High Rpm Rb20

[r32gtst sedan]

Hey guys im looking at building a rb20det that can rev to about 10,000 rpm ive got quote on machining and balancing and it all seems do able money wise and i dont see any reason as to why a rb20 couldnt rev to 10 when an rb30 can. So what i really want to know is if the rb20 has the same oil problem as the rb26 and if i need for fiddle around with the galleries or not. And i dont care if you dont like the idea its not your money or your car but any helpful posts would be much appreciated.

Thanks

Cameron

[Nee-san]

Is a dry sump within your budget mate ?

i see no reason from a geometry stand point why the RB20 will not rev to 10'000 RPM, just prepare yourself for a flood of "Don't bother put X Y Z engine in instead, which is certainly a reasonable opinion but not what your asking"

Give us your goals for the Car, I see you have an R31 So I'm assuming you want to keep the standard engine and not start chopping and changing which is fine.

The head will need the most attention as without a well developed head the point of spinning more RPM is completely lost, for example incorrect cam, valve, turbocharger,porting selection will make it an exercise in futility, You have to pick your powergoal and your powerband and then make your selections around the rest of that.

[The Mafia]

lol.

Spending a lot of money on a RB20 is like rooting a fat chick. Seemed good at the time, but you regret it afterwards.

[Nee-san]

And so it begins, haha.

[r32gtst sedan]

This is why my post count is so low because its a waste of time cuz all i get is shit but i do have a r32 gts4 and havnt changed my profile yet and a dry sump is considered but i just wanna know if i should buy a tomie or n1 oil pump and/or put restrictors in the head. Being a apprentice mechanic i see the same thing all the time and i dont wanna do that with my car and put a 25 or 26 in it and being a gts4 is hard to find an rb25.

Thanks

Cameron

[Nee-san]

dry sump it if you can.

Tomei is probably the go over N1 personally i have never had a problem with one but there are alot of sandy vagina's on here that don't like them, the RPM makes it a little more critical.

You will probably need head restrictors, talk to the person building the engine, unless that is you. in which case I would talk to someone familiar with the engine.

Edited March 15, 2011 by Nee-san

[JKR-32]

I would imagine the standard hydraulic lifters will pose a problem as well mate. You'll need to change to solid lifters.

Which come standard in the rb26

[R31Nismoid]

Issue is going to be in the head and getting it to hold the RPM. As it's a 20, the parts are not common nor are they cheap. Everything from cams, valves, porting. It's very much uncharted territory so a lot of it will simply educated, but not proven decision.

Oil - perhaps. However most RB20's seem to be OK in standard form up to around 8000rpm/260-280rwkw. It would stand to reason that you'd have to investigate and compare between 25/26 and 20 returns, feeds etc etc. Only way to get an idea for sure.

Given you are an apprentice mechanic, even doing the work alone it's going to cost you 6-12 months salary just to get the head together IMO.

I mean yes its good to be different, but a RB26 @ 8,000 will realistically do what a RB20 does @ 10,000-11,000rpm.

Food for thought.

Also consider a RB20 will run happily upto 8,000rpm & 260-280rwkw in stock form. Unless you are chasing upwards of 340rwkw, you'll never even use 10,000rpm which would mean you are effectively moving the RPM range from ~4500-8000 upto 5,500/6,000-10,000 and having nothing below that.

Good luck moving the weight of a GTS4 without any torque below such RPM. It would make for a dreadful street or track car. Only purpose would perhaps be drag. but then a cheap "dirty 30" (25/30) would be faster for probably 1/4 the expense.

[Nee-san]

Yep, He's right, this is what I was talking about when I said the head would be your biggest problem.

[R31Nismoid]

Indeed. Given i think figures of around 25-30% less flow (compared to a 25 head)... That's even oversized valves, massive porting etc.

Would exacerbate the problem of power delivery/RPM & torque band even more so with everything required to be "super sized" to be able to make use of 10k

[r32gtst sedan]

Cool thanks for the replies this was just a thought as i bought the car and it did a head gasket so i took the head off and there was alot of play in the pistons and i was looking into a rebuild. As our work sources parts form a place in which we can get up to 35% discount and can get ARP and ACL parts cheaper. Before i got the job i did a heap of work exp so i know the guys at just headworx (that will only mean something to the guys in W.A) and they do head machining and rebuilding aswell as block machining and repairs. So i will see how i go its something im still willing to investigate. Quotes i got include 60$ per cylinder for a bore and hone 380$ for a complete balance of the crank and rods and all up for head clean up, dismantle, rebuild and a pressure test somewhere around 1000$. But either way im going to rebuild the motor and see how i go.

Thanks

Cameron

[t_revz]

i used GTS behind ford. was 300 for acid bath,bore/hone and deck block. 250 for crank snout sleeve mod, plus ordered parts through them.admittedly i got it cheaper as we sub-contract them for the big jobs. they didnt seem to have done that many skylines but Josh behind the counter is more than willing to have a good chin wag and price up all options. maybe just drop in for a chat.

[R31Nismoid]

Cool thanks for the replies this was just a thought as i bought the car and it did a head gasket so i took the head off and there was alot of play in the pistons and i was looking into a rebuild. As our work sources parts form a place in which we can get up to 35% discount and can get ARP and ACL parts cheaper. Before i got the job i did a heap of work exp so i know the guys at just headworx (that will only mean something to the guys in W.A) and they do head machining and rebuilding aswell as block machining and repairs. So i will see how i go its something im still willing to investigate. Quotes i got include 60$ per cylinder for a bore and hone 380$ for a complete balance of the crank and rods and all up for head clean up, dismantle, rebuild and a pressure test somewhere around 1000$. But either way im going to rebuild the motor and see how i go.

Thanks

Cameron

Just buy a wrecker RB20 mate.

Cost you what, $500?

[Deano 1]

all i have to say is..... Its going to sounds Freaking AWESOME!!!

..... that is all..... ; D

[SimonR32]

Cool thanks for the replies this was just a thought as i bought the car and it did a head gasket so i took the head off and there was alot of play in the pistons and i was looking into a rebuild. As our work sources parts form a place in which we can get up to 35% discount and can get ARP and ACL parts cheaper. Before i got the job i did a heap of work exp so i know the guys at just headworx (that will only mean something to the guys in W.A) and they do head machining and rebuilding aswell as block machining and repairs. So i will see how i go its something im still willing to investigate. Quotes i got include 60$ per cylinder for a bore and hone 380$ for a complete balance of the crank and rods and all up for head clean up, dismantle, rebuild and a pressure test somewhere around 1000$. But either way im going to rebuild the motor and see how i go.

Thanks

Cameron

Very easy to get a RB25 NEO motor out of a stagea and slot it in...

Mayhem brings in tons of them and they are fairly cheap

[Beer Baron]

yeah agree with that a nice 20 at 10,000rpm should be a nice note. if you really want to do it and want it to live then you'll need:

solid lifter conversion

upgraded valve springs (for 10Krpm I would go double valve springs)

titanium retainers

consider new lighter valves too (helps a lot with high RPM)

new valve guides (of course)

and with that kind of RPM I'd be looking at some cams that will breathe effectively

you'll also need a turbo to match it as there is no point revving to 10,000rpm when your turbo is out of puff at 7,000rpm. something like a TD06 25G with an 8cm or even 10cm housing would be the go. all this gear will mean it will be a bit of a pig under 5,000rpm as all these mods just shift the powerband higher up the rev range, but if you're adding 2,000rpm to the redline I guess loosing 2,000rpm of response is the price you'll have to pay.

yes you'll want to get the bottom end properly balanced too and will be even better if you can get some light-ish pistons and rods and piston speeds increase a fair whack from 7,500rpm to your 10,000rpm goal.

you can do it and it'll be kind of cool, but it's not a wise way to spend money on your car. you can buy a good condition RB26 long motor with most bits needed for around $4-$4.5K. and it'll get you 200rwkw standard, with some boost and good exhaust and a tune it'll give you 250rwkw still with basically all standard bits. and will be a nice streetable package. plus it'll rev to 8,000 out of the box.

[Dobz]

If it's going to be a street car don't do it. As beer baron said the turbo you'll need to utilise the 10,000rpm will see you hitting full boost at around 5000rpm. The porting that would be done to achieve the 10,000rpm would have killed any off boost torque that the RB20 may have had, leaving you with a car that's slower than an auto Daihatsu Charade when it's off boost and that sort of lag on the street gets annoying very quickly.

Trust me i've just been though it, that's why i cut the crap and built my RB25/30. Don't get me wrong i loved my Rb20 when it was only lightly modded with an RB25 turbo because it still had that magic thing called response.

If it's going to be a race car that doesn't see anything below 5000rpm when on the track disregard all of the above.

[Nee-san]

He does have a GTS4 though, so being below 5000RPM at the lights will never ever be a problem.

It's not practical but,

Roll upto lights, bring car to 10'000RPM Dump the clutch like a clap infected tranny and off you go !

[bigmikespec]

If it's going to be a street car don't do it. As beer baron said the turbo you'll need to utilise the 10,000rpm will see you hitting full boost at around 5000rpm.

That is a pretty good power band if you ask me; better than most modded GTR's.

[Nee-san]

If he changed the gearing, IE Ratios and Diffs, as its already shorter then a GT-R in his car that would go a long way to making it streetable.