Rb25 Turbo On Rb20

[ako299]

whats the max psi i should run through a rb25 turbo (a1) condition on a rb20?

[_Ryan_]

use your standard RB20 actuator and you should get approx 10psi. This is all I would personally run if I valued my turbo.

[payback21]

12 ok 14 pushing it.

[ako299]

use your standard RB20 actuator and you should get approx 10psi. This is all I would personally run if I valued my turbo.

o so run less than a rb20 turbo? i have my setting now ( ..low 10psi and hi 14psi) i thought having the bigger turbo on a car that wont push it as hard could run a lil bit more than they do on the r33s???? i no they are still ceramic internals.

[_Ryan_]

o so run less than a rb20 turbo? i have my setting now ( ..low 10psi and hi 14psi) i thought having the bigger turbo on a car that wont push it as hard could run a lil bit more than they do on the r33s???? i no they are still ceramic internals.

I would not run 14psi.

Do a search on ceramic+stock turbo.

[The Dan]

I would not run 14psi.

Do a search on ceramic+stock turbo.

Search? Don't be silly. He might find the answer

[Rekin]

o so run less than a rb20 turbo? i have my setting now ( ..low 10psi and hi 14psi) i thought having the bigger turbo on a car that wont push it as hard could run a lil bit more than they do on the r33s???? i no they are still ceramic internals.

ive heard this before but I cant remember the logic used to get to this reasoning. Something regarding that the rb20 with 14psi it doesnt create the same load as a rb25 running 14psi due to the size difference and hence the rb25 turbo can push more on a rb20.

Someone smart should be able to confirm/deny this. Cbf working it out

[The Dan]

It has to do with shaft speed. The bigger turbo flows more air. Boost is only a biproduct of the restriction present in your engine. Considering the restriction doesn't change, the larger turbo has a slower shaft speed to generate the same airflow that the previous turbo did, therefore, there is less load on the bigger turbo

[JonnoHR31]

rb20s generally flow less than rb25s. so at the same boost the rb25 is flowing more air and therefore the turbo is spinning faster. 12psi is considered fine on a 25, 14-15psi would be about the same on a 20