RB30 or rebuild rb24

[Sydneykid]

Thanks SK,

Is that 475hp x .75 = 350kw at the fly? Allowing for losses atw that would equate to the 280 rwkw you mentioned.

Good, your calculator works the same as mine, which I have checked by running the engine up on the engine dyno and the chassis dyno. Can't afford to have an unverified calculator.

Your comment that 'anything over 475 hp costs the same' makes sense.

No only makes sense, but is in fact true.

But assuming the $ for a bullet proof engine aren't available and if a stock RB26 can make 280rwkw safely, why go to an RB26/30 except for a bit more torque (and a fair bit more messing about to install it). Is it the cost? What am I missing?    

I would never suggest taking a perfectly good RB26 out and replacing it with a standard internals RB30. That would be pretty damn silly. But if you have an RB20, or an RB25, or a badly stuffed RB26 bottom end, then it makes perfect sense. It will cost less and give a much higher average power.

What rpm limit do you observe for the stocker bottom end?

Irrelevant question really, the limit is 475 bhp, so reving a standard internals RB30 over 6,500 rpm is a waste of time. And they make so much average power (at that max power level) it is actually slowing the car's acceleration by reving it too far. Around 7,000 rpm is OK and 7,500 rpm, if it is balanced well. But if it is still making power at 7,000 rpm, then it is making over 600 bhp and you have exceeded the 475 bhp limit anyway.

Hope that answered your questions:cheers:

[R32-GTS]

My mates rb30det in his vc commodore made 487 rwhp with twin 2540's. He revs it to about 7200 max. . Ran a 11.6 quarter last week.

[pitchd]

ok so say i still want to stick to the ol rb20 style engine but use gtr crank and rods to make it a 2.4...

what else am i looking at internally to reliably run 260-300rwkw?

deffinately going to be a limiter hitting engine as its being built for drift purposes...

- adz

[Bl4cK32]

ok so say i still want to stick to the ol rb20 style engine but use gtr crank and rods to make it a 2.4...

what else am i looking at internally to reliably run 260-300rwkw?

deffinately going to be a limiter hitting engine as its being built for drift purposes...

- adz

4AGZE pistons are factory forged so they should be ok if the tune is good id think.

Rods and crank are ok, just get it all balanced up, and use a builder who knows his stuff

[GTR32]

Sorry Scooby just want to add my 2c:

SK:

Good, your calculator works the same as mine, which I have checked by running the engine up on the engine dyno and the chassis dyno. Can't afford to have an unverified calculator.

I think he was trying to clarify if it was 475 fly or atw, I don't believe your original post specified. But he should probably make sure he keeps that calc if it agrees with your dyno LOL! J/K

I would never suggest taking a perfectly good RB26 out and replacing it with a standard internals RB30. That would be pretty damn silly.

I was considering doing exactly that given the support I've read for this conversion, the apparently low cost and the impressive results people such as 88 (above) achieve. But I think I'm clear on that now.

Irrelevant question really, the limit is 475 bhp, so reving a standard internals RB30 over 6,500 rpm is a waste of time. And they make so much average power (at that max power level) it is actually slowing the car's acceleration by reving it too far. Around 7,000 rpm is OK and 7,500 rpm, if it is balanced well. But if it is still making power at 7,000 rpm, then it is making over 600 bhp and you have exceeded the 475 bhp limit anyway.

I didn't think it was that irrelevant given the discussion that sometimes surrounds rev limits for the RB26/30 but there is no question in my mind now.

Thanks SK

[88silhouette]

thanks 88, picture tells a thousand words. 226 ATW on 8 psi is excellent. stock bottom end?

yeah mate stock

[MADGT4]

I too would like to go the 2.2 or 2.4ltr option.....

I have heard that the RB20 rev's to some spastic Redline!

Another thing is..... I dunno if you guys are with me but i could not sacrifice the soud of my car for more power! How dramatically did the sound change with theses engines?

[Bl4cK32]

my car still sounds like an rb motored car. Its is roughly the same, if not quiter than my old motor.

[MADGT4]

Yeah i just love the sound of my RB20 screaming thats all.....

I could never give that up!

So does anyone know anything about the RB22 or 24 and the rev's question i asked above?

[Bl4cK32]

my redline on my rb30det with the std rb25de non turbo cams still makes power till up to 7000rpm. The redline is set to 7200....a set of cams and it can still rev like my old rb20 did, but it has more power now off boost than the rb20 did on.....gimme a pm some time, and ill show you if you like

[Cubes]

Simply slapping more cubes under the same head (valve & cam size etc) will cause the motor to rev less.

It will make its peak power earlier and drop power earlier resulting in the feeling of it doesn't want to rev out as much.

The RB25 head has bigger ports and valves, this will result in a motor that wants to rev harder than your 2.4ltr under a rb20det head that has 5mm per inlet valve less diamater.

Over both valves thats a 10mm diamater difference. No wonder the rb20det valves look like little baby toy valves next to the rb25 head.

For drift that often see's over rev's I would seriously look at getting yourself a R32 RB25DE block, GTR pistons (possibly forged), rods and crank, adapt the piston oil squirters if you are going to use stock pistons.

It will be a much much better drift motor vs the rb23/rb24det.

It will rev harder, spool earlier and make more average and peak power. Not to mention it will be much more reliable as you wont need massive cams and huge rev's to make the power.