# Making my own Intake manifold?



## GreenRallye (Aug 20, 2001)

How do i design the best intake manifold for my 16v turbo? does anyone know of sites or books explaining theory behind best intake. I've seen many different types of intake and want to know what the difference is, and what would be best for my setup..
Thanks alot
Thomas Olaussen
Rallye 16vT


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## ExtremeVR6 (Sep 6, 2001)

*Re: Making my own Intake manifold? (GreenRallye)*

what's your purpose? High Power? High torque? good looks <<grin>> some basic design theories are long plenums = better torque, shorter plenums = better horsepower ... ie longer: better accel, shorter better top end power. The other thing is the diameter... if you keep the diameter of the plenums smaller, you'll have better air velocity, fuel atomization will be better, and all that should = better torque... with a bigger diameter then you'll have more air flow (which could be better if you're running FI) cause simply, you'll get more air in... = more power... just my basic thoughts... I got no experiance or education about it. My .02 http://****************.com/smile/emthup.gif <shrug>


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## speed51133 (Feb 18, 2000)

*Re: Making my own Intake manifold? (ExtremeVR6)*

long runners doesnt mean more torque, it means more LOW END torque.
short runners=more top end power.
its way too complicated to just tell you. its also way too complicated to DIY and make it technologically really good.
i just had a thread that died out about 2 weeks ago titled "custom intake manifold project".
i documented step by step the whole thing.
take a look at http://www.rossmachineracing.com look at thier 16v intake. its a nice model to copy.


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## ExtremeVR6 (Sep 6, 2001)

*Re: Making my own Intake manifold? (speed51133)*

heh ... yup ... like I said no education, no experiance just some basic theoretical ... eh ... meanderings  http://****************.com/smile/emthup.gif leave it to the engineer to point out the errors in understanding ... thanks I've learned more.
wasn't that custom intake for a vr6? or for a 4cyl? I don't remember... 
So, speed... "theoretically" what would make for a good intake manny? the one at rossmachineracing? <<grin>>


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## nabilsx (Jun 8, 2000)

*Re: Making my own Intake manifold? (ExtremeVR6)*

check this out http://www.perfectchoicemotorsports.com then click "VW Aluminum Engine Accessories " really nice and cheap stuff.


[Modified by nabilsx, 6:25 PM 7-18-2002]


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## GreenRallye (Aug 20, 2001)

*Re: Making my own Intake manifold? (nabilsx)*

I'm hoping for 400bhp @ crank on my 16v turbo. 
Since i'm going turbo, its best with short runners? Thats what i had in mind. What about placement of the throttle body? Its usually located at one of the ends, like this:








But ive seen some intake's with the throttle body in the center\ middle. Whats the best way to do it? Will some of the cylinders get more air than others with the trottle body on one of the sides?
Thanks alot
Thomas Olaussen
Rallye 16v T


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## speed51133 (Feb 18, 2000)

*Re: Making my own Intake manifold? (GreenRallye)*

the ross intake is beautiful. is it PERFECT? i guess not, nothing ever is.
something like a blend between the schrick vgi and the ross intake would be MY perfect intake.
If your going to get 400hp, think about it. what the hell do you need lots of low end torque for. the turbo itself will pump out pleanty of torque. Think about traction control. Turbo lag and short runners can give you more traction down low by minimizing the torque down low. Keep in mind we're not talking like loosing 200ftlbs due to runner length, more like a small percentage.
im no expert. but the stock intake soaks up lots of heat due to its cross over the head design.
with variable runner length you get the best of both worlds. low end tq, and top end hp. with FI applications you also want the plenum to have enough volume to be able to "dump" air into the head. This is whats called a surge tank IIRC.
anyways, its a degreee in its own. just put some thought into it, design it, and build it. dont let formulas stop you from doing it.


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## jynssi (Jan 3, 2002)

*Re: Making my own Intake manifold? (GreenRallye)*

That shiny block looks like a p.o.s as a manifold.
If one's looking forward to have +400hp, one really should pay attention to the shape on the plenum. Not just the looks.
Shape should not favour a cylinder above another like that brick above.
Check the shape of the manifold if Audi IMSA. Or Skoda wrc-car.


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## nigel (Jan 3, 2001)

*Re: Making my own Intake manifold? (jynssi)*

Check out Corky Bells' book Maximum Boost he talks about the centrally mounted throttle body style (symetrical manifold) or one off to either side (log style manifold) he says that the symetrical style is better for even clinder filling. Also the volume of the plenum should be ebtween %50 to %70 off the displacement of the engine. 
Check out speed51133 post it is like 3 pages long and full of good (and funny stuff) on manifolds http://****************.com/smile/emthup.gif


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## MK1_F00L (Nov 13, 2001)

*Re: Making my own Intake manifold? (nigel)*

Well here is a site that you might want to take a look at
http://www.eng-tips.com there has been talk about intake manifold design...
I am designing one at the moment too in AutoCAD, but the fabrication cost might be something stupid if I don’t get the use of my school rapid prototyping equipment.
Well see if anything comes of this


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## speed51133 (Feb 18, 2000)

*Re: Making my own Intake manifold? (jynssi)*

quote:[HR][/HR]That shiny block looks like a p.o.s as a manifold.
If one's looking forward to have +400hp, one really should pay attention to the shape on the plenum. Not just the looks.
.[HR][/HR]​I would hardly say that about this intake.
























thats a pretty nice intake made for top end power.


[Modified by speed51133, 7:55 PM 7-18-2002]


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## Sandlock (Aug 10, 2001)

*Re: Making my own Intake manifold? (speed51133)*

Do any of the vrT guys use the shrick vgi in combo with thier setup? I havent seen one yet. Now that you mention it i would like to see the pros and cons on a dyno and peformance test of somekind. Dont gotta vr, so i dont really think about options for them. I'd like to know if the length change would f' up an otherwise smooth psi build up....


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## MUNKIN (Sep 23, 2001)

*Re: Making my own Intake manifold? (speed51133)*

I like that manifold but $700 could be spent on something better like forged pistons.


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## XSiVE (Nov 1, 2000)

*Re: Making my own Intake manifold? (MUNKIN)*

Nabil Pointed me to a site this morning that sold surge tank type intakes for the 8v.. the problem I saw was that the site resembled TeamPSI's purchace site.


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## GreenRallye (Aug 20, 2001)

*Re: Making my own Intake manifold? (XSiVE)*

I've already ordered Maximum boost.








I'm not woried about low end torque, since when i hit full boost, it will be plenty. 
If someone can post pics, i can show you an intake thats allready been made. (im not making it myself, just designing it)
The shape of the plenum can do wonders if made correctly. A friend of mine with a Sierra Cosworth went from 410hp to 445hp with just a new plenum and throttlebody. cheapest increase in hp ever he said. 

Thanks alot
Thomas Olaussen
Rallye 16v T


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## jynssi (Jan 3, 2002)

*Re: Making my own Intake manifold? (speed51133)*

Yep,like I said, it looks good but the manufacturer doesn't give a shhit for even airflow to the cylinders.
A brick like that favours the runner most far away from the throttle and leaves the one nearest gasping for air.
On full load thereis NOT even boost pressure in both ends of a plenum like that no matter how shiny it is.


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## speed51133 (Feb 18, 2000)

*Re: Making my own Intake manifold? (jynssi)*

so if i hook up 2 different boost gauges to an intake like that, one on one end, and the other on the other side, i'll get a different reading??
about how much different do you guess?
im NOT being sarcastic and starting an argument. I do however disagree.
I understand what your talking about, but I think that the differences are minimal, and small enough to be ignored in favor of a simple design that takes up minimal space in the engine compartment.


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## blue98jettavr6 (Mar 19, 2001)

*Re: Making my own Intake manifold? (jynssi)*

quote:[HR][/HR]Yep,like I said, it looks good but the manufacturer doesn't give a shhit for even airflow to the cylinders.
A brick like that favours the runner most far away from the throttle and leaves the one nearest gasping for air.
On full load thereis NOT even boost pressure in both ends of a plenum like that no matter how shiny it is. [HR][/HR]​Not looking for a cat fight but hear me out.
When that brick as you call is is fill with air then it will stay filled with air under pressure until you let off the thottle.
Now that block is full front to back with no where for the air to escape untill those vavle open.The 1st runner has as much air pressing up against thay closed intake valve as the 4st runner and intake valve.
My point is try and look at a plunem as a holding tank for air waiting for some releaf and the releaf is the opening valve. 
Check this out if the runner are larger in diameter that the valve opening,the plunem is larger in diameter the the runner than there is no loss in there in air flow. 


[Modified by blue98jettavr6, 9:22 AM 7-19-2002]


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## BUNNYLOVE (Jul 28, 2000)

*Re: Making my own Intake manifold? (XSiVE)*

Its definetly not Team Psi, no worries there.


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## DrewS (Feb 8, 2002)

*Re: Making my own Intake manifold? (jynssi)*

I would have to agree with Speed and Blue98. This is a boosted application. In the manifold there is a positive pressure against the valves. I would agree with you if this were a N/A application and each cylinder was scavenging for air.


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## jynssi (Jan 3, 2002)

*Re: Making my own Intake manifold? (DrewS)*

And I don't want to argue, but if the brick shape is good, why IMSA engine's plenum looks like this:
















These handle 720 bhp out pf the 2.2-litre engine
When engine produces 400hp, the velocity of the boost air is appr 100m/s around the 60mm diameter throttle. Do You really think that the situation in plenum is similar with a compressed air tank where the air doesn't move? AIr has inertia,like any other matter. This appears as vibrating pointer in boost gauge.
I have a flow bench capable of flow above 900cfm; which easily simulates 500hp. When measuring a plenum like brick, there actually forms a VACUUM to the nearest runner. It is true that the boost pressure prevents a vacuum to form,but it still leaves the 1st runner to smaller amount of flow.
In flow tests I can have little more than 1psi of pressure to the testpiece, like a plenum or intercooler.
Speed: Didn't You just build an intake like that? Measure the pressures and tell us. Please exhange the gauges and make sure You get similar reading, and no calibration difference affect the measurement. How much power Do You have?
A different air delivery to the cylinders appear as a different colour in spark plugs and repetitively dying plug in one/two cylinders. 
Furthermore with flow-through carbs the uneven airflow easily runs one cylender lean and destrys the engine; which is quite common when runnign with high powers and poorly designed plenums. 
ps. read the texts:
Jens Rösner's Audi page; Audi Pikes Peak



[Modified by jynssi, 2:32 AM 7-20-2002]


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## speed51133 (Feb 18, 2000)

*Re: Making my own Intake manifold? (jynssi)*

i do have 2 gauges. one is an electronic transducer type gauge(GM map sensor), and the other an autometer mechanical. one is mounted RIGHT after the throttle, the other at the opposite side. I'll record some readings, and then swap the sources, and see what i get....


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## Sergio Syncro (Jul 21, 2002)

*Re: Making my own Intake manifold? (speed51133)*

GreenRallye, do keep in mind that the turbo downpipe will need SERIOUS work and bending as it will encounter that axle that goes to the rear, plus the Rallye drivetrain can NOT hold more than 250 hp in stock form for a very long time !!
You might want to look into the Audi TT visco which is stronger + some serious differentials and a beefy clutch !
As for your intake you might wanna talk to these people here in Holland called 'Roma' who designed their own intake plenum for their 342 hp 16VG60 Golf II.








Or something like this UK chap who also added a turbo to his Golf:








To each it's own but being a Rallye owner myself and knowing of it's heritage and the rareness of this vehicle (less than 2500 still driving) i personally cannot see myself putting a turbo in that car as it simply is not a Rallye anymore that way.
It will certainly lose it's value ....
I can see the use of a 16V G60 conversion which can put out out 350 hp which is not too shabby and still leaves the Rallye with a certain dignity.
It's your car and you should do what you want but i NEVER want to be without that G-loader







The sound alone makes me go Hmmmmmmm..


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## SocialInvert (Jul 11, 2002)

*Re: Making my own Intake manifold? (Sergio Syncro)*

I never understood custom intake manifolds on a turbo charged car.Why not just match port you factory and be done.Maybe a custom piece cools down more quickly?I dont know,i figured since the air was being forced through the motor i realy did not matter.For an all out race car for sure,but for a street car?why bother.Why dont you guys hack and tig a g60 manifold to your crossflow engines if you want it on the front side?


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## speed51133 (Feb 18, 2000)

*Re: Making my own Intake manifold? (SocialInvert)*

people think if you have a turbo or supercharger, then everything else is usless, air is being forced through, so what difference does it make. this is not true. it would make MORE of a difference because sooo much more air is passing through there.
the "brick" design is not a whole lot different than some of the examples I've seen here. I have yet to do testing, but I'm not all excited to build a new intake even if I do get 1 psi difference or so. Thats not a big deal. The MAIN purpose was to eliminte the 3 foot long stock plenum. The throttle was sitting RIGHT on top of the turbo. That intake is a pain, always in the way. Intake temps ive been noticing are like an average 10 degreese cooler. Thats worthwile.
As to keeping the integrity of your ralley, come on. How much is it even worth? Your scared to loose its value? Mid 90's volkswagens are hardly collectable and do not appreciate.


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## mrkrad (Nov 9, 2000)

*Re: Making my own Intake manifold? (speed51133)*

Well in theory under boost (like 10-15psi) , the amount of air in the box would always be under pressure, equally at all points, but i'd still prefer a Round intake manifold over a square one any day


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## GreenRallye (Aug 20, 2001)

*Re: Making my own Intake manifold? (Sergio Syncro)*

G-lader allready gone. Converted to turbo last year, when the g-lader died. Either you modify it, or you shouldnt do anything at all. And stock Rallye's isnt that fun to drive. When i went for turbo, it was much more amusing to drive. I love turbo's.








Jabbasports Rallye Golf did break the orginal tranny at 330bhp. Then changed to a quaiffe 6-speed, and startet breaking almost everything when they passed 450bhp or so. At 410bhp everything worked ok. And it did 0-60mph in 3.9 sec, and 0-100mph in 8.3.
I've got a spare drivetrain, and sinter 4 puck sachs clutch, and will get a 6-speed quaiffe over the winter.
I think i will try to make something like the IMSA\sportquattro intake. If its good enough for IMSA it better be good enough for me too..








Thanks
Thomas Olaussen
Rallye 16v T


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## jynssi (Jan 3, 2002)

*Re: Making my own Intake manifold? (GreenRallye)*

I made a plenum like that to our circuit race corolla last summer, It was laboury to finish and even the 3mm AlMg3sheets, flanges and accelerating funnels cost more than $200.
So It's quite obvious why shape like that is not too common.


[Modified by jynssi, 8:05 PM 7-21-2002]


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## Sergio Syncro (Jul 21, 2002)

*Re: Making my own Intake manifold? (jynssi)*

Speed, as for the value i'd beg to differ !
I'm not sure about your situation back in the states but here in Europe a good condition Rallye will change owners for about 8000 - 10000 Pound Sterling for a full option and healthy version!
If you do the math you'll see that 10000 equals $16.000 usd !!








I'm not sure what you consider value but in my book that's a helluva price for a car that's about 12 years old !
Keep in mind that the Rallye G60 is not any other VW Golf.
It is so much different that i could fill 1 GB with data to explain them all ranging from a full welded chassis down to the special glued front windshield for extra rigidty. Also the engine is different from the 'PG' G60 found in the Corrado as it otherwise couldn't compete in the Rallye class it was in so the displacement was decreased and a big FMIC was added to compensate.
5071 Were build and the last one is still (with o miles !) present in the Belgium factory where ALL rallye's were build.
The first 2000 were all meant for straight up Rallye racing and can be identified as they have NO sunroof while the rest does ...
Of those half has been wrecked or stripped so about 2500 remain worldwide which is not much.
Green Rallye: You are right about the fact that the Rallye isn't impressive stock. Due to it's weight it's indeed a bit underpowered so i can understand your need for speed and the turbo mods.
I'm aiming for about 240 hp and will do so (hopefully) with the help of SNS and some serious mods. That should be enough for a daily driver and get the family from A to B in a fast motion








If i still feel the need for speed i'll take the Z28 for a spin


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## speed51133 (Feb 18, 2000)

*Re: Making my own Intake manifold? (Sergio Syncro)*

wow! what a rarity, a welded chassi. with a smaller engine, but a bigger intercoler.
if im lucky i dont get a sunroof.
sorry for not caring.


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## Sergio Syncro (Jul 21, 2002)

*Re: Making my own Intake manifold? (speed51133)*

Thank you for your mature and uplifting contribution.


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## TurboTom (Feb 5, 2001)

I'm sorry I just had to say something here in my defense. You (jynssi) 
dump all over an intake which took time to build and is actually seen here on the web. Yes it is a simple design for the plenum. I wanted it to LOOK nice as well as work good. It is also machined out of a solid block of aluminum. When I get unlimited funds to manufacture racing intakes for cars that have sponsor money running out of their a$$e$ then I will make intakes similar to the audi r8 or along those lines. But I have not seen any pics of your work other than what is on your site. If that is all you have done then you have no say in how an intake should be built unless you have built one better for your car. Now speed51133 took up for me because he is also DOING something. Forums are filled with "know it alls" You may know a lot but please keep the comments to yourself if you can't do it better (and show pics of YOUR work).
Thanks
Tom


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## killa (Nov 26, 2000)

*Re: Making my own Intake manifold? (TurboTom)*

Like Tom said, everyone knows it all, aluminum aint cheap, the manifold looks awsome in my book.
What's next? criticize Tom's fuel rail cause you guys can do them better??? HAHAHAHAHA, please.
Paul


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## jynssi (Jan 3, 2002)

*Re: Making my own Intake manifold? (TurboTom)*

Sorry if i offended You.
Pics of the Toyota's engine bay are on the way to the net, also pics of the S2 I'm working on right now. That is because I knew someone's going to mention this.
in the meantime check
pics already on the web (button: "kuvia") 
and the S2 
I know the toyota pic page is crappy,have patience. Howewer, I built the whole car from windshield to front bumper including both manifolds, intercooler, tubular frame and steering geometry.
So I think I'm valid to discuss here?


[Modified by jynssi, 1:23 PM 7-22-2002]


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## SocialInvert (Jul 11, 2002)

*Re: Making my own Intake manifold? (jynssi)*

OH YEAH!Well i built a Twin turbo Porsche with full race suspension,custom paint.Yeah,the whole nine.It was a kit from a company called ERTL.Man that thing is bad ass.







Please keep the "i built this,i built that" crap to yourselves.You all sound like you have little peckers and your intakes are your extensions.


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## speed51133 (Feb 18, 2000)

*Re: Making my own Intake manifold? (SocialInvert)*

quote:[HR][/HR] Please keep the "i built this,i built that" crap to yourselves.You all sound like you have little peckers and your intakes are your extensions.







[HR][/HR]​I GOT A BETTER IDEA!
how about you shut the hell up and quit saying stupid crap?


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## jynssi (Jan 3, 2002)

*Re: Making my own Intake manifold? (speed51133)*

had to bring this one up...
Thanks to Tuomas i there are pics of the engine bay of the Corolla.

engine bay of the super saloon corolla  
There is a plenum I made
It's similar with the IMSA one, but with four throttleplates instead of the large single one used in IMSA.
You can see that the boost air comes in to the conical chamber, from where the air is forced in to the second chamber through the appr. 10mm wide opening, that is as long as the plenum is. This opening has similar flow area than the incoming boost line tube has.
This way the boost air is rushed to the plenum from the whole length of it's side. This delivers equal amount of air into each cylinder, no matter how great boost or flow.
There are accelerating funnels in the second chamber.
This engine produced [email protected] boost.
I didn't want to add a pic to this forum because this doesn't allow the cahnging of size of the images. 
Super Saloon is a circuit racing class here in Finland.


[Modified by jynssi, 2:20 AM 8-1-2002]


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## speed51133 (Feb 18, 2000)

*Re: Making my own Intake manifold? (jynssi)*

i fail to see what you tried to explain. looks like a log to me without a pic of the inside.


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