Re: Plot of Engine Speed vs. Fuel Consumption

On Sun, 13 Apr 2008 23:13:02 +0800, "TE Chea" <4ws@[EMAIL PROTECTED]
> wrote:

>Such a graph must be stupid, of course consumption rises
>with rpm
>
>| gas mileage usually decreases rapidly at speeds above 60 mph.
>Not necessarily fr 60 mph, big factors incl
>[i] exhaust*manifold : cheapo 4-1 short branch * can give
>     ¾ of maximum torque @[EMAIL PROTECTED]
 low rpm <1000, but gives <½
>     of maximum torque @[EMAIL PROTECTED]
>3000 rpm, & even less @[EMAIL PROTECTED]
 higher
>     rpm
>[ii] voltage & ampere from small single coil ( esp if hot )
>      drop fast @[EMAIL PROTECTED]
>3000 rpm : sparks will be too small to
>      ignite enough fuel before pistons reach b-d-c, esp where
>      only cheapo carbon core cables are used
>[iii] cheapo mineral oil's coarseness are apparent only @[EMAIL PROTECTED]
 high
>        rpm when only the most slippery oil ( e.g. synthetic with
>        fullerene ) can produce high torque.
>[iv] gear ratios & axle (tyre) height

Needless to say, this guy is wacko.  By far the biggest factor in poor
fuel economy at high speeds is wind resistance.  Many vehicles (e.g.
big SUVs) run less than 3000 rpm at speeds above 60 mph and get much
reduced fuel economy due to their barn door aerodynamics. 

Of the above, only iv. will have any noticeable effect on fuel
economy.  To the extent that i. reduces power at high speeds it may
actually reduce fuel consumption.