Quote:
Originally Posted by 350TSS
What I understand from the article is that the most inefficient engine as far as pumping losses are concerned is a single cylinder...
...A 90 degree V twin should be somewhere between the single and the 180-degree twin - towards the single end of the spectrum because of the unequal firing order.
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Interestingly, (again for desmo-nerds!), I remember reading that the 1199 superquadro motor incorporated a pump to tackle this phenomenon.
From the Ducati press release...
"The pump is driven by the main oil pump shaft and effectively maintains constant vacuum in the crankcase area below the pistons, reducing atmospheric resistance during the down- stroke of the piston and controlling the internal “breathing” of the engine."
Apparently, the pump is an oversized oil scavenge pump which removes much of the air as well as the oil that's drained back into the crankcase. It scavenges air from beneath the pistons and minimises pumping losses. (The pressure is reduced by around 0.7 to 0.8 bar.)
I don't know whether this system was used on any other motors or models.