I replaced my 87 GTA 350 TPI exhaust manifolds with edelbrock headers. I'm wondering if I can use these 350 TPI exhaust manifolds on my 94 350 TBI Chevy truck for increased exhaust flow? The truck manifolds look smaller. I would assume the exhaust ports on these 350 heads, TPI and TBI are probably the same. Any comments?

 

Any comments?

 

I s'pose your GTA exhaust manifolds have a greater internal volume and better internal geometry than the ones on your truck. I think a visual comparison ought to do the trick. Still, I'm not sure whether such a swap is worth the trouble or not. Engines have come a LONG way since the bad ol' days of low-compression 1970's smoggers! Back then, just about ANYTHING was an improvement.

Unlike headers, exhaust manifolds (good ones) operate on the "expansion" principle. At low RPMs, the exhaust slug comes out of the port and disperses in the common chamber. This presents the least backpressure AT LOW RPMs. At high RPMs, the lack of direction causes excessive turbulence and backpressure increases. Where the myth of "some backpressure is good" came from, I'll never know. Low RPM torque comes from the open space of the manifold, NOT backpressure!

Of course, some manifolds are just plain sorry and were designed with tight spaces or corporate bean counters in mind.

 

jrr,
Thanks for the reply.
The TPI manifolds runners look a bit larger than the TBI manifolds and I believe the diameter of the exhaust exit, at the stock collector, is also a larger diameter which I believe would aid the exhaust flow and thus the engine output.
DS

 

If you really want to help your truck, put the Edelbrock headers on it, and get some SLP headers for your GTA.

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