oldred95

What size turbo are you running? Be specific. I want to know what flange, T4, T6, ect., what A/R and so on and how much power its making at what psi.

I am going to be building a forged Gen 1 383 with ported vortec heads with 2.05/1.60 valves and a comp XFI 268 cam, Edelbrock EFI manifold and so on and can't decide on what turbo would fit it best. The engine stands to make 450+ hp and torque NA at 9:1 and the turbo headers I've got use a 2 1/2 inch pipe with a T4 flange so I will need a turbo that can flow. I like the idea of 700-800 hp but I'm open to suggestions. I am wanting to go with a Borg Warner if it makes a difference. I would like something that spools by 3000 rpm and for the most part stays out of boost for everyday driving back and forth to work. I run 2200 rpms at 70 in OD if that makes a difference.

stock48

iTrader: (16)

I'd go with a BW S475, or 480 with the 83mm exh wheel, T6 1.10, or T4 1.15. You would prob be wasting your time with much more turbo than that with that block.

oldred95

You think a 1.10 AR would be big enough to not cause too much back pressure?

tarinitup

iTrader: (11)

I have a 91mm 1.08 AR on 408 cubes. If I could do it again I'd have a gt80 on my t6 kit.

oldred95

What would be the reason for using a divided turbo on an undivided T4 flange header system? To me it seems like the divider would only cause a restriction but their seems to be way more divided than undivided turbos out there.

oldred95

The S480 looks pretty nice. The S480 with a 1.10 AR would have a fairly quick spool but still support high hp on the big end would it not?

kbracing96

iTrader: (26)

A T6 1.10 a/r housing is HUGE when compared to most T4's like Magnums with there little 67mm turbine wheels. You need to know that a/r is not actually a size, but a ratio of area/radius. With a big turbine wheel like an 83mm of the 75/83 (s475) 80/83 (S480) you have a much bigger area (t6 opening (area) and the 83mm turbine wheel (radius)) so it flows a LOT of air. Here is an example of size difference. Both turbos are T4, .96 a/r, the the turbo on the left is a 94mm turbine wheel (PT88) and the right is only a 67mm turbine wheel (Magnum T76) both .96 a/r's. See the difference?



Mostly because you can't get an open housing for those turbos. BW doesn't make an open housing. You can knife edge the housing like I did on the T4 1.0 a/r housing I run on my BW 80/83.




Even with the small 83mm turbine wheel (you can get up to a 96mm), it should still should still be good for around 800hp or so,

oldred95

That is pretty substantial. Yea I still don't understand the whole A/R debacle. I know if its less than 1.00 its going to spool faster and more than 1.00 its going to spool slower. I just can't get over how the Borg Warners are sooooooooo much bigger. So what you are telling me is that a S480 1.10 with a 92mm turbine wheel on a T4 flange might be about right?

kbracing96

iTrader: (26)

That turbo will make a lot of power! and still spool decent

oldred95

So whats one like that going to be worth? Might as well go with a polished housing while I'm at it to match the headers. I don't plan on wrapping the headers but I will put a blanket on the turbo and down pipe to try and keep all the heat in I can. Obviously the wrapping the down pipe won't help with spooling any but it will keep the cab from glowing red hot.