Somebody PM'd me as to which size housing I run on Casper. It's the 1.15 A/R housing. This is the "right size" for our trucks for 2000-4000 rpm operation.
Exhaust Housing Size on Casper's GT4202R
- Thread starter McRat
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Just curious, would you happen to know off the top of your head what the A/R is on the compressor?
Compressor A/R is not too important with our trucks, but it's 0.60 A/R on 4202
Factory is about .58? and the VNT GT45 I have is 0.69.
Factory is about .58? and the VNT GT45 I have is 0.69.
Not sure what the RPM range is but the bigger the number the harder it is to spool but the more top end it has. On my car I went with the P-trim wheel so I went with a .85 A/R. If I had gone with a Q-trim I would have gone with the .63 to try and spool it better. Hope this helps
For our trucks a 1.28 needs nitrous to launch with, even at sea level.
The 1.15 is happy to 4000 without fading much, but at 4400, it is laying over. It would lay over anyhow since the compressor is way past it's map up there.
1.28 just sounds big :rofl: I was wondering about needing N2O myself. Lots of those supra boys run turbos so big that they can't make 5lbs of boost at WOT at 7000rpm. But if they spray it to 15-20lbs then turn it off the motor takes it up to mid to high 30s 
I just can't see the selce of a turbo that need N2O to work :dontknow:
I just can't see the selce of a turbo that need N2O to work :dontknow:
I got a 1.78 A/R on one charger I'd like to test. But it's VNT. I can turn it down to perhaps .5 if I close the vanes.
If a person had a chance to get a GT4708 with the options of a 0.96 or 1.08 or a 1.23 what would be a good choice?
How many RPM do you want peak power to be at?
I'm swapping the 1.15 to a 1.28? on Casper to do some more testing of high RPM operation.
We know that a 1.15 won't spool without nitrous when over 8000' DA.
I'm swapping the 1.15 to a 1.28? on Casper to do some more testing of high RPM operation.
We know that a 1.15 won't spool without nitrous when over 8000' DA.
I have got a 1.00 on my truck now Pat with a 1.10 on the shelf. How much harder do you think the charger will be to spool with the 1.10 on a single fueler?
A 1.1 is about right for our trucks. You should have no problems getting a 1.1 up on the charger at normal altitudes.
Keep in mind the compressor actually controls how much boost you can make at high RPM, not the turbine housing.
The turbine is just the drive motor for the compressor. If the compressor is too small, all the shaft RPM in the world won't change that.
Keep in mind the compressor actually controls how much boost you can make at high RPM, not the turbine housing.
The turbine is just the drive motor for the compressor. If the compressor is too small, all the shaft RPM in the world won't change that.
The compressor side is a 65mm tip with a 98 compressor exducer, I would hope to have enough air flow
How do you like the 1.28 so far? I havent been able to make it to the track yet but I did tow a good 12k lbs with it the other day. So far I dont think it is too bad but I haven't ran a 1.15 before.
Still collecting 1.15 data, and when I'm done I'll be able to quantify 1.28 behavior.