2.5L AAF engine mods

[BigDan1]

my gas 2.5L vw engine was due for a timing belt replacement ,so I removed it from the eurovan ... just took my cyl head off ...plan to shave .040 to obtain 9.5 cr instead of the original 8.5 ....
head will be ported also ...
my main problem is the exhaust manifold ,,,it has a bellow between no:2 & 3 cylinder ...causing a major restriction ...is there any year that had a better tubular manifold ..
thanks ,
Dan

[gti_matt]

Yup, the 1995 ACU engine's manifold. Problem is, the outlet is a dual-outlet six-bolt arrangement which means swapping the downpipe too.

[BigDan1]

I`ll get the down pipe at same time then !


just cant remember where i saw someone do all those mods to a 2.5L and gained 20 hp ...

[gti_matt]

Unfortunately both parts are a bit pricey new.

It was someone on this forum though. I think he had a red '93 that he put the ACU manifold and downpipe in as well as some other mods like polishing the intake or something like that.

[EV99]

Unfortunately both parts are a bit pricey new.

http://www.worldimpex.com/parts/genu...ol_127007.html
http://www.worldimpex.com/parts/genu...ipe_40038.html

It was someone on this forum though. I think he had a red '93 that he put the ACU manifold and downpipe in as well as some other mods like polishing the intake or something like that.

http://forums.vwvortex.com/showthrea...7#post70571917

(Pics gone from there but they WERE in there)

Header pic:


For ref the cast iron version:

[gti_matt]

http://www.worldimpex.com/parts/genu...ol_127007.html

Europarts $140 cheaper.
http://store.europarts-sd.com/exhaus...1995-1996.aspx

http://www.worldimpex.com/parts/genu...ipe_40038.html

Can't find that one on Europarts' site now but used to be there. Not sure what happened to it. Maybe I'm not searching on the right keyword...?

[url]
Header pic:


For ref the cast iron version:

Yep, note the different bolt connections for first exhaust pipe, hence why you need that too.

[EV99]

Yep, note the different bolt connections for first exhaust pipe, hence why you need that too.

Heh I had saved the pic of the red one:

[gti_matt]

Yep that's the one I remember (I remember it was a red van and red valve cover).

[BigDan1]

finally got a 96 manifold + down pipe from just around my place at a good price ....

my cylinder head is ready to reinstall ( pic soon)

Can I reuse the original bolts ?

[gti_matt]

Nope. Cylinder head bolts are stretch bolts and should not be re-used. Gotta get new ones.

[BigDan1]

ARP doesnt make any new ones ....

dealer only ?

[gti_matt]

ARP doesnt make any new ones ....

dealer only ?

Cylinder head bolts? europarts-sd.com has them. I got mine there.

[Kwabena]

Anyone have a picture of the downpipe for the ACU manifold?

I found one on google of both together, but a close up of the downpipe alone would be great!

[tds3pete]

http://groups.yahoo.com/group/ev_upd...unt=20&dir=asc

Will this help?

[Kwabena]

I found that one the other day.
Thanks though!
It's pretty good.
Wanted one with just the downpipe.
My mechanic in Ghana has found me the manifold, but now is looking for the downpipe and wanted a good pic...

[gti_matt]

my main problem is the exhaust manifold ,,,it has a bellow between no:2 & 3 cylinder ...causing a major restriction ...is there any year that had a better tubular manifold ..

I hadn't noticed before but note that the ACU manifold has it's own version of some sort of accordion-flex thing (although it looks welded in?) between the #1 cylinder's tube and the exhaust outlet too.

It's likely to flow better I guess but still has some limitations. The biggest gain with this one is that so far it's not known to suffer the same failures as the AAF manifold.

[ispy]

Anybody know the I.D. of the tubing on the '95 manifold?

[Scirocco53]

I can measure it, but I can tell you from the one that I have that it is very small, and looks like it does not flow well at all.