SameerP

I started thinking about this because i noticed a company had an ad in Autoweek that they will provide extrude honing services, you just send in the part.

In case you are unfamiliar with extrude honing, its a process whereby a gritty putty is forced through the manifold, which greatly smooths the interior of these parts, and allows better airflow, thus making more power. The Contour SVT was the first production car, IIRC, which used this...and Ford claimed that extrude honing gave the SVT Contour about 10hp.

I called APR and asked them about this, and they told me it didn't seem to be an effective thing for the A4...but they didn't really give me specifics (this is not a flame guys!).

So to y'all i ask...anyone have opinions? It might be interesting to send a manifold down to them and see what kind of results one can get.

Cheers

KrautRice_A4 atl-atl

I say go for it, it works for Jap turbo cars, if you have the money, try it!

siberian

Isn't that why they supply a new manifold with the stage 3 kit?

SameerP

is that its expensive, from what i understand, to design a great exhaust manifold for our cars, and the limited numbers of A4's means that it will not be a cost effective project for a tuner to undertake. I know the turbo complicates this picture...what i was thinking was that extrude honing might be a nice halfway point to manifold replacement.

So you need help when you move to CHICAGO Mark? Let me know, ill be glad to lend a hand

Cheers

Ray Khan

so it won't fir the stock manifold

Ray Khan

the turbo kicks. So there must be some nice gains to a better flowing or extruded stock manifold.

BOOSTD

yes, I did, and yes, it does. turbo spoolup is seamless.

audigone

Doesnt the stage three replace the manifold, ask these guys specifically.

DD

Not trying to be preachy, but some people are just unaware.

My gf is Japanese. Her grandparents spent time in Manzanar, the Japanese-American prison camp, during WWII.

They lost everything they had.

JakeL1.8T

...in a stock A4, the exhaust manifold is not the primary restriction. Some folks say it's a bad design, others say it's just fine, I don't really know one way or another. However, the bottom line that I've been told by 3 tuners, all of which do, or used to sell, an Extrude-honed manifold, all say that the teensy-weensy housing on the K03/04 turbos is the restriction, not the exhaust manifold.

I mean, think about a hose and water - if you kink one part of the hose, you could have a firehose before and after the kinked off part, and it doesn't make a whit of difference.

When APR gives us the big GT25 turbo, the exhaust manifold can't flow enough air in comparison to the new, larger housing'ed turbo, and therefore it was a wise engineering decision to give us a well-designed manifold.