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Can I Run A Rb25 Turbo On A Rb20 Without A Tune?

yoshiii335

By yoshiii335,
in Engines & Forced Induction

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yoshiii335 Rising Star

yoshiii335

Posted
Posted (edited)

Hello

I have read about putting rb25 turbos onto rb20's. One thing I cannot find a clear answer to is if the engine needs to be tuned to run it.

Is it ok to run a rb25 turbo on a r32 gts-t rb20 engine without a tune for a couple of months?

My mods I have are full turbo back 3inch exhaust with a sports cat and split turbo pipe, pod, and the return flow fmic.

I am going to put in a new aftermarket fuel pump such as a Walbro or Tomei.

The rb25 turbo that I have has the HKS actuator on it.

I live in Japan so not so hot as it is in Australia.

Will I be ok running the rb25 turbo on this set up?

Edited by yoshiii335
yoshiii335 Rising Star

yoshiii335

Posted
  • Author
Posted (edited)

It will be fine, my 25 turbo has been running 16psi on the stock ecu for 2years now with no problems

Oh, youve been running 16psi? I thought they were not good over 1 bar before they run high risk of breaking?

What kind of response and power have you gotten without a tune?

Edited by yoshiii335
Truffles Community Regular

Truffles

Posted
Posted

Oh, youve been running 16psi? I thought they were not good over 1 bar before they run high risk of breaking?

What kind of response and power have you gotten without a tune?

Well without putting the car on a dyne before and after (and then why wouldn't you get a tune anyway?) you won't be able to tell apart from the seat of your pants.

You can run the turbo over 15psi but there's obviously a much higher chance of it falling apart. 12-14psi is usually what is considered safe.

dopey Enthusiast

dopey

Posted
Posted

Car made 130kw atw and now has 170kw atw, i have herd the same thing about not going over 1bar. I have been keeping an eye on it and there is no shaft play and not blowing any smoke, being a auto may help take some wear and tear of it though

Ben C34 Grand Master

Ben C34

Posted
Posted

The 1 bar limit is the apparent safe limit on an rb25.

On an rb20 one would assume you could run more boost, as it is shaft speed that destroys the turbine, not boost pressure.

jiffo Mentor

jiffo

Posted
Posted

O.P. is apparently using stock ecu so anything much higher than 1.0 bar (depending on weather conditions) will probably have it coughing and farting.

I fitted a 25 turbo on my 20 in the Rustia, used the 20 actuator and it went very well.

Added a bleed valve to increase boost and it didn't like it. So I left it at the stock 20 actuator boost but reading the signal after the cooler.

Obviously the 25 turbo is not working as hard to pump a given boost on the 20 as it was for that same boost on the 25.

A good cheap upgrade for a 20 in my opinion.

Dose Pipe Sutututu Grand Master

Dose Pipe Sutututu

Posted
Posted

FWIW, I ran my sietbox 180SX (RB20DET) back in the day with a RB25DET turbo at 1bar on the stocker ECU.. went alright, until I got a CEFF1E remap (not sure if he is still around) and the car started to wake up

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