Safe Psi.

[Andyn]

Hey,

Just got my first turbs car as a new toy to play with (rb20) with ARC front mount(not sure what size), blitz bov, HKS pod, avcr boost controller, factory dump and cat, 3inch cat back. Atm its on 0.75 bar (which is about 10psi). I cranked it to 0.85 yesterday, and I believe that is about 12psi. Pls correct me if you disagree with these conversion.

Two questions:

1). Wondering what psi can I safely go up to, with these mods. (I have been reading around these forums and it seems like 12psi is safe with bolt ons + factory intercooler). Since I have front mount I'm assuming I can go up a bit more.

I will run standard boost for daily driving but just want to know for once off moments

2). My boost comes on from 3.5k rpm for each gear - so increasing the boost should not make boost come on in lower rpm right? but rather when u hit boost (3.5rpm) itll kick in harder? Correct me if im wrong.

Look forward to ur feedback

Andy

[blind_elk]

1. Mods have very little to do with the safe PSI limit. It is predominantly a function of the construction of the turbo itself. The factory turbo is built with a ceramic turbine wheel, and it is this component that is the "weakest link". As you increase boost, you increase the rpm at which the wheel spins. At a certain point, the ceramic unglues itself from the shaft and shatters. Best case is it sprays the front of any following car; worst case, it gives your engine's cylinders a terrific hone.

2. All you are doing is increasing MAXIMUM boost. It should still cut in at the same point, with the same "kick in the bum".

[shif_tea]

i don't agree with elk entirely, without a fmic i was only able to run 9psi (in an r33) before engine started pinging, however once i installed that i was able to increase it to 12psi safely, so mods do allow higher boost to be run. Once you get to a certain point though the turbo will become the weakest link in the chain, not sure what that is on an rb20.

With the boost increase you should feel more pull under acceleration but probably won't spool up quicker. Would probably have to look into dump pipe and larger cat amongst other things to help that.

[Johnny Cash]

I'm fairly certain that RB20's have a higher factory boost setting than the RB25's, due to engine and turbo size.

[super_s13]

hey guys i have the rb20 in my silvia as far as i know those conversions are pretty spot on as 1.0bar is 14.7 psi so they sound about right. As for the safe boost limit a mate of mine in Darwin was running 14psi through stock turbo for ages still is now i think although when i did it it spun the wheel off the shaft like the other guys on here were saying so they are right about that so i personally would only run 12psi to be safe or better still get a hold of a turbo off the VG30DET 300ZX APPROX $300 and use that it is a direct bolt on other than oil feed lines and they arn't hard to do and they have a steel rear wheel so can handle around 18psi then boost it to 1.0 bar and have fun how ever with these engines i wouldnt over rev them to much they tend to spin big end bearings G.L Let us know wat power figure you end up with

[benl1981]

Are you sure the VG30 is steel wheeled? I think they are quite a bit laggier than the RB25 turbo right?

[TTT]

1.) there is no "SAFE" boost limit.

turbo's can break at factory 10 psi or it might not break at 16 psi..

you run it, you risk it.

2.) having an intercooler will not save your turbo from damage. intercoolers are there for your CHARGE air (the air going in to your motor) and doesn't cool the exhaust gasses which is the heat that breaks turbo exhaust wheels.

3.) when you say boost comes on at 3500rpm.. you mean you have full boost (12 psi) at that rpm or starts to come on positive boost at that rpm.

if you want to put the boost up, go right ahead.. stock turbo's cost piss all and an upgrade to an RB25 turbo is not much more.

if you can't afford to have your car off the road (like me) don't risk it.