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Crank Strength And Upgrading Options.

LedZepLen

By LedZepLen,
in Engines & Forced Induction

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nismomiles33
nismomiles33

I used a grub screwed, machined and balanced, nitrated standard crankshaft (Nizpro spec??) .. should hold up with most, I was told that should be good for 800+HP.

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Sydneykid Grand Master

Sydneykid

Posted
Posted
SK, I might be misunderstanding, are you saying that if the revs aren't excessive then the rods should be able to handle a lot more than 4-500hp? I have my 30 limited to 6800rpm, reckon I would be able to push more than 400rwhp on the stock rods with that limit?

The real question is what is excessive RPM? Remember RB30's barely reved over 6,000 rpm standard. Adding around 500 rpm = double the load on the pistons and rods, so at 6,800 rpm you are already way more than double the standard loading.

Cheers

Gary

bubba Grand Master

bubba

Posted
Posted

Hmm, well that's not very comforting :/

Would it be advisable to lower the limiter? I don't rev past 6000rpm now anyway due to the tiny rb25 turbo choking the engine up and I've got taller diff ratios which help with the lesser rpm..

I imagine with the GT35R strapped on there I'm going to have an abundance of torque and might not necessarily need to rev it to 6800..

dano4127 Veteran

dano4127

Posted
Posted
Hmm, well that's not very comforting :domokun:

Would it be advisable to lower the limiter? I don't rev past 6000rpm now anyway due to the tiny rb25 turbo choking the engine up and I've got taller diff ratios which help with the lesser rpm..

I imagine with the GT35R strapped on there I'm going to have an abundance of torque and might not necessarily need to rev it to 6800..

Im going to be reving mine to 7200 once its tuned, I reckon 6800 is being a bit too concervative especially with forgies make sure you got a really good tune and it shoud be apples!

Sydneykid Grand Master

Sydneykid

Posted
Posted
Im going to be reving mine to 7200 once its tuned, I reckon 6800 is being a bit too concervative especially with forgies make sure you got a really good tune and it shoud be apples!

I was answering a question about standard rods and pistons, hence the mention of the 6,000 rpm

Cheers

Gary

dano4127 Veteran

dano4127

Posted
Posted
I was answering a question about standard rods and pistons, hence the mention of the 6,000 rpm

Cheers

Gary

Fair enough, just want to get this straight in my head are you saying not to rev over 6k with stock pistons and rods?

Sydneykid Grand Master

Sydneykid

Posted
Posted
Fair enough, just want to get this straight in my head are you saying not to rev over 6k with stock pistons and rods?

If only it were that simple. There is more than one limit on the strength of components question, there is knock, boost, RPM and torque to start off with. Keeping in mind that BHP is simply torque x rpm. For example, I hear quite often 400 rwhp is OK on the standard components. Well it isn't if you are using 7,500 rpm. It also isn't OK if you are running 1.5 bar of boost. Not to mention 70 plus knock all the time. My rule of thumb is quite simple, no more than 475 bhp (around 300 rwkw), 1 bar of boost, zero knock and 6,500 rpm limit. A standard internals RB30 will live a long life within those limits, I built one in 1999 that is still going strong.

Cheers

Gary

  • 3 weeks later...
Adriano Grand Master

Adriano

Posted
Posted
What about machining? some people say they've had theirs machined, though i thought RB30 cranks were nitrided from the factory and therefore, not a good idea to get them machined? can they be re-nitrided?

Yes, although if the crank needs machining, its easier/cheaper to get one that doesn't

drgnball34 Rising Star

drgnball34

Posted
Posted

had mine machined etc and even nitrided for good measure. Argo rods, ceramic coated cp pistons, jun pump and collar, ati balancer... All balanced. Setting rev limit to 8000rpm...although it will only be bounching at that over the dyno..I think street tune will be 7000rpm.

  • 2 weeks later...
drgnball34 Rising Star

drgnball34

Posted
Posted
stock crank nitrided i can vouch has handled 1068 rwhp @9000rpm 10 000rpm in burnout also threw 2 rods and the crank was still true. but im very interested in the stroker kit for the rb30

was there any mods done to the block???

jas/slo32 Proficient

jas/slo32

Posted
Posted (edited)

block was std never ran an oversize over 87mm yet,usuals like drilled galleries gtr head studs etc

this year the engine is grout filled running methanol and is solid mounted

Edited by jas/slo32
  • 4 weeks later...
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