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The mkiv Supra Owners Club

Nice crankshaft!


Chris Wilson

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I'd say some kind of F1 V10 engine judging by the throw and the number of crankarms. Those crankpins are daft long though. I was going to say a W engine initially.

 

Hollow crankpins and tungsten inserts. Mmmmmm.

 

Whatever it is it isn't cheap.

 

*EDIT* It is a V10. Only two lube holes per crankpin. The second closest pin looks well and truly fecked.

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I'd say some kind of F1 V10 engine judging by the throw and the number of crankarms. Those crankpins are daft long though. I was going to say a W engine initially.

 

Hollow crankpins and tungsten inserts. Mmmmmm.

 

Whatever it is it isn't cheap.

 

*EDIT* It is a V10. Only two lube holes per crankpin. The second closest pin looks well and truly fecked.

 

 

V10 eh! Didn't think of anything that exotic, but I should of realised with Chris's perversion towards megabuck race cars. :D :p

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The counterbalance weights look like they have been cast or forged which might put a purebred racing engine out of the picture. The piccy isn't good enough to tell really. There are no moulding splitlines that I can see, but if it was a billet crank I think the design would be simpler, and not so rounded.

 

McLaren F1?

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How can it be V10 when there's only 5 arms for conrods.

 

Does that mean that this one is a V16?

I'd be interested inknowing what kind of engine that is from, because its a pretty weird design. Some of the crankpins look different lengths and all the counterbalance weights are completely circular - meaning they aren't counterbalance weights at all and the mass and inertial will be sky-high.

 

Also, not all of the throws have a main bearing in bewteen, so despite all that metal the crank will be bendy.

 

I'm guessing its some kind of old-skool big litres race engine with a relatively small power output?

 

 

Anwyay - I was the only one who spotted the fecked crankpin in Chris' pic, so I claim whatever prize he's offering :)

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According to this it's out of an inline 8 (one of two in each car :eek: )

 

 

Now, that's a crappy engine configuration for crankshaft stiffness, especially if you don't have a bearing in between each thow. However, since they have put two adjacent throws right nex to each other with no bearing in between, the two opposing reciprocating masses might be close enough to cancel each other out effectively.

 

If this works, then there would be no need for counterbalance masses on the crankshaft, which that crank does not have. But why???

 

Long cranks suffer badly from torsional vibrations - the crankshaft acts like a big watch spring. The mass that effectively fixes one end of this spring is the flywheel. The flywheel (traditionally at the gearbox end) rotates at a more or less constant velocity whereas the rest of the crank pings back and forth, lurching around in finite spurts of torque as each piston goes through its power stroke. This sets up vibrations in the crank that get worse the longer the crank is. Maybe if you aren't too bothered about perfect primary balance so you don't need counterbalance masses on the crank (or can use two adjacent pistons to do the job) then maybe you can distribute your flywheel inertia evenly along the crankshaft? In that way, it is possible that the long cran kmight be split up into a series of smaller cranks that wpuld tend to revolve at a more even velocity (i.e. less vibration) as a whole.

 

Hmmmm... Method in their madness after all, methinks :)

 

BTW - on closer inspection, the crnkpins are all the same length. It was just perspective.

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