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I am putting a new car together. I had this 402 in another car with an S594sxe and manual trans. The response wasn't terrible but wasn't great either.
Sooooo I figured I would downsize the turbo in this new car. Its a Borg stock turbo, so billet 76mm and the 87mm turbine. Two reasons I hope it will be decent:
1. The sxe 76mm turbo map is a hair better than the non-sxe billet 80mm from Borg and people have run the billet 80mm on 402s and 408s with good success in the past.
2. The 87mm with 1.25 a/r housing flows closer to the 96mm wheel than the 83mm wheel...according to Matchbot. And Ive run the S475 with 83mm turbine on 6.0s in the past and was happy with it...so Im thinking the 87mm should be ok on a 6.6.
My goal is only 900whp and Ive made 800-820whp a few times (1.03-1.05 correction factor which is in my favor) with 6.0 engines using PT7675 once and twin S257sxe's another time.
So anyway long story short, any examples or thoughts on this?!
I'll have the car (tube chassis 72 Beetle) done by Feb and planning to dyno then.
Attached is the 76sxe compressor map. The red dots are the billet S480 at 70% efficiency, the blue dots are the 76sxe at 70% efficiency...a hair better everywhere.
Ug I can’t imagine needing or wanting a single T4 on any LS. I could easily spool a 1.32 T6 with a 4.8 and semi tight converter. I’d put a 19-0 converter on that thing and run a s485 minimum. Will heat the air less, make more power per pound with less back pressure, allow a more aggressive cam, etc etc… Spooling the thing would be a breeze with 400 cubes.
I ran a S476 with the 87/96 ech wheel in a 1.25 T4 on my 370” motor. No doubt it could/did make 900hp… Just feel like it’s leaning on it semi hard for no reason.
But hey, to each their own! Match bot rates turbos at a lot more power than they typically make IMO.
I think it will make the power on a manual no problem and be responsive. A stick car with a more responsive setup is just way more fun to drive. Let us know how it is if you go that way.
Forgot to mention its a T6 1.25, thanks for the deets. Maybe the T6 will help a little.
Ah, that’s much better… Use to seeing the 1.10 and 1.32. The 1.25 T6 is an odd ball to me. I’m sure it will make the power and then some. Feel like a larger compressor would be in a happier spot on the map with a healthy 400+ cube motor is all. Let us know how it goes!
Might be close to 900whp full tilt. I ran a FI s476 with a 96mm exhaust on a 5.3 and made 1050whp at 24.5psi through a manual. I feel there was, at least, another 50-75hp left on the table.
A buddy of mine runs the same FI s476 on a 6.2 with a manual. Its about tapped out around 980whp. Back pressure is getting up there. Could also be due to a less than ideal hotside.
I am putting a new car together. I had this 402 in another car with an S594sxe and manual trans. The response wasn't terrible but wasn't great either.
Sooooo I figured I would downsize the turbo in this new car. Its a Borg stock turbo, so billet 76mm and the 87mm turbine. Two reasons I hope it will be decent:
1. The sxe 76mm turbo map is a hair better than the non-sxe billet 80mm from Borg and people have run the billet 80mm on 402s and 408s with good success in the past.
2. The 87mm with 1.25 a/r housing flows closer to the 96mm wheel than the 83mm wheel...according to Matchbot. And Ive run the S475 with 83mm turbine on 6.0s in the past and was happy with it...so Im thinking the 87mm should be ok on a 6.6.
My goal is only 900whp and Ive made 800-820whp a few times (1.03-1.05 correction factor which is in my favor) with 6.0 engines using PT7675 once and twin S257sxe's another time.
So anyway long story short, any examples or thoughts on this?!
I'll have the car (tube chassis 72 Beetle) done by Feb and planning to dyno then.
Attached is the 76sxe compressor map. The red dots are the billet S480 at 70% efficiency, the blue dots are the 76sxe at 70% efficiency...a hair better everywhere.
85lb at 2 bar is a weak 402 or it’s being revd like a diesel
Hmm you have some pretty good parts for decent peak rpm. Pretty sure you would be over 85lbs at 2 bar with that setup also. I’d consider a bit more compressor but if you have it try it.
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S476sxe on a 402 
