Rb25/30

[phee]

Just so you know my Skyline went bang. Anyway they have pulled my engine out and it's in pieces at the moment, I haven't actually seen it yet but my mate who was at the w/shop yesterday said he was speaking with the owner of the w/shop about my car and they are going to offer me a deal on a forged rb30 bottom end. Mick (owner) wants me to ring him tomorrow. So... pros and cons on an rb30 bottom end on a rb25? What are they? When I find out what this deal is I'll let you know, as well as cost price. Are there any questions I should be asking tomorrow arvo when I speak with Mick?

[Maxx]

have a read

http://www.skylinesaustralia.com/forums/in...showtopic=15420

btw what mod have u done to yr car?

[phee]

thanks for that mods include:

G-Max Wheels rear: 18x9.5 with 265’s front: 18x8.5

Tein hight and rebound adjustable suspension

Full 3inch custom exhaust with Magic Cat and twin Mufflers

T04 turbo on X-Force highmount manifold

Turbosmart 48mm Pro-Gate wastegate

100mm think Front Mount Inter Cooler

Blitz blow off valve

Sard fuel pressure Regulator

Sard 550cc injectors

Walbro 500 horsepower fuel pump

Motec Enginge Management System

Exceedy 5 puck clutch

Pod air filter

Oil catch can

Thermo fan

Bonnet vents

Isotta Steering wheel

DBA 4000series sloted disks alround with braided lines

Braided fuel-line, blow-by, breather and radiator overflow hoses

New chrome radiator overflow tank

Gates Racing radiator hoses

Viper 790VX Pager car alarm

[readyGO]

go the rb30 bottom end.. it will haul

[VB-]

yes i say it will haul too. does anyone know if there are any cons with using the RB30 bottom end, aside from not having the money to do it?

[Bass Junky]

Engine height is taller on the RB30.

You may or may not be able to use any current strut brace.

You will need new intake piping.

that's about it.

[phee]

Cheers for that, there is a bit of a debate on PF at the moment about it:

http://www.performanceforums.com/forums/sh....php?t=67204609

Could make for an interesting read if any of you have the time.

[Cubes]

Owning an rb30det the only real cons are:

1. They need a rather large turbo for them to rev out, something along the lines of a GT35R .82 BUT it must have an aftermarket exhaust manifold other wise the exhaust manifold causes power to nose over around 5500-6000rpm.

2. Engine height, if you don't want to lower the motor you must drop on a greedy or gtr style plenum.

3. Legality..

There are no other cons, fuel economy is the same and its so so much nicer to drive around. Off the line lunge is rather impressive, so there's no more playing catchup.

I would say do it.. The cost of rebuilding a rb30 is the same as an rb25. The only added cost is the oil feed to the vct and IF you decide to lower the motor. I had some one reweld my engine mounts for $70. So the extra costs over an rb25 are I'd say well within $200.

If you run a GT30 or a turbo around that size you can expect a power curve similiar to the attached dyno graph.

As you can see peak power is made so much earlier in the rpm, power goes flat then noses over a little earlier than the rb25.

An RB30DET running the gt35r .82 still has more power downlow from 1000-3500rpm than an rb25det (stock turbo, 11-13psi, pfc, exhaust, fmic) making a peak of 190-200rwkw.

Your T70, a bit of a stab I would say the spool threshold will drop from ~4000rpm to low 3000's + you will see some boost much earlier in the rpm.

[NathR32]

Not meaning to high-jack, but can someone who has performed an RB25/30 conversion provide a rough cost breakdown of components?

[Cubes]

The actual motor rebuild is EXACTLY the same as what it would cost to do an rb20, rb25 or rb26.

Rods are cheap and plenty full as vlt's have been around for a long time, pistons, grab a set of cp's.

The only added cost I saw was $70 for the engine mounts, I ran the r32 rb25de head that has no vct so no costs involved there.

Bl4ck32 and I had our bottom ends done at the same time so we received a slight discount, so not really comparable.

The bottom end completely assembled with forged pistons and head fitted inc. parts was ~$4000.

We purchased a r32 rb25de head for $750 and had it rebuild + a little work (usual valve deshroud, mild port & cleanup, bronze valve guides etc). The rebuild and work cost $1100 inc. parts.

We then had to fit it which was as easy as pie.

I'm really happy how the rebuild has turned out, both motors return awesome fuel economy, don't use oil and best of all.. They haven't blown up.

[CruiseLiner]

one bad point is the fact it dont rev like a 26, but it doesnt have to, to make the same power.

each to there own, but sometimes a quick and high revving engine is a great combo

different horses for different courses

im planning on building a stock rb30 bottom end with a 26 head very soon for my overweight stagea.

then the big revving 2.7 stroker can be put in a nice light track car for thrashing, mmm 10k rpm+

[Cubes]

If you fit an ati balancer and ensure you fit the full oil pump crank drive the rb30's flick to 8500rpm odd. Which is well within a reliable valve train, much more and the valve train begins costing big $.

With regards to how quick the 3ltr rev's, I find the 3ltr free rev most definitely flicks through the rev's a lot quicker than my old rb20, a mates rb25 and one rb26 i've seen.

The rb20/25 and 26's rev up a little dougy sounding compared to the crisper sounding rb30. My rb30 is running lighter than factory forged pistons so it may be so that the lighter piston makes up for the slightly heavier longer rb30 rod.

Once on boost the 3ltr will rev quicker due to greater torque.

Listening to Sky30's on the dyno is a testament to this, the rev's once boost came on simply flicked and sound awesome, brrrraapp compare that to another rb25 making 300rwkw brrrrrraaaaaaaapppp and it appeared to actually rev slower... As it would as its making less torque.

I believe 88Silloute has a nice little vid.. now if thats considered slow reving.......

Its simply an old stock n/a rb30 with a 25 head, exhaust manifold and trust turb making somewhere between 200 and 240rwkw I forget exactly. I remember he mentioned the limter was 7200rpm.

http://kero.drifthost.com/videos/marks4doo...nout.Winner.wmv

Suitable turbo + a nice exhaust manifold and the rb30's do rev like buggery.