Rb25 And Rb 20 Turbo Exhaust Housings

[benl1981]

Does anybody know the no. cast on the side of the exhaust housing of the Rb25 and rb 20 turbos?

Has the rb25 got the 21U and the rb20 got somehting different?

Cheers

[bubba]

Pretty sure the 25 turbo said 21U on it, I'll check my old 20 turbo for you when I get home (if I remember ).

[MANWHORE]

25 turbo = 21 u

[benl1981]

thanks CHris

Hey - how about compressor side. Is the compressor housing on the Rb20 the same beisdes the Pressure T coming off it?

I.e. could you use an rb20 compressor housing on an rb25 and not change the turbo characteristics?

thanks

[WAN73D]

thanks CHris

Hey - how about compressor side. Is the compressor housing on the Rb20 the same beisdes the Pressure T coming off it?

I.e. could you use an rb20 compressor housing on an rb25 and not change the turbo characteristics?

thanks

i can't say i know first hand. but considering a lot of people upgrade to a rb25 turbo on their rb20's....i'd say the difference is the compressor housing because they upgrade for the larger flow. also i know for a fact that the compressor outlet attaches to a different size elbow for the two turbos. My thoughts -----> u'd b limiting the flow back down to an rb20 turbo standard basically.....tho not sure of this...someone back me up hahaha (if i'm right).

[bubba]

Just go the RB25 turbo, the extra lag is negligible and it's much more fun to drive

[MANWHORE]

thanks CHris

Hey - how about compressor side. Is the compressor housing on the Rb20 the same beisdes the Pressure T coming off it?

I.e. could you use an rb20 compressor housing on an rb25 and not change the turbo characteristics?

thanks

sorry about the delay. Just finished exams today. Rb25 turbo comp housing is 45v, rb20 is 16v.

Nah, they're different. It changes teh characteristics. If you're having surging issues, perhaps you need a bigger a/r exhaust housing like the nissan op6 housing.

They're really rare though - my turbo is an op6 turbo.

[Cubes]

The RB20 and VG30 compressor wheels are identical.

The cores are identical; that being the compressor wheel, center section and turbine wheel.

The Rb20 runs a small turbine and compressor cover to keep response up and spool down.

The VG30 turbo runs the larger OP6 turbine housing and larger 45v compressor cover.

The R33 Rb25 turbo runs a turbine housing that is apparently a little larger than the rb20's; be buggered if I was able to pick a difference apart from the markings. The RB25's compressor wheel is noticably larger and runs the larger 45v comp cover.

The R34 RB25 turbo is from what I've seen is the same as the R33 S2 turbo apart from that larger VG30 sized OP6 turbine housing.

The local turbo bloke here in Adelaide (ATS) told me the R32 and R33 turbine housings are a .6 and the VG30 and R34 OP6 turbine housings are a .7. There's nothing on paper stating their size but thats what he 'guestimates' without cutting one up.

In short the turbine housings are all interchangable. The Compressor housings are not; RB20 and VG30 compressor housings you are able to swap over

As for swapping comp covers on the R33/R34 RB25's, why one would want to do that is beyond me as they are the same size.

[benl1981]

So is the rb20 exhaust housing smaller than rb25 or not?

What are the usual markings on rb20 ones?

Thanks

[MANWHORE]

The 20 housing is smaller than the rb25 one (just like how the vg one is bigger than the 25 one).

PS: these are the markings on the comp and exhaust housings:

Edited July 19, 2007 by MANWHORE

[benl1981]

I have a supposed R33 turbo - on the exhaust housing it has "04U"

How can I be sure it isn't an R32?

Ill post pics tonight

[benl1981]

Yeah it has "04U" on it and "0313" and a random A

[MANWHORE]

what does it say on the comp housing?

[benl1981]

Well its a r33 compressor housing but it is an old gcg highflow so it may be a mix and match

[Cubes]

Ben,

A pic of my old rb20det turbo from a series 2 R32.

I've never seen an RB25det turbo with the rb20det O4U stamp. I'd say its a mix/match.

[benl1981]

thanks cubes.

The size looks pretty much identical.

Im sizing it up against the R33 one I have on the car..

[Cubes]

There's not really a noticable difference look wise between the rb20 and 25 turbine housings. Be buggered if I could tell the rb25 was larger.

The Vg30 or R34 GTT OP6 turbine housings are visually larger. Easy to pick.

[MANWHORE]

Bit confused here matey

So is this 04u one the one on your car? or have you sourced another GCG highflow?

If the one on your car has the 04u housing, that could explain the compressor surge issue - too small exhaust housing.

Its hard to tell from the pictures, but does that turbo you posted pics of have a leaking oil seal?

[benl1981]

Nah mate the one on my car is the 21U - you are right I have sourced another one. Apparently the oil seal is ok but it does look like oil is coming out the back. . I just posted another question regarding turbo balancing - I'm planning to use the smaller comp wheel on this one on my current one with the 21U housing.

It would have been better if I could have used this one since it is already machined.

Is there really any difference between the rb20 and rb25 housings?

I mean GCG use the Rb20/Rb25 housings interchangeably dont they?

[MANWHORE]

Ah ok, makes sense now.

Well, I can tell for sure that the rb20 comp housing is smaller. It is smaller inside too - evident by the fact that people need to get an rb25 elbow.

In regards to the rb25/20 exhaust housing, the housing is supposedly larger. I didn't measure the 20 housing when I had one, but my friend did, and he said it is larger.

It could be an internal area difference (e.g. like inside the rb20 comp housing - smaller than the 25 comp housing). They might appear to be similar outside, but inside it might be different.

There definitely would be a difference, otherwise nissan wouldn't have used a different number housing