I'm looking for the recipe.
working with a 346ci, M6, street car.
The goal is a TT setup capable of 6-900whp.
PTE 6266s looks good, but I'm unsure of the A/Rs that will work for me. research is showing bigger cube motors utilizing the .81 A/R, but what about a 346?
I want the A/R so I can find the Borg warner variant or something else in the 57-62mm area, The Borg Warner S300SX aka the S362FMW is the closest variant I've found, but they seem to be more directed to single turbo setups since .88 A/R seem to the the smallest they come with. looks like I might have to step down to their S200 line.
So whats my options for 57-62mm single scroll twins?

 

I have a 6265 setup with .68 AR. with open down pipes. Seems to pull up to 6500 plus with ease. I like the responsive feel but I am auto.

 

AGP offer a twin kit for the new Camaro's and use their BW S256 to S261, depending on power goals.

Any of them should be capable of your goals, although the 256 perhaps better for spool.

On paper, they do seem smaller than the equivalent Precision going by inducer etc sizes though.

Some guys seem to have good success with the 6262's too. Although having sued both a 6262 and 6266 on a 4cyl car, I would say go with the bigger unit. We lost nothing in spool and gained lots of power. Although the latter was the 6266CEA unit.

 

.68 65mm wheels on a 347"

 

awesome, I just found and went through their build thread, that S256 .63 combo seems ideal for what im looking for. I'm trying to not overkill and hate drivibility, which I've been good at so far. .63-.70 seem to be the sweet spot so far. and with 10.5:1 compression, spool shouldn't be an issue.

 

I went with 61/91 compressor 64/74 turbine .68 AR on a 6.0. Haven't finished yet but I wanted quick spool and I'm quite certain that I'll be able to pull to 7000rpm's.

 

What do you give up for the spool? Back pressure on the other end?

 

Yes back pressure but seeing as the T-61 turbos have a broad compressor map, I don't believe I'll have very much back pressure. I'm planning to run atheist 18lb boost and I should stay within the 75% effencie range from there to around 24-26lb range or from 700 to 1000hp. Those turbos together will be capable of aroun 1300-1400 hp. Not that I'll ever use that much. I may go with a smaller billet wheel on the turbos if they don't spool the way I expect, maybe a 61/84 compressor wheel.

 

Doesn't the cam play a role in the backpressure? I've seen a lot of claims and magazine racing on the 6266's but no actual examples of anything actually running, well there are two examples thus far. Lots of Hondas are making 500 with them. I hope it is as easy as just doubling the numbers. Seems like 800-850 ish is about the average. Hopefully we will have mine up in the next several months. Do you have a map for the 6266?

 

Not really.

But backpressure certainly will have an impact on cam choice that is most desirable.

ie, if you built a system knowing it would run high EGBP, you certainly wouldnt want a cam that had a lot of overlap which might allow that back pressure back into the cylinder.
Likewise with exhaust valve opening/closing. So a well timed but shorter duration exhaust might be preferred.

If you had a very efficient setup with low EGBP, then you could take advantage with a more aggressive cam profile.

 

Thanks, that helps.