Cal Vanize wrote:

As my research continues, I have been investigating possible engines for
a 601XL. The Corvair engines looked like a good candidate. The reports
seemed very good and the engine was surprisingly inexpensive for initial
purchase and long-term maintenance.

The stated expected TBO is 1500 hours and the Corvair Authority website
documents the use of a Corvair engine in a 601XL.

Everything seemed OK until yesterday when I read the most recent updates
on their website. Seems that the "untreated" automotive cranks have
been cracking in a very short time. Nitriding seems like the only
solution. But with standard cranks cracking at under 100 hours, what
would be the expected life of a nitrided crank. Twice as long, four
times as long, eight times as long? This would still fall short of the
1500 hour TBO stated by the Corvair Authority.

Does anyone have any first hand experience with Corvair conversion
engines? Any info on their realistic life and reliability?

TIA,

CV


Welcome to the real world of auto engine conversions, Cal.

I have never flown a Corvair, and of them only by reputation, so I'm
not much help with your crank problem.

I've flown several VW conversions, a couple of Subarus, and one Chevy
V6 in an RV-6, so I don't claim to be an expert, just another
experienced fool.

The Great Plains crank for my 2180cc VW is a massive chunk of steel.

It bears no resemblance the the auto market cranks I've ever seen.
But then auto motors _usually_ don't have to deal with propeller
loads... (if that helps?)


My ex-next-door-neighbor built a 601-HDS with a Rotax 912 and a 74"?
electric Ivo prop for power. Now that is a sweet setup.
He has over a hundred hours on it now and only has to feed it gas and
change the oil (and electric prop bushings).

His airplane is heavy - with every conceivable gadget to play with.
But the little Rotax just ignores it and slings the airplane into the
sky anyway.

Other than a minor problem with the oil tank plumbing (I saw the
"instructions" and yes they are ambiguous at best...) that caused the
oil temp to track the airspeed indicator on the first taxi runs, the
engine has performed smoothly and flawlessly.
Every time.

That's something I really like in an airplane motor...

Richard