# Digi ported head or crossflow head?



## kickster (Aug 15, 2000)

I am thinking of using my own head on a ABA block. Does a ported digi head work better than a crossflow non ported head?


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## A1Rocco (Oct 6, 2001)

*Re: Digi ported head or crossflow head? (kickster)*

I doubt it but it is not just the cfm that is the point of the crossflow, it's the fact that it is on the front of the head away from the hot exhuast. Cold intake air means more power.
James.


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## kickster (Aug 15, 2000)

*Re: Digi ported head or crossflow head? (A1Rocco)*

Cold air? Does the intake gets that hot? I have never touched it. 
Any other input?
thanks


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## Caleb (May 19, 1999)

*Re: Digi ported head or crossflow head? (kickster)*

Yes the intake does get quite hot especially with the exhaust manifold under it. The air also gets hot just while moving and turning corners. This is a thermodynamics thing. A cross flow head will most always flow better and produce more power. Maybe if you had a very very poorly designed cross flow it would not be as good as a very good non-crossflow but as a general rule the crossflow is an improvement. Notice that you don't see any new or modern engines with a non-crossflow head. Well there is a reason


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## Try'nBanME (Sep 17, 2003)

*Re: Digi ported head or crossflow head? (Caleb)*

the non-cross flow head can flow just as good as a 2.0 head. (with porting) 
But who really has some numbers to prove this








The Intake ports right above the hot exhaust ports *is* a negitive, even with ceramic coating the intake the heat still travals through the wall.
If the size and shape of the ports are the same than they'll flow the same. 
Also the ABA puts out 115 at the crank, right? 
And the JH puts out 90 at the crank. 
put the 2.0 block under the JH head and put on the Motronic Fueling, I Bet you will get 
115 or very close to that with that stock JH head... 
Pluse, It's Solid lifter! Do the ABAs have Solid lifter convertions? 
Im just rambling, but I hope my post makes some people wanna argue with me.


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## joeblow (Nov 9, 2002)

*Re: Digi ported head or crossflow head? (Try'nBanME)*

well the 1.8 heads can outflow the stock crosslows with minor porting but as they sad it still gets hot. One thing to think about while you are already having the work done is that one of the reasons the X flow works so well is it uses 7mm valve stems compared to the 1.8's 8mm stems. So what I hope to be doing is switching the valves to the new TT 41mm intake with 7mm stems (cut down to 6.5 at the port opening) and the 34 exhaust with the same stem shape as the intake. Then it should really give the X flow a run for its money.


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## Try'nBanME (Sep 17, 2003)

*Re: Digi ported head or crossflow head? (joeblow)*

Correct!


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## Peanut (Nov 8, 2001)

*Re: Digi ported head or crossflow head? (Try'nBanME)*

Bajan01 is having some head work done on a xflow head, so it will be interesting to compare ported non-crossflow with ported crossflow head. You know, apples to apples.
but for god;s sake, i don't know why anyone would put forth costly efforts on an 8v head when a 16v conversion is not terriblly complicatied and often times cheaper.

P


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## jessemthompson (Sep 15, 2003)

i have a digifant motor with a ported head and all the normal performance upgrades, at the track i kill my buddy with a 96 xflow and he has everything but a ported head, so i think the digi head with porting flows better than the xflow, i know my head outflows a stock 16v and you know that outflows the xflow


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## CorradoAbaTurbo (Aug 30, 2003)

*Re: (jessemthompson)*


_Quote, originally posted by *jessemthompson* »_i have a digifant motor with a ported head and all the normal performance upgrades, at the track i kill my buddy with a 96 xflow and he has everything but a ported head, so i think the digi head with porting flows better than the xflow, i know my head outflows a stock 16v and you know that outflows the xflow

There is quite a wieght difference between a A2 and a A3 car. Gearing also. I used to run a Digifant head on my g60, but with 8mm stems and a counterflow design I believe it is time to move on. Counterflow IMO is not a good design.


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## Try'nBanME (Sep 17, 2003)

*Re: Digi ported head or crossflow head? (Peanut)*


_Quote, originally posted by *Peanut* »_
but for god;s sake, i don't know why anyone would put forth costly efforts on an 8v head when a 16v conversion is not terriblly complicatied and often times cheaper.

No way, You have to buy two cames instead of one. and if your timeing belt brakes you have to buy eight new valves instead of 4. And parts on the 16v are more expensive..
.


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## Big Dac With Fries (Feb 1, 2002)

*Re: Digi ported head or crossflow head? (Try'nBanME)*


_Quote, originally posted by *Try'nBanME* »_
No way, You have to buy two cames instead of one. and if your timeing belt brakes you have to buy eight new valves instead of 4. And parts on the 16v are more expensive..
. 


guh? I always thought the 8v heads (counterflow) were free wheeling??
unless youve snapped a belt on a decked head . . .
- dac


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## Coupe__88 (Sep 14, 2003)

*Re: Digi ported head or crossflow head? (Try'nBanME)*

yes the counterflow head is above the exhaust manifold
BUT
the crossflow head runs over the valve cover which is also not the coolest of surfaces.
my unproven but something to thinkabout theory:the head is going to be hot on all sides so heat will transfer through the metal anyhow, and plus the intake air isnt inside the manifold long enough to receive significant radiated heat from the manifold. 
turn your head and cough








pardon that statement. just my 1563 cents


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## Big Dac With Fries (Feb 1, 2002)

*Re: Digi ported head or crossflow head? (Coupe__88)*

Thermodynamics notes here we come . . .

The counterflow is also lower in the engine bay compared to the Xflow, that flows right at the top of the hood . . . as we all know, hot air rises.








- dac


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## Coupe__88 (Sep 14, 2003)

*Re: Digi ported head or crossflow head? (Big Dac With Fries)*

from what i heard the 2.0 intake manifold was designed with safety in mind, i dunno if that means it absorbs impact or it wont come flying through your firewall or somethin yahoo for counterflow


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## Try'nBanME (Sep 17, 2003)

*Re: Digi ported head or crossflow head? (Big Dac With Fries)*


_Quote, originally posted by *Big Dac With Fries* »_
guh? I always thought the 8v heads (counterflow) were free wheeling??
unless youve snapped a belt on a decked head . . .
- dac

I mean, if it's stock and it breaks at 3k NO>
But if you have a nice cam and you brake it at 6k, YES.


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## Big Dac With Fries (Feb 1, 2002)

*Re: Digi ported head or crossflow head? (Try'nBanME)*


_Quote, originally posted by *Try'nBanME* »_
I mean, if it's stock and it breaks at 3k NO>
But if you have a nice cam and you brake it at 6k, YES.

thanks for clarifying that http://****************.com/smile/emthup.gif 
- dac


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## bajan01 (Nov 26, 2001)

*Re: Digi ported head or crossflow head? (Peanut)*


_Quote, originally posted by *Peanut* »_Bajan01 is having some head work done on a xflow head, so it will be interesting to compare ported non-crossflow with ported crossflow head. You know, apples to apples.
but for god;s sake, i don't know why anyone would put forth costly efforts on an 8v head when a 16v conversion is not terriblly complicatied and often times cheaper.

P


Well I stumbled on this thread by accident. To answer the second question, not many people have gone where I want to go with a x-flow 8 valve so I wanted to be one of the few daring enough. I don't know what the non x-flow 8v heads are flowing but my x-flow head came in at 187 cfm @ 0.500" lift. That's pretty good in my book. However, the mid to high 200's isn't to hard to get with a 16v head so that might just be my next project


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## dohc (Sep 28, 2001)

*Re: Digi ported head or crossflow head? (bajan01)*


_Quote, originally posted by *bajan01* »_
Well I stumbled on this thread by accident. To answer the second question, not many people have gone where I want to go with a x-flow 8 valve so I wanted to be one of the few daring enough. I don't know what the non x-flow 8v heads are flowing but my x-flow head came in at 187 cfm @ 0.500" lift. That's pretty good in my book. However, the mid to high 200's isn't to hard to get with a 16v head so that might just be my next project









True, but 16V's cost soo much more







believe me, not just double as would be guessed, but triple. I have a 16V head with larger valves...my side still hurts from when they pulled a kidney as payment








Also, the port size and shape isn't even close between the two heads.


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## Peter Tong (Jun 17, 1999)

*Re: Digi ported head or crossflow head? (Peanut)*


_Quote, originally posted by *Peanut* »_
but for god;s sake, i don't know why anyone would put forth costly efforts on an 8v head when a 16v conversion is not terriblly complicatied and often times cheaper.


Probably because swapping in a 16v head means we'll have to skip on out of this forum and into the 16v one







Either that or there is something in some folks that want to show that the old school 8v can be made to do well relative to the 16v....


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## Peter Tong (Jun 17, 1999)

*Re: Digi ported head or crossflow head? (kickster)*

ok...some data thanks to porttuning.com
Xflow head
http://www.porttuning.com/Flow 23.gif
Counter flow head
http://www.porttuning.com/8V Flo2.gif
Eurospec head (counterflow - with backcut, valve unshroud, undercut intake stems 8mm down to 7mm)
http://home.comcast.net/~pwton...9.jpg



_Modified by Peter Tong at 11:19 PM 4-21-2004_


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## WasserTuner (Oct 14, 2000)

*Re: Digi ported head or crossflow head? (kickster)*

here is some more crossflow info. I just tested a German 2.0 crossflow on our SuperFlow Flow bench and the head hit 142cfm then ported/polished it and retested it and it flowed and got 155cfm using stock valves. This was all tested at 28" h20. The difference in Peak power RPM goes from 6,270 @ 142cfm to 6,811 @ 155cfm
Should have some numbers with our new custom valves installed next week. 
Also FYI the Mexico head flows ~130 So if your looking for a hed to work on Make sure you get a German one.


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## dohc (Sep 28, 2001)

*Re: Digi ported head or crossflow head? (Peter Tong)*


_Quote, originally posted by *Peter Tong* »_
Probably because swapping in a 16v head means we'll have to skip on out of this forum and into the 16v one







Either that or there is something in some folks that want to show that the old school 8v can be made to do well relative to the 16v....

Not only that, but if you want to stay NA, a piston swap needs to be done.


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## kickster (Aug 15, 2000)

*Re: Digi ported head or crossflow head? (dohc)*

some one sell me a eurospec head


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## kervin (Feb 24, 2001)

*Re: Digi ported head or crossflow head? (Coupe__88)*


_Quote, originally posted by *Coupe__88* »_from what i heard the 2.0 intake manifold was designed with safety in mind

That's the deal. It was to prevent fires in a really big impact. On counter flow heads, the fuel system is over the exhaust manifold (with the intake in between. Just imagine, huge wreck, intake hits the fire wall and breaks, injectors could then put fuel directly on the hot exhaust manifold - BOOM
I figure I'd be a goner if I every hit something that hard!

I'm picked up a Digi 2 manifold yesterday. The runners look to be about 1 1/2 inches longer then what was stock with my 8v Scirocco. I've never really looked at the length and size of a crossflow runner. anyone know how then compare? That could be most of the difference in dyno numbers of the same block with other heads.


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## bajan01 (Nov 26, 2001)

*Re: Digi ported head or crossflow head? (Peter Tong)*


_Quote, originally posted by *Peter Tong* »_ok...some data thanks to porttuning.com
Xflow head
http://www.porttuning.com/Flow 23.gif


That X-flow head must be stock


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## Espen W (Oct 29, 2001)

*Re: Digi ported head or crossflow head? (Peter Tong)*


_Quote, originally posted by *Peter Tong* »_ok...some data thanks to porttuning.com

Counter flow head
http://www.porttuning.com/8V Flo2.gif


This graph has been used as proof of the greater flow of the 7mm valve stems. Not that I doubt that they flow better (I'm ordering some myself), but it is important to note that this head has been match ported as well, so it is sorta comparing apples to oranges.


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## Peter Tong (Jun 17, 1999)

*Re: Digi ported head or crossflow head? (Espen W)*

Espen, match porting doesn't really gain hardly anything, unless the mismatch is huge. If anything you probably want the intake manifold to be slightly smaller than the port to help against reversion...
AFAIK, most of the gains to be had are in the bowl, valve and valve job...thats why I kind chuckle when I see these "ported" heads on ebay and such...but what do I know compared to folks like Fumio Fukaya, and Collin G...
I can say that just an undercut to 7mm, backcut, and unshroud gave me 22% more on my head...with no modifications to the port. As you can see the gains dropped off with increasing lift. I'd guess this is because more of the 8mm non undercut section of the valve was in the way...
I'd love to put some of the TT valves in next time I have the head off...I'd love to see 180 cfm out of an 8v head...
The A2 manifolds in stock form only flow 133 cfm however...perhaps its time to think about doing something about that (extrude hone?)...


_Modified by Peter Tong at 9:46 PM 4-22-2004_


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## ABA Scirocco (May 30, 2001)

*Re: Digi ported head or crossflow head? (Peter Tong)*

Does anybody have flow numbers for a ported x-flow head?


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## bajan01 (Nov 26, 2001)

*Re: Digi ported head or crossflow head? (ABA Scirocco)*


_Quote, originally posted by *ABA Scirocco* »_Does anybody have flow numbers for a ported x-flow head?

See my earlier post...187cfm @ 0.500" lift. X-flow with stage 3 P&P, 40x33 valves with undercut valvestems (6.3mm down from 7mm from Jose at www.porttuning.com)










_Modified by bajan01 at 1:08 AM 4-23-2004_


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## Espen W (Oct 29, 2001)

*Re: Digi ported head or crossflow head? (bajan01)*


_Quote, originally posted by *bajan01* »_
See my earlier post...187cfm @ 0.500" lift. X-flow with stage 3 P&P, 40x33 valves with undercut valvestems (6.3mm down from 7mm from Jose at www.porttuning.com)









_Modified by bajan01 at 1:08 AM 4-23-2004_

Interesting. How much does it flow on the exhaust side ? Could this mean that the stock valves are plenty big ? I'm thinking about 41/34, but might just do 40/34 with undercut stems and backcut. The stock 33mm exhaust valve is not quite the ideal 85% of the intake valve size, but a 34mm exhaust is spot on. The big question is if the 41mm intake will provide a gain over 40mm. Some says yes, others say no.
Just remembered that Autotech sells a Cross Flow head with 42/34 valves. Does anyone have flow data on that one ?


_Modified by Espen W at 11:49 AM 4-23-2004_


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## Espen W (Oct 29, 2001)

*Re: Digi ported head or crossflow head? (Peter Tong)*


_Quote, originally posted by *Peter Tong* »_Espen, match porting doesn't really gain hardly anything, unless the mismatch is huge. If anything you probably want the intake manifold to be slightly smaller than the port to help against reversion...

True, but I have read about 10% gains on some cars. VW's might not be the most mismatched, though.

_Quote »_
The A2 manifolds in stock form only flow 133 cfm however...perhaps its time to think about doing something about that (extrude hone?)...

_Modified by Peter Tong at 9:46 PM 4-22-2004_

Would this mean that having a head that flows more than 133cfm is a waste of time ?


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## ABA Scirocco (May 30, 2001)

*Re: Digi ported head or crossflow head? (Espen W)*


_Quote, originally posted by *Espen W* »_
True, but I have read about 10% gains on some cars. VW's might not be the most mismatched, though.


FWIW, I checked 2 JH heads and compared the the match to 3 A1 intake manifolds, in every pairing the match was *TERRIBLE* I have no idea if my observations are typical of VW heads and manifolds in general but if they are, I find a 10% improvement quite believable


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## kervin (Feb 24, 2001)

*Re: Digi ported head or crossflow head? (ABA Scirocco)*

Hmmm, I guess I need to match up mine and soon!


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## mrkrad (Nov 9, 2000)

dont forget the intake manifold plays a large part on heatsinking the head. If you were to place a phenolic spacer on either head you'd notice significant rise on CTS, which would be bad (Detonation more likely).


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## xr4tic (Dec 10, 2001)

*Re: (mrkrad)*

It's the coolant, radiator, and fan's job of keeping the coolant temps in check, not the intake manifold.
If this was true, then the guys running ITBs with real short runners would be having cooling problems due to the loss in mass and area of the intake manifold.
Does anybody sell a phenolic-type spacer for the 8V? I'd be glad to try one out.

_Quote, originally posted by *mrkrad* »_dont forget the intake manifold plays a large part on heatsinking the head. If you were to place a phenolic spacer on either head you'd notice significant rise on CTS, which would be bad (Detonation more likely).


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## ABA Scirocco (May 30, 2001)

*Re: (xr4tic)*

I know there are phenolic spacers available for crossflow heads, I've not seen them for the counterflow head. The spacer wouldn't work very well on the counterflow heads because of the angle at which the port enters the head, putting in a spacer which is thick enough to has any effect would disrupt the airflow effectively cancelling out the gains or worse.


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## xr4tic (Dec 10, 2001)

*Re: (ABA Scirocco)*

Well, the PowerGasket I got for my Audi (1.8T, er, 2.0T now) is ~1/4" thick.
I would think that if you were to port match the head to the gasket, and then match the intake to just a slightly smaller size, that the extra thickness shouldn't hurt that much, if at all. Maybe it would help by giving the airflow just a little extra room to expand before angling down again. With airflow, you never know what might work








At the very least, I'll be adding some sort of shield when I install my header.


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## CorradoAbaTurbo (Aug 30, 2003)

1989 Cabby with 2.0l and ported cis 8v head and cis intake manifold ported w/big A2 tb
[email protected]
Same car but with German ABA head ported with short runner intake, dual ABA tb's
[email protected]
ABA head is definelty better and not much harder to fit


_Modified by CorradoAbaTurbo at 10:05 AM 4-25-2004_


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## Swollen (Jul 3, 2001)

Just another point.
I remember comign home after a drive and touching my counter flow intake manifold, it was warm to the touch.
Did the same thing with my cross flow manifold and it is cool to the touch, I'd say it's almost cold.
juts my $0.02.


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## Peter Tong (Jun 17, 1999)

*Re: (Swollen)*

At full power, say 190 cfm how long does air actually dwell before it is ingested into the motor... not long at all... I know that everyone wants this question answered but short of someone putting a temp sender into their runners and doing some datalogging its all going to be conjecture...(at least to me)...
The A2 intake manifold is a major restriction anyways...I haven't seen results for the std manifolds but I know the A2 manifolds are very restrictive...


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## xr4tic (Dec 10, 2001)

I found some phenolic gaskets:
stock manifold:
http://www.parts4vws.com/catal...A2101
w/Headers:
http://www.parts4vws.com/catal...2101H
I'm not sure it's worth $70 (or $90 for header version) though


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## Skaven (Nov 17, 1999)

*Re: (xr4tic)*

Great info here!


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## MrGTi91 (Mar 20, 2004)

*Re: Digi ported head or crossflow head? (Caleb)*

i have the setup with intake manifold right over my header, where can i get this cross flow head??


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## dohc (Sep 28, 2001)

*Re: Digi ported head or crossflow head? (MrGTi91)*


_Quote, originally posted by *MrGTi91* »_i have the setup with intake manifold right over my header, where can i get this cross flow head??

I might have a german one for sale if my brother doesn't want it.


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## Skaven (Nov 17, 1999)

*Re: Digi ported head or crossflow head? (dohc)*

How can you tell if its a german or mexican head? Based on the part# or something?


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## ABA Scirocco (May 30, 2001)

*Re: Digi ported head or crossflow head? (Skaven)*

It'll say Mexico or Germany right on the head.


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## Skaven (Nov 17, 1999)

*Re: Digi ported head or crossflow head? (ABA Scirocco)*


_Quote, originally posted by *ABA Scirocco* »_It'll say Mexico or Germany right on the head.

DUH... (runs into the garage with tail between legs to look at head)
Thanks! http://****************.com/smile/emthup.gif


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## Random Orbit (Jul 2, 2004)

*manifold spacers etc.*

About the spacers for the intake manifold, first off there are a pile of manufactures using plastic and ceramic for their manifolds ie. ford V8, second I belive that carbon fiber has great insulating properties so a person could sandwich a c/f spacer between a couple intake gaskets and if motivated could even build a heat sheild out of it. I don't think this would be too very expensive as c/f is becoming comonplace. I may be wrong but I don't think so. The cross flow head on the aba motor was not originaly designed for more power, the manifold was moved to the front for better crash ratings. the fact that it flows well is just a bonus. If manifold mass was a issue than you're totally right about the short runners and nobody would use ITB injection at all.


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## DubbyDriver (Oct 23, 2003)

I'm not sure but c/f might burst into flames if it gets too hot. frp can give off some noxious fumes when it gets hot too.


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## 91driver (Feb 25, 2004)

*Re: (DubbyDriver)*


_Quote, originally posted by *DubbyDriver* »_I'm not sure but c/f might burst into flames if it gets too hot. frp can give off some noxious fumes when it gets hot too.

What is bad about the NOx fumes? What other materials can produce them when hot/heated?


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## jamesn67 (Nov 15, 2001)

*Re: (Peter Tong)*

To your earlier point about porting and matching...keep in mind
that overall flow numbers are not the whole story. Flow field velocity is
important as well so as to keep low end torque. That's the whole
reason to use the smaller stem valves...less disruption to the
flow field. 
This is actually an interesting discussion. One would think that the
x-flow mani's would have longer runners and therefore potentially
better flow. But what about the entrance into the ports? Which 
set up has a straighter entrance? I haven't seen a x-flow in a while
so I can't recall myself. That would play a roll as well. 
One would also think that the air must be cooler in the x-flow case
which should be a bonus for that set-up as well. 
Love to see some analaysis results for these...I'll bet VW has done it.
Be cool to see that.


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## Digiracer (May 5, 2002)

*Re: Digi ported head or crossflow head? (kickster)*

Some of you have already seen this & it's alittle on the extreme side, but it's a great example of the ultimate power potential of a all motor Crossflow VW Engine.
http://www.usf3.net/about_engine.html
Given not many of us are running one on 12.7:1 compression with a dry sump oil system & custom intake but it's fun to dream.








imagine what 200 HP @7,200 rpm sounds like








So Kickster what do you have in the works?
I haven't talked to you in along time.
How's that 11:1 Digi running?


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## deer_eggs (Oct 4, 2006)

*Re: Digi ported head or crossflow head? (Digiracer)*


_Quote, originally posted by *Digiracer* »_Some of you have already seen this & it's alittle on the extreme side, but it's a great example of the ultimate power potential of a all motor Crossflow VW Engine.
http://www.usf3.net/about_engine.html


link didn't work... i'm eager to see what it has to say


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## fast84gti (Mar 2, 2003)

um.. Yeah. The internets have changed a bit in 3 years...









Many of the tubes have since been retrofitted with new ones.
Oh back on topic. I did some research, and the crossflow DOES NOT out flow the counter, once you port polish and put in 7mm stem valves into the counterflow..
Collin at TT still prefers the solid lifter counterflow for that reason.
And since he is a VW watercooled guru, I am not going to argue with him.
I was looking at my counter and cross flow heads side by side, and I didn't like the look of the stock valve throat onthe cross.
And supposedly the water guides are too close to the ports onthe crossflow. Hence less porting ability...


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## hyperformance06 (Jun 27, 2006)

*Re: (fast84gti)*

i opened my crossflow ports to match 38mm carbs with the port being the same dimensions pretty much all the way to the valve without running into the coolant passages. i dont see needing much more than a 38mm intake port on a 8v engine.


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## Jettaboy1884 (Jan 20, 2004)

*Re: (hyperformance06)*

Well, maybe this will help:
Counterflow Intake Port:








Counterflow Exhaust Port:








ABA Intake Port:








ABA Exhaust Port:


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## PeruEuro (Dec 28, 2006)

nothing beats xflo. nothing


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## Jettaboy1884 (Jan 20, 2004)

*Re: (PeruEuro)*


_Quote, originally posted by *PeruEuro* »_nothing beats xflo. nothing

I'm not so sure about that. Aside from the single fact that the intake can be isolated from the exhaust, the intake ports themselves seem to be worse in the ABA (in my opinion).
The ABA ports have a lower angle of approach, and they have a very nasty short turn radius to the seat. The counterflow ports have a slightly higher approach, and a much smoother short turn radius. The counterflow ports also have a slightly taller distance between the valve seat and the bowl, which allows the air to straighten out before flowing down and past the valve head (slightly more-so than the ABA).


_Modified by Jettaboy1884 at 4:45 AM 3-28-2008_


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## PeruEuro (Dec 28, 2006)

I acknowledge your opinion, but I still feel that the ABA's intake ports add more of a swirl effect in the combustion chambers. With the smaller angle and the more straight down style I.D.; its a crossflow...And the obvious cooler air they must be better than the counter flow.


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## PeruEuro (Dec 28, 2006)

I really like my obd1 8v crossflow head.
Its ported&polished, gasketmatched, shaved .0009 and I got fresh valves and stuff like that..All this was done by me at my Tech school...


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## Longitudinal (Nov 13, 2004)

*Re: (PeruEuro)*

Those ABA intake port pics are proof to me how important stainless undercut and back-cut valves are in the ABA: the air is basically hitting the valve from the side.


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## redGTInj (Jul 6, 2003)

*Re: (Longitudinal)*

anyone recently talk to Collin at TT about this debate???
i'm interested to see what he said


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## exjnv (Jun 8, 2006)

counterflow ftw!


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## redGTInj (Jul 6, 2003)

*Re: (exjnv)*

explain why....


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## secondgen (Jan 9, 2004)

*Re: (redGTInj)*


_Quote, originally posted by *redGTInj* »_anyone recently talk to Collin at TT about this debate???
i'm interested to see what he said










_Quote, originally posted by *redGTInj* »_explain why....

I've tried this, and it may have been that the shop was busy, but I never got an extensive reasoning behind why he prefered the counterflow heads.
I do have a feeling it has a lot to do with this though:

_Quote, originally posted by *Jettaboy1884* »_The ABA ports have a lower angle of approach, and they have a very nasty short turn radius to the seat. The counterflow ports have a slightly higher approach, and a much smoother short turn radius. The counterflow ports also have a slightly taller distance between the valve seat and the bowl, which allows the air to straighten out before flowing down and past the valve head (slightly more-so than the ABA).

Someone out there has to have a little more insight than me though. I love my counterflow, and you'll have to pull quite a few more teeth and have a damn good reason to convert to x-flow.


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## Jettaboy1884 (Jan 20, 2004)

*Re: (Longitudinal)*


_Quote, originally posted by *Longitudinal* »_Those ABA intake port pics are proof to me how important stainless undercut and back-cut valves are in the ABA: the air is basically hitting the valve from the side.

Exactly. Which is the primary basis for my statement above.
Here is an excellent article by Vizard, in which he illustrates the swirl properties, and port bias, in a head with two valves per cylinder.
http://www.popularhotrodding.c....html
Here are a couple lines from the book, "Smokey Yunick's Power Secrets" in which he is talking about port angle, and the "cone" of air that is formed as it passes around the valve: 

_Quote, originally posted by *Smokey Yunick* »_
"There is sometimes a tendency to drop the floor - the shortside radius - in an effort to bring the flow into the back-side of the valve at an oblique angle. This is completely, utterly and totally wrong! When you try to bend the flow right at the edge of the valve, the flow cone can't form evenly around the valve and total flow drops off"
"To get a uniform cone structure, it is important to turn the flow well above the valve, and let the flow come straight at the back of the valve head. There are always restrictions to what you can do inside the port, but if it is at all possible, the intake port should be dead straight for at least 1/2 inch before the flow is released to the chamber"

Just to clarify, Smokey is saying that ideally, the port would point straight down at the top of the valve. Of course, this is not exactly possible since there are packaging issues with the cam and lifters. However, hypothetically you could make a head with tall valvestems which would give room for a very high angle of approach. 
On a side note, 16v heads have a completely different science for the port angle. A 16v head with paired valves will cause the air to tumble across the valves as it is drawn into the cylinder. This is totally different from the swirl that happens in an 8v head.
Mike.



_Modified by Jettaboy1884 at 3:59 PM 6-26-2008_


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## LT1M21Stingray (Sep 14, 2006)

*Re: Digi ported head or crossflow head? (kickster)*

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


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## 4ePikanini (Aug 29, 2007)

*Re: Digi ported head or crossflow head? (Mtl-Marc)*

Big question here for me is :
I have a counterflow with intake on top of exhaust manifold. What are my options to make the intake cooler? After a drive the intake is so hot that it will burn a blister within 5 seconds.
Heat shield / Thermal wrap / ceramic ? Pros and Cons?


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## Jettaboy1884 (Jan 20, 2004)

*Re: Digi ported head or crossflow head? (fourie_marius)*


_Quote, originally posted by *fourie_marius* »_Big question here for me is :
I have a counterflow with intake on top of exhaust manifold. What are my options to make the intake cooler? After a drive the intake is so hot that it will burn a blister within 5 seconds.
Heat shield / Thermal wrap / ceramic ? Pros and Cons?

Wacky Wabbit Racer was using a NASA spec heat shield between the manifolds on his race car.
Looking down in this thread, it seems that Ceramic Coating is a bit easier and of similar cost when compared to properly wrapping a manifold and downpipe:
http://forums.vwvortex.com/zerothread?id=3897518
I believe the main drawback from header wrap is that it holds moisture close to the metal and encourages rusting... Maybe a combination of powdercoating and wrapping, plus a heat shield would give the best results.


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## FrancescoVento (Sep 8, 2007)

*Re: Digi ported head or crossflow head? (Jettaboy1884)*

X-flow pros: Cooler air.
X-flow cons: Horrible shallow-angled ports.
Counter-Flow Pros: More Vertical ports
Counter-Flow Cons: HOT HOT HOT! and air doing a 180 on the way out.
Has anyone done a stock to stock power comparison as a starting point? I'd be interested in seeing that.


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## Jettaboy1884 (Jan 20, 2004)

*Re: Digi ported head or crossflow head? (FrancescoVento)*


_Quote, originally posted by *FrancescoVento* »_
...
Counter-Flow Cons: HOT HOT HOT! and air doing a 180 on the way out.


Regarding your point above:
I have not seen or read anything to indicate that the gases "care" about which way they enter or leave the cylinder. So, this should really not be a factor. (Someone please chime in if you know otherwise).
Although the counterflow intake ports and manifold will be inherently hotter in comparison to the crossflow, there are solutions to significantly reduce the heat transfer.
I would be interested in seeing an air temperature data log for the counterflow and crossflow, taken as the air is flowing from the manifold and into the head ports. I think that (aside from sitting and idling) the temperatures would be pretty close.


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## FrancescoVento (Sep 8, 2007)

*Re: Digi ported head or crossflow head? (Jettaboy1884)*

I was thinking the energy in the airflow would be wasted as the gases were changing direction, but after some thought, it does seem I ignored a little thing called the compression and ignition stroke. I suppose after that it really shouldn't matter like you said. 
Proper measurements of temperature would indeed be nice to see.
Retrofitting 7mm valves seems to help the Counterflows a lot.


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## Peter Tong (Jun 17, 1999)

*Re: Digi ported head or crossflow head? (FrancescoVento)*

I've stayed counterflow myself, although some folks have had good results with the x-flows...
Upgrading the Eurospec head to TT's new solid lifter 42/35 intake and exhaust valves gained about 10% worth of flow up top (I had the head test flowed before and after on the same SF600 bench)...



_Modified by Peter Tong at 12:15 PM 5-28-2009_


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## ny_fam (Apr 3, 2004)

*Re: Digi ported head or crossflow head? (FrancescoVento)*

Think a new simple tests would give us an idea how hot the intakes get on 8v engines;
have people with non touch heat gauges drive for 30 minutes - pop the hood, record the intake manifold temp at the TB mount, and at the location where the runners meet the plenum. and record the outside temperature. 
with enough of these mk1/mk2/mk3/mk4 we can get a good idea
what the manifold temps and what ones run hotter.
I can run a thread in some of the other tex forums and collect some data.
Using a non contact thermometer http://www.harborfreight.com/c...93983


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## Peter Tong (Jun 17, 1999)

*Re: Digi ported head or crossflow head? (ny_fam)*

Hi Derek, 
AFAIK, Andrew S measured it awhile back with his counterflow setup... with his Megasquirt setup... at WOT the air temp is not much warmer than ambient as the incoming air has virtually zero time to dwell in the manifold and pick up any heat... so power wise you won't gain much of anything at all... 
if you can pick up intake air up from a source that is as close to ambient that is the trick... the area where the front of hood blends into the grill work, or rain tray area are known higher pressure spots as well... but that has nothing to do with the manifolds...


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## cesvilmal (Mar 24, 2009)

*Re: Digi ported head or crossflow head? (Peter Tong)*

are there any aftermaket maifolds for counter flow? how expensive is to have your head really well done?


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## bockscar12 (Nov 25, 2013)

There's a number of different manifolds for these engines. It would be silly to assume they all handle heat the same. Perhaps one style of intake is better than another? What's the ultimate combination?


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