Rb25Det Turbine On Rb20Det (R32 Gts-T) With Smic?

[Matvei27]

What do you guys think of installing a RB25DET Turbine (a refurbished one, obviously) on a R32 GTS-t with a RB20DET running a R34 GT-T side mount intercooler?

Will I just heatsoak it? (i.e. does this require an upgrade to front mount or can we still use the side mount at this level?)

Would like to hear if anyone has tried it as well, either with the GT-T SMIC or an aftermarket SMIC.

Not keen to wreck my front aero bumper and ditch the fog lights.

I currently have the stock turbine at 12psi with a AVC-R.

I imagine to get similar response out of a larger turbine I would need to up the power more, but I want to know if I can safely do so within the limits of the SMIC.

Thanks guys.

[KiwiRS4T]

R34 SMIC will require modification to fit. Will probably perform OK with that turbo but you may as well go straight to a return flow FMIC which should fit without too many modifications. If you already have an R34 SMIC just stick with it for now and change it if necessary.

[Matvei27]

I already have a R34 SMIC.

I am more asking if you can upgrade the turbine on this without going for a full FMIC.

I believe even the return flows will require me to ditch the twin fog lamps.

[AngryRB]

Could always add a water/meth kit with the R34 cooler, that might work assuming it will be tuned anyway

Edited December 2, 2014 by AngryRB

[GTSBoy]

Even just a water spray on the cooler will help.

The R34 SMIC will be fine on a 25 turbo on a 20DET at reasonable boost levels. It will make as much or more power on ~10 psi as you currently make on 12 psi and will heat the air less (due to less boost). Wind the boost back up to 12 psi and it will be heating the air about the same as the current turbo, but making power as if you were currently running 14 or 15 psi. As long as you don't do long uphill runs all the time, you'll probably never notice anything wrong.

[Matvei27]

What about the HKS 2530? Could I get away with that?

Basically I want to install a *slightly* larger turbo to run more boost, but don't want something huge and laggy and want to keep it within the confines of side mounts. Street car, stealth, fog lights, etc.

I can get a HKS 2530 for around 2x the price of a completely rebuilt RB25 turbine.

Ideally I would get a ARC 105mm side mount, but I have not been able to find one in good shape.

I imagine with that I could run a HKS2530 with bigger injectors and a new afm and make quite a bit more power than the stock turbine.

As long as I keep the R34 SMIC I can't really go above the limits of the injectors/afm.

Edited December 2, 2014 by Matvei27

[niZmO_Man]

My old R32 ran fine with a NEO6 turbo, standard everything including SMIC.

[Badgaz]

water to air intercooler box?

[GTSBoy]

http://www.sau.com.au/forums/topic/451297-fs-nsw-greddy-side-mount-intercooler-kit-suit-rb20/

[Matvei27]

Will the RB25 turbine lag more in the low end or are there really no drawbacks?

Is there a particular version of it I should look for when purchasing?

Would you recommend cams+gears to improve response or would I start to make too much power for a SMIC to cope with (either R34 or ARC)

Edited December 4, 2014 by Matvei27

[GTSBoy]

1st thing, please stop calling it a turbine. That word refers only to the exhaust wheel on the rotating assembly, not the whole device. Turbo is short for turbocharger, which is the correct term. Note that I'm not abusing you, just assuming that your 1st language is Finnish or something based on your name, and providing a small English lesson in order to reduce confusion.

2nd thing, yes you will get a bit higher boost threshold. Will take a few more revs to come on.

3rd thing. There are 2 main types of RB25 turbo. R33 is closest to RB20. Will likely be the best choice. R34 turbo has a bigger exhaust housing and therefore higher potential power, but it will be laggier, especially on a 20.

[Matvei27]

I speak Russian and Japanese. English is still my first language though because I am from the US.

I was calling it a turbine because in Japanese that is what turbo units are referred to as (the whole thing) so I keep looking at catalogs for HKS units and such and that is what they are listed for sale as.

Any difference between the S1 and S2 units or are all the R33 RB25 ones the same?

Your thoughts on cams/gears?

Will the Tomei turbo elbow I have (for RB20/25) affect responsiveness/spool times at all?

Edited December 4, 2014 by Matvei27

[GTSBoy]

Haha. Whatever the Japs call something (in English) is the last thing that anyone else should!!

I think S1 S2 differences come down to alloy and plastic compressor wheels. The Neo turbo definitely has a plastic compressor wheel, and I think that change came into effect for the S2 R33s.

Cam gears are NOT a waste of time/money, but they are of fairly dubious value until you have gone full house almost everywhere else. And running a SMIC and a ceramic turbo (and hence staying below 1 bar of boost) do not really constitute going full house!! And on an RB20 you wouldn't be adjusting the cam gears to give you max top end power, you'd actually be adjusting them to try to maximise the low end, given that RB20s are torqueless little things that wouldn't pull the skin off a rice pudding without 20 psi of boost. Anyway, I wouldn't do cam gears as my first priority.

I can't see the Tomei elbow being of any value. What is the advertising line that Tomei manage to sell them with? Why do they exist?

[Matvei27]

It's 3 inches instead of whatever size the regular turbo outlet/elbow is. So if you have a 3 inch front pipe it would match that. Less restriction than the stock elbow, or so they say.

Is the alloy compressor version worth it over the plastic ones?

They say the RB25 unit is good for up to 14psi of boost, but are you saying I should just keep it at 10~12 to avoid heatsoak?

Am I going to need new injectors and a new AFM with this thing too? If I am aiming at keeping it at around 200kw for the SMIC, that is right on the limit of both of those as well.

Edited December 4, 2014 by Matvei27

[GTSBoy]

With respect to the elbow......the outlet of the turbo itself is much less than 3". The elbow can either open out rapidly to 3" (like the Tomei one) or it can open out to a lesser size (like the stock one) and then you expand up to 3" pipe with a cone on the end of the intercooler pipe. The difference between those two options would be bugger all.

With respect to the boost level.....No Nissan ceramic turbo should be run over about 14-15 psi because they will explode. They are fragile pieces of shit. It's got nothing to do with the heat soak - that's a separate issue.

The heat soak issue is impossible to say anything more sensible about that what I said in my earlier reponse up the top.

[Matvei27]

Right. I don't want to run it over 14psi as that is the safe limit. (or so the tuning guide says) But up top you said to run it at 12, so I was wondering if I should stop at 12 or if I should go to 14.

So, do I want to get the one with the alloy or the plastic compressor wheels. Does it even matter since the thing is still ceramic?

And still need to know if I will need new injectors/AFM with this.

Hoping to just order all the necessary bits at once to put it on and try it out; I don't want to spend all the time putting on a new turbo to then find out I need to order other stuff.

Edited December 4, 2014 by Matvei27

[GTSBoy]

If you do not want to replace injectors/AFM then you will NOT want to run over about 12 psi on a 25 turbo on a 20. At 12 psi you will be making more power than you would with a 20 turbo at 14 psi, and you will be running out of both injectors and AFM capacity.

If you are happy to upgrade everything else, INCLUDING the intercooler, then go harder and run more boost. But not with a ceramic turbo. See below.

14 psi is not really the "safe limit". Some will die at stock boost. Some will die at 12 psi, some at 14 psi and some will hold on to the grim death at 16 or 17 psi. Lottery, and you will never know what you have until it dies. Many RB25 turbos have died at only 12 psi. My stock RB20 turbo ran for most of a decade at 14 psi.

There's not really any difference between alloy and plastic wheels unless you explode the ceramic turbine. Often when the turbine dies it will cause a plastic wheel to shred itself too. If those pieces get into the engine they can cause damage. Alloy compressors tend to stay in one piece.

To be perfectly honest, at this point in the life cycle of these engines, I wouldn't be putting an old second hand 25 turbo on any engine. I'd be getting a blown RB20 or 25 turbo and getting it highflowed with metal turbine to remove the risk of it killing the engine, and also allow more boost and power.

[Matvei27]

So, buy a RB25 turbo, chuck it in, run 12psi boost, and stop thinking about upgrading injectors. Sound about right?

Or are you saying I should get my RB20 unit high flowed instead of a 25 and run the higher boost on that (ostensibly for less lag?)

The price to hi-flow isn't terrible so I'll definitely order whichever is the better choice and bolt it on.

edit: I was told that RB25 hi-flowed would be too laggy.

So looks like options are:

1. RB20 hi-flow @ ? psi

2. RB25 standard @ 12psi

Which do you recommend? I am assuming #1 is safer and less laggy, and #2 has a better top end.

Limit of the injectors/AFM/SMIC is around 200rwkw, and I think either of these will get there, it's just a question of which is "better"

Edited December 4, 2014 by Matvei27

[GTSBoy]

A 20 highflow will probably be more laggy than a stock 25 turbo, but as the power potential will be much higher, you will live with it.

Limit of all the things you list (injectors, AFM and SMIC) is less than 200rwkW, depending on the size of your rwkW. US chassis dynos tend to read higher numbers than Aussie dynos, so it is hard to compare.

Typically, here in Oz we reckon you can get an RB20 up to about 180rwkW with everything going right for you. More like 170-175 typically. Higher numbers than these tend to come from optimistic dynos. RB25s tend to max out in the 210-220rwkW with everything going right.

Here's something to keep in mind. RB20 injectors are 270cc. RB25 injectors are 370cc. Can't push both sets to ~200rwkW.

[Matvei27]

Some of the information I've dug up with search is conflicting, like this from SydneyKid:

GCG Ball Bearing RB20 turbo high flow + Performance Metalcraft split dump + Nismo 3" exhaust - cat + Power FC + GTR injectors + 98 ron pump fuel + R34GTT SMIC + Jamex panel filter= 225 rwkw.

I believe he is using his in a race application, but that really seems like it is pushing it.

My car is just a street car, but it needs to be reliable.

Would I be correct in thinking that a RB25 hi-flow is too much power for my setup and that I should aim for either a stock RB25 or a hi-flow RB20?

Edited December 4, 2014 by Matvei27