Fan pulley - over running clutch

[BEACHHOUSEGURU]

Has anyone experimented w one way clutch, overrunning clutch OAP/OAD pulley on a corvair fan pulley. Did it have any positive impact on belt jumping, efficiency/performance, noise etc.?

Thanks
"Murph"

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[bbodie52]

Dayco OAP/OAD

Wouldn't an overrunning clutch have added weight to the rotating mass of the fan combined with the clutch assembly? The belt would still have to contend with accelerating the fan to keep up with the crankshaft pulley. The clutch would only release the belt during deceleration. It might work, but I'm not sure how you could make this work with the complex belt routing on a Corvair. This advanced pulley design looks very good for dealing with the heavy alternator mass, which is mostly irreducible. The cooling fan, on the other hand, lacks the complexity of an alternator and could easily have its mass reduced using lightweight magnesium in place of steel.

I believe a lot was accomplished just by eliminating the heavy steel fan and replacing it with a very lightweight magnesium fan. I believe Chevrolet engineers also experimented with a lightweight plastic fan, but ultimately decided on the magnesium fan.

This was Chevrolet engineers finding another way to cool the engine with less belt stress, by eliminating the 90 degree turn from the belt and doubling the number of V-belts with a double pulley arrangement. But unfortunately this overhead cam engine never made it into production. Big displacement V8 engines were much cheaper and more-common.

Chevrolet - Astro I

The Chevrolet Astro I concept car appeared in 1967 as a radical-looking fastback coupe designed for the show circuit. The car's height was under three feet, and hinged rear body/door section allowed access to the cockpit. A periscope rearview mirror on the roof provided a wide-angle view. Twin aircraft-style controls were used in place of a steering wheel.

[joelsplace]

Unless your engine can turn a lot more RPM than stock you shouldn't have belt issues. If you do something is wrong.
You probably already know that.
A one way clutch would help I'm sure but the above diagram looks to be just a slip clutch.
If you built a custom fan bearing you could incorporate a one way sprag into it.
There is a guy prototyping a custom fan that puts out a lot more air so you can slow it down and help the issue.