link399 link400 link401 link402 link403 link404 link405 link406 link407 link408 link409 link410 link411 link412 link413 link414 link415 link416 link417 link418 link419 link420 link421 link422 link423 link424 link425 link426 link427 link428 link429 link430 link431 link432 link433 link434 link435 link436 link437 link438 link439 link440 link441 link442 link443 link444 link445 link446 link447 link448 link449 link450 link451 link452 link453 link454 link455 link456 link457 link458 link459 link460 link461 link462 link463 link464 link465 link466 link467 link468 link469 link470 link471 link472 link473 link474 link475 link476 link477 link478 link479 link480 link481 link482 link483 link484 link485 link486 link487 link488 link489 link490 link491 link492 link493 link494 link495 link496 link497 link498 link499 link500 link501 link502 link503 link504 link505 link506 link507 link508 link509 link510 link511 link512 link513 link514 link515 link516 link517 link518 link519 link520 link521 link522 link523 link524 link525 link526 link527 link528 link529 link530 link531

Turbo A/R Discussion

  • z31t
    z31t
    Senior Member
    • 624

    #16
    You won't notice a big difference until you try to max the turbo out. When you see these 800+whp cars on 6xmm turbos they have the large a/r housings on the exhaust.
    lm7 swapped z
    350z 6speed
    s475 turbo
    microsquirt ems
    street car
    http://www.youtube.com/user/redz31t?blend=21&ob=5
  • liladair
    liladair
    Senior Member
    • 109

    #17
    I have a .65 on my open scroll 60-1 and it spools great. 15 psi spring in the wastegate right now and it holds steady. After I finish the harness for the new management system i will up the boost and see how well she responds at higher boost / power levels. Also changing from ported stock manifolds to tubular manifolds when they are finished. My car always goes thru big changes in a weekend because i drive it everyday lol.
  • james
    james
    Senior Member
    • 978

    #18
    i have tried a couple of different turbo combinations and A/R

    The GT35 (journal bearing copy) with 0.82 open scroll and log manifolds was lazy until 3500rpm then ran like a demon at 20psi and showed no signs of dropping off, the manifold pressure at 20psi spun the gauge needle right around until it read zero again. Those manifolds then failed, the turbo failed the journal bearing and bent the shaft. It was probably more the cheap turbo but I can see that turbo with perhaps a divided 0.82 would have been a really good match.

    can also understand what flawlez is saying about not needing a huge A/R

    My car runs Tube headers, Schneider cam and ported heads with a hybrid turbo i built out of leftovers. Its a GT35R compressor wheel on T04S front cover (machined to match) with your typical mild stage 3 turbine wheel and bored out stock housing. You would think its not a great combonation with a massive compressor wheel on the small turbine but this thing really moves.

    at 13psi my RB25det heavy duty clutch slips at anything over 5500rpm and it shows no sign of being any less punchy than the old Journal bearing GT35R.

    Yes the hot side is probally holding back power and no it hasn't been on the dyno but its a properly matched system all there way through and its breathing very well on a surprisingly small stock turbine housing.

    To anybody thinking of experimenting with their turbine housing sizes Setup a manifold pressure guage , wrap a thin copper tube around a pieces of 1" stock a bunch of times and plumb it into the turbine housing and run it to a boost gauge.

    Somebody with tube headers and a well matched perhaps a ball bearing turbo should in theory be able to achieve a higher boost pressure than manifold pressure.
    85 Turbo Slick Top
    __________________________________________________ _____
  • FlawleZ
    FlawleZ
    Senior Member
    • 1971

    #19
    Originally posted by 300zxturboftw View Post
    FlaweZ are you running a divided or open scroll? From what I've always understood that always plays a part in A/R as G-E discussed above.

    I could understand running a .63 open scroll, but wouldn't understand anything lower than .8 on a divided (which is the reason why most don't even make something that small).
    I know this is super late to reply but still helpful for those who may search in the future. My .63 housing is an open. Precision doesn't produce a divided housing on T3 frames. On a T4 I would have opted for something like a .82 divided.
    Originally posted by Andrew84zx
    tell her your car is so fast it will make her panties fly off
    545 RWHP & 540 RWTQ