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Discussion Starter #1
Just a quick question regarding the internals/tuning capability of the NEO motor.
Over the next few months i will be removing the engine from the car while the chassis is getting some love at The GTR Shop and plan on giving it a little refresh/tidy up while it out.
I will 100% be chasing more power, and future plans are ideally 500+Hp, Holset HX35/Garret/Borgwarner etc capable turbo and front facing plenum/intercooler/injectors and all other supporting mods.
While the engine is out my original plan was head off for a refresh(Stem seals/Gaskets/Clearances etc etc) and refit it with ARP Studs/bolts with a thicker MLS Gasket.
Question is will i need to fit Poncams or similiar to reach them sort of figures? and if poncams are fitted do i need different springs or are they just plug and play?
How much thicker do i need to go on the headgasket (If anything) and how thick is the stocker?
I may also consider getting ACL Bearings fitted and the bottom end checked over for piece of mind, is this worth doing or am i creating hassle opening the current bottom end?

Sorry if these questions have been answered before, bit hard to find info on the NEO lump!

Thanks
Chris
 

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The NEO engine in it's stock form will run 500hp reliably. It's far stronger and more robust than the series 1/series 2 RB25 engines.

Question: Will i need poncams?
Answer: Nope - it'll do 500hp with a totally stock head

Question: How thick to go on the head gasket?
Answer: 1.2mm MLS gasket of some sort. Commetic, Cosworth (same thing) don't spend big money on the HKS/Apexi branded stuff. It's no better.

Question: Are bearings worth doing?
Answer: Sounds like your doing a full engine rebuild pretty much, so you'd be bonkers not to do them. ACL bearings are OK - So are OEM Nissan bearings.

Question: Am i creating hassle opening the bottom end?
Answer: Yes it's hassle and expense. It depends on what sort of condition your engine is in. For piece of mind it may be worth doing but from experience i'd just whip off the end caps on the crank, check to see if the bearings are in good nick and if they are leave it alone and drive on. UNLESS your engine is an earlier NEO with a short nose oil pump drive collar. Then i'd strongly suggest you pull out the crank, get it polished and a long nose drive collar fitted. That's good piece of mind. Then while the crank is out, you may as well swap out the bearings and if your doing the bearings, you better do the rings and that means getting the block honed and washed. If your getting the block honed, better get it faced too as most failures from MLS gaskets are caused by an uneven mating surface.

Happy to talk you through it all if you drop me a PM or email :)

Cheers

CB
 

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Discussion Starter #3
Hi mate,

Fantastic reply mate much appreciated!
That's good news about the cams, I'm glad they don't pose a restriction at that sort of power.
Is the information kicking about regarding the better crank,rb26 rods, solid lifters etc etc true then on the NEOs? Ie all the best bits in one engine?
And 1.2 mm sounds fine,Cosworth or cometic were on the list as your right a HKS will just be re branded and priced up.
Bearing wise ideally I don't fancy doing them, as like you said your getting well into it then, And as far as I can tell the engine is mint, uses no oil,is super smooth and silent, can't fault it.
I will just inspect, and if it's the small collar crank/and or bearings worn I will do the whole hog.
If I can't avoid it I will be doing the lot, but if all is well I would rather just refresh the head while it's off (Get it done cheap enough) and fit a thicker/stronger gasket and just run it stock.
Would rather avoid a full rebuild from previous experience of building my own 4EFTE engines, costs spiral and looking at rb25 prices it's not cheap!

Thanks
Chris
 

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Howdy,
The NEO engine is very much the best of the RB bunch. Some will disagree, but each to their own.

Some of what you read is probably correct. The NEO engine has pretty much the same crank as any other RB25 engine. Some of the later ones had a long nose crank collar but it's a bit hit and miss. Some did, some didn't. (most didn't)

The Rods are exactly the same items that are in the RB26, so quite a bit stronger. The pistons have been re-designed to fix the premature ring land wear which, mated with the rods gives the engine it's superior endurance. The cylinder head has much smaller combustion chambers and valves than any of the other RB engines so they don't breath quite as well. Don't let this put you off, you won't notice any difference unless you put it on a flow bench. The big advantage is that they come with solid lifters just like the RB26. This means you have no issue with valve bounce etc. The only downside about the head is that the cams are very mild, like almost weaksauce levels of mild. Again, you won't really notice this at 500hp but they do come alive when you stick a set of something with a bit higher lift.

The other advantage is that they come with the N1 oil pump as standard from the factory, which flows slightly better.

Ultimately, it depends what your going to use the car for. If it's a nice fast road car, then bash in a head gasket and drive on. If you're going to spend any time on the rev limiter or constantly at high RPM (drifting, track work, street racing) then you should look really look at doing come oil control mods or the crank collar at the bare minimum.

My advice is (and always will be) to mess with your car as little as you possibly can to get your end goal. The NEO engine will run 500hp in totally stock trim, so do that - then figure out what you need next.

Good Luck!
 

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Discussion Starter #5
As far as i could tell it appears the NEO Is sort of like a final fling with all the best bits, Definetely appear strong just info is thin on the ground compared to the 26`s and Non NEO 25`s.
I thought the cams on the NEO were quite lairy? Or is it the opposite for economy etc?
If thats the case, if im trying to chase 500-550 out of the lump would it not be wise to give it a light port and a set of cams?
Ie making it breathe better and reducing stress/heat or am i talking bollocks?

My end goal wants to be a reliable lump which will be seeing mainly road, with possibly the odd track day etc but i believe i have quite a bit of mechanical sympathy.... Lol

Thanks
 

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Discussion Starter #6
Ie if these cam specs are anything to go by.
RB26DETT 240°in 236°ex lift 8.58mm 8.28mm
RB25DET Neo 236°in, 232°ex lift: 8.4mm in, 8.7mm ex
RB25DET 240°in, 240°ex lift: 7.8mm in, 7.8mm ex

In all honesty im not too clued up on cams...
 

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Yeah, the RB26DETT out of the R34 had different profile cams from the R32/R33.

My advice would be to build a 495hp car (sounds weird, i know but bare with me) The standard NEO engine will take 550hp but that's coming towards it's reliable limit. At just under 500hp they are fairly bullet proof if looked after. Also, have you ever driven a 500hp R34? If not, then you're in for a shock. They are FAAAASSSTT. I don't mean somebody who says they have 500hp on a ****y backlot dyno. I'm talking real world, 500 crank hp on a dyno dynamics dyno. They are shockingly quick. I can't envisage you needing any more power.
 

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Discussion Starter #8
I understand mate yes, in all honesty 500 with nice response will no doubt be plenty, they are relatively light thinking about it!
I havent expierenced a GTT with that sort of power, Im just greddy haha!
A HX35 With a 12CM Twin scroll housing should do that with ease i hope!
 

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Discussion Starter #9
Just a little update on this and after a bit more advice.
Turbo is a Holset HX35 12Cm and my power goal is a nice 500-550.
Current plans for the engine are give it a stripdown, full healthcheck and fit full new engine gasket set, ARP Headstuds, Oil pump collar,Tomei poncams and balance the rotating along with my clutch and flywheel. Will also fit an external oil drain while the engine is stripped down

What are peoples opinions? I dont really want to go well into the motor because if i was it would be the whole hog...
I know there strong internally so after a refresh and these light mods will it cope with the power im after?

Thanks
 

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Discussion Starter #11
Hi again mate, And it's mainly road use. May do the occasional track day but I'm pretty mechanicaly sympathetic!
Only reason I'm considering the mods is because the engine is out of the car while it's getting resprayed etc.
Ideally I wouldn't mind just fitting a clutch and leaving it unopened. But if I have to it would have a full gasket set, cams, head bolts, balancing etc.
What puts me off is how strong/tight the engine is currently. For the life of me can't get it to use oil, It's super smooth, great oil pressure, can't fault it!
 

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Hey all, not exactly sure on how to use this site and wanted to get some advice, I recently picked up an imported R34 25 GT Four Awd RB25 Neo, Id really like to keep it non turbo, but I'd like a little more power, what type of things can I do to it that will give it a bit more punch??
Was told its a rare model so Im not looking to change its looks or exhaust sound
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Anything that improves breathing an engine is an air pump the more air you can get through the more fuel = more power so intake and exhaust mods are the first call followed by improving gas flow though the engine but this is where it starts to get expensive.
 
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