Who Is Running a GT91?
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Joined: May 2004
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From: Phoenix, AZ
Who Is Running a GT91? I currently have the T4 GT91 with the 94mm turbine wheel, Anyone ever take BP readings with one? What is your setup and pressure ratio?
I have a 370 and going with PRC 260cc ls3 heads, But I'm thinking about upgrading to the 97mm turbine wheel and going to a T6 flange. This car is going to be a light (2,900 lbs) street/strip car with a stalled auto. I don't want to spend the extra money if it's not necessary, I'm looking to be at around 1.5:1 at 20 psi of intake pressure.
I have a 370 and going with PRC 260cc ls3 heads, But I'm thinking about upgrading to the 97mm turbine wheel and going to a T6 flange. This car is going to be a light (2,900 lbs) street/strip car with a stalled auto. I don't want to spend the extra money if it's not necessary, I'm looking to be at around 1.5:1 at 20 psi of intake pressure.
Even with the 97mm wheel you will never see 1.5:1 with that turbo. You'd need at least a 111mm wheel to achieve those readings. Jose could tell you better than me but from what I've seen on a outlaw drag radial car I did a cam for he doesn't even see those readings and his turbine wheel measures 130mm. Granted this is a 434 but it's still relevant.
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Thread Starter
Joined: May 2004
Posts: 1,658
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From: Phoenix, AZ
Even with the 97mm wheel you will never see 1.5:1 with that turbo. You'd need at least a 111mm wheel to achieve those readings. Jose could tell you better than me but from what I've seen on a outlaw drag radial car I did a cam for he doesn't even see those readings and his turbine wheel measures 130mm. Granted this is a 434 but it's still relevant.
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Verdad Gallardo Thread Starter
Joined: May 2004
Posts: 1,658
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From: Phoenix, AZ
I know KILLER-LS1 mentioned he was at a 2:1 pressure ratio with this turbo, I don't know exactly what the intake pressure was but I believe it was 17 psi on his 408. I also read he was dropping pressure across his intercooler. I'm just trying to make a decision as to keeping the T4 94 turbine or if switching out to a T6 97mm turbine is even worth the extra $, Now is the time since I will be sending it out to Forced Inductions.
At high boost yes.
Any mechanical pressure gauge will work, just need to be able to watch it or a way to record it.
This.
It would be worth it in my opinion even though you wouldn't see the pressure ratio you wanted at high boost. That said, it's not necessarily a bad thing and it will still make good power. The 2.0:1 scenario is much more likely at high boost and the worse drive pressure gets the further you move past the higher efficiency islands of the compressor map at those pressure ratios. Some turbo's like high pressure ratio's some don't. Someone like Jose could tell you better about that than me though.
This.
I know KILLER-LS1 mentioned he was at a 2:1 pressure ratio with this turbo, I don't know exactly what the intake pressure was but I believe it was 17 psi on his 408. I also read he was dropping pressure across his intercooler. I'm just trying to make a decision as to keeping the T4 94 turbine or if switching out to a T6 97mm turbine is even worth the extra $, Now is the time since I will be sending it out to Forced Inductions.
