When is 3" Piping Justified?
Thread Starter
Racer
Joined: Mar 2003
Posts: 261
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From: Philadelphia PA
When is 3" Piping Justified?
GM developed a 2.5" piping system to support the stock LS1 and LS6 motors.
It has been proven that stock engines can gain 15-25 RWHP from a good set of headers (with a tune) and 8-10 RWHP from removal of the stock cats.
At what RWHP/RWTQ does larger 3" piping become justified (i.e., significant gains throughout the entire RPM range)? Is a header upgrade with or without larger, aftermarket cats alone enough? It seems the header manufacturers think so, but I want some proof.
Anyone?
It has been proven that stock engines can gain 15-25 RWHP from a good set of headers (with a tune) and 8-10 RWHP from removal of the stock cats.
At what RWHP/RWTQ does larger 3" piping become justified (i.e., significant gains throughout the entire RPM range)? Is a header upgrade with or without larger, aftermarket cats alone enough? It seems the header manufacturers think so, but I want some proof.
Anyone?
Last edited by AN1313; Dec 22, 2004 at 04:23 PM.
Thread Starter
Racer
Joined: Mar 2003
Posts: 261
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From: Philadelphia PA
Could it be that headers alone (no X-pipe) are worth up to 15 RWHP and the X-pipe is worth up to 10 RWHP? This would explain why the best header/X-pipe systems make a max of around 25 RWHP.
Since removing the stock cats is worth around 10 RWHP, is there essentially no gain from going with a 3" X-pipe over the 2.5" H-pipe for non-max effort applications?
Since removing the stock cats is worth around 10 RWHP, is there essentially no gain from going with a 3" X-pipe over the 2.5" H-pipe for non-max effort applications?
Team Owner
Joined: Mar 1999
Posts: 22,025
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From: At the beach in little Rhody
What I was told when I bought mine, since the QTP system can be assembled with either, was that their 2-3/4" system was fine for a stock cubic inch motor. Not sure it is a horsepower cutoff, but rather it might be a cubic inch cutoff that determines the need.
Thread Starter
Racer
Joined: Mar 2003
Posts: 261
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From: Philadelphia PA
I was thinking that the more HP you are making, the more exhaust gasses you have to flow. Therefore, there would be a point where it makes sense to upgrade to a bigger pipe diameter.
Do 346 CI engines with max-effort head and cam combinations (i.e., <500 RWHP) really benefit from larger pipe diameter?
Do 346 CI engines with max-effort head and cam combinations (i.e., <500 RWHP) really benefit from larger pipe diameter?
Instructor
Joined: Jun 2002
Posts: 239
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From: Port Orange Fl
if you spend most of your time at wide open throttle and lots of revs, then a bigger pipe is better, but if you are a daily driver at lower rpm and using lower torque more a smaller pipe is better, Corvette exhaust flows very well even stock. FYI look under a Viper 2 1/4 pipe for the big V10
Thread Starter
Racer
Joined: Mar 2003
Posts: 261
Likes: 0
From: Philadelphia PA
So for a street application with a medium size cam and stock Z06 heads, 1 3/4" headers going into the stock 2.5" H-pipe makes the most sense? If I want more HP, I can delete the cats or go for a non-exhaust mod.
All the high end headers seem to be packaged with 3" X-pipes these days. So these "systems" are for high HP (>500) or racing type applications (narrow, high RPM range)?
All the high end headers seem to be packaged with 3" X-pipes these days. So these "systems" are for high HP (>500) or racing type applications (narrow, high RPM range)?
