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89Mm Crank

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because we were hijacking gav240z build thread, I thought I'd start a new topic here.

 

Lurch you mentioned Les Collins is building an L24 with an 89mm crank.

Does Les Collins make these cranks?

What is cost of such a crank?

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Details are in my build thread but basically. Les said the crank starts life as an RB crank then gets modified with the journals reduced and off set ground to increase the stroke. Or something like that. So it has a 89 mm stroke makes it just over 3 ltrs. Your best bet would be to talk to Les about availability and pricing. As always good things cost money.

Jeff

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LCR have the cranks modified. Cost is around $2500.

 

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Les is having longer flywheel bolts made by ARP, so a std L6 flywheel can be used with a spacer, instead of having a billet flywheel made (the flywheel mounting face is shorter on a RB crank and a L6 flywheel won't bolt up).

 

Or go to the mob that make cranks from scratch? Bit pricey...
They're in Melbourne somewhere,,,

Yes, a news billet stroker 6 cylinder crank from Auscrank is $7000.
I'll stick with my modified RB item, thanks...
 

Edited by Lurch ™

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And to clarify it makes a 3.35L with an over-bored and clearenced L28 block not an L24.

post-100549-0-56799900-1453678027_thumb.jpg

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is the 90mm crank in Green Hornet done the same way........from an RB?

 

yes $7000 for a crank is pricey. 

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is the 90mm crank in Green Hornet done the same way........from an RB?

 

yes $7000 for a crank is pricey. 

 

No, the one on the Green Hornet is a billet - So Greg spent $7k.
It IS fully counter-weighted though - the RB isn't.

 

Motorsport isn't cheap - How fast do you want to go?

Edited by Lurch ™

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Motorsport isn't cheap - How fast do you want to go?

 

 

 

 

Yes that comment did make me laugh!

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Motorsport isn't cheap - How fast do you want to go?

Yep very true.

 

However this is my favourite

 

Power, Reliability, Cheap

 

Choose only two !!

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Does it count if you are cheap and the car is the other two?

Haha - I like the way you think

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when I do get a Z, whatever it may be, I don't intend on setting any land speed records so very unlikely I'll be spending $7k on a crank, $2500 maybe.

 

my questions have been purely out of curiosity.

 

$7k for a locally made counterweighted 90mm crank is reasonable. Kameari L6 3.1L race crank is about $7500 U.S

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Back on topic...

 

What will be the end result as far as engine capacity using the L24 engine and 89mm crank that Les Collins is building.

 

Just another thought.....Why not modify an L series crank and turn it into a stroker?

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Back on topic...

 

What will be the end result as far as engine capacity using the L24 engine and 89mm crank that Les Collins is building.

 

Just another thought.....Why not modify an L series crank and turn it into a stroker?

That's a bit of an open ended question, but with a std L24 bore of 83mm, with the 89mm stroke crank it makes it 2889cc

With a 84mm overbore it becomes 2959cc

With a 85mm overbore it becomes 3030cc

 

Yes you can offset grind a std L series crank 2-3mm undersize, but the pin size starts getting quite small, which in turn can make it hard to find suitable rods & bearing sizes.

 

The beauty of the RB crank is it's a MASSIVE stroke increase with the off-the-shelf con-rod available ;)

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What you actually need to take into account with any build is the incidental increase in cost for an item. To say an LCR modified RB crank costs $2700 is correct but the true cost is the biffetence between this price and the other option. In most cases this is reconditioning an old crank. By the time it's crack tested polished balanced checked for alignment etc etc (properly) the price difference to the RB option is probably not as much as it seems. Remembering also that you get a new crank. Another of the advantages of the 89mm option is the availability of very well priced high quality rods that retain a big end journal size that is robust.

But each to their own.

Edited by CBR Jeff

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What's the weight of the RB crank?

I have never seen the RB crank.

But if the L series crank is anything to go by.......really heavy ^-^

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Apparently an LD28 crank is 1 kg heavier than a standard L28 crank.

Edit found this post from Nzeder.
http://www.viczcar.com/forum/topic/5359-l28-crank-weight/?p=60553

 

So anything lighter than that has gotta be an improvement.

  1. L28 Crank = 20KG
  2. LD28 Crank = 22KG
  3. Modifed L28 in my old L30 = 19KG

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That's pretty good considering the extra stroke!

Indeed, but the engine acceleration rate these motors have with the bigger stroke makes it inconsequential anyway.

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