5" versus 4" exhaust

[mrjohnwayne]

Originally Posted by merlin5577

+1.

With the stock turbo and a (relatively) stock truck the 5" will not help perfomance any, and with the catalytic converter removed might actually hurt it. Turbochargers need a certain amount of back pressure to fuction properly, and in this case, bigger is not better. A 4" exhaust will work just fine.

I agree with this!

To the OP - a 4" can and will actually take away from the low end on these trucks. because of lower "back pressure" you also have a lower drive pressure on the exhaust side of the turbo. lower drive pressure takes longer to spool the turbo. 5" will make it even worse.

Again on a stock truck with an edge and air intake 4" is all you need.

[vinniepro]

go with 5 inch, more flow threw the pipe more power better milage nicer sound

[FaselZ71]

Originally Posted by vinniepro

go with 5 inch, more flow threw the pipe more power better milage nicer sound

This is a stock turbo diesel he needs some backpressure for torque and to spool that turbo... 5" will only reduce back pressure thus adding turbo lag and lowering torque!


P.S. Yes I'm sorry for the rudeness I've been acting really awful lately and I'm not sure what the matter is but I'm sorry...

[stumpuller454]

Originally Posted by FaselZ71

This is a stock turbo diesel he needs some backpressure for torque and to spool that turbo... 5" will only reduce back pressure thus adding turbo lag and lowering torque!

I was gonna say that but.........you did!

[gmctrucks]

Leave it alone your going to waste your money why don't you change out all your fluids to Royal Purple.

[merlin5577]

Originally Posted by vinniepro

go with 5 inch, more flow threw the pipe more power better milage nicer sound

Not necessarily true. A 5 inch will flow more all things being equal, but we are not talking equal. Hotter gasses flow faster then cold gasses so a smaller pipe (within reason) will keep the heat in more, increasing flow.

Plus as mentioned before, this truck has a stock turbocharger.

[merlin5577]

Originally Posted by gmctrucks

Leave it alone your going to waste your money why don't you change out all your fluids to Royal Purple.

+1

One of the best moves I ever made.

[batty1214]

I just installed a CATerpillar 3208 diesel into a 1995 ford 9000 truck and they sent a 4" down pipe and exhaust with it... so I thik that a four would probably set you up quite nice

[bradrhale]

4 inches out of an 8 cylinder cat?? sounds right to me. i have 6 coming out of these 3406's.

[Lonesome7.3]

You all are forgetting something. With a five exhuast, he can say he has five inch exhuast. Duh.

I am running five in now and I have to go bigger. But then again, I have way more done to my truck. Stay with four unless you plan to change a bunch of stuff in the near future.