soulezoo

It is evident that some tuning is in order. My experience with the old twins was that the secondary spooled faster and then total boost was dependent on the primary "catching up" and supplying the extra air.

It seems to be the opposite here where the Primary is already fully spooled (to its 27-30 psi) then the extra time to get to 60 must be from the secondary... which is wastegated at 40 psi... hmmm... makes me think for sure.

Mike Holmen

Sounds like a wicked set-up bud. The worst case for me is going from no throttle coasting at 50 mph and then nail it. It takes more time to spool them like this than going from stop. You're gonna have to take some pictures for us to drool over and see what Piers has going on. I would go over and check out his operation, but my wallet might get a little thinner.

soulezoo

I'd love to share pics and more info but have an obligation not to that I have to respect for now. The worst case as you put it is the same for me too... that is when I get surge, about the only complaint I can make so far. It is a very nice, well put together setup and they are using my feedback to improve future sets.

RonA

There are 2 dyno events on saturday. One in Dublin, one in Redding. Might as well strap it down and see what you got.

soulezoo

I need to in the worst way, but Erik always schedules these things the same weekends I have my military duty... so I can't be there. looking for a weekend that does not conflict though very soon... need to do the Wed. Nite Drags at Sac raceway too...

soulezoo

I spoke about surge here and in a post a while back... I was under the impression that BB turbos did not "break-in" like journal bearing turbos. My point is now that I have put some miles on the turbos, I no longer get that surge. Nothing else has changed but the time on the turbos... I can only assume that maybe there is a "break-in" period. I see no difference in spool time though.

jaaron

I would assume that this happens because you are in a higher gear going 50 mph than from a dead stop so therefore it takes more power to get the engine RPMs up as fast.

Mike Holmen

Ya I just drop out of OD and go into 3rd, then drop the hammer. Its mostly because of the lock-up clutch and OD that makes it difficult to get the rpm's spooling. Mine twins have got faster from breakin. You can hear the turbo spooling still during the shutdown. I have about 10 seconds of spinning then I assume that it has stopped. Does your primary have coolant lines? How about the secondary? I'm curious on how did Piers set that up? Once I get sometime I'm putting together a garrett twins 3782/K-31. I'm betting that it will be a wickedly fast spooling set-up.

jaaron

is this in dublin, tx?

soulezoo

No, Dublin, CA.... in the Bay Area

soulezoo

Mike-- Both Turbos are watercooled and ball bearing. The water lines are in series... from bottom rad hose outlet to primary to secondary to heater core.

BDS

Sounds like a sweet set-up...I know from following the PSD world for a long time the Garrett BB turbos are popular. There are a few PSD's running the GT42 BB water cooled. I do remember the GT38R... which is a direct replacement drop in turbo for the PSD.... being extremely expensive to rebuild once the bearings get some play ... The GT38R costs around $1700+ new and ~$1200 to rebuild. I hope yours last a long time for you.

I am only commenting on the GT38R since it is all I really know the garrett BB facts about.
I still like the idea of BB twins and yours is an awesome set-up to say the least!

Good Luck with them.
Brent.