Upgrade an rb25neo

[Tekitsune]

Hello, just just bought an 1999 enr34 with a stock rb25neo and I'm looking to upgrade the engine to 500whp I know some basic things but wondering if there are things I'll need to do to upgrade the stock block and all the bits and pieces to achieve this.

[GTSBoy]

Although the best way will be to put in an LS7. Why anyone would mess with an RB when they live in the country where the LS7 was built is a mystery that can never be solved.

[joshuaho96]

4 hours ago, GTSBoy said:

Although the best way will be to put in an LS7. Why anyone would mess with an RB when they live in the country where the LS7 was built is a mystery that can never be solved.

I frequently tell people interested in buying a GTR to either pick a 996 Turbo or E92 335i 6MT. Either one is close enough to being what you wanted from a GTR while being much, much cheaper. I just have brain damage and had to have one anyways.

[Kinkstaah]

1 hour ago, joshuaho96 said:

I frequently tell people interested in buying a GTR to either pick a 996 Turbo or E92 335i 6MT. Either one is close enough to being what you wanted from a GTR while being much, much cheaper. I just have brain damage and had to have one anyways.

these are not the same

[joshuaho96]

5 minutes ago, Kinkstaah said:

these are not the same

They aren't, but it depends on what interests you about an R32-R34. If it's the front engine I6 turbo that tunes well with a manual transmission an E92 335i 6MT is so incredibly cheap. You can get a super clean one for 20-25k USD tops. Put an LSD in it, tune it, have fun with it. If it's the general idea of AWD + turbo and a manual transmission the 996 Turbo is absolutely much more expensive, it's less practical but it's also basically a complete track-ready car from the factory. At least the Mezger doesn't have heaps of oil control issues. And in the US the 996 Turbo and R33 GTR are roughly the same price these days. 996 maybe a bit more now that the hype has abated for old Skylines here.

[Tekitsune]

I got my enr34 for 10k through an auction has 55000km and no rust 

[Murray_Calavera]

43 minutes ago, Tekitsune said:

I got my enr34 for 10k through an auction has 55000km and no rust 

What's the budget for building it up to 500whp?

[Tekitsune]

I would like to keep it around 15k but if I need more to make it reliable and not have to worry about the car breaking I can go more. It's my project car so I'm just trying g to figure out what needs to be in it i know basic things like turbo cams injectors I'm just unsure of the size and the specifics so I'm spending alot of time on Google and its mostly rb25 and rb26 not alot on neo

[Lithium]

On 18/05/2025 at 4:19 PM, joshuaho96 said:

I frequently tell people interested in buying a GTR to either pick a 996 Turbo or E92 335i 6MT. Either one is close enough to being what you wanted from a GTR while being much, much cheaper. I just have brain damage and had to have one anyways.

M240i xDrive is the way.  3litre straight 6 coupe w/single turbo, ZF8, Rear biased 4WD.  It's more Skyline GT-R than the R35 by miles.

[robbo_rb180]

22 minutes ago, Lithium said:

M240i xDrive is the way.  3litre straight 6 coupe w/single turbo, ZF8, Rear biased 4WD.  It's more Skyline GT-R than the R35 by miles.

 

[Lithium]

16 minutes ago, robbo_rb180 said:

 

Almost midnight purple, too

For ages I was like, dammit - GTRs are too out of my price range to start with before modding... then it turns out you can have a 3litre, a ZF8, a single turbo - all things I'd likely do (at least similar) to a GT-R, but there from factory as well as all the other nice modern car things you get.   Then you look at what you can do with B58s and ZF8s, people are in the 7s with this platform already with the cast alloy block and still 8 speed.

Edited May 20 by Lithium

[Kinkstaah]

AWD MK5 Supra when?

[Lithium]

2 minutes ago, Kinkstaah said:

AWD MK5 Supra when?

Mechanically that's essentially what the M240i is, it's just not pretending it's not a BMW

[Murray_Calavera]

14 hours ago, Tekitsune said:

I would like to keep it around 15k

Will you build and tune it yourself or do you need to pay for labour? 

[Tekitsune]

I will do the build myself but I will be paying for the tune because I don't know how much about that and would rather it be done right and by a professional 

[Kinkstaah]

1 hour ago, Lithium said:

Mechanically that's essentially what the M240i is, it's just not pretending it's not a BMW

I mean, the 240i is not a Supra... make it drop a few hundred kg, have a sportscar chassis, clearance for wheels etc...

Maybe I want a hardtop Z40i XDrive or something :p

I do agree with you though and have long said the B58 Supra/240i/340i/440i is the new R Chassis/JDM90's turbo rocket for mod lovers to ... not always appreciative response lol.

Doesn't make it not true though.

[robbo_rb180]

On 18/05/2025 at 3:48 AM, Tekitsune said:

Hello, just just bought an 1999 enr34 with a stock rb25neo and I'm looking to upgrade the engine to 500whp I know some basic things but wondering if there are things I'll need to do to upgrade the stock block and all the bits and pieces to achieve this.

Back on topic for you for a post

Will it be on pump or ethanol?

2025 Spec RB build:

G30 660 .83 would be good 
artec manifold
turbosmart 45mm external gate
1000cc Injectors
Kelford cams 264 and springs
Pistons and rods for insurance
Oil pump with billet gears
Headdrain and all good oil mods
Quality intercooler
3.5 inch dump pipe to decent exhaust
Link plugin Ecu or what ever your tuning is comforatble with
Bolt on Trigger Kit - Nzwiring kit is go to
ARP Headstuds
Quality headgasket
quality fuel pump- a TI/walbro 525lph PWM would be the go
Quality fuel reg

Will be over $15K AUD
Enjoy the noise of rb on gate at over 7400rpm.
Start looking for gearbox conversions if your hard on the gear.

Now I've been there and done that with rb powered street car (2007-2022) much prefer newer stuff. Anything 90's Japanese is not a great experience these days and highly over rated.
My 2015 Brz with a heap of suspension mods is such a better car even with out the power of my old s chassis' even on track.
If wanting to play light chassis and decent power for a  giggle a k swap 86/brz would be the go

Check my old build for engine stuff

I really need to pay attention to post 2016 BMW stuff but seem all very heavy 1600+kg
 

[Murray_Calavera]

Budget for sensors and wiring as well. Depending on how safe you want to be with the engine, you could be flirting with $2K AUD in sensors and wiring. 

[MBS206]

3 hours ago, robbo_rb180 said:

Back on topic for you for a post

Will it be on pump or ethanol?

2025 Spec RB build:

G30 660 .83 would be good 
artec manifold
turbosmart 45mm external gate
1000cc Injectors
Kelford cams 264 and springs
Pistons and rods for insurance
Oil pump with billet gears
Headdrain and all good oil mods
Quality intercooler
3.5 inch dump pipe to decent exhaust
Link plugin Ecu or what ever your tuning is comforatble with
Bolt on Trigger Kit - Nzwiring kit is go to
ARP Headstuds
Quality headgasket
quality fuel pump- a TI/walbro 525lph PWM would be the go
Quality fuel reg

Will be over $15K AUD
Enjoy the noise of rb on gate at over 7400rpm.
Start looking for gearbox conversions if your hard on the gear.

Now I've been there and done that with rb powered street car (2007-2022) much prefer newer stuff. Anything 90's Japanese is not a great experience these days and highly over rated.
My 2015 Brz with a heap of suspension mods is such a better car even with out the power of my old s chassis' even on track.
If wanting to play light chassis and decent power for a  giggle a k swap 86/brz would be the go

Check my old build for engine stuff

I really need to pay attention to post 2016 BMW stuff but seem all very heavy 1600+kg
 

From watching the 6 hour, it seems they've really got the class A2 Ford Mustang sorted, as it was cutting it up in lap times with he X1 cars, which are all those late model turbo BMWs.

I have no real idea about either of them, but watching what was happening at the 6Hour, it made the Mustang which is meant to be in a slower class look very impressive.

[joshuaho96]

16 hours ago, Lithium said:

M240i xDrive is the way.  3litre straight 6 coupe w/single turbo, ZF8, Rear biased 4WD.  It's more Skyline GT-R than the R35 by miles.

The trouble for me is the automatic takes away so much from it. And the E92 has hydraulic power steering. Even after putting in an LSD you're looking at re-mapping the xDrive to be more like a Skyline which is just a lot of effort for something that is supposed to be easier and cheaper. I consider the E92 335i 6MT to basically be the obviously superior car to something like an R34 GTT. Half the price out here, the N54 makes so much more power so easily, is a far more refined car, etc. You do have to deal with the nightmare of the N54's foibles vs the B58 which is comparatively miles better and if a turbo does fail it's only one of them vs two and a lot less pipe spaghetti. 

996 or 997 Turbo has the AWD system mapped like a Skyline. Basically always RWD unless engaging the front axle makes sense. A coworker let me drive his 997.2 Turbo 6MT and it's absolutely tremendous. I don't think I'd want more power in a street car.