OHV exhaust manifold sizing?? - Second Generation Forum

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OHV exhaust manifold sizing??
Thursday, April 28, 2005 11:21 PM
Anyone else ever notice that the exhaust manifold on a 94 2.2 Cavalier is significantly smaller than a 90 2.2 one? Porting the exhaust manifold is my last step, and I gotta choose which one to use. The hot rodder in me says to use the bigger one hands down, but I find it strange they shrunk the manifold when they added power (roller cam in 94).... ?

Tonight I finished porting my head (pics tomorrow), got the MPFI intake already ported, located a 95 2.2 motor, and got the fuel fitting situation figured out for the 95 2.2/MPFI swap into my 90 Cav.

Any thoughts on the manifolds?



JLP
01' 5 speed Z <--- 03' 15.2 @ 90
79' Blue Monte <--- 03' 12.18 @ 110.86

Re: OHV exhaust manifold sizing??
Monday, May 02, 2005 6:20 PM
I'm pretty sure the older 2.2 manifolds are smaller than the 2.0 OHV manifolds also. Why? I have no clue. I can only guess that it was made smaller for a different powerband.




Re: OHV exhaust manifold sizing??
Monday, May 02, 2005 8:41 PM
Thanks for the reply James.

The 2.0 OHV motors used a pretty crappy style manifold. It was a straight tube connecting all the cylinders, and had one small outlet pipe leading to the downpipe.

In 90 with the addition of the 2.2, it got a new manifold more resembling a header. Much larger than the 2.0 style. It actually is a pretty decent piece, with nice smooth transitions inside of it.

The 94 manifold I have resembles the 90 exactly in appearance, other than being smaller. I went ahead and ported the bigger 90 one.. I figure my car is a light 5 speed setup anyways, so torque wont be *quite* as important.

Interesting discovery though. Hmm, I currently have a 93, I'll check the manifold on that.



JLP
01' 5 speed Z <--- 03' 15.2 @ 90
79' Blue Monte <--- 03' 12.18 @ 110.86
Re: OHV exhaust manifold sizing??
Tuesday, May 03, 2005 4:11 AM
The cast 2.2 manifold used up to 93 is substantially larger than the 94-96 part. I checked an old post of mine to see what I found when I installed the 94-96 spec engine in my 93. I'd written that the "runners" of the older manifold were about 1/4" larger and the "collector" was about 1/2" larger. I think James may be right, that GM was trying to enhance torque with the smaller design. I also wonder if the later manifold tended to aid emissions. More iron in the manifold would tend to retain heat better at idle. Anyway, I felt that the roller cam engine and larger exhaust manifold were a good combination when the engine was still NA.

-->Slow
Re: OHV exhaust manifold sizing??
Sunday, May 08, 2005 7:45 PM
i found that out also when i bought some parts off my friend with a 92 auto, i ported that one also before putting on my car. An amazing difference in size when compared to my 94's.if your still looking for a 2.2 let me know.


cavaliers been laid to rest
The saturn is being born
a new cavalier is in the mist
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