Downsizing Rb25 Turbo

[sh@un]

I need to use my car in traffic a whole heap, and the engine spends most of it's working life under 3000rpm.

I'm craving more torque between idle and 2500rpm or so- Does anyone know if there's a smaller sized 'turb that will direct fit in place of the current one??

It's a non-neo RB25 if it matters.

[zebra]

Rb30

But to answer your question rb20 turbo will fit

[GTSBoy]

It's a Stagea. Your problem is not lack of torque, it's too much weight. Gas axe off the back half of the car.

[R31Nismoid]

3ltr Shaun, just slap your head on a stock-rebuilt bottom end. Get away with it for a couple grand tops IMO.

I know someone else who did a 3ltr into a Stagea, owner loves it. Made a ridiculously huge difference as it's used for towing as well

[Dan_J]

r32 or slightly more smaller a31/c33 turbo, Nic_A31 may have one

also depending on cooler, shorten piping as much as possible for more response

Edited August 28, 2012 by Dan_J

[GeorgesR34]

install an electric turbo that sits 3 psi on ideal. lol

[R31Nismoid]

Yes sitting on idle @ 3psi would be ideal

[DVS JEZ]

Rb20 turbo on an rb25. Mate has one in his GQ patrol. Things a response monster in the bush

[sh@un]

Cutting the back off the car would probably be a bit loud'n'breezy, and reduces security somewhat.

While the big-block idea sounds great, it's sorta more re-engineering and expense than I could be bothered with.

I suspected an RB20 turbo might fit; Sounds a very doable option...

[Lithium]

You haven't even said what turbo you currently have, or is it running the stock turbo? If so, you have the wrong kind of car

[KiwiRS4T]

RB30 did it for me - but rather than downsizing the turbo get an electronic boost controller and it will come on to boost a little (just a little) earlier.

But seriously if you stick an RB30 block in your set up and change nothing else who is going to know?

[wolverine]

Shaun, lets import a couple of RIPS bottom ends, engine swap, engineering etc at the same time might save a few bucks?

[discopotato03]

I know of one person that has a GCG BB Hi Flow based on an RB20s turbocharger , at least I think the turbine housing is from an RB20 . This is on an early auto Stagea .

For torque at low revs cubic inches are hard to beat , it can have torque from lowish revs with a smallish turbocharger and thats fine provided you don't expect much beyond say 5-5500 revs .

I think its a good idea to lose the ceramic std turbo anyway and doing so makes them breath better exhaust wise and makes the engine work as a more efficient air pump .

Aftermarket wise as I said possibly an RB20 GCG Hi Flow or a HKS GT2530 would be the go .

The thing is that most go looking for more mid range and higher end performance and use larger turbos to achieve it . If you want same maximums as std and a bit more low down punch overall the turbo needs a little more exhaust flow than the RB25s Hitachis turbine has but in a turbo that boosts a little earlier .

A .

[hypergear]

install an electric turbo that sits 3 psi on ideal. lol

Here's a Electric turbocharger that powers the car to 3psi even the engine is at 0 rpm with car key out ignition. lol

Pretty big difference in torque down low

No its not for sale. Just a hobby I'm building.

Any way, if it is a stock turbo and you find it laggy then it might not have all of its turbine wheel, but assume its fully functional and so's the car then you might consider trade your R33 with some thing high comp NA.

[Piggaz]

Why not get a proper tune done. You know your current issues you have with it. Having the timing retarded so it doesn't knock uptop or however you have it set up won't be helping anything.

[TTT]

1750kg, slushomatic, 2.5L low comp (kind of) motor.

it's never going to have anything usefull under 3000rpm.

[wolverine]

Once rolling they are fine but they are fat slugs off the line.

[scotty nm35]

The converter should fix that, the engine should rev to 2500 and boost almost instantly I would have thought.

Going to a smaller turbo wont help move the whale...

[zebra]

f**k big converters in street cars, make them feel like soggy pieces of shit

speaking from expirence here

[Cowboy1600]

Sell it and buy a Falcadore?

Extreme, I know, but certainly a better car for the driving you are describing.