R33 Rb30 Conversion

[matlowth]

My crank has been balanced and all the rest of it, and it regularly see's 7500rpm.

I know of one running to 9000rpm running a factory (abeit modified) crank.

Anything past 7-7500 and I think you'd need to look at aftermarket rods.

Cheers,

matt

hey guys,

anyone looked into the safe RPM limit of an RB30?

I have spoken to someone who said that anywhere over 6600rpm is asking for trouble. I was looking at using a 7000rpm limit, but was told i would be treading lightly on reliability.

any info?

[Gradenko]

Yes, it has a non-balance related harmonic at 7500rpm. I've been told to set the redline at 7200rpm on mine.

[Skyrine-Dave]

what about a viscous-filled harmonic balancer?

i had/have the option to go for eagle rods, but i have been told they are heavier than standard, altho stronger.

prepped arb30 rods would be easier to source in the event of a breakage too i would imagine... and more cost effective

[Cubes]

Yep,

As Matt stated anything over 7000-7500rpm and you should look at rods.

Its all related to piston speed.

[GiJOr33]

if you have rods, and pistons all balanced with the crank and flywheel/clutch then you should be able to take it past 7500 no problem. But the power levels will be big well before 7500rpm so you don't really need to take it past that. An Rb25 harmonic balancer is also a good idea, but as sydneykid will tell you, he uses new RB30 ones with no problems!

Andrew

[matlowth]

Re: visous balancer - not too sure.

If you can afford it, I'd go the aftermarket rods just for that extra piece of mind.

If you really want to rev hard, spend the $$ and get the crank balanced too.

Can I ask why you're concerned with reving to 7500rpm?

My motor makes peak power around 5800-6000rpm and thats with bigger cams and a turbo that'll flow roughly 700hp. They don't need to rev as hard as a 26 to make power.

Cheers,

matt

[DoughBoy]

All motors have inherant harmonic issues, so you can't single out the RB30. You'll notice that anyone building up a "decent" modified V8 has plenty of aftermarket harmonic balancers to choose from, and this part is generally always changed.

Unfortunatley, the options from Japan for the RBxx series are the ATI/HKS fluid damper ($1200), the Greddy billet alluminium hub (no balancer, ~$600) or a Route 66 rubber damper ($1000). The ATI item is the best available, buying it through HKS also gives you the pulleys, if you go direct to ATI you can get it a hell of alot cheaper but no pulleys (go go Gadget fabrication) and there are 8 or to choose from with alloy or steel shells.

Having said that, there are plenty of RBxx motors using a standard one without any dramas. However, at high RPMs I think that the harmonic balancer contributes to oil pump failure and also crank damage - I've seen a few RB26 cranks with the keyway split or the hub for the oilpump damaged.

So I guess you can add this part for a no-holds-barred, no beg-your-pardon's type motor. But it's not a necessity.

[Jaws]

An Rb25 harmonic balancer is also a good idea,

So will a Rb25 harmonic balancer will fit onto a rb30 crank?.

[Skyrine-Dave]

i just wanted to make sure i could take it to 7000rpm limit and not be shattering any oil pumps I would like to go forged rods but have heard melancholy stories about eagle rods and cannot afford 2k for carillio/argo's.

[GiJOr33]

On an RB30 i would consider anything over 8000rpm as high revs. From the reading i've done, anything under that i fine. An RB26 i would consider over 9000rpm as high revs.

RB25 balancer will go on the RB30. All RB balancers do (i've been told by people i believe). I will know for certain in a week or so

Andrew

[DoughBoy]

All inline 6 cylinder engines are internally balanced, therefore the clutch and harmonic balancer do not have to "carry over" any external weighting and are neutrally balanced.

Looking at an RB26 vs an RB30 balancer there is not much external difference, but given the fact that the RB26/25 are a later model motor I would assume that they are both a) made from better materials and processes and B) there is less chance of the rubber cushioning material to be damaged since it should be a lower mileage motor.

It all comes down to the fact, how much horsepower can you afford to make?

edit: all the RB series are interchangable, from harmonic balancers to flywheels/clutches.

[Cubes]

From every one I've spoke to who have built high reving RB30's and making over 700hp they all tend to change (or stiffen up) the bottom end by using an aftermarket cradle & different re-inforced sump.

Apparently by stiffening up the bottom end it shifts the harmonic issues higher in the rpm range that will never be touched.

Not once was it mentioned people playing around with harmonic balancers.

?!?!?!

[matlowth]

Oh - I forgot to mention - the RB30 I mentioned earlier which rev's to 9000rpm (and makes 800-850hp) was a GTR - so the bottom end is stiffer because of the front diff. The torque is what warps the blocks though - not the revs. Although I haven't heard of any twin cam RB30's doing that.

On another note - what are people doing with the head studs? I'm still using factory ones - but has anyone gone bigger?

Cheers,

matt

From every one I've spoke to who have built high reving RB30's and making over 700hp they all tend to change (or stiffen up) the bottom end by using an aftermarket cradle & different re-inforced sump.

[GiJOr33]

Yeah i'll be going bigger. ARP head bolts

[BU5TER]

If you get the Argo rods they come with the after market rod bolts, I'm pretty sure

[the phantom]

The RB25 and RB30 harmonic balancers, whilst being physically interchangeable appear to have a different construction as already mentioned. However the point of interest is that they also have consequently different states of harmonic tune as they have differing effective weighting on the damper section. Speculating, one would assume it is to compensate for the different harmonic characteristics of the different cranks i.e. the RB30 is a longer stroke than the RB25. I have long wondered about the harmonic issue talked about at 7500 RPM, but it seems no one has ever done a proper test to see what exactly is going on. Is it a TORSIONAL harmonic issue? Is it a BENDING moment issue? Anyone ever had a close look at the damper used on the Autospeed monster RB30 by Nispro? That looks like it has substantially more mass to it on the damper ring.

For my long serving RB25/30 I used the RB30 balancer with no apparent long term effects, and a strictly enforced 7000 RPM limit. Without testing though I can't say wether or not it was the right decision.

[OVL-747]

The "AFM = restriction" is a myth, you just have to have the right sized one for your application.  Spread the word.

not so much the afm , but the rest of the inlet piping may cause a very high restriction , as seen on the test on the vl turbos inlet on autospeed.

but i agree with u , correct size of afm for ur application and it wont hinder anything.

[OVL-747]

 

On another note - what are people doing with the head studs? I'm still using factory ones - but has anyone gone bigger?

 

Cheers,

 

matt

why does everyone rave on about head studs , why not use the original stretch bolts , but use a torque to yeild ratio when tourqing them down. instead of just bolting it down to the specs in a work book.

sydneykid - do u agree with me or do u see no need for it?

and as for rod bolts , im still not sure if arp make ones to suit an rb30 rod , though a simple way around it is using sr20 bolts , just need to buy 2 sets (as there is four pairs in one set , 4 cyl's of course)

[Sydneykid]

Hi Guys, we use RB26 size ARP head studs (not bolts) and ARP main bearing studs in all of our engines.

Hi OVL-747, if the pipework is causing a restriction then it is too small.

[matlowth]

I was curious more than anything else... As I mentioned - my car still uses factory ones.

Re: rod bolts - not too sure about ARP bolts, but I've got Tomei rod bolts which are around about the same price.

Cheers,

matt

why does everyone rave on about head studs , why not use the original stretch bolts , but use a torque to yeild ratio when tourqing them down. instead of just bolting it down to the specs in a work book.

sydneykid - do u agree with me or do u see no need for it?

and as for rod bolts , im still not sure if arp make ones to suit an rb30 rod , though a simple way around it is using sr20 bolts , just need to buy 2 sets (as there is four pairs in one set , 4 cyl's of course)