Thanks for the anology Mayf,
A basic qustion from me while on the subject:
With all conditions being equal ie temperature and humidity.
How much less oxygen, percentage wise is available at 5,000 ft compared to sea
level.
Or another way, with a perfect EFI fuel map at sea level, how much do I lean
(theoretically) at Bonneville with all other conditions the same apart from
altitude.
Chris Harris.......................NZed.
Not having done this, only listening to you all, I have a coupla
thoughts...
1) Assuming that the air pressure is about the same from morning to late
afternoon ( It's not), and the air temp goes from about 75 in the morning
to
around 95 in late afternoon, then you will experience a decrease of
approximately 3.6% in horsepower even if it is in perfect tune. Just a mass
of air conition. Throw in the slight pressure change from morning to late
afternoon, then the effect is a bit excerbated. The horsepower due to drag
reduction matches the loss in hp due to density change, but there are a lot
of things which say later is better: like reduced tire rolling resistance,
warmed up components for greater clearances for less friction (albeit,
small) plus maybe some other things. Now if you are running NO2 and/or
boosted, you can make up for the power loss due to density change and take
advantage of the less dense air for drag and go faster in the afternoon.
So,
NA run mornings, All others run afternoons, late..
IMHO...
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