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I would climb to a safe altitude, then slow my rate of climb to 800fpm, picking
up extra speed.
Then I would lean until 50 degrees lean of peak if your engine allows for that
and you have an all cylinder probe system with EGT and CHTs for all of them. If
you can't lean enough or can't see each cylinder's temp, I would stick to full
rich until cruise.
This will save gobs of fuel, and actually keep the engine cooler. It doesn't
matter if you're running the engine at full MP, as long as you don't leave the
engine close to peak for more than a second or two. John Deakin at avweb
explains how to do this: BMP (big mixture pull) very well. Basicly you lean for
a target fuel flow. For a given engine, MP, RPM and Fuel flow the mixture is the
same so you should be at the same point in the lean/rich of peak graph. So you
set climb to your normal MP and RPM for climb, then lean for the target fuel
flow and confirm the temps are where you expect them to be.
Before doing that on a climb, I would first practice everything on level flight.
Marcelo Pacheco
Gary Casey wrote:
> <<Once your waste gates are fully open, that is above about 21,000 ft
> you may want to change some engine settings.>>
>
> I think you meant "fully closed." Yes the fuel control, even though it is
> not altitude compensated, thinks it is at a constant altitude if the
> manifold pressure is constant. There will be a slight leaning effect with
> climb as the back pressure drops, making the volumetric efficiency of the
> engine increase slightly with increasing altitude. Certainly at
> higher-than-cruise manifold pressures you don't want to tinker with the
> mixture, but at cruise manifold pressure I don't see any reason not to lean
> to a cruise condition. The engine doesn't know whether you are climbing or
> cruising - except for cooling and I don't think cooling would be worse in a
> low-altitude climb that it would be at a 25,000 foot cruise condition.
> Again, I don't have any IV-P experience.
>
> Gary Casey
>
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