3b manifold on 7a

[andy112]

Hey Ive got a quick question, will a 3b manifold fit a 7a head without any modification?

[Acidburn]

I was thinking about this as well as it would be interesting if it does, i'd have thought it would do, and because the inlet does not go over the top of the engine it should hopefully bring the temp down slightly, hopefully keeping the glorious sound of the 20v.

[gedu]

It should, as only things you need to machine on 7a head when fitting to 3b/aby/adu/aan is hall sensor place and water manifold.

of course, what it does to torque and power curves is anyones guess

[Error404]

if someone wants to donate a 3B manifold i can test fit it when i swap man 7A IMs over.
does the 7A TB mate up to the 3B IM?

[stiglet]

Is this for an unmodified 7A?

[anton]

the manifold would fit the head but not the throttle body, 7a has a dual stage throttle (2 butterfly valves) 3b has only 1. if this is for a na engine it is not advised as the long runners are there to improve torque, you may get a small increase in top end. but assuming this is for a turbo application, you should be all good have a look on motorgeek, i'm sure someones running a 3b manifold on there na 7a.

Ant

[20Vcqdriver]

the manifold would fit the head but not the throttle body, 7a has a dual stage throttle (2 butterfly valves) 3b has only 1. if this is for a na engine it is not advised as the long runners are there to improve torque, you may get a small increase in top end. but assuming this is for a turbo application, you should be all good have a look on motorgeek, i'm sure someones running a 3b manifold on there na 7a.

Ant

I second those comments. If adding to a normal 7A you would loose low speed torque, not something the NA 7a has a lot of!

[stiglet]

Yep was thinking this. I think the manifold on the 7A is for harmonic resonance. I don't know what RPM's it's designed for, likely for mid range torque.

[andy112]

Sorry guys it was late here and I forgot to mention that this is an exhaust manifold. The reason I'm asking is because I'm getting a flange made and I need a 1 piece gasket to get the pattern off of and the 7a has 5 individual gaskets. So with out modding the head will it fit? Based on etka a few runners for the 3b have 3 bolts holding them and the 7a has two will the tab for the third bolt get in the way?

[anton]

yes, no fitment issues, i'm currently using an s2 gasket on my 7a. many people are using 7a heads on a 3b and aby

Ant

[Acidburn]

yes, no fitment issues, i'm currently using an s2 gasket on my 7a. many people are using 7a heads on a 3b and aby

Ant

Probably why the gasgets cost that much (unless it was alex who was saying how much he spent?)

[anton]

was al i think, but mine was the same from audi, got mine cheep from azman tho.

Ant

[stiglet]

Probably why the gasgets cost that much (unless it was alex who was saying how much he spent?)

I bent over for mine.

[andy112]

One more question anyone know the size of the ports on the gasket? I had to order my gasket and was just wondering if anyone can answer before I get it next week, don't worry your self over it if you don't, I was just curious.