The thing is, I'm really planning to go with a GT42R-76, but there is no compressor map available. Can't I just use a T76 compressor map since the compressor wheels are the same?

I researched the GT42R-76, but I found that only precision makes it, and though they have a compressor map, they haven't released it to the public. So, is the 76 close enough?

thanks,

Chris

 

My friend who built my turbo kit has a 331, C4 T72 combo and went 10.00 on drag radials on 15psi.. I think the T76 would be plenty for you. How fast you want to go?


Jeremy

 

I'm putting together a billet/dart custom 331. I think the GT42R-76 will do enough for around 15psi, but according to a normal T76 compressor map, I'm already down to 65% efficiency by 6500 rpm. I'll be revving it to 7k.

It actually looks pretty good at 4k, which is when I expect it to reach max boost, which in this case would be 15 psi on pump gas. The compressor would be at 78% efficiency. As stated above, though,, it drops off until at 6500 it's already down to 65%.

I'd like to be able to have some fun on race gas. I was thinking 25psi, but by 6000 rpm, a normal T76 would already be at less than 65% efficiency. Any more rpm than that, and it's off the charts. I think that means, the turbo would cause boost to fall off.

Chris

 

I am still learning, and still have alot to learn, but if it helps I got a buddy that has a 310, Victor Jrs , and a GTS 76 with a 96 ar... he ran the best of a 5.80 @ 121 1/2 @24 psi runs consistent 6.00... 5.90 passes. Not sure if that helps but hope so...

 

its enough to run botom nines just how fast do you wana go

 

The 76maps you are currently looking at more then likely are the older 76 with a p-trim that was derived for turbonetics many years back. The newer units can shift the map to the right by 10-25% depending on the turbine wheel used.

Jose

 

Also remember the 76GTS and GT42-76 use the same wheels. The 76 shaft is turned but the wheels are the same.

Jose

 

Thanks Jose. I talked to you just a couple days ago on the phone about the GT42R-76 for my engine. I'd kill to get my hands on a compressor map for this turbo. I honestly can't even find all the specs for the turbo. I think you're right about the map I was looking at, though. I'll look up a 76 GTS make and take a looksee.

Thanks,

Chris