3" Catback??
Thread Starter
Melting Slicks
Joined: Jul 2002
Posts: 2,072
Likes: 3
From: Walled Lake MI
3" Catback??
I might be able to get a good deal on a custom bent 3" catback for my 87, would this actually help or would it just make the car louder ,which is ok too. Right now I have the stock 2.25" exhaust with a set of KBD Targas, if I were to do the swap should I keep the targas or get something like a set of Flowmaster 40 series...opinions please :cheers:
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: 3" Catback?? (Storz)
Your stock cat-back with crinkle bends is likely much less than 2 1/4" at the bends so a 3" mandrel-bent is a very good idea.
You should also upgrade the front Y and go with a hi-flow cat to get the most gain. You will likely have to upgrade the mufflers to match the 3" cat-back.
Then an AFPR will allow you to add more fuel at WOT to match the increased air flow.
You should also upgrade the front Y and go with a hi-flow cat to get the most gain. You will likely have to upgrade the mufflers to match the 3" cat-back.
Then an AFPR will allow you to add more fuel at WOT to match the increased air flow.
Racer
Joined: Jun 2002
Posts: 428
Likes: 0
From: Dallas Tx
Re: 3" Catback?? (Storz)
A Stock 87 350 has most of the exhaust restriction in the mufflers themselves. 2.5" duals are adequate. As you modify for more HP, flow needs increase. A 383 developing 400 HP will benefit from 2.75" and over 450 HP will like 3" duals, or some equivalent siamesed arrangement.
At WOT and high RPM, the muffler is often still the greatest restriction.
Downside of large pipes on a stock motor is reduced exhaust gas flow velocity. This can reduce HP slightly, especially at mid RPM's. Wrapping the exhaust will offset this to some extent.
Also, on any motor, when you improve exhaust flow with headers, better mufflers, or larger pipes, you really should check the WOT fuel mix to make sure it is still optimum for best HP. Often it will lean out some. Checking with a Diacom, etc. is the only way to know for sure.
At WOT and high RPM, the muffler is often still the greatest restriction.
Downside of large pipes on a stock motor is reduced exhaust gas flow velocity. This can reduce HP slightly, especially at mid RPM's. Wrapping the exhaust will offset this to some extent.
Also, on any motor, when you improve exhaust flow with headers, better mufflers, or larger pipes, you really should check the WOT fuel mix to make sure it is still optimum for best HP. Often it will lean out some. Checking with a Diacom, etc. is the only way to know for sure.
Thread Starter
Melting Slicks
Joined: Jul 2002
Posts: 2,072
Likes: 3
From: Walled Lake MI
Re: 3" Catback?? (tkrussell)
the muffler is often still the greatest restriction.
Are the targas considered a pretty free flow muffler or are they restrictive compared to say a flowmaster or borla muffler
[Modified by Storz, 9:16 PM 7/19/2003]
