Where can I buy a Type-IV "stroker" crank? Options

[Charles Deutsch]

Scat quoted me a price of $1499 for a 78 mm, one piece chromoly billet, T-4 crankshaft and I can buy one from Aircooled.Net for $500 but are there any other places that I can check for prices?

Thanks.

[Charles Deutsch]

An item that is easily overlooked is the rod length if you are building a stroker engine. If the stroke goes up the rods have to get shorter unless you move the barrels and heads away the same amount as the stroke increase. The "short rod" problem can result in  much higher loads on the small end and can result in even the end of forged rods pulling loose. Seems this used to happen to off-roaders for years until the problem was solved. Good luck.

I keep reading this but it's not intuitively obvious to me that piston speed decreases as the length of the connecting rod increases so I tried to do the math. The equation I get for the position of the connecting rod small end as a function of the angle of rotation of the crank, a, the crankshaft throw, T, and the connecting rod length L is:

x = T* Cos[a] + L*Cos[ArcSin[T*Sin[a]/L]]

then dx/da and d^2x/da would be