# 8v Crossflow vs Counterflow characteristics (RPM limit and Flow)



## theguy6989 (May 3, 2006)

I plan on going turbo with my 8v. With that being said I'm trying to decide between solid lifter JH head and a OBD1 german crossflow head.

I don't really plan on going over 8,000 rpm with the setup. I know the PG hydro heads have valve float around 7,500rpm but what about the crossflow heads?

I know both heads have the flow potential. I like old school power so if I could stay counterflow it would be preferred. And yes I know crossflow is much easier to work with and turbo fitment.


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## ps2375 (Aug 13, 2003)

So, if the PG has "valve float around 7,500 rpm" what makes you think an ABA head would be any different? Same valves(other than them being 7mm stems), springs and followers...You don't mention what block this head will be on. There will be some additional mods to the ABA head to fit a 1.8L block or for the counterflow head to fit an ABA block. The mods aren't big or hard, but they are there. I was going to do an ABA head on an RV block with a ported mkIV intake. (Car got hit before I could finish the motor.)


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## B4S (Apr 16, 2003)

Why would you take an 8v to 8000rpm? With boost, you'll get more than what you're after, by 7000 easy.

To get any useable power out of an 8000 rpm VW engine, you'll need waaaaaaaaaaaaaaaaay more flow than these heads can provide, and a huge turbo.


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## ps2375 (Aug 13, 2003)

B4S said:


> Why would you take an 8v to 8000rpm? With boost, you'll get more than what you're after, by 7000 easy.
> 
> To get any useable power out of an 8000 rpm VW engine, you'll need waaaaaaaaaaaaaaaaay more flow than these heads can provide, and a huge turbo.


Have to agree there, on an NA motor with a decent cam, by 7200 the power could be falling off pretty good. It might rev beyond that, but not much good will come of it.


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## nairmac (Jan 22, 2004)

The OBD I cross flow head has better flow than the OBD II cross flow, the ports were shaped differently and are a bit larger I believe. The cross flow also has more potential overall when ported than the counter flow. If you're going turbo, just use a good factory OBD I cross flow and leave it- spend your money on a good turbo, intercooler and management. Port work isn't as cost effective as good turbo bits if you're looking for 200hp or less. I personally would stick with hydraulic lifters if adding boost also.


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## ps2375 (Aug 13, 2003)

I would think the counter flow head would flow better, being that it's intake side has a better angle(steeper) for air entering the cylinder. The exhaust side seems to be identical on both. The cross flow would be better if boost is on the table, as it does leave more room on the back side of motor for plumbing and such.


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## G60 Carat (May 14, 2004)

The cross flow (ABA) has bigger ports, especially the intake side! I mean sided by side in my garage, instantly noticeably bigger, like it would take immense porting to get a PG to ABA size. I took a picture of it with digital calipers, but I can't find the pictures. 

Despite that, the valve sizes are the same, but valve stems are 7mm cross flow vs 8mm counter flow. Between port size and the thinner stem size, it's a no brainer the ABA has potential to flow better. But at what CFM will these differences come into play?

There is also a very good flowing OBD2 head out there, it came on the 96 cars, maybe some 97. It's German casted and has no air injection crap on the exhaust side, and no velocity humps in the intake side. (Which is what hurts your high RPM efficiency) It came single valve spring, but can be upgraded with the TT HD valve spring kit. I ended up with one of these by accident, when it was sold to me as an OBD1 head (easy mistake when looking at it) Once I took it apart it was a bit of a surprise it wasn't dual valve spring.  The ports and overall condition were so nice I decided it was worth the $200 to just order the springs for. Plus with HD springs you're good for at least 7000rpm, and probably 7500rpm. My rev cut is set at 7000rpm with a Schrick 272, and some minor port work. It takes quite a big turbo (big turbine .A/R) to really keep making power up there, it's more for over rev protection. Really any turbo with .63 A/R or under is not going to love life past 7000rpm.

If you're shooting for 200whp on a turbo crossflow/1.8, you can do it on a stock head, stock cam and all. You can also bolt an ABA head down on top of a 1.8 block with no mods needed (other then the 5 seconds it takes to knock out the flywheel side locating dowel) Use the ABA head gasket and it blocks the oil drain overhang with no leaks or other issues. Even though I did a 1.8/ABA hybrid myself this time, I would say it's better advice to just start with a OBD1 2.0 ABA. 

On the other hand, you could also just go 8v counterflow turbo and hit you're goals. Which is the direction I started heading (G60 turbo) but the packaging issue of having intake and exhaust on the back side, potential heat soak issues, along with the plumbing, and serviceability down the road. I just found it much easier to use the ABA head.


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## LeftcoastTigger (Dec 31, 2009)

*On the subject of cylinder head gas flow - -*

Were any big block 1.6ltr cross flow 2v engines fitted to North American VW's?

Some MkIII Euro's were fitted with 1600 APT engines, and MkIV's an AKL

I want to experiment with in cylinder gas flow by modifying the ports, bowl, and valve sizes of the smaller head

2.0ltr ABA engines and their cousins have ports and valves too large for my project, and there's no point using epoxy or sleeving valve throats if that work can't be transferred to an oem head

Thanks in advance for any feedback :wave:


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## ps2375 (Aug 13, 2003)

Not unless they went to mexico or canada.


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## G60 Carat (May 14, 2004)

LeftcoastTigger said:


> Were any big block 1.6ltr cross flow 2v engines fitted to North American VW's?
> Thanks in advance for any feedback :wave:



Can't speak for Mexico, but we never got a golf engine smaller than 1.8 from the MK3 on. 
Our Mk3's had 5 engines 1.8 (counter flow), 2.0 ABA, 1.9 diesel, 1.9 TDI, 2.8 VR6
MK4's had 2.0 AEG, 1.9 TDI, 1.8T, 2.8VR6 (12v & 24v we officially never got the MK4 3.2 VR6/R32 in Canada)

The heads on the 1.6 you are talking about and our North America spec ABA heads look amazing similar. Is there any difference? (That euro 1.6 block looks crazy though!)


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## ps2375 (Aug 13, 2003)

With that much webbing cast in, it is most likely an aluminum block.


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## kpn3nc (Jul 5, 2008)

go full aba and boost it, I wouldn't waste my time with a solid lifter counterflow turbo setup.


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## srgtlord (Jun 4, 2010)

Just go find a 1.8T motor and be done with it


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