What's a good A/R combination?
 

hey i'll be shopping for a turbo soon but i wanna know wat AR combination is everyone running.im looking at t70's. more then enough,but wat AR should i pick?the car is a 98 ss all stock with an automatic tranny and it will be a daily driver.i want around 500rwhp and nice strong powerband all the way through 6500 rpms

You want to go .96A/R.

What a/r for twins? Innovative or gt40s
stock motor now
later 370, 6.0 heads
3.10 or 3.20 gear

.96 on the exhaust turbine correct?wat about the front?

I'm running a T-70 w/ a .96 AR turbo exhaust housing... You'll love it... With your tranny, you'll load up real quick better than me. :burn:

I would talk to Jose, but more then likely a pair of .68's or close to that.

Yes .96 on the turbine. As for compressor, their isn't much in the way of changing those.

the compressor a/r is not as versatile as the turbine a/r. Basically, since the compressor side doesn't really change much in turbo dynamics, the turbo manufactures will leave it at a set "baseline".

However, the turbine a/r is where the magic is at and where the a/r talk is guided at.

The higher the ratio, the more peak power you will attain while compromising a bit of turbo response. The lower, well, you get the opposite....

Now, ppl are running a .96 single setup. On a twin, theoretically, you should expect that turbo to spool slower, corrrect? So, with a 408 twin setup, should you consider running a lower a/r (let say on a t70-t76) or stick with it .96 since the motor is also pushing alot more air per bank?

I would like to match a pair of super-t's t70's or t-72's .96a/r.

I have a pair of 96s on my turbine side and they spooled great

i had the .96 and i could not stand it - big lag but it made good power on top end. i switched to a .81 and it is much more fun , quicker boost just great on my auto trans daily driver car. :hail: .81

A pair of 96's What What??

twin t-64s ceramic bearing
350 cubes
.81 A/R turbines(on center housings)
starts boosting around 3300rpm pulls hard to 7000
works good on the street. backpressure matches boost

.96 is WAY too big for a twin setup, Use .68 housings. Also, t70 is way too klarge for only 500 rwhp. Use 60-1 hi-fi's or similar.

How would a single T70 with a 1.0 AR go ?

Agreed, but remember, you're turbo is rear-mounted.

Good question... Overkill, or would it benefit?

yeah i will go with the .96 that way i dont hit boost while driving like an old lady

Really?? I'm running twin 67's with .96 A/R. Boost comes in at about 3500, carries to red line (what ever I want, right now 6800, but easily could be 7200). No problems what so ever on getting boost. NO LAG. Launch off trans-brake is fun again. My HP and times are in my signature.

David

Navy Dave: That is with the 408ci right? Can i ask why you didn't go with a larger turbo?

You have a 408, he has a 346. That makes a good bit of difference for A/R needs.