Basic RB20 questions

[SX APPEAL]

OK, I did my searching, and was honestly expecting to find the answer to this question in about 30 seconds but guess not. What is the stock boost on an RB20, or any of the RB series for that matter? Is this info just such common knowledge that its not even worth posting ANYWHERE on here? I couldn't even find it with google or wiki.

Now the next question, to which I was also expecting to find the answer rather quickly. Say someone like myself were to finish the RB20DET swap, everything is absolutely 100% stock, except for perhaps a front mount and obviously the fuel pump, how much could this person safely increase the boost level, and what sort of power would be seen?

Assuming stock power on an RB20 is about 215 at the crank at I'm guessing 5-7psi (Like I said, still not sure) could it be turned up to say 10-12 to see 250-270 at the crank? Or is that too optimistic?

Thanks for the help.

[cachanilla86]

You cant run more than 12 PSI if boost, because the Ceramic turbine wheel will explode, and the 270cc Injectors max out at 10-12 PSI. He's still using the stock KA24 fuel pump...with stock everything, even teh open differential, last Thursday he ran a 9.28 on the local track. (1/8 mile)

He Used a R32 X-member, and a slightly modified transmission mount, and is using the stock mounts.

[Sil240]

Stock boost on a RB20 is 10 or 11 psi I believe.RB25 is 7 psi

Not 100% sure, never used the stock turbo.But I know guys that switch to the RB25 turbo, re-use the RB20 WG actuator.

Yeah they say 14psi is the limit, I wouldn't tempt it and would stay at 12 psi. Plus at that level that little turbo is probably pumping hot air.

Plus like the other guy said you'll probably be maxing out your injectors.

I believe to hit 275whp you would need a RB25 turbo, larger exhaust, FMIC, larger injectors, some kind of ecu tune.

I think I heard 230 WHP is the max for the injectors. Not 100% sure though.

[SX APPEAL]

Wow 10psi stock, thats quite a bit higher than I would have thought. Guess I'll need to look into tuning and injectors then, already have a T3/T4 I could throw on if need be. I'm guessing the stock turbo is T2 flanged though right?

[SX APPEAL]

Wait, rereading everything... At stock boost 10-11psi the RB20 is making 215 to the crank, roughly 185 to the wheels in an S13, but by bumping it to 14 its up to 230 at the wheels, roughly 267 at the crank??? Can 3-4psi give you 50 horsepower?

[Sil240]

The RB20/25 turbos are T3 flangesThe RB26 turbos are T2 Flanges

Your T3/t4 turbo will bolt right on.That's what I'm doing.

Dunno really check SAU they have a dyno thread up there check it out.

[glitched]

I'm still new to the RB world as well, And i couldnt find that informatin searching this board either. I had to go digging through posts at that australian skyline forum.

For some reason I thought it was 7 or 9, and then when you put a rb25 turbo on an rb20, it runs at the same psi, but is techinically flowing alot better.

I wouldnt take it passed 11, 12 maybe on stock injectors.

Also, before you begin increasing boost you NEED to have a free flowing exhaust and a FMIC.

[AZ89two4Tsx]

How about I add to the noob questions.

What is the stock rev limit on the RB20?

[dizzywithsunstroke]

just to confirm, stock rb20 boost is 10psi, rb25 is 7psi.and yes rb20 and 25 have t3 flange.

[yotik]

redline is 7600rpm

I was a little shocked too when i first saw my boost gauge climb to 10psi on mine.

[lexrob]

My rb throws just about 10.5-11psi... gauge error i guess.

From my understanding the rb20 and 25 turbos are hybrid t28's, both with ceramic turbines. The N1's have steel.

So... i dont know how much gain switching would accomplish. T3/T4 is what i want to get is it a "disco potato" did they come stock on anything.

[b00stinbmx]

as far as power goes. my bone stock rb20 with 255 walbro, FMIC made 219whp and 184tq. 10psi. my motor seems to be pretty healthy but thats in a 1990 240sx se hatch. so the 20 can make pretty decent power at stock form, i bet i could get 300whp out of it with a rb25 turbo but im going t3/t4 instead next yr prob. its still fun as s*** though with the stock 20 turbo.

[lexrob]

I dont know about other opinions but there is like NO BOOST lag. Its like a honda just got to get in it. Its like full spool by 4k....

[placham]

I'm seeing 0.8bar solid till redline on my RB20DET, all stock except Syko turbo elbow and 3" exhaust, was same before and after cam swap. And I believe when I had the motor in the clip with cast turbo elbow it was boosting at around ~0.7bar or 0.6bar with no load.

Think the full 3" turbo elbow raised the boost some what .

And my Greddy gauge is hooked up directly to the intake plenum where stock boost sensor goes. I dont know if mechanical and electric gauges would very in readings.

So I'm seeing 0.8bar which is around 11psi.

Hope this helps.