Is it really worth the extra ££££££

Regarding the ball Bearing option of a turbo is it worth paying the extra $700+ with what spool time you would gain over the same turbo but journal.

On a small/mid size turbo the gains wont make much difference imo, on a big turbo every little helps.

If i was looking for a new turbo now i would look towards the batmowheel stuff, not much info yet but what has been about seems good.

i went for the T61 DBB option for the quicker spool (albeit on a t61 its an overkill) and extra cooling.

The wheel technology is prob more important for spool, I would not use a journal bearing now, new design is ceramic ball bearing which is handy as like my T6 there is no water cooling, check out Billet Turbo and Comp Turbo. If you want to know how much free'er a BB is my T6 spins for 21/2 mins after switching off with the motor on tickover.

I'm definitely going for dbb. Not sure if it will make a great deal of difference but as said, every little helps. Unless trying to build a car on a budget I would always recommend dbb.

I was looking at the batmo stuff but I really want dbb and as far as I know they aren't available yet?

I would always go with a DBB turbo, as a percentage of the overall single conversion cost i believe the gains are worth the extra. If you were to drive a Supra: one with a journal bearing turbo, one with a DBB turbo of the same size back to back you would notice the difference in response.

DBB every time

Ball bearing turbos are able to handle the thrust loads of a high boost turbine much better and much more safely than even a 360 degree thrust plate in a plain journal bearing turbo. I am not very convinced about improved spool, a journal bearing needs pressurised warm oil to spin properly, it would be interesting to see how long a plain bearing turbo sins for without exhaust flow, but WITH continued pressurised oil flow to its bearings. One snag with BB turbos is a bearing or shaft failure can allow tiny ball bearings to escape places where they are most definitely unwanted.

If you want to know how much free'er a BB is my T6 spins for 21/2 mins after switching off with the motor on tickover.

As dude has said, my 42R spins for a couple of minutes after shutoff. It's cool

I am not very convinced about improved spool

I did a back to back test between a T67 journal and a T67DBB turbo on my Supra a few years back, with datalogging and everything. The low down response is hugely improved with DBB.

Numbers, graphs, and discussion here:

http://www.mkivsupra.net/vbb/showthread.php?68090-Dual-ball-bearing-turbo

When you are going for it and shifting above 4000rpm with bootfuls of throttle, it makes almost no difference. It's the low down stuff for street driveability that DBBs shine at. Most of us spend most of our time there, so it's certainly worth it.

-Ian