Cant find 70 p-trim compressor map

imjoesnuffy

I just break stuff!
Joined
Sep 13, 2005
Looking for a compressor map, I have even searched for a turbo map for a 70 P-trim. Coming up empty here and google leads me no where. Anyone have a link?

Need to find the efficiency range before I try anything else. I have hit as high as 30psi @ 6000 rpm in third gear on 93 octance with dual nozzles :) and zero knock, dont want to move out of the efficient range before I start doing anything with fuel or throw some timing at it.
 
Here is a "Garrett T70" Map...... dunno if that is the map you are looking for or not.
 

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That map is about the only thing that you will find out there, that has been published. But to be honest, if you're curious about being able to push that turbo any further, I'd highly recommend you start looking at your back pressure. Not knowing your back pressure or which turbine housing and compressor cover it has, it's really a crap shoot for us to say yes or no you can turn it up more. However, with that said, the P-trim turbine wheel has been pushed harder, as well as the 70 comp wheel.

Having the capability to monitor your back pressure before the turbo, would tell you if your combination could take more boost or not. Typically, customers will mount a pressure gauge or pressure sending unit just before the turbo and log their back pressure. The general rule of thumb we use is, once you've hit a 2:1 back pressure to boost pressure level, you're pretty much done. And with our very restrictive 3-bolt style turbine housings, those limits come up very quick on a purpose built motor. An example of this would be, if you are running 30psi of boost at the intake, and your back pressure is 60psi, you're done. But if say your back pressure was below 60psi, you technically could run more boost. The other method is alot less complicated, as you increase boost at the track, the point where the car stops making more mph could also be the limitation point. If the tune is there to take the extra power that is. I would be hesitant to push a 70 P-trim turbo much past 35psi. At least back in the day when I ran that turbo, 35psi was my limit. That was with an older LT70-1, P-trim with .85 A/R.

What turbine housing and compressor cover does your turbo currently have?

Hope some of this helps.

Patrick
 
I agree with Patrick. You will hit the backpressure limit before you come close to maxing out the compressor.
 
Wont have to worry about that for now, lol. Lifted a head/blew a head gasket at the Nats. I kept picking up MPH with zero knock on 93 octane, fastest was 126.42. Now I know where the boost limit for my motor is.
 
Dammit John...I didn't even get to see it run.

You didn't miss much. 60 foots kicked my butt all day. Best I managed was a 1.74. Best pass was a 10.84 @ 125 I did run 126.42 on one pass, but trying to go fast on a 255 radial isnt working for me. I'll be back saturday, but not in the GN. :rolleyes:
 
how the heck is that map read and applied to buicks? i always see people asking about maps but nobody seems to know what to do with it.
 
Wont have to worry about that for now, lol. Lifted a head/blew a head gasket at the Nats. I kept picking up MPH with zero knock on 93 octane, fastest was 126.42. Now I know where the boost limit for my motor is.
and what would that have been? What was boost/timing at when detonating? that was 30 today?
 
and what would that have been? What was boost/timing at when detonating? that was 30 today?

I'll be the test dummy to share with everyone. Maybe someone can learn from my mistakes.

That run when the gasket let go was 32-33 psi. My gauge only goes to 30 psi, but it was at 30 psi at the 1/8 mile mark and was buried before the traps. Normally it will pick up 2-3 psi on the big end. My powerlogger recorded the burnout but didn't capture the run. I had it set to autorecord and inadvertantly hit the space bar after the burnout, I think. Blame it on staging lane jitters or just me being a dumba$$.

Timing was at 24.8 in first and second. 21 in third in the previous run and I didn't change that for this run. This was all done on 93 octane, with zero knock on any run. I had a little knock (2.7 kr) before a week earlier at 25 psi when testing at a 1/8th mile track. I let out of it, but it may have weakened the gasket then.

This is the same head that blew a gasket this spring and I didnt have it checked then, so it may be warped (possible contributing factor???). After that run I noticed the heater core hose blew off, I parked it for the night. Thursday morning I bypassed the heater core, checked the dipstick and it was clear. Started it up, no issues, then noticed it was running hot, pulled the cap off the radiator, noticed the water was low. Thinking the water loss was from the hose blowing off, I added more. Temps came back down, then back up. Added more water then checked the dipstick again and milkshake. Cut it off the party's over.

Hindsight is 20/20, when the heater core hose blew off, it was because the cooling system had been pressurized, not because it got hot or a loose hose clamp. deet da deee
 
sweet spot

I've got stock ported heads and a PT70 with .63 exhaust housing. I have 3" ATR single shot exhaust with TA headers. Just triying to find the sweet spot for my combo. What kinda boost and timing? any suggestions would be awsome.
 
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