X pipe diameter?
Thread Starter
Melting Slicks
Joined: Mar 2004
Posts: 3,472
Likes: 18
From: Lake Ozark, MO
X pipe diameter?
Would there be any adverse affect to installing a 3 inch X pipe on a 2.5 inch system? X pipe is on the shelf so no added cost incurred is the reason for asking.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
I've heard mixed results from people that installed an X-pipe. Low RPM engines will probably not see much of a gain...at least not worth the install time and effort. For higher RPM operation...I've heard it can help some, and improve sound.
Team Owner
Joined: Nov 2004
Posts: 20,715
Likes: 25
From: Sorrento Italy
Drifting
Joined: Sep 2006
Posts: 1,986
Likes: 21
From: Columbus MN
This has been discussed quite a bit on the CF. Do an advanced search. The effect on performance gets mixed responses.
Check out the http://www.popularhotrodding.com/eng...xh/index1.html article for the theory.
As for me, I got a big jump in output from GMPP 350 HO crate his autumn due solely to exhaust changes, but I don't know how much gain came from switching from block hugger headers to full length headers and how much came from the H-pipe cross over I added.
Check out the http://www.popularhotrodding.com/eng...xh/index1.html article for the theory.
As for me, I got a big jump in output from GMPP 350 HO crate his autumn due solely to exhaust changes, but I don't know how much gain came from switching from block hugger headers to full length headers and how much came from the H-pipe cross over I added.
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
I also feel if you are jumping from 2 1/2 inch exhaust to a 3 inch X you would have problems with the transissions on the sizes??
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Nah, I've seen 2.5" to 3" size adapters at Autozone for a few bucks each. I've gone from a 4" collector to a 2.5" pipe before.
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
I just want neater work on my car.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
You're right there, and I agree. It did look awkward with a large step down in size like that.
Melting Slicks
Joined: Dec 1999
Posts: 2,116
Likes: 156
From: Mid West
Cruise-In III Veteran
Dr. Gas has some nice smooth transitions that could be welded in so the assembly would be tidy looking.
http://www.drgas.com/store/product.p...&cat=14&page=1
http://www.drgas.com/store/product.p...&cat=14&page=1
Melting Slicks
Joined: Dec 1999
Posts: 2,116
Likes: 156
From: Mid West
Cruise-In III Veteran
Actually, the one I use starts out at 3" and reduces to 2.5". I got it from Dr. Gas so I could run 3" pipe up to the x-pipe and then run 2.5" back to my Borla mufflers that I already owned for several years.
Melting Slicks
Joined: Dec 1999
Posts: 2,116
Likes: 156
From: Mid West
Cruise-In III Veteran
The x-pipe helped eliminate a nasty resonance near cruising speed that I was getting with the Borla's. Before the new exhaust the Borla's sounded like glass packs to me (way too noisy), but after I put the 3" pipes on the car sounds sweet. 
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
It depends how restrictive your exhaust is now.
So what what i'm saying is that the more restrictive your exh sys is now the more the X-over will help. The more free flowing exh capacity u have now the less improvement u will see.
As for the 2.5" to 3" back to 2.5" it would only reduce restiction and act as more of a balance/resonance chamber and that should be an improvement also.
Just the problem is will it all fit?
Hope this helps and good luck.
cardo0
Thread Starter
Melting Slicks
Joined: Mar 2004
Posts: 3,472
Likes: 18
From: Lake Ozark, MO
I'm going to give it a go. Going from 3 1/2 in collectors on the BB header to 2 1/2. 3 " X-pipe will be installed immediately after the crossmember and reduce to a 16" length of 2 1/2, then into the Flowmaster 40s. (everything will stay under the car and not exit the rear).
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
I'm going to give it a go. Going from 3 1/2 in collectors on the BB header to 2 1/2. 3 " X-pipe will be installed immediately after the crossmember and reduce to a 16" length of 2 1/2, then into the Flowmaster 40s. (everything will stay under the car and not exit the rear).
Dumping out the rear at least lets you run away from the noise.
The other problem is dust. If you have turn downs at the end of the exhuast system it really kicks up the dust, clouds of dust and the wilder the cam the more dust you kick up.
Safety Car
Joined: Nov 2005
Posts: 3,961
Likes: 573
From: Lompoc, CA. Santa Barbara County
Earlier this year a forum member posted dyno results for his X-pipe and it was approx 5% accross the rpm band. But he was running stock iron exh manifolds too. This was on a GM crate 383 shortblock installation.
So what what i'm saying is that the more restrictive your exh sys is now the more the X-over will help. The more free flowing exh capacity u have now the less improvement u will see.
As for the 2.5" to 3" back to 2.5" it would only reduce restiction and act as more of a balance/resonance chamber and that should be an improvement also.
Just the problem is will it all fit?
Hope this helps and good luck.
cardo0
So what what i'm saying is that the more restrictive your exh sys is now the more the X-over will help. The more free flowing exh capacity u have now the less improvement u will see.
As for the 2.5" to 3" back to 2.5" it would only reduce restiction and act as more of a balance/resonance chamber and that should be an improvement also.
Just the problem is will it all fit?
Hope this helps and good luck.
cardo0