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Rb25 Turbo Onto Rb20

bj_dove

By bj_dove,
in Engines & Forced Induction

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RedDrifter Experienced

RedDrifter

Posted
Posted

Ive done the swap aswell and you will find a god increase in power for the same boost.

If your not using a bc make sure you swap over the Actautors as the Rb25 one is set around 5psi from memory and the RB20 is set at 10 psi i think.

As jas/slo32 said its quite easy to do.

Cubes Grand Master

Cubes

Posted
Posted (edited)

Does the RB20DET's compressor elbow that connects to the IC piping bolt up to the R33 RB25DET turbo?

I know the R34 Compressor covers outlet is slightly larger than the RB20DET's. As a result you have to use the R34's elbow.

Has any one taken to time to measure the Comp wheel of an rb25 turbo?

I have a few approx measurements..

R34 RB25 Turbo.

Inducer - 49mm

Exducer - 66mm

Approx Trim - 55

VG30DET Turbo

Inducer - 46mm

Exducer - 63mm

Approx Trim - 54

The R34 RB25 and VG30 turbo's share the same slightly larger turbine housing. Apparently it measures some where around the .7 a/r where as the rb20/25 is around the .6 a/r. I was told the sizes by a turbo shop.

When I pull my rb20det turbo off I will measure its wheels and also compare.

Edited by Cubes
silver gts-t Grand Master

silver gts-t

Posted
Posted
Does the RB20DET's compressor elbow that connects to the IC piping bolt up to the R33 RB25DET turbo?

I know the R34 Compressor covers outlet is slightly larger than the RB20DET's. As a result you have to use the R34's elbow.

Has any one taken to time to measure the Comp wheel of an rb25 turbo?

I have a few approx measurements..

R34 RB25 Turbo.

Inducer - 49mm

Exducer - 66mm

Approx Trim - 55

VG30DET Turbo

Inducer - 46mm

Exducer - 63mm

Approx Trim - 54

The R34 RB25 and VG30 turbo's share the same slightly larger turbine housing. Apparently it measures some where around the .7 a/r where as the rb20/25 is around the .6 a/r. I was told the sizes by a turbo shop.

When I pull my rb20det turbo off I will measure its wheels and also compare.

yeh you need the rb25 turbo elbow. rb20 doesnt fit

predator Grand Master

predator

Posted
Posted
Does the RB20DET's compressor elbow that connects to the IC piping bolt up to the R33 RB25DET turbo?

no.. tried it.. bolts holes don't match up that well, and smaller diameter hole on the flange. You sort of *could* get it to work via redrilling, but could cause problems.

predator Grand Master

predator

Posted
Posted

all i can say on that is.. good luck!

I don't know why people always take them off when they sell them as they can't be too useful for anything else, but you tend to find a large number of the rb25 turbos without them, and they can be a bitch to track down. ;)

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