i just got a turbo II. i have been following turbo II's for a long time now. i wanted to know what is the highest someone has gone on boost and with what turbo. i heard that around 16psi is the farthest you can go with being safe. ill see what you guys have to say.

 

I think that anything past 10-12 PSI in the stock turbo is inefficient and wont really add any power. I think most people usually keep it around 10 PSI.

 

my stock turbo boosts up to 22 psi in 4th gear.... the only saving grace i have is the 720 cc secondaries, but its still horrible for the car, hence why i don't boost as much as i did with the last motor, my own foot is my manual boost controller stupid stuck wastegate

 

your not getting crap out of your stock turbo at 22psi. why dont you fix your car and not be an idiot.

-Chris

 

because i'm not being an idiot, i'm not letting it get anywhere near 22 psi... why don't you fix ur attitude and not be a dipshit.

 

It used to see regular 14psi.
I wa trying to tune it for 17psi, but the turbo promptly pukes it's oil seals in a week.
I did see 18psi by mistake trying to "tune" an MBC - doh!


-Ted

 

Stock turbo say under 12 for maximum "efficiency" in my opinon.

 

on my 87 TII i set my stock turbo at 11, it was great, got a fair amount of power from that thing

 

yeah i plan on upgrading the turbo to a gt25 turbo, spearco custom intercooler, haltech, fuel system and getting the motor rebuilt and street ported. then i want to see what kind of boost i could put to it

 

Damn, that'll be one hell of an FC. You'll get some serious power out of that setup.

 

12 Psi s4 turbo is maximum efficiency,
14Psi on s5 turbo is maximum efficency,
After this they are just spinning more.
I have ran 20PSI but not on stock! as i am sure you can see.

 

I have hit 16psi on a fluke. Downshifted onto a freeway onramp, Stomped it, Boost skyrocketed befor the twin-scroll actuator could open. 16psi at 3500rpms is FAST.

Now it varies between 10-13 depending on the weather. Fun stuff.

 

13 accidentaly.....i would boost 9.5 usually.

 

damn 20psi is a lot i would think. i dont think with my new setup im going to boost over 16psi but i believe with that setup it will put me over 400hp. thats enough

 

i am at the 400hp mark with my setup.. plan along those lines

 

what are you using to control it? EFI?
Also engine wise what do you have done?
What are you dyno numbers?

 

i think ill be boosting more around 400rwhp with my setup. a lot of those t4 setup already accomplish 400hp. the gt25 turbo is a lot bigger.

 

How do they have different compressor efficiencies? They have the same core.

 

Same core... Yes,
However the turbine housing is different between the two the S5 turbine housing allows for a little more flow but enough to make a difference! they are both impact type exhaust housings, But the S5 is different in desing.

 

The compressor housings aren't any different inside either, only the exhaust. How would exhaust affect the compressor wheel efficiency?
Where did you get this information? Pretty heard to prove without a compressor map, which is not available for the stock turbos, and I doubt anyone has made one. I suppose you could do testing with an temperature probe, but I doubt anyone would take the time to do so with both turbos back to back.

 

what mods would you need to get the stock turbo of a s4 upto 12psi?

 

[QUOTE]Originally posted by fc3sturboII
[B]yeah i plan on upgrading the turbo to a gt25 turbo,

i always thought that this turbo is 2 sizes smaller than the turbo that comes on the stock fc which is a t04 s-trim

 

i havent seen the turbo yet. but i heard it was a lot bigger. spools up real quick too

 

i havent seen the turbo yet. but i heard it was a lot bigger. spools up real quick too

 

I always thought you needed something like a GT35ish to hit 400 on our cars? I suppose if you upped the boost a lot, you could hit 400 but no one has thrown this out on the table yet so I assume that I'm wrong.