turbodailydan

currently running a 57trim t3/t4 on my b18r. just thinking if it would be worth loosing the journal bearing and putting a roller bearing core in there...

would there be much difference in spool up time or is it just less likely to drop off between gear change?

anybody running a 57trim roller bearing?

current dyno graph (flywheel power) @ at 1.2bar..

inspector01

More info on your setup would be very helpful, engine specs, manifold, etc., but if you are dropping out of boost with a 57 trim on a B18, you are doing something wrong. I have full boost by about 3k-3.5k rpms.

TheShodan

iTrader: (14)

By "roller bearing" core, as you referring to the GT-R series "ball-bearing" cartridge?
If that is what you mean, then the answer is no, you will not see a significant increase in response by simply changing the cartridge. To see the benefits of a ball-bearing cartridge, the aerodynamics of the compressor and exhaust wheels themselves need to match appropriately with the CHRA, or "core". The wheel design and ball-bearing center section work TOGETHER to achieve better "spool", not just the CHRA alone.

According to what turbodailydan is saying, he's about 370-390whp at about 17.8psi or so. He's about right at 2.24PR on the 57 trim map, and should be close to about that power anyway. Something is definately holding him up in responsiveness. He should be about 21.6lbs/min by 3400rpms on a GS-R engine, but if he's an LS, that is different. His maximum pressure issue It could be his exhaust configuration, timing, or fuel. But powerwise, he's about right. Some power levels may vary (I know how you H-T guys like to get picky) but these are mainly general approximations.

turbodailydan

quick spec:

b18c
wiseco forged pistons
eagle rods
ITR head
ITR camshafts and stock pulleys
ITR inlet manifold
ITR throttle body
ITR flywheel
ITR gearbox/LSD
garrett t3/t4 57 trim
tial 38mm ext w/s
AFI ramhorn manifold
AFI 3" downpipe
custom full 3" stainless exhaust system (turbo back)
garrett core backdoor style fmic
Omni 4bar map sensor
hks evc5 boost controller

by the way it doesnt drop out of boost on gearchange.. im merely asking as im just curious as to what the benefits would be, as was looking on ATP turbo's website and they list 2 types of 57trim, a journal bearing and a roller bearing (gt core)

thanks

turbodailydan

full boost at 3-3.5k on a 57trim?? when does your vtec engage??

my vtec crossover is around 4.8k rpm, turbo starts to go around 4.5k rpm and takes off at 5k rpm id say.

inspector01

Vtec is at 5k i think, it was quite a bit slower spooling when I had a top mount manifold, but I ended up switching to a mini log and spool was a lot faster (open dp also gave me a lot better spool, that is when I could get it by around 3k, full exhaust was still 3.5-4k). Even when I had the top mount and a T3/T67 I had full boost by 5.5k-6k and that is a lot bigger than the 57 trim.

turbodailydan

what cams were you running? spec?

TheShodan

iTrader: (14)

The cams were more than likely Type R or GS-R. That won't change your "spool" really. The only benefit from switching CHRAs (or "core") would be the fact that uses water lines now. But that can be done on most Garrett CHRAs.

inspector01

Rods and Pistons GSR, Stock ports, stock cams,