Quote:
Originally Posted by AdamP
If frictional and pumping losses are insignificant on overun, the fuel used be to overcome the even smaller losses on idle must be even less significant!
Posting videos to youtube doesn't change the laws of physics unfortunately, or my job would be significantly easier :/
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So you continue to deny the science.
Gravity provides kinetic energy which overcomes pumping losses and power to ancillaries. Air con alone takes 4 to 5 hp intermittently. A bit less for alternator usually. All powered by gravity, not fuel, when on over-run but by the engine when coasting.
In the video it was assumed, correctly, that idling a 2 litre car uses about 0.36 litres of fuel per hour or 6 millilitres per minute to overcome pumping and friction losses and run at idle. Ten hours of idling would use a minimum of 3.6 litres, which is what the stop start is there to avoid. That's without taking account of the power/energy/fuel used to power the ancillaries brakes and steering etc. All of which are otherwise powered by gravity acting on the mass of the car pushing it down even a slight gradient in a high gear. Luckily the video even explains the effect of gearing, so I don't need to so much.