Anybody running twin 64-70mm turbos with .96 ar housings on a 400-408ci motor? If so what spool time are you guys seeing for full boost? I know every combo is different...all i want is a general idea as i'm about to buy a couple MP 64 or 70mm with .96 ar housings, haven't decided on 64 or 70mm yet. I'm looking for 750-800whp with a 401ci motor.

 

I'd go 64mm like i've mentioned before. Should be a good combination with .96's. I'm swapping my .68's for .96's on my twin 60's but will not get to test them for quite some time

 

think i'm gonna give the 64mm/.96 ar a shot Orr....i was planning on 8:5:1cr but will now step it up to 9:1 to help out with spooling those two .96 housings. If I can see full boost(13-15psi) at 4k or a little over, I can live with that...i'm not planning on being a stoplight bulley so big boost at 2500rpm is not needed.

 

A little more detail on Orr89rocz's particular experience is here:
https://www.theturboforums.com/smf/index.php?topic=134941.0

There's juicy tidbits like this all over the place. Just takes a lot of thumbing around.

 

I keep forgetting this a fox body 5.0 site so asking about spooling twin .96 ar housing might be a bit far fetched when all a 5.0 needs is a single .68 ar housing.

 

Fixed that one for ya' . There's soooooooooo (is that enough o's) many different types of builds goin' on with this site that the name changed a few years back. Turbo T/A (Carm) on here has a '69 Trans Am / 406 SB Chevy that had twin MP T70's on it with better-than-good results, it's a mid-8's car with 3.00 gears and a TH400. There's even video proof. I think he ended up goin' with a pair of .81's on his turbines, as his .96's weren't gettin' full boost until 4500+rpms (?).


---==Temio Williams
Yuba City, CA

 

for a while there, I was thinking of buying the t70s and at the same time get a pair of garrett/precision .81 a/r housing that fits a p-trim wheel....and then sell the .96 housings from the t70s to 5.0 or 355 chevy guys. I just think twin .96 housings on a 401ci will spool too late and i'm not looking to rap this thing past 6200rpms or so.

 

what size turbine wheel ???

 

master power P trim has a 64.5mm exducer / 74 mm inducer on the turbine wheel. 76 trim. This is on all their T4 turbos from 60 to 76mm compressors.

I am thinking my turbine housing may be abit small for my motor at .68 a/r housing, and I have .96 a/r housings ready to go on. But I'm starting to also think some of the problems I may be having are due to driving this 60mm compressor fairly hard. But it should be good to near 400whp a piece. I'm only asking 300-350whp each through these things at the moment so I shouldnt have problems with .68 a/r. They spool very quick but my motor doesnt turn high rpm either so it works out ok. I just noticed some issues that I think are backpressure related so I figured .96 housings will help me out. Hard to say I got alot of things to test for to see what is going on with this motor.

Turbo T/A's car is the only other setup I know of that is doing twin 70s with .96 a/r's and he said it spools pretty late. I'm kinda surprised at that based on his 1/4 mile performance. That motor is making sick power, i figured it would spool that turbo up quick. I guess there really needs to be a .8x a/r available as an in-between for these turbos.

 

I think i'm gonna go ahead and get the t70s with the .68 a/r housings and try that out....with dual 3" exhaust all the way back, i shouldn't run into any "major" backpressure issues for 750whp or so because even with the smallish .68 a/r, the bigger 70mm compressor wheel won't have to work as hard as a 60-64mm wheel for a given amount of boost and all that should add up to less BP.

 

Just run a good intercooler and you shouldnt have too much loss on that end

 

Even if it spools late, it won't affect it at the drag strip if he is launching off a transbrake. If anything it will be better for power. But on the street you may appreciate the faster spoolup.