I'm not sure how much benefit in reduced windage losses you would get f= rom applying a vacuum to the crank case. The biggest areas for gain here are= in oil pan design, windage trays and crank scrapers that work to screen the= oil droplets from the air down into the sump and protect the oil surface fr= om the 'wind' in the crankcase. Yes, this can make a substantial difference=20= in a race engine, but as Paul said at 2700 rpm it's questionable just how mu= ch power could be recovered from windage reduction.

There are two benefits from crank case vacuum that you haven't mentione= d. The first is reduced dilution of the fuel air charge in the cylinde= r and its effect on power. During the intake stroke, cylinder pressure is we= ll below atmospheric (naturally aspirated) so ring leakage flows into the cy= linder. With crank case vacuum, the ring leakage flow is reduced and at= times even reversed. There are three effects as a result: First, the area b= etween the top ring land and the cylinder is full of exhaust products, parti= ally burned fuel and raw fuel all of which are detrimental to the power= stroke. During the intake and compression stroke, some of these products ar= e swept into the combustion chamber where they reduce power. Crank case= vacuum helps to remove them from the cylinder. Second, the air leaking= from the crankase is fuel lean and its addition to the cylinder is also det= rimental to power. Third

ring leakage into the cylinder carries with it a small amoint of oil. T= his also displaces fuel air mixture and reduces power, but more importantly=20= oil has a very low octane rating and contributes to detonation.

The second benefit is improved oil life. Unburned fuel and exhaust gass= es are continually leaking from the cylinder during the combustion, exhaust=20= and compression strokes and contaminating the oil. The oil contains various=20= additives to prevent damage to the engine as a result of contamination with=20= these chemicals. As contamination increases, the additives are expended and=20= protection is lost. Crankase vacuum helps to volitize some of the compounds=20= and draw them out of the oil and into the exhaust. This was a beneifcia= l consequence of the positive crankcase ventilation (PCV) system on car= s in the early '70's. While the vacuum generated in the crankcase was slight= , the system scavenged vapors from the crankcase and greatly reduced contami= nation of the oil. This resulted in extended oil changes intervals from 3 th= ousand miles in the '60's to 4 or 5 thousand in the '70's. Of cour= se today, thousands of people throw perfectly good oil away every 3000 miles= anyway. Old habits die hard.