Reeves Calloway. Now I understand why people say they rev so well -> with a 79.5mm bore and 80mm stroke, they are only VW motor that is nearly oversquare... 
I'm looking to use 1.8L pistons on 1.6L rods and crank to make an oversquare motor. Topped with a worked JH head, I would try to tune the intake so that it could flow enough to make power at high RPM.


_Modified by Jettaboy1884 at 1:16 PM 1-4-2008_


----------



## chois (May 12, 2000)

The 1.5 was available with a 79.5 bore x 73.4 stroke. People poo-poo the cast cranks, but it revs nicely.


----------



## ny_fam (Apr 3, 2004)

*Re: (Jettaboy1884)*

Most likely from the super vee days or IMSA Racing. I'd like to know more about the specs and racing from those days.
There was a thread on the ffp-motorsport.com a while back on these engines and what they can do in different race trims. Few good articles from Robert Collins. But can't find them on the net anymore. I have them in PDF. send me an PM if you want a copy.
Cheers


----------



## MkIIRoc (Feb 20, 2005)

http://www.not2fast.com/vw/stuff/collins.txt
Little biased, me thinks. But some good info!


----------



## ny_fam (Apr 3, 2004)

*Re: (MkIIRoc)*

Here is another good link
http://www.pumaracing.co.uk/ David Baker and Puma Race Engines
few references to the Golf 8v


----------



## 8valvinsleeper (Jul 13, 2007)

*Re: (ny_fam)*

An older guy brought his digi2 jetta motor into my machineshop to have some work done. IT was mostly stripped and was just the head and block separated with no pistons or anything in it. We honed the cylinders to make them smooth, did a SERIOUS port & polish job, shaved the head 0.035", converted to solid lifter, titanium valve retainers, big valve conversion and polished combustion chamber. He claimed that he was building a custom intake manifold with thick, short runners and a huge throttle body. We sent all the parts back to him and he says that he put everything together and he claims that he got 100bhp per litre at a different dyno. He claims 182 hp from a 1.8 N/A. But idk, he would have to flow 260cfm in order to achieve that and i honestly dont think we ported it out THAT MUCH. the porting job on my cylinder head right now is 170 cfm for the intake ports.


----------



## ny_fam (Apr 3, 2004)

*Re: (8valvinsleeper)*

Thats serious power for a 1.8 NA setup.
the general rule of thumb is 1.1 HP per 1 CFM in a 4 cylinder for a full race setup. So the head is flowing some where in the neighborhood of 170 CFM.
Depending on fueling,cam and compression ratio that could be 182 WHP. Its been done in the past.
Cheers


----------



## Jettaboy1884 (Jan 20, 2004)

*Re: (8valvinsleeper)*


_Quote, originally posted by *8valvinsleeper* »_... the porting job on my cylinder head right now is 170 cfm for the intake ports. 

Often overlooked, but equally as important is how much CFM the *exhaust* ports will flow. I've read that it is very hard to make 8v exhaust ports flow 80% of the intake ports CFM.

_Quote, originally posted by *ny_fam* »_...the general rule of thumb is 1.1 HP per 1 CFM in a 4 cylinder for a full race setup. So the head is flowing some where in the neighborhood of 170 CFM.
Depending on fueling,cam and compression ratio that could be 182 WHP. Its been done in the past.
Cheers

That's interesting to know. Does anyone know the CFM values for counterflow 8v's? From Stock, to modified, to the Eurospec? (I see that 8valvinsleeper is saying 170 CFM is achievable)
I know that in Brazil, they take 8v's very far by using alcohol injection. I'd be interested in learning a few things from them. http://****************.com/smile/emthup.gif


----------



## Jettaboy1884 (Jan 20, 2004)

*Re: (Jettaboy1884)*

Here are a few cutaway 8v heads that I had saved on my PC.
Could anyone suggest some improvements to the intake & exhaust ports, as well as the combustion chamber?
Thanks in advance.
This is a 8v Digifant head. It's important to note that a couple of the cuts are a bit off-center, so the port appears narrower than it really is:
Intake:
















Exhaust:

















Here are a few pics of a crossflow 8v (ABA):
Intake:
















Exhaust:
















And here are two more pictures of a counterflow 8v head:
Intake:








Exhaust:


----------



## BellCityDubber (Jun 13, 2007)

*Re: (Jettaboy1884)*

wicked thread.
full of good info.
I'm watching this.... http://****************.com/smile/emthup.gif


----------



## ny_fam (Apr 3, 2004)

*Re: (BellCityDubber)*

Anyone know how to figure out the acoustic length of a tube with bends in it? or should I say its effective length ?


----------



## Jettaboy1884 (Jan 20, 2004)

*Re: (ny_fam)*


_Quote, originally posted by *ny_fam* »_Anyone know how to figure out the acoustic length of a tube with bends in it? or should I say its effective length ?

That's an awesome question that I myself have wondered about...
My question is this: In a curved tube, do the waves actually follow the curve (meaning the outside edge of the wave would have to travel faster than the inside edge)? Or, do the waves bounce/reflect off of the runner wall, as it makes a turn, thus scattering the wave and decreasing the strength?
Mike.


----------



## set_au2 (Jun 12, 2007)

*Re: (Jettaboy1884)*

If the cross sectional area doesn't change and the bend radius is not very small then it is ok to treat it as a straight piece of pipe. Remember, it is common practis to not even take flow velocity into consideration when calculating acouostic wave tuning so the bend isn't likely to be the major factor in wave tuning errors.


----------



## ny_fam (Apr 3, 2004)

*Re: (Jettaboy1884)*

I read an article some place that said the wave will bounce and reflect if the radius of the bend less then 10 x the diameter of the tube.


----------



## billyVR6 (May 8, 2000)

*Re: (MkIIRoc)*


_Quote, originally posted by *MkIIRoc* »_Little biased...

That's an understatement.


----------



## CaptEditor (Feb 23, 2004)

*Re: (ny_fam)*


_Quote, originally posted by *ny_fam* »_I read an article some place that said the wave will bounce and reflect if the radius of the bend less then 10 x the diameter of the tube.

Wouldn't shorter waves refect more easily? Couldn't higher rpms be affected more than lower rpms because of that?

-Kevin


----------



## ny_fam (Apr 3, 2004)

*Re: (CaptEditor)*

The waves I'm talking about are perpendicular to the runner its self. Primarily the induction wave.
Most common pressure wave cause;(grapeape racing)
The most commonly known cause of a
pressure wave is the piston as it moves down the
bore. On the intake stroke, the piston makes a
negative pressure wave that travels form the piston
toward the intake tract. Once that negative pressure
wave reaches the plenum area, it is reflected as a
positive pressure wave That positive pressure wave
travels back toward the cylinder. If it reaches the
intake valve just before it closes, it will force a little
more air in the cylinder.


----------



## billyVR6 (May 8, 2000)

*Re: (ny_fam)*

I was only considering straight intake runners for tuning the intake harmonic and RPM that I want.
I still plan to keep them straight as possible, but in a recent read on some 12v variable intake info and seeing cut-away and tech diagrams, the pulse seems to work with a pretty heavy curve in the intake runner. This opened my eyes just a little bit as I thought the pulse would redirect or get weak when forced to follow a radius.
This might relate to the curve of the stock 8v manifold runners...
if not, then just for example;
























(Image data sourced from [email protected])


_Modified by billyVR6 at 2:20 PM 1-30-2008_


----------



## 84_GLI_coupe (Apr 3, 2001)

*Re: (billyVR6)*

If you guys want some more of David Vizard's writings, pick up "How to Build Horsepower, Volume 2" (Cartech, S-A Design series). Most of it is carbs, but there's a couple solid chapters covering manifold acoustics and equations.
Here's some other resources I've come across:
4th year mechanical engineering lecture 
FSAE student report on manifold design 
Grapeaperacing's article 
I've run the equations for my counterflow, but the only thing I'm not so sure about is the 0.8L plenum volume for 7500rpm peak on my ABA bottom end with 280° (105° LSA) solid cam. I've still gotta measure how much room I've got in my MK1 for the intake, especially if I'm going to be using straight taper runners. I'll be using stainless steel, better thermal properties and easier to fabricate with.
One of waaaay too many projects for this winter.


----------



## Jettaboy1884 (Jan 20, 2004)

*Re: (84_GLI_coupe)*

BillyVR6 - Thanks a million for the pics regarding the VR6 intake. I actually had no idea that it worked in that manner. So, it appears that the flaps do not actually open a second shorter air tract as I initially thought; but instead open up a chamber that is shorter, and causes the intake pulses to reflect back to the valve faster. That is really interesting!
84_GLI-coupe - Thanks for the links. I am reading the second article now, and will read the other two soon.
Regarding the 0.8L plenum that you calculated, I found this citation in the "Team Integra" article posted below - 

_Quote, originally posted by *Dave Thompson of Thompson Engineering and Endyn article* »_
http://www.theoldone.com/archi...n.htm
The plenum volume is critical on N/A engines, and a basic rule of thumb is: The smaller the plenum, the lower the rpm range, and bigger means higher rpm. The throttle body size and flow rate also affect the plenum size: Bigger TB, smaller plenum, small TB, larger plenum.


Oddly enough, that article also states that a smaller plenum should use a larger throttle body, and a larger plenum -> a smaller throttle body. 
I want to add that I'm stoked that this thread has come this far. This in-itself is motivating me to keep learning about NA power. 
Thanks!

_Modified by Jettaboy1884 at 11:08 AM 2-4-2008_


_Modified by Jettaboy1884 at 11:35 AM 2-4-2008_


----------



## Holden McNeil (Jul 26, 2004)

*Re: (Jettaboy1884)*

The recent posts above got me thinking about how to construct a variable length intake that actually changes intake runner length dynamicly with RPM.... If you could work the math (and the obvious engineering hurdles) out you might be able to create an intake manifold that changes it's shape to compliment the change in pulse frequency throughout most of the RPM range.... Think a 16v manifold that can compress to a psudo-SRI at higher RPMs... http://****************.com/smile/emthup.gif


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## Jettaboy1884 (Jan 20, 2004)

*Re: (Holden McNeil)*


_Quote, originally posted by *Holden McNeil* »_...you might be able to create an intake manifold that changes it's shape to compliment the change in pulse frequency throughout most of the RPM range.... Think a 16v manifold that can compress to a psudo-SRI at higher RPMs... http://****************.com/smile/emthup.gif 

Interesting that you bring that up. I have seen pictures of a rotary motor that used ITB's with sleeves that could extend or shorten to provide the perfect "tuned" runner length through the RPM range.
I believe this is an example of one, the 787B engine. Note how the runners look like two pieces. In this picture, they are fully extended:
Edit: Youtube video of the 787B Go to 9:53 and see the variable runners in action:
http://www.youtube.com/watch?v...20RX7










_Modified by Jettaboy1884 at 5:18 AM 2-1-2008_


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## 84_GLI_coupe (Apr 3, 2001)

*Re: (Jettaboy1884)*

Here's a good article from Team Integra that covers a lot of the other stuff, but the best bit (imo) is the recommendation for plenum diameter vs throttle body diameter. http://****************.com/smile/emthup.gif


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## Jettaboy1884 (Jan 20, 2004)

*Re: (84_GLI_coupe)*


_Quote, originally posted by *84_GLI_coupe* »_Here's a good article from Team Integra that covers a lot of the other stuff, but the best bit (imo) is the recommendation for plenum diameter vs throttle body diameter. http://****************.com/smile/emthup.gif 

That is an excellent article! Lots of great information in there. (Don't forget page 2)
Thanks for posting it up. http://****************.com/smile/emthup.gif


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## Jettaboy1884 (Jan 20, 2004)

*Re: (Jettaboy1884)*

The Team Integra article came from this site below, which has a large listing of technical articles. I have been reading a few of them, and am finding some great information that is applicable to all NA motors:
http://www.team-integra.net/se...how=1


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## PowerDubs (Jul 22, 2001)

*Re: Let's talk about making Naturally Aspirated horsepower (Andrew Stauffer)*


_Quote, originally posted by *Andrew Stauffer* »_Most give up around 130whp when it comes to 8v. Seems to be the limit of bolt ons. 

Yea that is about right if you go here and do the math (aprox 150 crank hp) http://****************.com/smile/emthup.gif 
http://www.pumaracing.co.uk/PP03.htm
Here is a thread where I did the math for the R32 VS the 12v
http://forums.vwvortex.com/zerothread?id=3572092


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## ABA Scirocco (May 30, 2001)

*Re: Let's talk about making Naturally Aspirated horsepower (PowerDubs)*


_Quote, originally posted by *PowerDubs* »_
Yea that is about right if you go here and do the math (aprox 150 crank hp) http://****************.com/smile/emthup.gif 
http://www.pumaracing.co.uk/PP03.htm
Here is a thread where I did the math for the R32 VS the 12v
http://forums.vwvortex.com/zerothread?id=3572092



Interesting discussion over there, a lot of good info on that site although the calculations on that particular page result in hp numbers that are, in my experience, a little on the low side. I did the calculations based on an 8v race engine that I've worked on and got 158hp but on a well calibrated engine dyno the engine actually makes about 185hp and we believe it may be possible to push the engine close to 200hp.


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## ny_fam (Apr 3, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (ABA Scirocco)*

I agree with you ABA Scirocco. I've been talking with a few FSV (Formula Super Vee) racers, these guys have the built engines. 1600cc making 185 HP. 
We seem to be missing a few important mods that would get us into the higher numbers. 
http://www.race-cars.com/carso...s.htm


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## ABA Scirocco (May 30, 2001)

*Re: Let's talk about making Naturally Aspirated horsepower (ny_fam)*

If we were allowed to run the fuel injection and dry sump systems like the FSV engines, I have no doubt we'd have have over 200hp with our 2.0L-8v but we're restricted to wet sump and a single 2 barrel carb.


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## Jettaboy1884 (Jan 20, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (ABA Scirocco)*

A buddy of mine is letting me borrow "Power Secrets" by Smokey Yunick. Definitely a good book with lots of tips about things that can commonly go overlooked...
Can anyone else recommend some good books about making power in fuel injected engines?


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## chois (May 12, 2000)

*Re: Let's talk about making Naturally Aspirated horsepower (ABA Scirocco)*


_Quote, originally posted by *ABA Scirocco* »_If we were allowed to run the fuel injection and dry sump systems like the FSV engines, I have no doubt we'd have have over 200hp with our 2.0L-8v but we're restricted to wet sump and a single 2 barrel carb.

I agree. I think that number is achievable at 1.8.


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## 84_GLI_coupe (Apr 3, 2001)

*Re: Let's talk about making Naturally Aspirated horsepower (chois)*

I think it's time for me to ditch the counterflow and go solid lifter ABA/AEG head with swirl ports, seeing as solid lifter conversion has come down to a fraction of what it used to be. Gonna be way easier for me to make my intake manifold too. Gasket matched 30x34mm intake ports kinda lose out to stock round 33mm with lots of meat. Stock lower intake is closer to what I need anyways. I gotta make my own header now, so counterflow will be too tight to fit two custom manifolds onto.


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## chois (May 12, 2000)

Chuck found some cool stuff when he started pulling the motor apart in the new project. It seems to have an old 1.6 supervee motor - the head is pretty interesting, big valves and the exhaust ports cut into the manifold stud threads. The pistons are cosworth forged pieces. All that detail and a stock weight crank though...
Found a home for the supervee head and putting it back together as a 'mule' for this season with some mild improvements.


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## Jettaboy1884 (Jan 20, 2004)

*Re: (chois)*

That's pretty cool. I'd like to see the pics of the ports cutting into the studs.
I have an old 1.6L that was supposedly built by Reeves Calloway. I cannot confirm this, but it did have a baffled oil pan and the block was tapped for an oil return. The pistons are pretty nice quality, ,but they are marked like OEM. I'll have to post up some pics...


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## ABA Scirocco (May 30, 2001)

*Re: Let's talk about making Naturally Aspirated horsepower (84_GLI_coupe)*


_Quote, originally posted by *84_GLI_coupe* »_. Gonna be way easier for me to make my intake manifold too. Gasket matched 30x34mm intake ports kinda lose out to stock round 33mm with lots of meat. Stock lower intake is closer to what I need anyways. 

If you can, get a lower intake manifold from a Mk4, at a glance, it looks quite similar to the MK3 lower manifold but on closer inspection you'll find it's much nicer piece.


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## Mk1Racer (Apr 16, 1999)

*Re: (ny_fam)*


_Quote, originally posted by *ny_fam* »_Yea when I grow up I want to build and race formula cars








Some of older 1.8 Super Vee rabbit engine powered cars made 235 HP.
The current F3 rules most be quite restrictive.
Great article on the super vee history
http://www.grmotorsports.com/b...e.php


What a cool, cool thread. That Super Vee article was great! I remember them as support races for many of the races I went to in the late 70's and early 80's. About 13 or so years ago, I had the chance to buy a Ralt RT-1 Super Vee, complete w/ 1.8 Bertils motor, for $10k. I wanted it sooooo bad, but w/ my first kid barely out of diapers, and the second one on the way, there was just not enough spare change laying around!








Great thread guys, keep it up!
That being said, is anyone familiar w/ the early CIS intakes. These are the ones w/ the shorter runners and larger plenum.


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## Jettaboy1884 (Jan 20, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (ABA Scirocco)*


_Quote, originally posted by *ABA Scirocco* »_
If you can, get a lower intake manifold from a Mk4, at a glance, it looks quite similar to the MK3 lower manifold but on closer inspection you'll find it's much nicer piece.

Not to mention that the runners are much larger than the Mk3. IIRC, if you take the gasket that goes between the upper and lower halves of the manifold, the Mk4 runners are about 4mm larger diameter vs. the Mk3.

_Quote, originally posted by *Mk1Racer* »_
What a cool, cool thread... [Snip] ...That being said, is anyone familiar w/ the early CIS intakes. These are the ones w/ the shorter runners and larger plenum.

Thanks for the kind words. As for Mk1 intakes, you will find a difference when comparing a Mk1 Rabbit/Scirocco/Jetta intake with one from a VW Fox with Digi 2. IIRC, the Fox will have slightly longer runners. You can send a PM to ny_fam as he works primarily with modifying Mk1 manifolds. He is sure to know some of the nuances between each variation. http://****************.com/smile/emthup.gif


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## 8valvinsleeper (Jul 13, 2007)

*Re: Let's talk about making Naturally Aspirated horsepower (Jettaboy1884)*

My boss is helping me modify a crank trigger system for a chevy so that it will fit my mk2. We are basically just drilling a 4-bolt pattern onto the magnet plate and rebalancing it then we plan to make a bracket and have it go in place of the A/C condenser with 1:1 ratio toothed pulleys on the crank and on the trigger wheel. We are gonna hook this up to an msd ignition box and get more precise ignition timing. He made one identical for his 2.0 X-flow Turbo scirocco and with all of the prior modifications, it gave him a 18 hp increase in the bottom end before the turbocharger spools up. The msd box is timed with the turbo so that it advances the ignition timing really far while the turbo isnt supplying boost and then it backs off when it spools up. The fact that these distributors run off an intermediate shaft pulley on a belt gives the motor really inconsistent ignition timing. He has seen 20 hp increases on built up 1.8 8v motors just from doing this. Most people can build their own one with $300. I'll post a DIY if mine turns out to be worthwhile.


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## Mk1Racer (Apr 16, 1999)

*Re: Let's talk about making Naturally Aspirated horsepower (Jettaboy1884)*


_Quote, originally posted by *Jettaboy1884* »_
Not to mention that the runners are much larger than the Mk3. IIRC, if you take the gasket that goes between the upper and lower halves of the manifold, the Mk4 runners are about 4mm larger diameter vs. the Mk3.
Thanks for the kind words. As for Mk1 intakes, you will find a difference when comparing a Mk1 Rabbit/Scirocco/Jetta intake with one from a VW Fox with Digi 2. IIRC, the Fox will have slightly longer runners. You can send a PM to ny_fam as he works primarily with modifying Mk1 manifolds. He is sure to know some of the nuances between each variation. http://****************.com/smile/emthup.gif 

The information that I have, from a very reliable engine builder that builds a lot of race VW engines, says that this early mainfold will give you measurable hp increases and moves and widens the the torque curve. Real numbers seen both on a flow bench and on a dyno. Not to mention, decreased lap times on the track.


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## 84_GLI_coupe (Apr 3, 2001)

*Re: Let's talk about making Naturally Aspirated horsepower (ABA Scirocco)*


_Quote, originally posted by *ABA Scirocco* »_
If you can, get a lower intake manifold from a Mk4, at a glance, it looks quite similar to the MK3 lower manifold but on closer inspection you'll find it's much nicer piece.

That was the idea!








I'll have to weld mounts to the runners for my counterflow BBM fuel rail, but that shouldn't be a problem.
I'll be heading out this weekend to compare OBD2 ABA and AEG heads. I know both have swirl intake ports, but not sure what else would be different for flow. For the AEG head, the head bolt holes have to be drilled out to fit the 11mm bolts, and the spring seat area has to be machined to fit dual valve spring seats. Beyond that, I can't remember anything else from when we did our last ABA/AEG hybrid.


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## ABA Scirocco (May 30, 2001)

*Re: Let's talk about making Naturally Aspirated horsepower (84_GLI_coupe)*

I've never had a really in depth look at an AEG head, if you end up using one, would you be able to document the differences between the ABA and AEG heads, preferably with pictures?


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## 84_GLI_coupe (Apr 3, 2001)

*Re: Let's talk about making Naturally Aspirated horsepower (ABA Scirocco)*

I'll bring the camera along this weekend, how's that?
I know for a fact that the AEG head needs to be machined for dual valve springs, we had to make the tool to do it.
The other difference that I know of is that the early AEG heads don't have the EGR feed ports in the exhaust ports, while the newer ones do. Not sure on the year split though. It's about a 6-8mm hole parallel to the port on the bottom, comes out almost beside the lower stud hole.


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## Jettaboy1884 (Jan 20, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (8valvinsleeper)*


_Quote, originally posted by *8valvinsleeper* »_My boss is helping me modify a crank trigger system for a chevy so that it will fit my mk2... [snip] ...Most people can build their own one with $300. I'll post a DIY if mine turns out to be worthwhile. 

This is very interesting. Do you know how it compares to the Ford EDIS-4 system?


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## chois (May 12, 2000)

*Re: (Jettaboy1884)*


_Quote, originally posted by *Jettaboy1884* »_That's pretty cool. I'd like to see the pics of the ports cutting into the studs.


Here is the head.
































The pistons.








What we are trading the head for.








Progress on the rods, and crank.


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## 84_GLI_coupe (Apr 3, 2001)

*Re: Let's talk about making Naturally Aspirated horsepower (Jettaboy1884)*


_Quote, originally posted by *Jettaboy1884* »_
This is very interesting. Do you know how it compares to the Ford EDIS-4 system?

Sounds like he's talking about the GM HEI system, which is one of the options for MSnS. I'm running an EDIS-4 coilpack driven directly by a pair of ignition drivers inside my MS ecu, ABA wheel and VR sensor in block.
Ok so as far as crossflow intake manifolds go, I measured stock unused gaskets at work.
MK3/4 lower: 36mm
MK3 upper: 35.5mm
MK4 upper: 41.5mm
Looks like the MK4 one has good taper to it, so it'll already have lots of meat for matching and smoothing as well as optimal sizing. 36mm lower is perfect for 40mm intake valves, optimum 80% area of valve for a decent flowing head (good race setup can get away with 85%).


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## 8valvinsleeper (Jul 13, 2007)

*Re: Let's talk about making Naturally Aspirated horsepower (84_GLI_coupe)*

so just for clarification, does the length of the intake runner change so that it can get the optimal advantage from the high pressure wave behind the intake valves? I know that when the air rushing into the cylinder head is stopped by the closing valve, the air closer to the valve is slightly compressed by the air that was still rushing in. Is this why different lengths of runners give different power/torque advantages for different engine speeds?


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## Jettaboy1884 (Jan 20, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (8valvinsleeper)*


_Quote, originally posted by *8valvinsleeper* »_so just for clarification, does the length of the intake runner change so that it can get the optimal advantage from the high pressure wave behind the intake valves? I know that when the air rushing into the cylinder head is stopped by the closing valve, the air closer to the valve is slightly compressed by the air that was still rushing in. Is this why different lengths of runners give different power/torque advantages for different engine speeds?

In a nutshell, Yes. By changing the length of the intake runner, you are changing the amount of distance (and therefore time) it will take for the pressure wave to travel up and back down the runner. By timing this pressure wave to arrive right as the piston starts coming up, and before the intake valve closes, it is possible to cram a little extra air into the combustion chamber...


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## Jettaboy1884 (Jan 20, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (84_GLI_coupe)*


_Quote, originally posted by *84_GLI_coupe* »_
Ok so as far as crossflow intake manifolds go, I measured stock unused gaskets at work.
MK3/4 lower: 36mm
MK3 upper: 35.5mm
MK4 upper: 41.5mm
Looks like the MK4 one has good taper to it, so it'll already have lots of meat for matching and smoothing as well as optimal sizing. 36mm lower is perfect for 40mm intake valves, optimum 80% area of valve for a decent flowing head (good race setup can get away with 85%).

That's pretty good information to know. I find it very strange that the Mk3 lower starts at 36mm at the head, and then tapers down slightly as it bends up to meet the upper half. That would mean that air velocity would actually increase as the air negotiates that turn. IMO, the Mk4 intake is doing it right: Starting out at 36mm and tapering to a larger diameter as it makes the (nearly) 180 degree turn. That should allow the air to negotiate the turn at a much lower velocity vs. the Mk3. http://****************.com/smile/emthup.gif 


_Modified by Jettaboy1884 at 1:51 PM 3-1-2008_


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## 84_GLI_coupe (Apr 3, 2001)

*Re: Let's talk about making Naturally Aspirated horsepower (Jettaboy1884)*

Keep in mind that that's just the gasket diameters, which the manifold castings never match. Chances are it's even, I just don't have a manifold to measure yet.


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## jerrymic (Apr 19, 2007)

*Re: Let's talk about making Naturally Aspirated horsepower (84_GLI_coupe)*

I have a mk4 manifold and it matches quite nicely to the gasket... much much better than the mk3


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## Jettaboy1884 (Jan 20, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (jerrymic)*

I was reading a great thread on an SHO forum, and the following links were posted to some good articles that are worth reading:
Cylinder Head Porting:
http://en.wikipedia.org/wiki/Cylinder_head_porting
Cylinder Head Porting written by David Vizard:
http://www.popularhotrodding.c....html
Manifold Vaccum:
http://en.wikipedia.org/wiki/Manifold_vacuum
Boundary Layer (Not specific to airflow in an engine):
http://en.wikipedia.org/wiki/Boundary_layer
Laminar Flow (Not specific to airflow in an engine):
http://en.wikipedia.org/wiki/Laminar_flow
Ekman Layer (Not specific to airflow in an engine):
http://en.wikipedia.org/wiki/Ekman_layer
I found this user on Youtube who has a lot of instructional videos about engine components. Many of them are probably common knowledge to us, but some have little tidbits of things I never knew:
http://www.youtube.com/profile_videos?user=n2s&p=r 


_Modified by Jettaboy1884 at 10:23 PM 3-8-2008_


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## Jettaboy1884 (Jan 20, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (Jettaboy1884)*

Another Good link:
http://www.iskycams.com/techtips.php


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## Jettaboy1884 (Jan 20, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (Jettaboy1884)*

TTT.
Can anyone recommend some other good books about building NA engines?


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## Jettaboy1884 (Jan 20, 2004)

*Re: Let's talk about making Naturally Aspirated horsepower (Jettaboy1884)*

Can't let this die...
I'm building a fresh 2.0 counterflow 8v - Woot!


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## fukengruven1982 (Jan 8, 2005)

*Re: (MkIIRoc)*

8v's rock


_Modified by fukengruven1982 at 3:29 PM 11-2-2008_


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## objectional_content (Oct 24, 2008)

*Re: (fukengruven1982)*

has anybody considered using a hemi-spherical or domed piston??


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## twinair (May 12, 2008)

*Re: (chois)*

Check this out and then tell me if you think the 16V is superior to the 8V.
http://www.not2fast.com


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## Jettaboy1884 (Jan 20, 2004)

*Re: (twinair)*

That's a very cool site!
*Edit* Here's the VW-specific page, but I recommend checking out the whole site:
http://www.not2fast.com/vw/

Thanks!!! http://****************.com/smile/emthup.gif 




_Modified by Jettaboy1884 at 8:17 AM 11-4-2008_


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## Tom A (Oct 20, 2004)

*Re: (Jettaboy1884)*

You guys might find this interesting, I know I did.
There is an active racing Series in South Africa called Formula GTi, that uses a spec VW "Parts-Bin" engine. They use a 1.8 block, dry sumped, 2L crank and rods, bore it out to 82.65MM using Audi pistons 11:1 compression, with 40MM side draft carbs, a stock Hydro head and a 288º cam.
This combo gives an output of 150hp at 6700rpm.
Details here: http://www.formulagti.com/
The gentleman I corresponded with about the setup did not mention if that HP number was at the crank or the wheels, but they use a Hewland tranny, so the losses would be lower than a stock unit, I would think.
Either way, that is an impressive number, particularly with stock heads.


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## 16racer (Nov 30, 2005)

*Re: (Tom A)*

















This car runs with the http://nwpro4alliance.com/. Wildest vw I've seen. 2L, crossflow, crank trigger ignition, inline electric water pump, 15.5:1 on alky, ect. Still can't beat the 2.3 ford guys though. 


_Modified by 16racer at 6:34 PM 11-10-2008_


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## demelok (May 7, 2006)

*Re: (16racer)*

so finally i put all my homework together and finished collecting all my parts. but i am very oped to advice
i'm still rocking hyd lifters here so bare with me im not as extreme as all you haha
ohk heres the list
# 2.0 ABA xflow swap obd1
# head ported to gasket
# 3 angle valve job
# decked head
# TT HD dual valve springs
# mk4 intake manifold swap
# 276 TT cam
# mk4 2.0 injectors
# shaved flywheel
# usrt smart linkage
# mk4 exhaust manifold swap
# 2.25" tt catback
blocks still at the machine shop ,its getting decked,dip'd and honned .
also on the aba swap i never wired the VSS in so i never had tach and had a very fast rev limiter. i was told my car was taching out @ 5900 rpm if i didnt wire that in. and i believe it , it cuts out pretty quick.
so if i did wire it in i would be looking at full range tach for the aba @ 6300 then burnt chip would push that a little bit higher.
and also i havnt ran o2's in this car ever! never had them wired up. and i doesnt really seem to be effecting it that much.
i'm pretty happy with the results so far. considering all i did was slap the 270 in my head without and headwork. so im really looking foward to the results now.
i havnt finished the swap yet. of all the goodies. but heres some numbers of last year
# WITH OLD 270* AUTOTECH CAM
# 15.5 at 88 mph - import wars
# 15.4 at 85 mph - import wars








*cough* daily driver
any advice? thanks

*previously posted in the Naturally aspirated section* 


_Modified by demelok at 12:32 PM 6-27-2009_


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## mars-red (Mar 2, 2004)

What a great thread! Figured I'd chime in, since I finished phase 1 of my daily driver 8 valve build within the past year. My initial goal was to do an ABA block under a digifant RV head, with the compression bumped a little and a mild cam, so that I could keep Digifant 2 (for now). I rebuilt an OBD-I ABA block with all factory parts (added a VWMS windage tray though), rebuilt a Digifant head after doing some real basic dremel work and having my local machine shop mill 0.050" from it and cut new valve seats. Ended up using a TT 268 cam, with stock springs and retainers and an adjustable cam gear. It feels nice and strong, sounds grisly, and is a decent daily driver setup. Haven't had it dyno'd though. I'm currently coming up with a plan to convert to megasquirt so that I can eliminate the digifant airflow meter, and run a really aggressive cam (276 or 288), which would also require heavier valve springs. Phase 3, further down the road, might be a wasted spark conversion and a junkyard ITB setup.


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## Jettaboy1884 (Jan 20, 2004)

*Re: (mars-red)*


_Quote, originally posted by *mars-red* »_What a great thread! Figured I'd chime in, since I finished phase 1 of my daily driver 8 valve build within the past year. My initial goal was to do an ABA block under a digifant RV head, with the compression bumped a little and a mild cam, so that I could keep Digifant 2 (for now). I rebuilt an OBD-I ABA block with all factory parts (added a VWMS windage tray though), rebuilt a Digifant head after doing some real basic dremel work and having my local machine shop mill 0.050" from it and cut new valve seats. Ended up using a TT 268 cam, with stock springs and retainers and an adjustable cam gear. It feels nice and strong, sounds grisly, and is a decent daily driver setup. Haven't had it dyno'd though. I'm currently coming up with a plan to convert to megasquirt so that I can eliminate the digifant airflow meter, and run a really aggressive cam (276 or 288), which would also require heavier valve springs. Phase 3, further down the road, might be a wasted spark conversion and a junkyard ITB setup.

Sounds like a good foundation. http://****************.com/smile/emthup.gif 
Once you get the megasquirt tuned, the motor will be much nicer compared to the Digifant...


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## pipper (May 23, 2009)

*Re: (chois)*

WOW







those have to be the biggest ports ive ever seen hmmmmmmm makes me think mine has too much meat left on it lol







one thing i think we need to discuss more is squishe how close is close enough! taking into consideration the strech on the rod at higher rpm. as for 130hp







my friend did 160.9(flywheel) with a stock 2.0 audi long block and cylinder head only mods are 298 estas cam toyota throttles and a dicktator engine managment on the same dyno i only made 140(flywheel)


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## mudanddust (Oct 24, 2007)

*Re: (16racer)*

any idea what pistons those guys run?


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## Jettaboy1884 (Jan 20, 2004)

*Re: (mudanddust)*

Thanksgiving Bump.


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## Achtventilzyllinderkopf (Nov 17, 2009)

*Re: (Diggatron)*

I've been driving my friend's 85 scirocco, stock 1.8 CIS, the only mod is.... he sliced the muffler off. I was at a light next to an mk3 tdi gti.... and I spanked it


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