How To Tell A S1 & A S2 Rb25 Turbo Apart

[the big JC]

Im looking at putting a RB25 turbo on my RB20 silvertop and from what i have read S2 RB25 turbos are the best for this and also that the water and oil lines on an early RB20 will not line up with the RB25 turbo.

So my question is firstly how do i tell if my RB20 is an early one or a late one? and secondly how do i tell S1 RB25 turbos from S2's? so far ive seen 25 turbos with 45V2, 45V3, and 16V stamped on the comp covers.

Cheers Josh

[R31Nismoid]

Oil & water lines line up for both S1 & S2... they are identical turbos save for the compressor wheel.

And the difference is so little there there is no noticeable performance gain/increase over one or the other.

Some people have said they felt 100-200rpm sooner boost delivery etc etc... so in real world terms you'll never notice it

Any RB25 turbo will do.

Rest of the info is in threads that you can find from the sticky guide.

http://www.skylinesaustralia.com/forums/Rb...et-t109753.html

[the big JC]

Oil & water lines line up for both S1 & S2... they are identical turbos save for the compressor wheel.

And the difference is so little there there is no noticeable performance gain/increase over one or the other.

Some people have said they felt 100-200rpm sooner boost delivery etc etc... so in real world terms you'll never notice it

Any RB25 turbo will do.

Rest of the info is in threads that you can find from the sticky guide.

http://www.skylinesaustralia.com/forums/Rb...et-t109753.html

Thanks for that but how bout telling an early Rb20 motor from a late one

[robots]

Early ones have RB20 letters on timing belt cover. Late ones don't have.

[the big JC]

Early ones have RB20 letters on timing belt cover. Late ones don't have.

Really? Cos ive never seen a rb20det without RB20 stamped into the timing cover

[R31Nismoid]

Thanks for that but how bout telling an early Rb20 motor from a late one

Are you talking red top vs silvertop?

because all silvers are the same.

There are TWO series of red-tops, ONE series of silvers

[the big JC]

Are you talking red top vs silvertop?

because all silvers are the same.

There are TWO series of red-tops, ONE series of silvers

Well that awnsers my question, My understanding was that red tops were the early version and silvertops were the later version but then some of the suff i read seemed to indicate that there were also 2 versions of the silvertop.

So dose this mean that an RB25 turbo will go straight on my silvertop without having to change to RB25 oil & waterlines or having to get custom ones made?

[R31Nismoid]

No idea, read the thread i linked.

I cant remember if you use RB25 or RB20

[dmr]

make sure you also get the elbow from the RB25 turbo, so it can fit up to your cooler piping easily.

Edited August 3, 2008 by dmr

[sonoramicommando]

http://www.skylinesaustralia.com/forums/In...+identification

according to this link S2 R33 turbo/R34 trubo are the best (not sure if it is still the case on RB20DET) because it has the largest stock Nissan turbine housing with casting mark OP6. I pulled the rear housing off R34 turbo to put on R33 S1 but not sure if i will follow thru, the turbine housing wasn't exactly to easy to take it off.

[Lithium]

To tell if you have an S1 or S2 RB25 turbo is pretty easy if its off the car- the S1 has a twin-fin "alloy" compressor wheel whereas the S2 has a black plasticy feeling single fin looking setup. You'd know if you saw it.

[bubbabooga]

another way to tell difference between s1 and s2 rb25 turbos..

is on series 2 they have the small 10mm pre load bolt next to the water feed i think??

iv been told this is only on bb series 2 rb25 turbz...

good luck