i was always under the impression that the stock turboII HT18 was unbalanced and had a big hotside and a small compressor side.
what are the a/r's for the turbine and compressor for the stock turbo?
for some reason i always thought the stock hotside had like a .80 a/r and the compressor had like a .50 or so. i have been wondering about this for a while so someone help me out.

 

I'd email Brian at bnrsupercars if no one can give you a good enought anwser. I don't know the numbers, but I'm guessing you're right, which would be why his hybrids are supposed to work so well, but my memory of thermodynamics is fading, so I might not know what I'm talking about.

 

**** emailing him, heh. i'll ask him today when I'm up there.

 

Digging from memory (I don't recall the compressor size),

but I *think*

S4 is .84 hotside
S5 is 1.00 hotside

*think!!!*

 

eh go ahead and email him i didn't make it out there on my trip outside of the house :P

 

I always thought it was the stock hotside that limited the stock turbo's performance. I'd like to know myself.

 

no way, it would have to be the compressor size. the compressor side on that turbo is tiny compared to the hotside. people always complain about the turbine side holding them back when they strap a massive t04 compressor onto the stock hotside.

josepi: i thought s4 and s5 turbos were the same except for the wastegate stuff?

 

I read a thing saying that the combined A/R of the S4 housing was 1.0 with the twin scroll open, and it was .8 with it closed so it spools faster.

So I'd imagine they are both 1.0, but it's still sorta small for a rotary engine. A/R is only part of the equation.

 

All I know is when I hot the stock turbo I asked why it didn't hold boost too well in the high RPMs and people said that its because of the hotside of the turbo. But really I don't know.

 

A/R doesn't really mean anything...

I think the stock turbo is .86 which makes what 250hp..

and you could get a TO4 with a .86 ar and make over 400. and it would be alot bigger.

A/R number is just a ratio. so you make both things bigger. and the A/R stays the same. but the turbo is biger.

 

what does a/r even mean? something radius?