weather forecast and altitude
I sure hope the weatherman is wrong, as it is showing 40% rain on Saturday....
I need our experts here to clarify this for me, a technical dummy, regarding altitude effects and supercharged engine (forced-air). someone said here that at 2700 ft above sea level will have a negative effect on our GTs performance, which make sense to me. However, I came across this at Wikicars.org (which says the supercharger compresses the air "back to the sea-level"....). Now, me don't know
confused
"Altitude effects
A Rolls Royce Merlin engineA supercharger remedies this problem by compressing the air back to sea-level pressures, or even much higher. This can take some effort. On the single-stage single-speed supercharged Rolls Royce Merlin engine for instance, the supercharger uses up about 150 horsepower (110 kW). Yet the benefits are huge, for that 150 hp (110 kW) lost, the engine is delivering 1000 hp (750 kW) when it would otherwise deliver 750 hp (560 kW). And while the engine might be fooled into thinking it's at sea level, the airframe is quite aware of the halved air density and the plane thus has half the drag. For this reason supercharged planes fly much faster at higher altitudes.
A supercharger is only able to supply so much pressure because the compression increases the air temperature, and the engine is limited in maximum charge-air temperature before engine knock occurs. The boost is typically measured as the altitude at which the supercharger can still supply sea level pressure (100 kPa or 1000 mbar) and is referred to as the critical altitude. Throughout WWII British superchargers generally had higher critical altitudes than their German counterparts and, when combined with higher octane fuels that the Americans supplied, that allowed for higher boost levels. British engines were generally able to outperform German ones."
Ed
