TurboAv

iTrader: (6)

Sticking with going front mount twins. Master Power T70's with either .68 or .96 AR exhaust housings, 9.3:1 ironblock forged 370, ported 243 heads, Vic jr, intakeelbows.com elbow, 243/247 .624/.624 on a 116 cam, C6 manifolds to the turbos, TH400, 4200 stall(building boost on the brake) otherwise 3200 stall at little to no boost, 4000lb GTO with 3.46 gears and 26" tires. Trying to get at least 6800-7000 rpm out of it. Yes I know you don't need a lot of rpm with turbo motors, but I only have two gear choices, 3.46 or 3.07. I will try 28" tires if the 26's wont cut it, then after that I will change to 3.07's.

I can get a good deal on a set of brand new MP T70's with .68 housings for $950 shipped or I can pay full price for some .96 housing ones from a dealer.

I will be running two JGS 50mm wastegates, so will the .68's choke me off early in the rpms or will they be ok?

kbracing96

iTrader: (25)

What are your HP goals? I can tell you this, I've made over 500rwhp with a single MPT70 with a .68 a/r on a 346, so 2 of them will easily make 1k rwhp.

TurboAv

iTrader: (6)

I want to keep it "streetable" at around 700-750rwhp through a TH400. I will probably start off around 550-600rwhp to just get used to the power and increase it up as I get used to the car.

So the .68's will let me rev to 6800-7000?

TurboAv

iTrader: (6)

Well I waited to long to ****** up those .68 MP T70's. So now what should I do? .68 or .96? I wish I could get them in .81, lol.

kbracing96

iTrader: (25)

Twin .68 won't be a restriction at that RPM, you'll barely be working those turbos at those HP levels. Anything bigger and you will REALLY have a hard time spooling them.

TurboAv

iTrader: (6)

Shoot me PM for a couple of those bad boys shipped to 85354. Have you tested out the new anti surge housing ones yet?

kbracing96

iTrader: (25)

Sold one of the new ones to a local guy, has it on his 05 5.3 truck and loves it!

71 chevy

iTrader: (18)

im doing a .68 t70 on a 325. everyone says its too small but I would be HAPPY with 500rwhp.

my question is , how soon does the boost come in and where does the power start to fall off.

kbracing96

iTrader: (25)

I ran a .68 T70 first on my 4.8, and then on the 5.7. Was my favorite turbo on my setup. It hit fast and hard on both motors. The 4.8 was all in by about 3000 and made 505rwhp at 11psi, the 5.7 was a bit lower, like about 27-2800. Never dynoed it, but at 5000' elevation, trapped 110mph in my 5500lbs truck. I really liked it!

I have a the same turbo on the stock 5.3 in my dads 72 Chevy 4x4 and it does GREAT, only running about 5 psi with it and he is thrilled.

TurboAv

iTrader: (6)

What did you spin the 4.8 and 5.7 up to?

kbracing96

iTrader: (25)

I have shifted both of them about 6200, but seem to be quicker at the track short shifting them about 5900. Have a buddy with a built 370 and a single TC76 with a .96 a/r that shifts his 5400 in a 4900lbs 4x4 truck and runs 10.2 with it at sea level. He ran a 10.6 with it at 5000' elevation with a .68 a/r.

TurboAv

iTrader: (6)

So 7000rpm with twin .68's is totally fine on my 370 and 243/247 .624/.624 cam? I know it's essentially like running one each on a 3.0L 4 cyl motor.

kbracing96

iTrader: (25)

Yes, easily! You will have WAY more turbo then you will need for your goals.

TurboAv

iTrader: (6)

That's reassuring. It makes me wonder why the shop I'm getting the kit built at is really trying to push me into getting the .96 housings though?

71 chevy

iTrader: (18)

sweetness. gives me encouragement that it wont be too bad afterall. were these stock motors or built up? Im planning to run around 15 psi . as I said , anything over 500rwhp would be GREAT.

kbracing96

iTrader: (25)

The 4.8 was all stock except for a Vince 210/218 .551/.551 116lsa cam. 5.7 got the same came swaped into it, but it's forged flat top pistons and rods with 317 6L heads (9.25 to 1 comp) with yellow ls6 valve springs and ARP studs. Nothing really special.

kbracing96

iTrader: (25)

In fact, you could get by with MPT60's w/.68 a/r's and still be plenty efficient on the turbos with a 750hp goal.

Tiago

iTrader: (27)

deffinately 0.68s.

TurboAv

iTrader: (6)

750rwhp through a TH400 though. Probably around 950-1000bhp right? Once I get better heads and more experience I'll turn it up to 950-1000rwhp.

kbracing96

iTrader: (25)

Paris made 600rwhp on a mostly stock 5.3 (01 LS6 cam) though a TH400, a loose converter and a 9" in there Fairmont.