Warm air for the Q-Jet...

[johnny]

I am basically an empiricist. As a pilot, the comparison is easy, and if you're flying recip equipment you get a demonstration every time you do your
pretakeoff engine checks. Pull the carb heat, the engine loses RPM. Return to ambient air, the RPM resumes. This says to me, hot air doesn't
produce the power ambient air does. I realize there may be a bit more restriction when the heat is on, but not sufficient to produce the RPM drop we
see.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell

 

[Jim Hupy]

Just a fact of life, johnny. 02 molecules expand with heat, like most
stuff, except clutch fan fluid. Less 02, less horsepower, the basic
principle behind supercharging. Works with people. Morning runs, lots of
cool dense air, big dose of endorphins. Warm soggy afternoons, well, you
get the picture.
Back in my YOUNG and stupid days, I used to love to get my 1957 BMW
R-60 out, crank it into life with the kick starter, swing a leg over, and
find a crisp curvy 2 lane to ride. Pretty soon, I was going way too fast,
and enjoying it way too much. Cool morning air, force fed into me at 80 mph
plus.
Finally got smart and parked it for good in 1986. Still resides in my
shop. Covered with dust now. Still walk by it and remember those morning
solitary rides.
Jim Hupy
Salem, Oregon

On Wed, Apr 8, 2020, 4:48 AM Johnny Bridges via Gmclist <

> I am basically an empiricist. As a pilot, the comparison is easy, and if
> you're flying recip equipment you get a demonstration every time you do your
> pretakeoff engine checks. Pull the carb heat, the engine loses RPM.
> Return to ambient air, the RPM resumes. This says to me, hot air doesn't
> produce the power ambient air does. I realize there may be a bit more
> restriction when the heat is on, but not sufficient to produce the RPM drop
> we
> see.
>
> --johnny
> --
> Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
> Braselton, Ga.
> I forgive them all, save those who hurt the dogs. They must answer to me
> in hell
>
>
> _______________________________________________
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[john r. lebetski]

Going WOT you probably have more output with cold air as greater density. But going down the road you are about 15% open throttle do you don't need
more density as air/fuel is intentionally throttled. Warmer air is what the carb was calibrated to at factory. Cold air will put it slightly lean,
needing more throttle opening to get same output. More throttle opening for same specific output means worse economy.
--
John Lebetski
Woodstock, IL
77 Eleganza II