[Diy_efi] Venturi effect crankcase breather

[Adam Wade]

--- don.broadus at exeloncorp.com wrote:

> Improved ring seal.. maybe
> 3-5 HP but the exhaust velocity must be high to pull
> a good vac.  

I spoke recently with a drivetrain engineer at Harley
Davidson on this subject.  He said the primary
advantages from such a setup were a decrease in
aeration (foaming) of the oil, due to lower crankcase
pressure, and a decrease in air pumping losses
incurred by moving a mass of air from place to place
by the motion of the pistons.  Lowering the density
lowers the pumping losses INSIDE the engine.  Ring
seal is a tricky one, because according to the tests
done by Harley, the optimal crankcase pressure for
ring sealing is in a fairly narrow band not too far
from atmospheric; in other words, it is easy to overdo
it and cause issues with the ring seal, and ring life.

=====
| Adam Wade                       1990 Kwak Zephyr 550 (Daphne) |
| "It was like an emergency ward after a great catastrophe; it  |
|   didn't matter what race or class the victims belonged to.   |
|  They were all given the same miracle drug, which was coffee. |
|   The catastrophe in this case, of course, was that the sun   |
|     had come up again."                    -Kurt Vonnegut     |

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