Need Information To Do A 150 Hp Conversion On My C-150

In rec.aviation.owning Homesick Angel wrote:
: Dear Cory,

: Any idea How do I get my 182 to cruise along at 5.5 GPH? (without
: burning something up cause it's leaned out too much? or falling out of
: the sky) It's a 1957 and real light for it's size and got a STOL kit.
: Getting hard to afford gas for it, but don't want to give in to my
: husband and get one of those old-fashioned taildraggers.

A 182's pretty heavy, but it'll probably stay aloft on 5.5 gph. Bottom line
is: absolute best fuel economy is flying at best rate (since that's where
induced+parasitic drag is minimized). That's usually too slow for most, and will be
cooking the cylinders due to low airflow and high angle of attack, but strictly
speaking, it's best fuel economy. Usually, (since the drag curve is pretty flat
around best rate), you can increase the speed a fair bit above that without hitting
the parasitic drag wall.

For instance... I run my PA-28-180 at 65% in cruise, leaned to peak EGT, and
run 120mph IAS at 8-8.5gph. For bopping around the local area (in no particular
hurry), about 45% power leaned until it wheezes will give me 100mph IAS at about
5.5-6gph. CHT's stay at 375 or below... life is good.

It also might be worth taking a look at some lean-of-peak information. Bottom
line: below max cruise power, it's impossible to damage your engine with the red knob
alone. Deakin (on avweb) is a big evangelist on this... if you run lower power, lean
it 'till it wheezes and you won't hurt anything. Now, if CHT's get too hot doing
this, it's enother matter. If you wheeze it at too high of power, you'll melt it
quickly. Keep those things in check, and it's clean engine, clean plugs, good fuel
economy, and acceptable speed... might not be the fastest, but it's it all about the
flying anyway?

-Cory

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* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
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