Crankcase pressure on a SZ 90 PS

[pipino12]

A friend of mine at the field broke the pump of a brand new OS90SZ PS upon installation. We were thinking of getting rid of the pump and use crankcase pressure to pressurize the system.
Anybody tried it, do you think it would work?




Corrado

[Raptor Rulezzz]

I haven't tried it but I guess it should work, similar to a YS.

Just try it!!

I recently mounted the whole SZ carb/regulator & pump on a OS91C-spec PS Viperhead and it ran VERY well... maybe your own little conversion wil work too :lol:

Cheers,

Richard

[Jared Granzow]

The engine may or may not run good, but the os regulator will not stop the fuel from flowing through the carb when the motor quits like the cline does. You will have fuel all over the place.

[DavidH]

but the os regulator will not stop the fuel from flowing through the carb when the motor quits like the cline does.

That is interesting. I would think the regulator on the SZ is a fuel demand regulator just like the Cline. So I would think when the engine quit and the carb didn't need fuel that the regulator would not allow more fuel to pass.
Is that not the way it works?

David

[SteveL]

I heard it works more like a restricter than a regulator. It would be nice to know because I would prefer cranckase pressure over a pump.

[DavidH]

Would be simple enough to try without the pump and use crankcase pressure. Just hook a pressure line from the fitting in the back plate to the vent line on the tank. Insert a check valve in that line and go fly. If the regulator is a fuel demand regulator. Should work fine.

David