crankcase evacuation system.

[hitz]

  I'm thinking about putting an exhaust vacuum evacuation system on my (stock internally) Saturn engine and wondered if it was worth the trouble? A dry sump system is not in the budget right now.

  I'm trying to have the lakester ready for some shake down runs at Speed Week or World Finals this year and get some kind of idea of the base numbers. I'm hoping for about 145 HP. It's all just a guess now.

  Harvey

 

[JackD]

You need to vent the motor no matter what, and a slight vacuum that doesnt unload the lube oil is even better.
Exhaust pulses are free energy and where would you rather put the nasty vented stuff other than the exhaust pipe ?

[hitz]

  Thank you, Jack. Thats all I needed.

  Harvey

[Speed Dreamin]

Be careful.  Drag racers have been using exhaust evac systems with some degree of success.  However if too much vacuum is created the oil does not get to the wrist pins.  Filtered air should be allowed to enter the engine, much like a PVC system.

[JackD]

Adequate pin oiling is more related to design of the system to oil them than handling crankcase pressure.
Pin flex will reduce the assembly clearance and take the cush of the lube away.
Oil escape passages in the bottom ring land make their contribution also.
Some race applications have drilled rods from the big end to the small end of the rod, and even oil nozzles through the side of the block that provide a constant spray, primarily to cool the dome but serves to oil the pin also.