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Discussion Starter #1
Im wondering if The turbo for my new set up is to small

motor is 351 .030 so its a 357 , 9.5:1 compression , forged bottom end , going custom cam , tf 190 11rs cnc 66cc heads , victor intake with edlebrock elbow and 85mm tb

turbo kit is a b&g kit with a precison 76/75 , precison 46mm wastegate and a tial 50mm blow off valve

wondering if i should go with a bigger turbo and gate or go dual gates

trying to make 800 rwhp
 

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Im wondering if The turbo for my new set up is to small

motor is 351 .030 so its a 357 , 9.5:1 compression , forged bottom end , going custom cam , tf 190 11rs cnc 66cc heads , victor intake with edlebrock elbow and 85mm tb

turbo kit is a b&g kit with a precison 76/75 , precison 46mm wastegate and a tial 50mm blow off valve

wondering if i should go with a bigger turbo and gate or go dual gates

trying to make 800 rwhp
T4? If so it’s going to be on small side. It will work but the more crank the boost up the more back pressure issues you will have. The deal with an efficient turbo is you gotta get out what you put in... That said, you would be better off selling that and getting a Cheap Borg s400 style with T6 turbine.
 

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I had a very similair setup on my 352. Made 787rwhp thru aod at 15psi. Could have made more if I would have put a better exhaust on.
Like mentioned, the back pressure will be high.
 

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Back pressure will be an issue with that turbo, had one on my 8.2 based stroker and would spool instantly but the small exhaust housing was definitely hurting me in the higher rpm range and compressor housing will start hitting the high end of the MAP and not be as efficient too.
 

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Discussion Starter #8
street and strip

the turbo is a t4 .96 ar , its gonna be a street/strip car , car will be driven to the track and also to meets and cruises , I made this thread cause i was concerned with back pressure issues with the 76/75 , it will be shifted around 6400 , 6500 at the most. so im guessing a s480 would probably be a better turbo, and if so what ar should i run 1.32?
 

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the turbo is a t4 .96 ar , its gonna be a street/strip car , car will be driven to the track and also to meets and cruises , I made this thread cause i was concerned with back pressure issues with the 76/75 , it will be shifted around 6400 , 6500 at the most. so im guessing a s480 would probably be a better turbo, and if so what ar should i run 1.32?
I ran a 1.10 housing on my s480
 

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I think you are fine.

I ran a Precision .96 AR T4 flange 7675 CEA wheel for a while on an ON3 and then on a Ponydown system.

It made around 1000 HP+ on my 363 at 25 psi and spooled instantly. I ran right at 5.40's at 130 MPH 1/8th mile in 3250 lbs with full dual exhaust. The 3.5" downpipe split to dual 3" to Borla pro XS. That turbo dyno'ed 1200, but that was on a Dynojet. They seem to read high, but the ET and MPH was good. Powerglide transmission, 1.68 low gear, 4.10 rear gear.

I'm now running a T4 from Forced Inductions with a ported 1.25 A/R turbine housing. I use a modified B&G hotside. I bought the headers from them and made my own turbo piping, I still use a single RG-45 gate placed right below the turbo flange in my system. I tried a big fancy expensive gate, but the RG45 worked much better so I put it back on.

My system is good with the single RG-45, but I put it in a better spot than most kits. I can dial any boost I want from 9 psi (spring) to 30 psi.

My car is exactly 3200 lbs race ready and goes right at 150MPH in the 1/8th through exhaust to the rear axle. It has a lot of backpressure, but still makes good power. This is actually the real exhaust flow limit for the T4 1.25 AR, so a good T4 is nowhere near as power limiting as most people think.

I really doubt you need to go to a T6. A T6 will a lot bigger, heavier, and a Precision 7675 with a CEA wheel would easily go 1000 with the turbine housing you have if your engine is decent.
 

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Discussion Starter #11
thats very impressive, the car is around 3160 with driver also shooting for high 8s in the 1/4 around 150 , you're engine is deff better but i think 800 or better should be possible with my set up , do you think the gate im using is enough ? precison 46mm? and also i see youre also running holley, are u using co2 for boost control?
 

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thats very impressive, the car is around 3160 with driver also shooting for high 8s in the 1/4 around 150 , you're engine is deff better but i think 800 or better should be possible with my set up , do you think the gate im using is enough ? precison 46mm? and also i see youre also running holley, are u using co2 for boost control?
The turbo limits my power, and the flange size (T4) was actually the least worry I had until I got over 1200-1300 HP.

You should be able to get close to your goals with the PT 7675 with a CEA wheel. It really depends on your tune and engine. The turbo is more than capable.

I'm not sure how the 46mm Precision gate is made. The Turbonetics RG-45 gate I use worked better in my car than a Turbosmart 60mm.

Waste gates can't be judged just by gate size. Remember what they do. They bleed pressure off. The flow volume through the gate depends on the pressure on the hotside. A 46mm should flow enough for the turbo you have if the gate is in a reasonable position.

The dome size also matters, especially in relation to the valve size if the drive pressure is high. A Turbosmart 60mm had terrible control because the dome diaphragm area was small compared to the valve area. This allowed hotside pressure to radically affect the opening of the Turbosmart valve.

I haven't seen a gate like yours so I can't really say, but my RG-45 is good in my system.
 
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