s475 turbine size spool characteristics on mild 4.8
 

So I sold my truck with the big turbine china billet s480/6.0L combo and I'm building something a little less rowdy.

I'm looking at the two VSR small turbine china borg copies. the cast 75mm compressor one is incredibly cheap ~$450 and the billet 80mm is $700

3800 lb truck, 80e 3400 stall, 8.8 w/3.73's 29" stiffwall slick. SBE 4.8, stock 241 heads, 212/220 ~.600 lift on a 114+2

probably do two 450's in the tank again, and my power limit will be my deka 80's

the actual question:

with my power limit being the 80s (maybe 700 wheel on e70?) what do you guys think of the small turbine stuff on a 4.8

I think the s475 83 turbine would be great. That turbine is really a 75mm turbine if you labeled it like every one else does by exducer. How many success stories you seen with a 7875 on a 4.8. Yours will be a 7575. One detraction will be the 1.10 ar but honestly i went from a .90 to a 1.25 at one point and it spooled the same. I think ar is alot less important then people make it out to be. If anythink it will spool a little later and save the stock short block by not making huge torque too soon.

right? I havent seen a/r make a huge difference.

I do like the borg copies, they have just been a lot more robust and longer lived than the various 7875's we've played with.

I'll have to check that out. Sounds like my kinda show.

I believe it is on Powermotive automedia , called Horsepower Wars. I was drawn into it because Lyle and the Customs by Bigun team are locals to me.

yeah I binge watched the whole season last night. haha

but both turbo teams used big back wheel turbos.

I'm wondering what the spool is like between the big wheel and the little wheel versions on a small cube motor

thats what I wanna hear!

can you give any more specs on your set up?

curt has a bad ass notch seen his post when he first got it going didn't even have a cage lol

Really? So a BW S475 is just a 7575mm? My PT7675 is larger? Then what makes the BW S475 give these fantastic 1/4 MPH I'm seeing? Is it simply the T6 flange?
This has been an interesting thread.
Thanks,

the small back wheel 475 is pretty close in size to the older 75mm turbonetics turbine wheel

the crazy power from s475's and s480s is probably coming from the big back wheel turbos

I've only seen that term used relatively recently. What does 'big back wheel' refer to? The turbine side or the compressor side?

yes turbine side. its what the cool kids on sloppy mechanics facebook say when they talk about the 96x88mm turbine :D

It's more about the ratio of compressor to exh wheel IMO. A 75mm compressor will spool much quicker than an 80mm compressor with the same "big back exh. wheel". For a single setup, I wouldn't mess with T4's ever again if I didn't have to. The 1.10 or 1.32 T6 S475 will spool easily with a mild 4.8 if the tune and combo are setup properly. I'd go 1.10 T6 if I had a choice, but with the cheap china stuff I don't think that's an option?

I run the 1.32 T6 VSR S480 on my 4.8 and I can spool it semi easily (about 2-3 seconds to 6-7lb lauch boost) at targeted 20lbs 1 sec into the run. Converter is holding me back as it's way too tight. (14 blade stator PTC) Still clicks off 1.3x 60's 5.6-5.7 1/8th mile times and 9 flat at 152ish on 20lbs. That's baby revving it and only 6300 or so thru the traps. Gear and converter change in the works this winter.

I know you have a light car and all but, damn.... that's moving! I'm going to go forward with my twin GT35's for now. May even try one side as the GT35 and the other with the PT7675. But I still have a wandering eye for a S480 every week.

FWIW, my RX-7 is around 3100lbs, which is heavier than my twin GT35 LS swapped notchback mustang.

You def need a matched pair to run twins correctly. You’ll have all kinda of weird stuff going on if you mismatch the turbos.