RB30 Crank runout / straightness

Hey team!

Building a 1000HP RB 26/30.

Having some conflicting information on the stock crank. With a bearing in 1 and 7 on a V mount and measuring the middle journal with a dial indicator it’s about 1.5 thou and that follows all the way through the crank.

A lot of people are telling me all rb30 factory cranks and straight 6 cranks are bent and the amount measured isn’t bad.

Have you contacted a crank grinder to see if that can be improved? I have to assume that anything with 1000 hp (166 hp per cylinder) would require nothing less than perfection in every process possible.

I believe some companies can straighten the crank

Alternatively you can get it offset ground although that will put the clearances off

1.5 thou is concerning and I believe it would reduce main bearing life

I can freight it down south to be ground. It’s funny in any of my other builds I never checked the crank for straightness just paid to have it balanced and the clearances all measured up.

Some people have said less than 2 thou is an acceptable tolerance and some are telling me that at 1000HP the crank will probably bend 1.5 thou the other way anyway lol.

I’ve never ever had issues with main bearings on an RB it’s always just been big end stuff long term. I found a crank to buy from PRP old stock but I could get it here and it’s also a little bit bent. A Nitto standard stroke crank is $5k aud as well so at that point I’d of been better off going a stroker.

Update to anyone that might be in a similar situation.

Reached out to a couple big players and the general consensus was that they normally get them under a thou once straightened but just from incorrectly storing them they can bow and bend.

Was told that 1.5 thou would straighten out once bolted down and ran and not to worry.

That overcomplicates it. Andre feel feel free to add you’re opinion also lol

I wouldn't risk expensive 1000 hp engine build with crankshaft being 1.5 thou bent especially if that journal has oil supply holes. I usually go with 0. I can accept 0.5 thou on central journal without oil supply hole but this is as far as I'm prepared to go. Other people experience isn't good enough for me in that matter, they risk their own money, not mine besides we don't know what oil clearances they had. For instance if you plan your oil clearances to be 2,5 thou and the crank journal is 1.5 thou out of shape it leaves you only with 1 thou of oil clearance which doesn't sound promising...