RB25DET max boost?

[Zacho]

ok..... would a rb26 bottomend be a direct bolt up to a rb25 head? And I am going to be running a big single so i dont have to worry about f'ing the turbo up... just the motor.

You can't just use rb26 rods or pistons, you have to use them both iirc. But honestly if your going through all that trouble I'd get forgies.

cschepp, we can't tell you how much a complete rebuild would cost because everyone's definition of "complete" is different. at 600 atw I would guess the shortblock would be the cheaper part of the build in comparison to everything else.

[Skym]

It does with R32 RB25DE head.

Not sure about R33, R34 RB25DET head, as it has VVT. But might be able to be modified to fit if VVT is sorted (I think oil feed??).

I think the differences are mentioned in the RB30 guide, which RB30 would be a better upgrade bottomend wise for hp (RB26 bottomend for response) -

http://paulr33.skylinesaustralia.com/docs/RB30_DOHC.pdf

400whp+ RB30 in a R33 chasing down a WRX (inside, out side shots) -

http://www.youtube.com/watch?v=YVaSuluegD8

Gives you an idea what it drives like. Just need wide rear tyres with slicks or semislicks to get some traction (RB30 = alot of torque).

[BrianV8]

i believe they do but someone would have to confirm.

I believe greddy or hks makes a single top mount for the rb26 head

[cschepp]

ok..... would a rb26 bottomend be a direct bolt up to a rb25 head? And I am going to be running a big single so i dont have to worry about f'ing the turbo up... just the motor.

[kenbeaton1001]

speaking of r33 turbo and tuning, does anyone know anyone around the nova scotia area that can tune my r33 gtst? the japanese owner only put 35000 kms on it and it still cuts out and, im not saying its slow but, i want it faster. XD

[Skym]

I noticed Japanese tuners don't push stock RB25DET internals past 415whp max (high boost setting) with headgasket upgrade. Then it's time to fit lower compression RB26 bottomend inside RB25 shortblock.

It drives like this when you have a boosted up RB25DET bottomend with high mount single -

http://www.youtube.com/watch?v=jU2isjD54Vw

With RB26 bottomend -

http://www.youtube.com/watch?v=S3hwZomhiCQ&feature=channel

Note it sounds a little bit different.

With stock turbo they don't push past 13.23psi (low boost, everyday setting) to 16.17psi (high boost setting, mainly used for overtaking or dyno).

Some outside Japan have produced up to around 322whp with low boost level of 12-13psi with stock RB25 turbo (using a MAP ECU, so no MAF sensor restricting intake). I assume it's a Series 1 RB25 turbo.

The Series 2 RB25 turbo's do fail on compressor side of turbo.

[cschepp]

are you guys sure that it can only handle 450 hp? I want to possibly hit 600 next year obviously with supporting mods. How much do you think it would cost for a complete rebuild of the engine?

[BrianV8]

i've heard of people running more than 15 pounds on the series one turbo's, don't expect it to last forever though. series 2 turbo no way. If you want to run that kind of boost with a rb25 turbo it has to be the NEO. Even then at 8 grand the neo turbo tends to dip off due to not being able to flow enough air

[bigstuffdee]

What I ended up doing was intake+exhaust ,then removed the stock turbo solenoid and installed a manual boost controller which I was able to tune at about 18psi. Seems to handle it fine with the original turbo.oh and we also put in an autometer boost gauge awesome looks for a fair price.

[BrianV8]

ya i've got a series one and i'm at 400 wheel on stock internals, think thats as close as i want to get to 450 crank

[cschepp]

rb25det series 2 engines can only handle 450 on stock internals.... Thats kind of depressing!

[Snow]

Yea running an RB20. But I know it is most definitely a ball-bearing turbo. BACK OT!

[BrianV8]

oh this thread was about the rb25 motor, didn't realize haha, but yeah that turbo is good for as much as you can throw at it. I actually heard that the factory neo turbo's are made by garrett. Steel wheel and ball bearing

[Snow]

woo!
Sweet. I will double check and I will be cranking it up after fuel upgrades

[BrianV8]

no if its a neo its a steel wheel turbo, you can throw as much boost as you want at that one. If you do arp head studs too you can go past your 18 pound limit and make about 500hp due to slightly stronger internals