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Which Turbo Has Higher Chance Of Detonation? Rb20 10psi Vs Rb25 7psi?

R33 Jared

By R33 Jared,
in Engines & Forced Induction

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R33 Jared Enthusiast

R33 Jared

Posted
Posted

Can't wait to get grilled. Can't wait.

SCENARIO:
I have an R33 GTS-t which 2 years ago I converted to a complete Aspirated setup (L Plates).

I now have a daily which I use 99.9% of the time but I still enjoy my R33 on odd occasions.

I want to revive my RB25 back to it's original turbo form because I'm still absolutely in love with the R33.

[Keeping in mind I'm still a Green P Plater (19y.o.)]

- When I do this:

> No FMIC

> RB20/RB25 turbo depending on which turbo has lowest chance of detonation on my RB

> Have a heat plate rigged up to hide the turbo as much as possible

> Will run the lowest psi physically possible

I've never lost a demerit point for speeding, that's not why I want to run the turbo.
I'm not interested in performance increase/decreases, I'm interested in having my R33 back in

it's beautiful original turbo form with the health of the motor at 100% consideration. I drive the car

to the beach on the odd occasion maybe once a month, that's the only use it gets.

Thanks for reading, someone please respond from a thermodynamics perspective.

post-142920-0-75910300-1459297708_thumb.jpg

GTSBoy Grand Master

GTSBoy

Posted
Posted

Thanks for reading, someone please respond from a thermodynamics perspective.

Not possible. No-one here has a good enough grasp on the thermodynamics, nor is it likely that anyone has the experience of running a DET engine with one or the other turbo without a cooler.

Here's my advice. Don't consider an RB20 turbo. Too old, too small. RB25 turbo all the way, Probably even an OP6 to get the bigger ex housing and reduce exhaust back pressure a little. Install a fricken intercooler. Factory sidemounts are laid up in piles at the wreckers. But even if you don't the standard wastegate setting is 5 psi and you will not detonate running that pathetic amount of boost. It will barely heat the air up 30°C. There's the only thermodynamics I can put into the discussion.

R33 Jared Enthusiast

R33 Jared

Posted
  • Author
Posted

Here's my advice. Don't consider an RB20 turbo. Too old, too small. RB25 turbo all the way ....... the standard wastegate setting is 5 psi and you will not detonate running that pathetic amount of boost. It will barely heat the air up 30°C.

Appreciate your response, I had a feeling I was going into this setup in the dark. It's only for a few months so maybe the RB25 turbo is the appropriate temporary

solution until I can safely put my GT30 back on it.

Kinkstaah Grand Master

Kinkstaah

Posted
Posted

Do you mean no FMIC, or no intercooler at all?

The sensible option (if any, really) is use the turbo the ECU is expecting to see, which would be the R33 turbo. Realistically for the engine size its a really, really small turbo as is.

If its legal in a few months, spend the months getting the GT30 setup right and just drive it then.

paulr33 Grand Master

paulr33

Posted
Posted

the lowest psi you can run is the gate spring, on the RB25 manual tuborcharger from memory it is 7psi, on the auto RB25 turbocharger it is 5psi from memory.

if you want lower boos than this, then you can simply wire the wastegate flap open and youll probably get 1 or 2psi if you are lucky at full load

ECR33 manual is 385mmhg which is 7.4446 psi
ECR33 auto is 270mmhg which is 5.220 psi

Murray_Calavera Mentor

Murray_Calavera

Posted
Posted

I'm trying to read between the lines a bit here...

So, you are worried about getting fined for driving a turbo skyline on your P's, therefore you don't want to run a sidemount intercooler because you think it will increase the chances of getting caught?

If this is the case, just install the factory sidemount and cross your fingers that you don't get caught.

If someone (said highway patrol officer) can spot a factory sidemount, they can spot the difference between extractors and a turbo exhaust manifold. So your screwed anyway. Might as well not take the chance on damaging your motor as well.

But of course common sense says you've been waiting a fair amount of time already, might as well just wait that little bit more.

Jordy32 Experienced

Jordy32

Posted
Posted

Running a car designed and fitted with an intercooler from factory without an intercooler is not clever, from both a logic and "thermodynamics" perspective.

Driving a turbo car on your P's is stupid, just wait until your fulls. Is stock R33 turbo power really that exciting that you'd risk lots of money and your licence for?.. No it really isn't.

donburtron Enthusiast

donburtron

Posted
Posted

My advise would be get a hi flowed turbo and bolt it together with the standard manifold..

Must better turbo and no worries with detonation and options to increase boost..

You can pick a good one up for around 1k give or take a couple hundred

niZmO_Man Grand Master

niZmO_Man

Posted
Posted

the lowest psi you can run is the gate spring, on the RB25 manual tuborcharger from memory it is 7psi, on the auto RB25 turbocharger it is 5psi from memory.

if you want lower boos than this, then you can simply wire the wastegate flap open and youll probably get 1 or 2psi if you are lucky at full load

ECR33 manual is 385mmhg which is 7.4446 psi

ECR33 auto is 270mmhg which is 5.220 psi

I think the gate is 5psi but the solenoid bleeds it to 7 or something like that. R32 have 10psi gate spring.
Dose Pipe Sutututu Grand Master

Dose Pipe Sutututu

Posted
Posted

I think the gate is 5psi but the solenoid bleeds it to 7 or something like that. R32 have 10psi gate spring.

you are correct

If you want to run no intercooler, best to go E85 or WMI

Ben C34 Grand Master

Ben C34

Posted
Posted

Rb30et had no intercooler standard and they didn't sht themselves.

If it used to be running a gt30, that would be harder on the motor than the little r33 7psi setup.

And they ran a stupid low compression ratio as part of the no intercooler package.

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