Please help me decide..

[bubela]

I'm currently running a PT6262 .58 hot side dual ball bearing turbo on a steedspeed T4. ~3.0L motor. It made 440whp/400wtq on Maximum PSI's dyno last year at 17psi on 93 octane. My best 1/4 is an 11.3 @129. (best trap is 131mph at 18psi with a little 100 octane mixed in)

Some time this year I'll be swapping to a DTA and E85.

My goals for the car are:

1) Daily Driver
2) 10 second 1/4 (mid to low 10s.. maybe 9's?!?!)
3) 600 wtq 700 whp (ish)

I see a lot of good things on the internets with this new PT6466 dbb turbo. Will I be happy with a larger hot side on the 6262 or will I like a (.68, or not so small .81) 6466 better? At the strip, I'm actually seeing 8-10psi in first gear with my current set up. I originally went with this "small" turbo and the smallest hot side for response. And I got it. (And Love it!) Any ideas/guess on what I'll flow on this car with E85 in it's current configuration?


summation: 6262 or 6466?

[JuCo]

This is just an example, 3.4l 2JZ motor

http://i738.photobucket.com/albums/xx26/SoundPerformance/62vs64vs67.jpg

Personally, the larger turbo will give you better power up top, with little compromise on the bottom end. Its a win..win...my vote goes to 6466. If your budget minded I'm sure you can reach your goals with a new hotside.

http://i738.photobucket.com/albums/xx26/SoundPerformance/62vs64vs67_ReidsCar.jpg

Now check this above dyno. The 6466 vs a 6766 on a stock 2JZ. It out performs the larger 6766. Once again not BMW motors, but it atleast gives you a reference point.

[bubela]

Thank you JuCo for the info. Definitely continues to sell me on the 6466. Any idea on the A/R sizes with these set ups? I'd imagine spool would be a little later with my 3.ol (amongst other apple/orange factors) than these graphs.

Anyone see me choking up top with a 6466 and .68 housing reaching towards 30psi?

[nucci]

If you switch to E85 and tune spool more aggressively, you will see 300-400rpm improvement over gas. That may make a 0.82 6466 respond awful close to your 6262...



Anyone see me choking up top with a 6466 and .68 housing reaching towards 30psi?
You posted this while I was posting - if you continue on the same path as your 440whp/17psi setup, 30psi gets you in the 700whp range, and you shouldn't have any issue with a smaller housing at that level. You can see in the results posted above that the 0.82 holds 36psi flat out the top on the 3.0L stock block at over 800whp.

Double edit - the 3.4 liter engine posted above has a free flowing 3.5 exhaust and the 3.0 liter has a 4.0 exhaust IIRC so if you have a much more restrictive setup, you may experience choke earlier.

[BavarianLove]

6466 Do it you will Bob!

[BadBoostedBmwM3]

I just can't believe the 6466 spool (basically) the same as 6266 but it has a great top end. It almost makes the 6266 and even the 6766 obsolete.
IMO, I'd always buy a 6466 over the 6266. The 6766 is only useful for that little bit extra.

[bubela]

Hmm.. response similar to my current set up sounds real nice. Current exhaust is a no cat, dual flowmaster, 3".

[milKt]

bigger

[bubela]

Just spoke to Justin at Precision Turbo (.net)

He's telling me that the 6466 is "capable" of 45psi. Said I'd be fine with a .68 on the 6466, no need to go with the .81. I'd lose a good 500RPM on the spool over my current set up. That I'd possibly see 700hp out of my 6262. (with a larger .68 A/R)

This didn't really help make the decision more decisive for me.

[Z3speed4me]

Mike will be building my motor with a 6466 T4 divided housing, (prob 1.0 a/r maybe .84), using a twin-scroll Radowskifold. Just gotta start ordering parts and such soon...

I won't be done til July / August probably; dunno what your timeline is for "needing" this done if you want to wait for results. I will be pushing pump gas as far as I can...which can at least give you a feel of your possibilities beyond what I want to do.

[BadBoostedBmwM3]

Mike will be building my motor with a 6466 T4 divided housing, (prob 1.0 a/r maybe .84), using a twin-scroll Radowskifold. Just gotta start ordering parts and such soon...

I won't be done til July / August probably; dunno what your timeline is for "needing" this done if you want to wait for results. I will be pushing pump gas as far as I can...which can at least give you a feel of your possibilities beyond what I want to do.
You should be all over 600whp on pump gas.

[Z3speed4me]

That is the plan...we will see :D

[bubela]

dunno what your timeline is for "needing" this done if you want to wait for results.

I think that is what I will do. I'll push the limits with my current set up on E85 and see where that puts me. If it's not enough, I'll swap next year.

Talking with Precision did actually clear some things up. Justin didn't seem to think compressor surge would be an issue. I should get around 25 psi out of it, even towards redline.