Pulling 250rwkw+ from RB25DET!

[Skyrine-Dave]

Hi,

Just wondering what is required to pull 250rwkw+ (more on the plus side) from an RB25DET ?

assuming i have an aftermarket ecu, 3" exhaust, large intercooler, pod filter. What needs to be done to this motor to acheive a reliable power figure.

would be looking for alot of mid range street usable power.

[predator]

u will also need larger cap injectors, large clutch (if not already fitted), fuel regulator, larger fuel pump, and a well matched aftermarket turbo.

If you want 250rwkw with the emphasis on the plus you'll also probably need to go strengthened interals - or at least have a few $k in the bank in case things like pistons or rods pop.

... do a search and you will see many people have chased the same and their thoughts and things.

[Skyrine-Dave]

yeh got a 550hp fuel pump, would use 550cc injectors, dont have a fuel reg, malpassi seems to be the common one, so possibly employ one of those.

[BOOSTD]

Check the HKS versus Garret Thread

[riggaP]

First up you'll need $$$$$

Go out and buy the Aug-Sep issue of Speed Mag. They have a 3 stage RB25DET tuning guide from 7 different performance shops. Should help heaps.

[predator]

hmmm.. i tend to discount the "tuning guides" from magazines as *too* much of a guide, because from what I have seen, they make out like its going to cost massive $$$$$. They go to the most expensive workshops, choose only brand new components sold in Australia by Australian distributors, and add massive labour costs to get their XXX rwkw. For instance, wouldn't surprise me to see a $15k-$20k bill attached to an RB25DET 300rwkw skyline build, when I'd say most on these forums has been able to get it done for well under that thru some intelligent self-research and tracking down of parts themselves.

Anyway, better go get the latest Speed mag and check for myself As a general guide, yup, something to look at..

[rob77]

I think you'll find ben from hpi is running close to 290kw @ treads and still on stock internals. I think he's upgraded his fuel pump and injectors, but still on stock internals. Buy the latest HPI and read up on it, I think he's a member on here as well... somewhere

[Steve]

Ben is using a head gasket to drop the CR from 9:1, I have been recommended to go for around 8.6:1. This is how cars in japan have been making up to 300rwkw+ on stock internals. JMS have made 446rwkw on stock internals, so I would think that 250+ is no real challenge.

You will need money though, and not be too shy with it:D

Good turbo: dont skimp the turbo too much, if you want the best be prepared to pay for it, the more you spend here, the better the end result. I would recommend something like a HKS 2835 or similar, which can be had from Japan brand new for under 4K if you include duty and taxes. Second hand, they come up from time to time for probably half that but be careful, as you can only buy the entire cartridge if they need rebuilding.

Inj and fuel pump: if you upgrade the injectors and pump, you dont need a pressrue reg, these just allow you to stretch injectors fitted. Alternatley, you could stretch the stock injectors this far (250rwkw) with fuel pressure reg and fuel pump only - they will be right on the edge, but it has been done.

Clutch: I recommend twin plate, do it right the first time:)

Z32 AFM, or if you are using map, the stocker will be gone.

Catch can: as you wind boost up, more blow by will make it into the engine, which will increase the likelyhood of detonation:(

Stock BOV could be having trouble if you have wound the boost up, so you might need to upgrade.

A REALLY GOOD TUNE - pay good money for a good job.

That should get you there

A few other things to think about.

A cold air partition if you are using a pod, with CAI is a very worthwhile addition.

Decent brake pads to help you slow down quicker/ reduce fade.

Pineapples to stop axle tramp.

If you havent done suspension - give it some serious thought for driveability sake.

Make sure you have good flow to your intercooler.

A decent manifold can really improve spoolup time and decrease back pressure.

Get some decent tyres, you'll need them:D

After you have done the above, just throw on some cams, exh cam gear and you will be well into the plus side (assuming you went injectors rather than just fuel reg.)

[Cubes]

You can pull it out of the stock injectors you just have to leave a little bit of head room when tuning the AF. So run it a tad rich.

If you are getting 550cc injectors you don't need a better fuel reg as an adjustable fuel pressure reg is used when you run out of scope with the standard fuel pressure so you up it a little. Not needed with 550cc's

A decent highflowed turbo should do the trick.

I know GCG's Stage 2 highflow does it, other than that a GT30 could also do it but then custom manifolds external wastegates etc.. blow the budget out of the water.

The GCG turbo comes on hard at around 3500rpm.

[Skyrine-Dave]

thanks for the info... just wanting to weigh up my $$$ and choices between the 25det or a 30det

my car is all primed ready for a big power motor with every support system upgraded (minus engine and turbo )

Thanks for the info guys

Dave

[Cubes]

I looked at Raists RB25/RB30 dyno run compare and that made my ming up.. Imagine the difference I am going to notice from the RB20DET

[Skyrine-Dave]

well your car is going to fly joel

imagine your car, then throw in 3 of your mates (200kgz)

thats at least the extra load i gotta lug around on a daily basis.(before i get in)

So the extra torque wont hurt in getting it moving... it will just hurt the poor rb20det gearbox

anyone know if the VL turbo 5spd (MX7) would fit ??

[R31Nismoid]

Originally posted by Steve

JMS have made 446rwkw on stock internals, so I would think that 250+ is no real challenge.

446???

our of a internally stock RB25 ?

I'm looking into all this ATM.

My aim is for 300+rwkw.

ATM i'm tossing up between RB26 or a RB25 rebuild.

And it's been suggested if i go the RB25 rebuild, then throw a 30 block under it.

[Steve]

RB25

[Skyrine-Dave]

Originally posted by Skyrine-Dave

anyone know if the VL turbo 5spd (MX7) would fit ??

anyone ?

[Cubes]

With the correct cams and headwork the RB30/25 will shiet all over the RB25 with sensible rev's.

If you are aiming for 9-10k revs the the rb25 is a better bet, but realistically the 9-10k rev's is unrealistic.

I've got a 30% Extreme clutch in mine so it is fairly soft on the gearbox and can slip easily if it is slightly ridden. SO.. I'm hoping it will get the rb20det gearbox through until the RB25 gearbox is slotted in there.

[Steve]

Joel, good luck. With all the added torque of a 3L, my money is on you not having much left in your box apart from metal filings - sorry to say.

Clint32 blew his up with a 2L and 230odd rwkw, can you imagine what 30%+ more torque is going to do? Hope you got a bus pass:p

[Skyrine-Dave]

yeh i kinda agree... could be safe to use the rb20 box to run the motor in, but i can see the added torque bending my gearbox over and working it to death

[Cubes]

lol.... I'll drive it easy.. Its going to be running the std. turbo for a little while until the good gearbox is in also..

heheh yer I've got an old dunga Mazda 626 that isn't reg'd at the moment I may have to reg it..

[Skyrine-Dave]

your stock turbo would be boosting fairly easily due to extra capacity/flow. Would this be bad for a newly built motor... running boost all the time.

wouldnt it be quite hard to drive off boost with a stock rb20 turbo?