Custom Rear mount questions
Custom Rear mount questions been thinking of doing a rear mount on a friends car. Building a forged 6.0L and looking for around 700rwhp.
Questions-
1. Sizing a turbo, how different is this for a rear mount than a front mount, A/R differences, what is better/needed for rear mount?
2. Manifolds/headers/ exhaust piping size- We have shorty headers but if manifolds will achieve these HP goals with better spool up that will work. Will it? And what size piping is optimal for going from engine to turbo? Im guessing 2.5" Y-pipe going to a single 2.5" over the axle to the turbo. I know it sounds small but giving the long run I think it would hold heat in and allow for better velocity. Am I wrong? Will it achieve 700rwhp?
What size is everyone else using? 3" ok? worse? better?
thanks,
Questions-
1. Sizing a turbo, how different is this for a rear mount than a front mount, A/R differences, what is better/needed for rear mount?
2. Manifolds/headers/ exhaust piping size- We have shorty headers but if manifolds will achieve these HP goals with better spool up that will work. Will it? And what size piping is optimal for going from engine to turbo? Im guessing 2.5" Y-pipe going to a single 2.5" over the axle to the turbo. I know it sounds small but giving the long run I think it would hold heat in and allow for better velocity. Am I wrong? Will it achieve 700rwhp?
What size is everyone else using? 3" ok? worse? better?
thanks,
Teching In
Joined: Feb 2006
Posts: 35
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Originally Posted by pwrtrip75
been thinking of doing a rear mount on a friends car. Building a forged 6.0L and looking for around 700rwhp.
Questions-
1. Sizing a turbo, how different is this for a rear mount than a front mount, A/R differences, what is better/needed for rear mount?
2. Manifolds/headers/ exhaust piping size- We have shorty headers but if manifolds will achieve these HP goals with better spool up that will work. Will it? And what size piping is optimal for going from engine to turbo? Im guessing 2.5" Y-pipe going to a single 2.5" over the axle to the turbo. I know it sounds small but giving the long run I think it would hold heat in and allow for better velocity. Am I wrong? Will it achieve 700rwhp?
What size is everyone else using? 3" ok? worse? better?
thanks,
Questions-
1. Sizing a turbo, how different is this for a rear mount than a front mount, A/R differences, what is better/needed for rear mount?
2. Manifolds/headers/ exhaust piping size- We have shorty headers but if manifolds will achieve these HP goals with better spool up that will work. Will it? And what size piping is optimal for going from engine to turbo? Im guessing 2.5" Y-pipe going to a single 2.5" over the axle to the turbo. I know it sounds small but giving the long run I think it would hold heat in and allow for better velocity. Am I wrong? Will it achieve 700rwhp?
What size is everyone else using? 3" ok? worse? better?
thanks,
For the rear mount you are going to want as much heat as you can get to the turbo so have all the piping coated, or covered with high temp dressing.
A/R still depends on where you want your power band to be, and with a remote setup id imagine for a desired powerband youd have go smaller a/r(compared to underhood turbo) to make up for the loss of heat and speed (power) of the exhaust hitting the turbine.
And from what i have heard the stock manifolds are a popular choice considering they can store more heat, not sure about the flow though...
please take this information with a grain of salt hopefully this post will inspire someone in the know to answer your question. and fix some of my mistakes.
best of luck
steven
Alot..alot alot of threads on this...search a little then come with more poinnted questions. But yes, rear mounts are generally less efficient... but can be made to make alot of power and go fast. Alot is the same, alot is different.
I did alot or searching and reading. No one really says anything about pipe sizing, like what size pipe will support XXX amount of HP. Theres that line between high velocity and enough flow that Im curious about.
Pipe size STS used 2.25" I used 2.5" and went to a muffler shop with a mandrel bender. The exhaust pipe is 3" into the turbo. It was the best $375.00 I've spent on the kit so far. Any bigger and you can't fit it where you want. I think 346ci a a/r of .81 is about right for a street car. some are running a .70 a/r and they are boosting real quick. and a .96 for a strip car. I ran a T60-1 and it hit boost quick but fell on its face in the upper rpm range so I stepped up to the T-70. I'm sure for 700 rwhp you would need to build a solid bottom end, and you might as well go bigger c.i.d.. Sorry for all the rambling, I've been 
and watching the UNC game. Also headre wrap on from the Y pipe back I gained 500 rpm of full boost. was 3700 now 3200 rpm
and watching the UNC game. Also headre wrap on from the Y pipe back I gained 500 rpm of full boost. was 3700 now 3200 rpm 
