Odd pressures from twin setup.

RonA said:
He should get the turbo tomorrow. If he can get 50psi out of the 480 I'm going to be jealous. I guess there is something to be said for injectors rated in gallons per second.
Click to expand...

This sounds like Ron isn't going for big numbers this weekend???
:doh:
 
NoSeeUm said:
That was sort of confusing me. I had learned in the past that decreasing volume per stage due the gas compression and the discussion became involved with decreasing cross sectional area. I guess I assumed that for this application the two were roughly the same. DF did say that even for cross sectional area method you still needed to subtract the area of the hub.

Jim
Click to expand...

There is only so much air that can be blown through a hole. The inducer is essentially a hole, and the absolute maximum pressure drop across that hole is never going to exceed 14.7 psi. Somewhere before that number is reached is when a compressor chokes out.
 
Diesel Freak said:
There is only so much air that can be blown through a hole. The inducer is essentially a hole, and the absolute maximum pressure drop across that hole is never going to exceed 14.7 psi. Somewhere before that number is reached is when a compressor chokes out.
Click to expand...

If I understand what you are saying correctly ( which is probably NOT the case), that is only true for the primary (the 14.7 part).

Paul
 
I would guess that he had too small of a primary, Ron said he sent him a S480.
 
Yep. He decided to try a larger primary . He switched from the GT42-02 to the S480 and it started acting normally. Getting 43-45psi out of the 480 with80+ total.

Ron
 
RonA said:
Yep. He decided to try a larger primary . He switched from the GT42-02 to the S480 and it started acting normally. Getting 43-45psi out of the 480 with80+ total.

Ron
Click to expand...

Yea, I really liked the comment from him "man it wraps that boost gauge so fast it bounces off the peg" :rockwoot:

Since I know you won't bring it up......Congrats on the great numbers with the "little twins" :clap::clap:
 
RonA said:
Yep. He decided to try a larger primary . He switched from the GT42-02 to the S480 and it started acting normally. Getting 43-45psi out of the 480 with80+ total.

Ron
Click to expand...

Nice, well I guess I know what turbo I'll be buying now!

Jim
 
Funny thing is he did the odd numbers with a standard s400-74-1.32 as well as a gt42-02. Thats the odd part. Exact same numbers but the only difference is the gt did it earlier.
 
Bponci said:
Funny thing is he did the odd numbers with a standard s400-74-1.32 as well as a gt42-02. Thats the odd part. Exact same numbers but the only difference is the gt did it earlier.
Click to expand...

Damn, already changed the sig LOLLOL
 
Diesel Freak said:
There is only so much air that can be blown through a hole. The inducer is essentially a hole, and the absolute maximum pressure drop across that hole is never going to exceed 14.7 psi. Somewhere before that number is reached is when a compressor chokes out.
Click to expand...

OK thanks.

In other applications, many times the compressor stages are sequencial essentially forming one common casing composed of all the individual stage casings, with the compressor wheels all on the same shaft at the same RPM. The reduction in volume from one stage to the next is consistant compared to the PR of the stage in front of it. Hence, my confusion on the subject.

In compounds the two compressors have the ability to run at very widely different RPM/PR. To my thinking, this is like changing the effective volume for each stage dynamically. Simply stated, I thought you were trying to describe some magical thumb rule relating cross sectional area vs volume that eased the overall calculation. That still more or less correct? IE: The .707 rule of thumb if the PR's are around 2?

It seems most set-ups run with matched pressures for max Hp. I seemed to have discovered, accidently, that my EGT's run cooler if I run closer to matched PR's (vice matched pressures) as you have described above. I have never really understood why until now.

Jim
 
Last edited:
i think now someone should explain how to properly match the turbine housings...if there is such an equation
 
You must log in or register to reply here.
Top