DIY WB update

[Greg Hermann]

At 12:30 AM 8/14/98, Bruce wrote:
>Speaking of lean cruise.
>I can't find any real big gains in going real lean anyway.  Still need to
>burn x amount of fuel to make a given amount of power to actually move the
>car.  Maybe, better results, in a lighter car, but then you give away all
>the road hugging weight.  the instant you have to run more throttle opening
>from the leaner AFR, then your using more fuel anyway due to the greater air
>flow.  While you might run 10% leaner, if you have to use more throttle
>opening you might be using a larger total amount of fuel.
>Just completely the opposite of what pumping loses would dictate.
>Again, theory falls short of real life....
>Bruce

Gearing is part and parcel of tuning. Gotta go to a taller gear along with
the leaner af ratio--which cuts the quantity of air back down to where it
was before the throttle got opened a bit more. The extra load on the engine
from the taller gear allows the wider throttle opening and consequent
reduction in pumping losses.

Part of the reason for higher power on the rich side of stoich is selective
burning of the hydrogen in the fuel before the carbon gets burned. The
hydrogen fraction has a higher heat of combustion than the carbon does,
hence more heat and power for a given amount of air with a somewhat rich af
ratio, but less mileage because not all of the fuel (some of the carbon
part) is being burned.

Greg


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