# AEG HEAD VS. ABA HEAD question



## bulldoser62 (Apr 10, 2004)

Ok so i have done my searching so don't tell me to use the *"search button"*I just pulled a valve spring of my ABA and found out I'm one of those special people. i have a obdII German head.








My question is i have a AEG head and a BEV (same head) head laying around I've read post where people are putting these heads on a ABA bottom ends but there is no hard facts (that i could find) to support these heads are any better. the intake ports on the ABA head look much better for flow. the AEG and the BEV intake ports have a big hump in them. (maybe to help the air flow start to spin?)
People are saying that the AEG head makes more power. Anyone have flow bench numbers for these heads stock? the other thing is the AEG and the BEV head have holes in the exhaust port for the secondary air wouldn't this be a bad thing for the flow out the exhaust. any info would be great. 
*ABA INTAKE PORT BELOW*








*AEG/BEV INTAKE PORT BELOW*







y6 
*THE HOLE IN THE EXHAUST PORT*










_Modified by bulldoser62 at 5:42 AM 1-12-2007_


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## all-starr-me (Jul 14, 2003)

*Re: AEG HEAD VS. ABA HEAD question (bulldoser62)*

why not measure them and see which is bigger? I'm sure you could remove the swirl hump with some porting work. you would need to plug 3 oil returns along the rear of the head on the AEG to use it.


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## bulldoser62 (Apr 10, 2004)

*Re: AEG HEAD VS. ABA HEAD question (all-starr-me)*

So have you done this swap or are you just reading other posts. (all-starr-me) 
Yes i know i can just go in there and hack up the port that is not what im looking to do. any idiot with a dremel can do this. i want to know for sure why this hump is in the head. Is it to help get the fuel and air to mix better? 
From what i can tell there is nothing that will need to be plugged. i will post pics later. the only thing for sure is that the exhaust side of the head the very outside head bolt hols will need to be drilled out to fit the ABA head bolts other than that the head is a direct match. 
there is myth's out there about this setup but i want facts. this is a AEG head it is a 8v head *NOT A 20V HEAD.*
i will post pics later and i will measure the ports as best i can 


_Modified by bulldoser62 at 6:18 AM 1-13-2007_


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## doodpod (Apr 27, 2004)

*Re: AEG HEAD VS. ABA HEAD question (bulldoser62)*

From what I've read, you're right about the swirl. It might help mix the air & fuel better, but the intent is to swirl the mixture as a way to help it fill the cylinder at lower rpms. As I understand it, this is one of the reasons the AEG makes better low-end torque than the ABA. The shorter deck and larger bore the the AEG is the primary reason for the greater torque though; this intake design is just a way to help fill the cylinders because of the shorter stroke.


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## dvlax40 (Jan 17, 2006)

wait for jeff to post he'll kno lol


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## doodpod (Apr 27, 2004)

*Re: (dvlax40)*


_Quote, originally posted by *dvlax40* »_wait for jeff to post he'll kno lol

I'll drink to that notion


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## at_the_speed_of_2.l0w (Jun 18, 2006)

*Re: AEG HEAD VS. ABA HEAD question (doodpod)*


_Quote, originally posted by *doodpod* »_larger bore the the AEG... 

...shorter stroke.























ABA and AEG have the SAME bore and stroke. Arrrrrg. Rod length and stroke are not the same! 
The MKIV (AEG, etc.) 8V has the same 5 oil drain holes that the 20V heads have. If you want to put it on an ABA block you will still have to plug the three middle holes.


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## ABF Jeff (Nov 16, 2005)

*Re: (doodpod)*


_Quote, originally posted by *doodpod* »_
I'll drink to that notion










Fraid to say I haven't had any experience with this particular hybrid... My mentality is that ABA heads are easy to find cheap, there's almost no point in messing with an AEG head...
As far as bolting it on, you will definitely need to put a MKIII 8V cam gear on it, which may or may not interfere with the cam sensor on the AEG head. The oil passages on the 20V head are only an issue because the 20V head sticks out over the block, the 8V does not... As for the port design and such, I do like the idea and theory behind the swirl ports, but the fact is that with the ABAs flatter rod ratio and capacity for high manifold vacuum, they would likely be more of a restriction than an asset... If you are trying to keep them for the added torque, I imagine you could make up the difference with a good cam choice and a good mild port to keep the air velocity up. Obviously speak with a good machinist about that, but it's all gravy from there on out.
The manifolds should be fine, but anything you buy in the way of exhaust should be taylored to an ABA because if it's taller block.
But honestly, why would you be so adament about using that head?


_Modified by ABF Jeff at 2:20 PM 1-13-2007_


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## all-starr-me (Jul 14, 2003)

*Re: AEG HEAD VS. ABA HEAD question (bulldoser62)*

all mexican obd2 heads also have that hump in the 8V to promote swirl and low speed velocity, so it will depend where you are looking to make power. The ports themselves should be larger on the AEG by little, even though the valves are the same size to keep velocity up, but a little port work on the ABA will help it out. Just buy obd 1 spring seats separately. 
That would be best to run dual valve springs on the ABA head. It seems that would be the best flowing, least extra work head to use, because, like you said the head bolt holes would need opened up, and I would still plug the 3 returns even though the gasket covers them just to keep them from ever leaking and you would need to change the cam gears. 
I have most variations of the ABA head on hand and all the manifolds from mk3's and 4's so I know them fairly well.


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## bulldoser62 (Apr 10, 2004)

*Re: AEG HEAD VS. ABA HEAD question (all-starr-me)*


_Quote, originally posted by *all-starr-me* »_ I would still plug the 3 returns even though the gasket covers them just to keep them from ever leaking 

Like i said be for these heads are identical as far as the face of the head goes *THERE IS NO HOLES THAT HAVE TO BE PLUGGED!!!!* pics below 

_Quote, originally posted by *ABF Jeff* »_
But honestly, why would you be so adament about using that head?


Either way i look at it i will have to get the dual valve springs. or buy a obd1 ABA head. so i was trying to figure out which head would be a better one to start with since i have them laying around. (trying to keep costs somewhat low.) 
I would like to find out if this "swirl" intake would help with a "scavenging" effect and if it would out perform a ABA head. both with mild port work. 
Anyone know of a shop with a flow bench in the PNW. prefer Oregon 

*ABA HEAD*








*AEG HEAD*


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## bulldoser62 (Apr 10, 2004)

*Re: AEG HEAD VS. ABA HEAD question (bulldoser62)*

i was doing some reading in my "Water cooled Volkswagen performance handbook" and noticed this paragraph. QUOTE, page 56
maybe this is my answer http://****************.com/smile/emthup.gif






















During the 1996 model year, VW modified the 2.0 liter heads to reduce combustion noise, exhaust emissions, and boost performance and economy. The intake port is a "swirl" design for better mixing of the air and fuel, and the port is offset from the axis of the intake valves for even more mixing as the incoming air/fuel charge enters the combustion chamber. The cam profile has been altered to match. As a result, these heads show big performance gains with porting and polishing and a performance camshaft. Bump the intake valve size from 40 to 42 millimeters, and the exhaust valve from 33 to 34 millimeters, and this head really starts to perform.


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## AgentAl (Dec 26, 2006)

*Re: AEG HEAD VS. ABA HEAD question (bulldoser62)*


_Quote, originally posted by *bulldoser62* »_these heads show big performance gains with porting and polishing and a performance camshaft. Bump the intake valve size from 40 to 42 millimeters, and the exhaust valve from 33 to 34 millimeters, and this head really starts to perform.


somehow i still remain sorta skeptical. i read in the big high altitude supercharger thread where neuspeed did a P & P on the 8v head in their test car and got only 10whp. seems to me you would go through all of this on a NA car and performance would be bumped about the same (+/- 7-8) with the addition of bigger valves and the cam. if it were as easy as bolt up the aba head and realize the same gains as porting the bev/aeg head then it might be worth it imo, however, from reading all of this im still not sure if its that easy


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## Jefnes3 (Aug 17, 2001)

*Re: AEG HEAD VS. ABA HEAD question (bulldoser62)*


_Quote, originally posted by *bulldoser62* »_
Anyone know of a shop with a flow bench in the PNW. prefer Oregon 




Call John at Bahn Brenner.
I am unsure if he has a flowbench, but he'll know where one is.

-Jeff


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## ABF Jeff (Nov 16, 2005)

*Re: AEG HEAD VS. ABA HEAD question (Jefnes3)*

I'm pretty sure Deano has one... last time I was up there, he was talking about starting to do more machining and headwork in-house.


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