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S14 Turbo On Rb25det?

h2k

By h2k,
in Engines & Forced Induction

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h2k Enthusiast

h2k

Posted
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I have a R33 skyline with a RB25DET stock turbo.

Now what I've gathered from reading forums is that it has a Garret produced T25 turbo with ceramic internals wich don't like very high boost.

A buddy of mine is replacing his T28 steel internal turbo on his 200sx s14 engine and I was wondering if it is a good upgrade on my engine, but most of all if it is bolton?

Now I've read trough lots of forums but some claim that the T25 on my skyline has a T3 flange to fit on the exaust header?

Will A T28 from a 200sx be a direct bolton on mye RB25DET header and is it a good cheap ugrade as the T28 should be slightly bigger then the T25 I have? also it has steel internals and should be safe to run 1.2bar boost on it.

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https://www.sau.com.au/forums/topic/123721-s14-turbo-on-rb25det/
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R31Nismoid Grand Master

R31Nismoid

Posted
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Will A T28 from a 200sx be a direct bolton on mye RB25DET header and is it a good cheap ugrade as the T28 should be slightly bigger then the T25 I have?

No it is not a bolt-on upgrade

And no its not a good cheap turbo upgrade :P

h2k Enthusiast

h2k

Posted
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No it is not a bolt-on upgrade

And no its not a good cheap turbo upgrade :P

Why not?

The T28 is bigger then the T25, but not much. so it should produse more air mass and handle more exaust better.

The T28 has steel internals and should handle 1.2-1.3bar safely where as the T25 rarely handles over 1.0 bar over time without the ceramics to crack.

And do you know there is a flange difference or do you only think so?

R31Nismoid Grand Master

R31Nismoid

Posted
Posted
Why not?

The T28 is bigger then the T25, but not much. so it should produse more air mass and handle more exaust better.

The T28 has steel internals and should handle 1.2-1.3bar safely where as the T25 rarely handles over 1.0 bar over time without the ceramics to crack.

And do you know there is a flange difference or do you only think so?

You ask for the answer, i give so you can receive the information, and then you question it :P

The Stock RB25 turbo does not handle 14psi at all, not that they make much power over 12psi anyway as its just huffing hot air around.

I think you have some mis-information

The flange is not the same, one is T3 the other is T28... otherwise i would not have said

No it is not a bolt-on upgrade
h2k Enthusiast

h2k

Posted
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I thought skyline turbos were bigger than T25's??? what exactly are they T3?

Well I thought that the RB25DET had at T25 wich is smaller then the T28 on the SR20DET engines.

And bigger is better, so why would not the T28 be a upgrade? I want the "why's" and "why not's":D

Or does the RB25DET have a T3/T25 hybrid of some sort?

Now Im confused because I've always thought that the engine had a small standard T25

Husky33 Veteran

Husky33

Posted
Posted
Well I thought that the RB25DET had at T25 wich is smaller then the T28 on the SR20DET engines.

And bigger is better, so why would not the T28 be a upgrade? I want the "why's" and "why not's":D

Or does the RB25DET have a T3/T25 hybrid of some sort?

Now Im confused because I've always thought that the engine had a small standard T25

The rb25 turbo is not a t25 turbo, it is bigger and would make alot more power if the wheels weren't ceramic.

salad Veteran

salad

Posted
Posted
The T28 has steel WHEELS and should handle 1.2-1.3bar safely where as the T25 rarely handles over 1.0 bar over time without the ceramics to crack.

the rb turbos have ceramic wheels.

the flanges are different, T3 instead of T28 as mentioned before

nothing will bolt up, questionable power increase. definitely not worth the money of gettin manifold modded, lines, dump pipe etc.

and your goin from ball bearing to non ball bearing.

T3 is not a turbo, it is a flange

Lithium Grand Master

Lithium

Posted
Posted

Just so you have a bit more of an idea on why there could be confusion - both the SR20DET T28 turbo and the stock RB25DET turbo run the SAME turbine wheel, which is also the same as the one on the POS T25 turbo which came on CA18DETs and S13 SR20s. This could be why some people say the Skylines have a T25 turbine. So do Silvias :ermm:

T28s from Silvias (as stated before) are T2x flanged while the Skyline units are T3 flanged (despite having a T25 turbine wheel) - and all the inlet and dump pipe plumbing fit to the two turbos differently as well, so doing the swap would be quite a fabrication-intensive task. The housings on the RB25 turbos are larger - and I'm pretty sure (not 100% though) that the compressor wheel on the RB25 turbo is also larger than the T28 unit.

In terms of making more power because "SR20 T28s aren't ceramic and can handle more boost" - the ability to hold together at higher boost is irrelevant. A T28 from an SR20 would be maxed out at the level an RB25DET unit can reliably run up to anyway - so while the turbo can run over 1bar on an SR20, it'd be useless on an RB25 because all it will be doing is blowing hot air and getting sad - and more than likely dropping boost.

It is definately not a worthwhile upgrade.

h2k Enthusiast

h2k

Posted
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Posted
Just so you have a bit more of an idea on why there could be confusion - both the SR20DET T28 turbo and the stock RB25DET turbo run the SAME turbine wheel, which is also the same as the one on the POS T25 turbo which came on CA18DETs and S13 SR20s. This could be why some people say the Skylines have a T25 turbine. So do Silvias :D

T28s from Silvias (as stated before) are T2x flanged while the Skyline units are T3 flanged (despite having a T25 turbine wheel) - and all the inlet and dump pipe plumbing fit to the two turbos differently as well, so doing the swap would be quite a fabrication-intensive task. The housings on the RB25 turbos are larger - and I'm pretty sure (not 100% though) that the compressor wheel on the RB25 turbo is also larger than the T28 unit.

In terms of making more power because "SR20 T28s aren't ceramic and can handle more boost" - the ability to hold together at higher boost is irrelevant. A T28 from an SR20 would be maxed out at the level an RB25DET unit can reliably run up to anyway - so while the turbo can run over 1bar on an SR20, it'd be useless on an RB25 because all it will be doing is blowing hot air and getting sad - and more than likely dropping boost.

It is definately not a worthwhile upgrade.

Thank you for a very informative answer :dry: seem to have cleared all this up with that.

I'll tell my buddy with the T28 to throw it at someone else =)

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