what size exhaust?
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New User
Joined: Oct 2004
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what size exhaust?
I am trying to find what size exhaust to run on my new 3.0 in my 91 ranger. I currently have jba headers, a new catco converter, and a one chamber flowmaster on it. It just doesn't seem to have enough back pressure. My engine has an intake,underdrive pulleys, plenum spacer and a hot grind cam. It seems to pull hard off the line to about 4,000 rpm, but just seems to run out after that. Should I get a 2 chamber and bump it down to 2.25" tubing. Right now it is 2.5". Thanks
Post Fiend
Joined: Jan 2000
Posts: 5,860
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From: Metro Detroit (Redford)
Back pressure really is not good for power production, but engines are generally designed with a certain amount of back pressure in the equation since factory exhaust is fairly restrictive. To take advantage of lower back pressure other mods might be needed, but I am not the one to get into those specifics.
However, if it pulls really hard up to 4000, then is back pressure really the issue? Or is there some other problem. Perhaps you need more fuel? A performance EFI engine may need bigger injectors or something like that. And what about the intake side. Aren't Fords rather well known for being restrictive on the intake side?
Anyway, just some thoughts.
However, if it pulls really hard up to 4000, then is back pressure really the issue? Or is there some other problem. Perhaps you need more fuel? A performance EFI engine may need bigger injectors or something like that. And what about the intake side. Aren't Fords rather well known for being restrictive on the intake side?
Anyway, just some thoughts.
Elder User
Joined: Apr 2005
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From: UTI student
A performance EFI engine may need bigger injectors or something like that.
I forgot about that I have to run 24# injectors on my 3.0 /2.5 hybrid. I would take it to a dyno tune and have them look at it. You may be starving for fuel at higher RPM's
I forgot about that I have to run 24# injectors on my 3.0 /2.5 hybrid. I would take it to a dyno tune and have them look at it. You may be starving for fuel at higher RPM's
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I had bigger injectors on it when I first built the engine, but they were too big so I had the stock ones flowmatched and I have an adjustable fuel regulator. I have it set to factory pressure so I guess I could try to play with it a bit.
