How Much Boost Will A Stock RB20DET Motor Handel

[rb20detsilvia]

i was just wondering how much boost a stock rb motor will handel i have a 92 240sx with a rb20det it has 3 inch exhaust and big fmic and intake but my injectors are stock and the local shop said that with 3 inch exhaust i wouldnt want to up my boost any more till i got bigger injectors and in order to do that i would need an ecu updated or power fc i was just wondering if any one could shed some light

[Joe]

personally i wouldnt go over 10psi on a stock engine.

the turbo and injectors are very weak above that point.

[rb20detsilvia]

they said with the 3 inch exhaust it would be about 10 psi so even if i get bigger injecters and a power fc i th e turbo wont handel much more? does anyone know if ther is a way to run bigger injectors without a power fc or updatted ecu

[Bronze MFP]

I'm running .8 to .9bar (13.xx psi) with no problems. I don't hold that boost for long though, so I can't really say how everything will hold under extended use like that. The cermic turbine on the turbo starts to come apart at 1bar and over, but I don't seem to have any fueling issues so far. i really need a wideband o2 sensor to be sure.

you can't run bigger injectors without some sort of ecu upgrade. the cheapest would be to put a socket on your ecu and burn a new program to control the larger injectors. power FC would probably be your next best bet. some people like the SAFC, but it messes with your timing maps and should be used for fine tuning a rom burn rather than all out tuning.

[rb20detsilvia]

is that with stock injectors

[Bronze MFP]

yep sure is. i have a set of 550cc's ready to go, but i've been lazy and havn't socketed my ECU for the program to support em. plus the stock injectors max out at where the turbo starts to self destruct, so i havn't really seen the need to plop in the injectors until i get a bigger turbo and z32 MAF

[rb20detsilvia]

so you think id be ok to get a boost controller and bump it up to 13 psi what kinda power does yous make

[Yellow4g63]

Kamin is right keep the boost to 10psi. Thats about where it should be with the mods you have right now. The injectors could take you to 14psi, I did that but I had a PFC in it. I'm sure the injector duty cycle was pretty high lol since there only 270cc injectors. The other thing is that POS stock turbo, It might beable to hang for a while at 14psi but it won't last as long. So unless you have another turbo ready to go on an don't give a damn then I say go for it. It should put you at around 230hp or so at that much boost. I'd watch the A/F but it should be fine since the Walbro pump over powers the stock regulator anyway. You do have a 255lph pump in the car right?

[rb20detsilvia]

Ya well thanx but that sux so guess its time to save up another 2000 to do the right upgrades lol if i wanted to run 18 psi what would i need to get size injectors and turbo

[Yellow4g63]

I would get some 660cc injectors or bigger. I plan to run some denos 660cc injectors, but I might just scrap them and run 720cc or bigger. Keep an eye out in the rb for sale section I'll have my PFC up there for sale soon and the price will be very good.

[rb20detsilvia]

Whats A Good Price

[Yellow4g63]

Whats A Good Price

just so Kamin dosent get pissed off lol. whats your email and I'll email you about it. unless they have PM's on this forum.

[rb20detsilvia]

[email protected]

[Joe]

lol he asked, you can answer just dont whore your stuff in threads and i dont have a problem with the discussion of selling things.

[rb20detsilvia]

What about fully built how much boost and how much power has been seen out of one

[Bronze MFP]

10hp@ 5psi

So far i think carlh holds the highpower RB20 title unless other evidence is presented. before he melted a hole in his piston, he was pushing ~380hp at 17psi on some big garett turbo (gt3071?) but this was on stock internals. He's rebuilding, so keep an eye out for him posting some insane power number afterwards.

[SeVa-S13]

Carl got I think an uncorrected 387whp on a GT30R. He's rebuilding with forged pistons, as am I, and I think Yellow4G63 is trying to get rods too. Withint the next year the RB20 is really gunna be tested stateside.

[hazw8st]

they said with the 3 inch exhaust it would be about 10 psi so even if i get bigger injecters and a power fc i th e turbo wont handel much more? does anyone know if ther is a way to run bigger injectors without a power fc or updatted ecu

13 psi is saft as long as you have a pyrometer/EGT installed and are monitoring the EGT....

[Carl H]

13 psi is saft as long as you have a pyrometer/EGT installed and are monitoring the EGT....

eh not true, well to an extent.idealy you should have an incar wideband, egt will indicate a lean condition but not imediately.if you can have both in car wideband for instant updates and egt for high load situations (say a long dyno pull back to back or a highway pull).13psi is creeping up near the rb20's destruction of turbo threshold so better to be happy with a stock setup and then upgrade the turbo and injectors.

[hazw8st]

Ideally, if the pistons were cut down one point and plasma coated, the engine could be boosted to 18 lbs with no issues. Boost is not the killer here, the c/r is the killer. Turbos are easy to replace compared to engines, if the engine is over-boosted, the bottom end bearings will wear prematurely. Also, if a turbo is overspun, the turboshaft will overflex due to the high rpms and the shaft will inevitably snap at the compressor housing bushing. The best setup is a compromise of a nice efficient turbo setup that has relatively decent spool up and a high boost capability, an EGT gage hooked up in series with a defueler, 8.5:1 c/r plasma coated shaved pistons, a boost controller and a rpm cutoff. That way, the turbo won't beat up the engines bottom end by squeezing down on the bottom end, the EGT's will stay within reasonable limit and the engine won't over rev, causing the turbo to overspin and grenade.

[rb20detsilvia]

sorry new to this whats an in car widban and etd

[SeVa-S13]

Wideband importance > EGT importance, I feel like I'm at a DSM forum. And the 20's stock CR is 8.5:1 already so dropping that for the sake of a few extra horribly inefficient psi out of a stock snail is pretty pointless. There are plenty of easily swappable turbos for the stock mani that would be a much better and easier choice for more power at a moderate level, with supporting bits of course.

[hazw8st]

Nissan Fairlady Z/ Nismo GT35RS...

[Yellow4g63]

I think Yellow4G63 is trying to get rods too. Withint the next year the RB20 is really gunna be tested stateside.

Ack don't remind me about the rods. It's mission impossible since I'm not home to send out a stock rod . Ohhh and I think I'll smash carls 370hp on stock bottom end hands down

[Carl H]

Ideally, if the pistons were cut down one point and plasma coated, the engine could be boosted to 18 lbs with no issues. Boost is not the killer here, the c/r is the killer. Turbos are easy to replace compared to engines, if the engine is over-boosted, the bottom end bearings will wear prematurely. Also, if a turbo is overspun, the turboshaft will overflex due to the high rpms and the shaft will inevitably snap at the compressor housing bushing. The best setup is a compromise of a nice efficient turbo setup that has relatively decent spool up and a high boost capability, an EGT gage hooked up in series with a defueler, 8.5:1 c/r plasma coated shaved pistons, a boost controller and a rpm cutoff. That way, the turbo won't beat up the engines bottom end by squeezing down on the bottom end, the EGT's will stay within reasonable limit and the engine won't over rev, causing the turbo to overspin and grenade.

im not sure what you said, infact you lost me mid way thru.english much?

[hazw8st]

im not sure what you said, infact you lost me mid way thru.english much?

No, not nearly enough for your liking.....

[Carl H]

Ack don't remind me about the rods. It's mission impossible since I'm not home to send out a stock rod . Ohhh and I think I'll smash carls 370hp on stock bottom end hands down

387, get it right, biotch!lol either way both of us need to get our cars back together.

[Yellow4g63]

387, get it right, biotch!lol either way both of us need to get our cars back together.

LoL sorry 387 lol. 1st one to get there car running and hit 400hp wins lol.

[Sky80]

So what was your setup CarlH when you hit 387? And what was the reason it went boom?(i know what the motor did, i mean like was it lean or what?) And what turbo are you running one person said gt30r the other said gt3071

And on another note... with injectors in the rb20 for instance shouldnt each cc stand for one hp? So i mean 650s would be plenty for any setup or well unless you want to go beyond 650whp? or am i wrong about this?

[hazw8st]

The last thing you need is a weak bottom end and the added friction of overfueling the vehicle at midrange rpm, which actually powerwashes the oil off the sides of the cylinders creating massive friction and parasitic hp loss.

The fastest way to blow an engine is to overfuel it and overboost it. Looks as if you were quite successful at both.