Rb20det Stock Turbo 15psi After Mods?

[Kanaric]

It such high PSI unusual? I know it's above what is recommended so i'm looking at wastegate actuators right now.

I have tomei turbo elbow, 3" back non-cat exhaust + intercooler.

If this isn't unusual since people put the RB20 actuator on the RB25 is the other way around possible?

Thanks

edit: hmm now it gets to like 11-12.5 psi and it's like the engine is cutting. Seems I might have another issue.

It isn't tuned yet could be the problem there.

Edited January 28, 2015 by Kanaric

[GTSBoy]

It's not normal. Stock RB20 boost is about 10 psi. Add a big cooler, a big exhaust and maybe open up the intake and you can reasonably expect to see 12-13 psi without needing a boost controller. Almost certainly not well controlled 12-13 psi though - you'd probably see it peak at that and fall well off towards 10-11 at high revs. 15 psi though is out of bounds. It shouldn't happen without a boost controller.

An RB20 should not be boost cutting at 11-12 psi unless you have a highflow turbo. There is no real "boost cut" in the 20 ECU. There is a load cut which is essentially when you exceed a certain amount of AFM signal. If you put a big turbo on then you can pull more air at the same boost and trigger that cut.

If the engine is untuned and for some reason the ignition timing is quite retarded then you might have excessively nasty exhaust temperatures and might be spinning the turbo up hard enough to make really high boost. Might. Maybe. Don't quote me on it.

[GH05T]

running out of fuel? what pump is in it?
if this is the case your gonna lean out and pop in a short amount of time.

[BlueRB240]

I remember when I had stock turbo and injectors, Ran it @ 14psi on the stock ecu with a walbro 255lph pump and it started to lean out (13.5's) A/f. Maybe I could have richened it back up if I had a ecu that could tune back then. The stock injectors are 270cc tho so maybe not.

[GTSBoy]

Maybe I could have richened it back up if I had a ecu that could tune back then.

Unlikely that you could have richened it back up with a tuneable ECU. The top end of the fuel map in RB20 ECUs is up to 100% duty cycle - effectively using all the available injector. Like 10:1 mixtures. If it was leaning out then it was not going to be possible to add fuel without adding physical capacity. I effectively had to turn my boost back from ~14 to ~13 psi when I tuned my RB20 in order to not run the injectors over the top of their capacity.