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I wouldn't say it's so much a internal wastegate problem as it is an undersized spring in the actuator while running increased boost. Both of the stock 20 turbos I've been in contact with have been fine... but they are running .9 bar with no boost controller (no cat, 3" exh, and pod filter)... yet no spikes.

If HKS sells their 2835 with an internal option... I'd imagine it's able to flow the amount of waste gas needed not to spike... They shouldn't be like FC S4 TII RX7's who have to port their internal gate in order to up the boost safely.

hrmmm.... well i dunno then.

like i said when i cranked the boost to 14psi i would get boost spikes, possibly due to the boost controler not being setup properly but i still think its due to the shoddy turbo elbow design.

when my s13 was on the road i had the following setup : stock smic, 3" catback, punched cat, hks intake.

i saw 10psi all the time with no spikes except on very cold nights, but even then it would only spike to 11psi.

my stock tubo has a touch of shaft play, none round and round but some back and forth.

as for the power bit, i suppose that since no one has really bolted one to an rb20 its all guess work for now.

we'll have to see how she goes with it on there.

My old motor was running the stock dump like yours but cut part way down and welded to 3" pipe with no cat and with no spike... the only difference I can see is that mine (now in a buddy's car... has FMIC now but didn't spike with the SMIC either) has no cat at all and was boosting 12-13psi max boost with no boost controller.

Anyway... here is an post from a while back with a RB20 and a 3040 setup:

MRPrez's RB20 w/ 3040 turbo

Hello guys.. I just Got my Turbo package wcich is GT3040 with .63 exhaust housing, Tial 38mm wastegate and i also got an apointment with my mech. for the next thursday  and he said after installation we power run it to see if i need to upgrade my Injectors and if so he will get me 600ccs (God help me with my fuel cunsumption :)). so fingers crossed.  

He's running a .63 a/r... but going by these... that looks like the right size

Guy here changed from 0.61 on HKS 3037 (bit smaller comp wheel only compared to 3040) to 0.87 and went from 256rwkW @ 1 Bar with full boost at 3500rpm to 280 at 1.2 bar but no boost until 5200rpm. Would be heaps slower on the road.
HKS actully recommend the 0.87 for the 3037 kit they sell for RB25.

If you get the GT3071R take note of which turbine it has . There are different versions , the earlier ones used the GT30 84 trim turbine and the re baged 2835's use the 84 and 90 trim versions of the 56.6 major O/D turbine . These are a factory cropped GT30 turbine not known for stellar performance . They are generally found in GT28 style integrally gated turbine housings while the GT30's generally use Garrett or HKS non gated GT30 housings .

Chow A .

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