T66 vs SP63

LESS lag with a Q trim? I thought the Q trim was a more aggressive exhaust wheel?!?! Now I'm really confused. Damnit, I just bought a P trim T66! I've seen some pretty impressive dynos of this turbo too... Maybe I should have spent the extra $$ for an SP63.

poweraddict, the RPMs turbos spool at is mostly effected by the turbine side (ie the trim and a/r). The rotational inertia effects the time it takes to spool past the boost threashold.

pooshda, sorry there aren't any magic turbos that I've ever heard of Unless you want a good flowing exhaust side (which means its going to spool later) to go with that SP70, its not going to make a lot of power. Now I don't know the details of it at all, but if you look at Steve Vache's site, there are dyno graphs of a SP70 .81 and a SP63 .81 on the same car, Al S's. The SP63 makes a bit more power (~560rwhp) at 1 psi less (19) boost. The SP70 compressor likely needs more airflow to be effecient than the stock cams (and maybe a .81 housing) can support. I'm sure Larry will correct me if I am wrong, but me thinks the SP70 probably likes a LOT of flow

Larry, do you find the larger a/rs make more power at every boost level, or just high (22+) boost?

BLKMGK, I ordered a water cooled turbo. Corky Bell claims they last about twice as long, and turbo timing isn't as important. Plus I didn't want the thing cooking my oil road racing. I called SP about it, and they said $100 more and I would have to wait a week or two longer for it (SP63 .70). I didn't want to wait, and the dyno sheets I've seen show the T66 to be about equivilent to the SP63. Ryan Woon has made 655 on the .81 P trim T66, with 27.5 psi. Of course, the T66 has a larger and probably heavier compressor wheel (look at the measurements on Steve's site, the SP63 has a small exducer).

Here is a copy of a post from the big list on BB turbos:



>Ball bearings have been used off and on since the 30's. It's certainly
> >possible that ball bearing turbos handle axial loads better than plain
> >bearings, but in terms of friction, ball bearings have inherently more
> >drag than plain bearings especially when they are flooded with oil. The
> >real question is how much axial loading is there, and why. There are
> >lots of methods of controling axial loads with ball, needle, tapered
> >needle and roller bearings.
> >
> >As far as the stories, if you go to Garrett's site, they claim ball
> >bearings spin up faster. They make no claims at all about longer life,
> >better axial load control, or any of the other things I have heard about
> >ball bearing turbos. If I really wanted to know about plain vs. ball
> >bearings, I'd ask a truck mechanic (one with a few smarts, not like some
> >of your typical diesel techs). Truckers put more stress on their turbos
> >than we can imagine. Just think about what it takes to haul 40,000 lbs
> >up a hill like the Grapevine on I-5 in CA. That turbo is screaming its
> >little heart out all the way up the hill...we're lucky (and flat hauling
> >ass) if we get a continuous run at full load for a whole minute, they do
> >it for 5, 10, 15 minutes straight. That's a real workout. If ball
> >bearings are so superior, the trucking industry wouldn't even bother
> >with plain bearing turbos. Last I heard, the jury is still out there
> >too.
> >
> >Lance
> >'93 TT 6 speed Coupe




Has anyone tried putting oil pressure into a BB turbo and comparing it to regualr bearing turbo?? The regular bearing turbo spins easier! It is only when the two turbos are dry does the BB spin easier. Think about it, less surface area bearing wise. I have personally never seen a BB turbo spool any faster and with the new 360 degree thrust bearings available I see no reason to use a BB turbo ever from a reliability standpoint.


Lar
SP