Author Topic: Gmc v6 (lgz) exhaust “downpipe” help  (Read 1268 times)

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Offline Slide

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Gmc v6 (lgz) exhaust “downpipe” help
« on: August 09, 2018, 03:26:41 AM »
Gmc/Chevy has these 3.6 V6 with the exhaust manifold collector cast into the head. There is a single port exiting the head on each side.

It then goes through a pipe with a cat, and then on the Chevy Colorado/gmc canyon, finds its way into a real crappy, unequal length “Y” pipe that has a cat/resonator in it... It merges there and then goes to the back through a muffler and resonator.

I really am at a loss for trying to find power in this bit of pipework. Getting rid of the cat/resonator (not sure which it is) reports gains of about 15 whp on the dyno with little to no tuning.

If I’m going to take the resonator out, I was debating fabricating the Y pipe into as close to equal length as possible for the collector.

Space is limited but I could probably get real close to equal length if one of the tubes has a real tight 180 U... not excited about that.

So I guess my question is, does the equal length of the piping matter since the merge collection of 3 cylinders has already occurred in the cast head?

Does it matter how close or far away the y pipes collect from 2 to 1?

I’m trying to find pics and post.