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Not Getting Full Boost With Rb25 Turbo On Rb20

replicate

By replicate,
in Engines & Forced Induction

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replicate Community Regular

replicate

Posted
Posted (edited)

Hi guys

I've just installed an RB25 turbo on my RB20 retaining the RB20 actuator. Now since there wasn't provision on the RB25 turbo to connect the actuator to, I drilled a hole in the intercooler pipe between the intercooler and the intake manifold. Works well but i am only getting 0.6bar or about 9psi. At first I thought it had something to do with the hose I used as the original hose that was connected was a combination of 3 hoses joined together. Two with a larger internal diameter and one thinner. So since i didn't need the length i just used one of the larger diam hoses. This morning i joined up the other two pieces which included the smaller diam hose and now i'm only getting 0.5 bar.

Now as i understood it, using the RB20 actuator on the RB25 turbo should give me a base pressure of 10psi, up from 7psi or so. On the stock turbo I was already getting 0.5 to 0.6 bar. So 8 or 9psi. Which sounded right as I have a turbo back 3 inch exhaust. So i thought with this setup i'd be getting around 11-12psi or 0.8 - 0.9 bar.

Any thoughts on this? My only idea is that the stock intercooler is posing a restriction as it is stock and i believe quite oily as well, judging by the amount of oil present in the intercooler pipes.

Edited by replicate
1400r Veteran

1400r

Posted
Posted

quick guess your not using the standard actuator to compressor hose?(this is my pet excuss for everything now)

You should try and keep it if you can.

My 2530 ran .7 bar through the stock cooler just like my standard turbo did.

Cubes Grand Master

Cubes

Posted
Posted (edited)

I've always had a bit of a boost drop issue.

I've put it down to the crappy designed aftermarket dump pipe that v's up 10mm or so in front of the turbine wheel, the 'performance specialists' didn't stretch the pipe over the flange correctly.

I've seen another dump done like this since by another mob.

Edited by Cubes

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