After running the 70 with .96 a/r on my 5.3 I do think it would do fine on more cubic inches..... However..... How far out of effeciency rance would it be at say 15psi on a 5.7L motor?

I'm very strongly considering the 76 with the same size exhaust housing on the new motor.... Ill be running up to ~15psi with meth on the new powerplant.....

 

with a mild 2001 zo6 cam on a 5.3 the mp70 is done at 14psi. going from 14psi to 18psi gives no extra power. i would think on a 5.7 the turbo would be done at 12-13psi and on a 6.0 even sooner.

i think a mp76 would be ok on a 5.7 at 15psi but i bet it would be maxed right about then.

i dont know anything about the mp76 so what i am saying is just a guess but i have ran a basic t76 and it ran out around 14psi on a camed 6.0.

 

Do you think a bigger turbine would have helped? I remember the backpressure was pretty high....

 

i had a .96. i dont think a larger exhaust housing would have helped much. if you look at a compresor map for a t76 it was running out of air right where you would expect it to.

 

That's exactly what I just went through and have on my truck now, but i won't really be able to do any real testing on it till spring and I have the 80e in the truck. I don't want to brake the 65E, The MP T76 spools just a bit slower then the 70, both have the p-trim wheel and .96 housing, but that's what I expected it to do since it is a fair bit bigger compressor. It's still plenty fast, don't get me wrong. It does feel a bit stronger and more efficient, but I'm only running 9 psi in high boost right now, which is like 7 PSI at sea-level. This spring it WILL get put though some serious testing at 15-18 psi, .

Here is a comparison pic...

 

Is this a daily driver? What cam? What stall? If this is Weekend Warrior truck maybe go a little bigger. But if this is a daily driven street truck I might settle for a 76. FWIW, I plan on doing a 5.7L(LS6)/T76 combo as well.

Bill

 

Weekend /strip toy.... Ill be going from my current SS3600 converter to a PI 3000. The 5.7L longblock already has a GT2-3 cam and good heads but I'm considering changing it for a low 220s single pattern Isky turbo cam (definitely leaving the heads). It'll turn some 3.73s.

I am honestly not wanting to sink huge money into this thing for an upgrade which is why I'm sticking with a MP turbo. I COULD keep the 70, but I know it really wouldn't do it justice.

 

Im boosting a 6.0 with ls6 cam and i was trying to figure out wich MP to go with my self. 70 or 76 Im not sure wich would be the one i need. Im wanting to run 10 to 12 psi.

 

I'd say the 76 for sure for you.... That 70 would pretty well stay at max capacity on that motor at that boost level

 

even a 76 is a little on the small side for a 6.0 expecialy in the 10-12psi range. 76 for sure.