which exhaust tube diameter
Thread Starter
Junior Member
Joined: Aug 2015
Posts: 31
Likes: 1
From: Virginia
Car: 1985 T-Top RS
Engine: 350
Transmission: currently a T-5
Axle/Gears: 3.23
which exhaust tube diameter
Have an 85 z28 that I have dropped a crate motor that is rated 290hp. I have read many threads and I am unsure if I should use 2.5 or 3 inch pipe. A little help please.
Supreme Member
Joined: Apr 2006
Posts: 4,482
Likes: 10
From: Northern, CA
Car: 1989 Iroc-Z Camaro
Engine: TBI,5.0
Transmission: Automatic 700R4
Axle/Gears: Eaton Posi,3.42,LPW Ultimate Cover
Re: which exhaust tube diameter
There are many , many here that build there car taking into consideration and upgrade in power some day. There are those that plan for "a lot" more power and will run true duals with long tube headers. Some use 2.5 pipe to keep backpressure/velocity/etc.
That is the only time 2.5in IMO should be considered.
A nice true 3" system with "shorty" headers is what IMO should be used for power in the range your in.
That is the only time 2.5in IMO should be considered.
A nice true 3" system with "shorty" headers is what IMO should be used for power in the range your in.
Last edited by Ron U.S.M.C.; Oct 9, 2015 at 01:25 AM.
Joined: Aug 1999
Posts: 19,282
Likes: 103
From: Lawrence, KS
Car: Met. Silver 85 IROC/Sold
Engine: 350 HO Deluxe (350ci/330hp)
Transmission: T-5 (Non-WC)
Axle/Gears: Limited Slip 3.23's
Re: which exhaust tube diameter
Here's the direct-fit, 3" system that I'm using in my 85 IROC (GM crate 350/330):
Hooker 2055's (Jeg's 520-2055). Catco high-flow converter (Summit CTO-9118). Hooker catback (Summit HOK-16823HKR).
JamesC
Hooker 2055's (Jeg's 520-2055). Catco high-flow converter (Summit CTO-9118). Hooker catback (Summit HOK-16823HKR).
JamesC
Joined: Mar 2014
Posts: 4,557
Likes: 817
From: South Ms
Car: 89 Firebird
Engine: 355 TBI
Transmission: 700R4
Axle/Gears: 10 Bolt.Posi-3.73s
Re: which exhaust tube diameter
There are many , many here that build there car taking into consideration and upgrade in power some day. There are those that plan for "a lot" more power and will run true duals with long tube headers. Some use 2.5 pipe to keep backpressure/velocity/etc.
That is the only time 2.5in IMO should be considered.
A nice true 3" system with "shorty" headers is what IMO should be used for power in the range your in.
That is the only time 2.5in IMO should be considered.
A nice true 3" system with "shorty" headers is what IMO should be used for power in the range your in.
Joined: Apr 2004
Posts: 3,001
Likes: 62
From: Salt Lake City, Utah
Car: 1988 camaro "SS"/ 1991 305/T5
Engine: 383 LT1 in progress/LT1TBI 355 soon
Transmission: Probuilt 700R4 3600 stall/ T5
Axle/Gears: Moser axles, 3.42 Eaton Posi
Re: which exhaust tube diameter
The only thing I HATE about the 2055's are the collectors. When I had mine I measured the collectors and they were only 1.75!! That's why for a budget build I use the 2460's, a Doug's D901 y pipe modified with a 3 inch outlet. Much better flow in my opinion
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