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Pipe size opinion?

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Old Mar 12, 2008 | 05:21 PM
  #1  
85SILVERBULLET1's Avatar
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From: Rio Rancho, New Mexico
Car: 85 Trans Am
Engine: 383 ci
Transmission: Liberty Geared Tko 600
Axle/Gears: Moser 9" 4.11 gear wavetrac locker
Pipe size opinion?

Ok so i am at the cross road on the y-pipe setup. I had hedman shorties, custom y-pipe 3 inch pipe back to a flowmaster with 4" tips. I am ditching this set-up for Hooker long-tubes coated and a true dual set-up. I am going to be running spintech mufflers and i will prob dump before the rear axle. Here is my question. Should i go with 2.5" pipe or 3" pipe. The motor on N20 is going to be 600-650 rear wheel horsepower and NA it will be at around 400 hp. I am at 5000+ feet. What do you guys think?
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Old Mar 13, 2008 | 07:06 AM
  #2  
calebzman's Avatar
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From: Charleston, SC
Car: '85 TA
Engine: 350 turbo
Transmission: T56
Axle/Gears: 3.70 posi 9bolt
Re: Pipe size opinion?

A dual 2-1/2" exhaust flows more than a single 4", so I don't see how that can't be enough.
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Old Mar 13, 2008 | 07:42 AM
  #3  
L69HAWK's Avatar
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From: s.n.j.
Car: 1984 T/A WS6
Engine: L69 305
Transmission: 700r4
Axle/Gears: fact G80 with GT4 3.73
Re: Pipe size opinion?

Originally Posted by calebzman
A dual 2-1/2" exhaust flows more than a single 4", so I don't see how that can't be enough.
u might want to read that again. he has 4" tips and a 3" c/b

with that kind of power i would go 3" dual. only b/c when u juice it it won't flow enough imo,with 2.5" duals. and 400 h/p is enough to justify 3" if its at the wheels that ur talkin about.
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Old Mar 13, 2008 | 10:28 AM
  #4  
85SILVERBULLET1's Avatar
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Joined: Feb 2007
Posts: 169
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From: Rio Rancho, New Mexico
Car: 85 Trans Am
Engine: 383 ci
Transmission: Liberty Geared Tko 600
Axle/Gears: Moser 9" 4.11 gear wavetrac locker
Re: Pipe size opinion?

I put the car on the dyno last year and made 338 rear wheel horse power with lots of problems(@5000 feet). I had a pertronics dizzy that had all kinds of issues, a carb that was to small, a crap fuel system ,+ the small exhaust. We were only able to twist the motor to 5700 rpm before it had detonation to the moon. The cam is rated to 7200 rpm so we were not even close to full potential of the motor. Anyway since the last dyno visit i have purchased, holly 950hp BY Bigs, msd dizzy, digital 6, hvcII coil, msd 8.8 wires, Hooker long tubes, and i am working on a full aeromotive fuel system with a sump.

Anyway back on topic i think 3 inch will prob work. Does anybody have any pics of a dual exhaust with 2.5 or 3" and spintech mufflers. I did a search and did not find much mabe a sound clip would be cool.
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Old Mar 20, 2008 | 12:30 PM
  #5  
85SILVERBULLET1's Avatar
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Joined: Feb 2007
Posts: 169
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From: Rio Rancho, New Mexico
Car: 85 Trans Am
Engine: 383 ci
Transmission: Liberty Geared Tko 600
Axle/Gears: Moser 9" 4.11 gear wavetrac locker
Re: Pipe size opinion?

bump for a pic of a spintech set-up
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