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

Matvei27

By Matvei27,
in Engines & Forced Induction

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GTSBoy Grand Master

GTSBoy

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There's not much conflicting there. The highflow turbo is going to be able to make 225rwkW. The GTR injectors will flow it. He didn't mention what AFM he was using but it is unlikely that it was an RB20 one. ** The only sticking point is the R34 SMIC which I would have thought would be getting bloody hot at that power level.

** It is important to remember that RB20 and RB25 turbo AFMs are supposed to be the same. RB25s are known to be able to get up towards 220rwkW on those AFMs, so it would seem that RB20s should be able to as well. But I was running up against the 5V limit on mine at <180rwkW. It is very important to realise that some people tend to "tune" above the max voltage of their AFM, which can be a bit risky. Not suggesting that SK did, just that you need to know everything about a setup before taking any lessons from it.

Have a look at the Hypergear thread for information on what RB20, RB25 and Neo turbo highflows are capable of. If you want a laggy setup that doesn't make enough power to justify itself, then a 25highflow on a 20 would be a reasonable choice. Some people like the sudden boost rush at 4500rpm. I don't.

Matvei27 Community Regular

Matvei27

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Posted (edited)

If I am understanding you correctly you are basically saying that:

1. RB25 hi-flow is not worth it

2. RB25 standard is not safe b/c ceramic

i.e. you are telling me to hi-flow my stock RB20 snail.

But for the price to do that ($1500?) should I just buy a HKS 2530 and run it at lower boost levels?

Edited by Matvei27
GTSBoy Grand Master

GTSBoy

Posted
Posted

RB25 stock, run at 12 psi will be fine. Some risk of it dying, but fine. Don't push it harder than that because now you're spending money on everything else for a turbo that you can't push very hard.

RB25 highflow can and will make a lot of power on an RB20 but will be quite laggy. Given you said you don't want lag......

Check the Hypergear thread. Highflow <$AU1000. Check the exchange rate. Sleaze these and other Aussie forums for a blown RB20 turbo that you can buy and get sent to HG. Freight finished product back to US. Spend <$US1500 on a superior product.

Matvei27 Community Regular

Matvei27

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I can get a HKS 2530 kit brand new for $1800 USD though.

Doesn't that make $1500 for a RB20 hi-flow kind of a waste?

Can I run the 2530 at a low enough boost level?

And what boost level are you suggesting I run a RB20 hi-flow at?

Edited by Matvei27
Matvei27 Community Regular

Matvei27

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20psi definitely wouldn't work with my SMIC as Rekin said he had heatsoak on his ARC unit at 15psi with a 2530.

I don't care about the price as much as I care about getting the best option within the limits of my setup.

What kind of boost do people run the RB20 hi-flow at?

That being said, you could also get a RB25 turbo with a set of Tomei poncams and gears for a similar price to a RB20 hi flow.

Couldn't you run the RB25 at 12psi and use the tomei kit to fix the low end so it has the same responsiveness as the stock RB20 unit?

Edited by Matvei27
GTSBoy Grand Master

GTSBoy

Posted
Posted

Adding cams NEVER makes the bottom end better.

Put gears on it if you like. Go for your life. At least they're cheapish, so the very marginal benefit you get from them won't be too much wasted money.

What I have said above is very simple. IF you are going to buy a decent turbo capable of running 20 psi and making bulk power, then you proceed to run it at low boost, you have just wasted all that money.

If you are going to stay at low boost to keep your SMIC and foglight and aero bumper (and no comment from me on the driving enjoyment to be gained from having those things compared to having more power) then just buy an R33 turbo and be done with it. Upgrade nothing else.

Matvei27 Community Regular

Matvei27

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OK then I am going to order a RB25 turbo and will consider adjustable gears only if the lag bothers me enough to warrant the money.

I have a new fuel pump but would you recommend changing the injectors or not necessary?

GTSBoy Grand Master

GTSBoy

Posted
Posted (edited)

The injectors and the AFM kind of run to about the same max point, so change one means change the other. EIther or both of those means change engine management too. You really should do the ECU anyway, because you will make a lot better power with a tune instead of allowing the stock ECU to run rich and smokey at 12+ psi of bigger turbo.

Edited by GTSBoy
Matvei27 Community Regular

Matvei27

Posted
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Posted (edited)

I have a RB20 power FC already, which was hard to get.

I'm thinking if I change the injectors and AFM and upgrade to the ARC side mount instead of the R34 GTT side mount (105mm core vs 80mm core) I should be okay for 12~14psi on the RB25 stock turbo.

Sound right?

Edited by Matvei27
Matvei27 Community Regular

Matvei27

Posted
  • Author
Posted (edited)

Or...just put a front mount on it

buy a 2530 and crank 20 odd psi down its throat

That's not the point of this thread.

Obviously that's one solution.

At this point all I want to know is how to get the most out of the RB25 turbo with a side mount.

My car is barely legal as it is, the last thing I need is a FMIC telling everyone to pull me over.

Edited by Matvei27
Matvei27 Community Regular

Matvei27

Posted
  • Author
Posted (edited)

SydneyKid has basically told me that changing my ceramic turbo for another ceramic turbo is a waste of time/money,

so I'm now between getting a RB20 hi-flowed or buying a 2530.

Opinions? Price is around the same. Which is the better choice for my setup?

1bar or so seems low for the 2530, but might be perfectly fine on the hi-flow RB20?

Rekin said he never tried the RB20 hi-flow that he had and just went straight to the 2530 (which heat soaked at 15psi),

so my inclination is to just try the RB20 hi-flow and see how it goes.

Edited by Matvei27

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