Amazon: - Race prep a B16 for historic racing - Page 2

blueosprey90 · Dec 18th, 2018, 21:42

"Care to tell us more about the hybrid ghost crankshaft?"

Well, for starters, it doesn't fit the block!

It's a billet crank by Marine Crankshaft in California. It's hybrid because it has a MGB 5 main bearing flywheel flange. It's ghost main because it has 2 ghost mains - looks like a 5 main bearing crankshaft, but only has 3 main bearings.

The rear of the block and rear cap had to be machined to "accept" the MGB flywheel flange.

The crankshaft itself had to be modified and rebalanced to clear the oil pump boss on the block - the oil pump boss and the oil pump themselves were shaved for additional clearance.

I was afraid about the oil pump clearance when I ordered the crank, but I'm apparently the test mule on this application, as it had not been done previously to the best of my knowledge.

In the best of all possible worlds, a little more meat should have been taken off one of the counterweights to clear the oil pump, but my oil pump boss had been damaged when the first crank broke. This just means that I need to keep a spare, shaved oil pump on standby should I have an oil pump failure down the road.

Photo of stock 3 main bearing crankshaft and the ghost main as delivered.

Vintagewrench · Dec 20th, 2018, 11:38

Quote:

Originally Posted by blueosprey90

It's a billet crank by Marine Crankshaft in California.

The new crank looks great. I've found that added counterweights like this will help smooth out the torsional vibration periods fours suffer from and less vibration means more power.

The weight of the extra counterweights may slow down the cranks ability to rev-up as quickly as the MG shaft, but this can be compensated for later if necessary by lightening the flywheel and clutch assembly.

Ron Kwas · Dec 20th, 2018, 13:40

Forum;

I agree...I expect the torsional vibration characteristic to be completely different (and better!) with the ghost crankshaft...I'd love to see a Finite Element Analysis comparison of the two...that would be a fun assignment for an engineering student...anybody know any?

Cheers

Dec 18th, 2018, 21:42	#11
blueosprey90 Master Member Last Online: Yesterday 22:18 Join Date: May 2017 Location: New Milford, Connecticut	"Care to tell us more about the hybrid ghost crankshaft?" Well, for starters, it doesn't fit the block! It's a billet crank by Marine Crankshaft in California. It's hybrid because it has a MGB 5 main bearing flywheel flange. It's ghost main because it has 2 ghost mains - looks like a 5 main bearing crankshaft, but only has 3 main bearings. The rear of the block and rear cap had to be machined to "accept" the MGB flywheel flange. The crankshaft itself had to be modified and rebalanced to clear the oil pump boss on the block - the oil pump boss and the oil pump themselves were shaved for additional clearance. I was afraid about the oil pump clearance when I ordered the crank, but I'm apparently the test mule on this application, as it had not been done previously to the best of my knowledge. In the best of all possible worlds, a little more meat should have been taken off one of the counterweights to clear the oil pump, but my oil pump boss had been damaged when the first crank broke. This just means that I need to keep a spare, shaved oil pump on standby should I have an oil pump failure down the road. Photo of stock 3 main bearing crankshaft and the ghost main as delivered.

Dec 20th, 2018, 13:40	#13
Ron Kwas Premier Member Last Online: Today 02:57 Join Date: Jul 2007 Location: Connecticut, USA	Forum; I agree...I expect the torsional vibration characteristic to be completely different (and better!) with the ghost crankshaft...I'd love to see a Finite Element Analysis comparison of the two...that would be a fun assignment for an engineering student...anybody know any? Cheers

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