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

In rec.aviation.owning Homesick Angel wrote:
: The bigger engine will drink more fuel, so it will cut down on the
: amount of hours you can fly. Can't remember the exact numbers but
: probably run out in about two hours.

I don't normally buy this argument. With very few exceptions (planes that are
horribly underpowered to begin with), more HP doesn't buy you appreciably more speed.
Power required goes with the cube of the speed, so normally powered planes aren't much
slower than souped-up ones. Just because you have more power, doesn't mean you need
to use it. (and in most cases it's silly to do so). If you pull the power back on a
bigger engine, it'll burn roughly the same amount of fuel as on a smaller engine.

There are only a few things to counter this...
- reduced efficiency running at really low power settings on a fixed pitch prop (CS
running oversquared would help a lot)
- Added weight of the larger engine (generally not too much anyway)

: I usually fly conservatively, so I'd fly at say 50% power instead of
: 75%. It was so much fun taking off and landing that about all I did

... So they should burn almost the same fuel... It's the same 75HP whether its
75% of 100 or 50% of 150... roughly 5.5gph.

Of course climb/hauling is the real (and legitimate) reason to do it.

-Cory


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

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. He's
rebuilding a Champ right now his 75 HP versus my 230 HP. When I have a
Cub I want to fly fast and I fly the 182 like a Cub, poke along nice
and slow. Guess growing up in the muscle car era brainwashes you. I
figure in a few years I might have to change to sport pilot, but for
now I'll keep the Beast from the East and pray for gas prices to go
down so I can afford a trip to maybe Alaska or the Seaplane fly-in in
Greenville and make it in a day or two instead of a week of two in a
tail dragger (I have still trouble flying a straight course, wind, neat
stuff to side track to, sightseeing and not pin point navigating).
Still prefer the compass and map to my GPS. Just way behind the times
I guess. Well take care. Good luck in your educational endeavors.
Never could get into the book learning thing unless it was something I
was interested in and back in the 1970s girls weren't engineers,
pilots, mechanics, architects, etc which all interested me a lot. So I
had to settle for second and third choices for a while until I just
started to do what I wanted to do, working in a lumber mill running
saws and planers, detailing and auto body work, manning remote
firetowers in the woods of Maine, going out west to fight fires. Now
stuff like that is fun. Right now its mostly farming and keeping our
grass strip mowed (some times the goats are allowed out to graze and as
the price of gas goes up the amount of time the goats will have
possession of the runway will be directly proportion to any price
increases). Until I get one of those electric robotic mowers and
program it to do the job with less pollution and noise. Guess I need
the plans for one of those if somebody's got them?

Hope everybody's enjoying flying. I thought I was a math-head but some
of you people are way out there. Just don't let that stuff distract
you so much that you fly into something or fall out of the sky. Watch
out for all the cell phone towers and other towers out there. Be safe
and God bless. The Homesick Angel, Carol

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

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

: 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.

Don't know what altitude you're talking about but at 7500 and 20 squared
you are looking at 9 gph. At 15 inches and 2000 you will get about 6.5
gph. At this point the nose will be pretty high and you will only be
getting about 95-100 MPH IAS. To get to 5.5 gph wouldn't be any fun at
all. If you have to have 5.5 then sell the plane and get something that
can reasonably do that.



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.

On the big bore Continentals you need to be below 65% before you try
that. Plus having a carbed engine makes LOP impractical.

"Newps" wrote in message
...
On the big bore Continentals you need to be below 65% before you try that.

No. You don't.

Karl
Gami Serial# 19

In rec.aviation.owning Newps wrote:
: Don't know what altitude you're talking about but at 7500 and 20 squared
: you are looking at 9 gph. At 15 inches and 2000 you will get about 6.5
: gph. At this point the nose will be pretty high and you will only be
: getting about 95-100 MPH IAS. To get to 5.5 gph wouldn't be any fun at
: all. If you have to have 5.5 then sell the plane and get something that
: can reasonably do that.

He didn't ask how to make it fun... just if it was possible to fly a 182 at
5.5 gph. I answered that it most likely was. Truth be told, if you're after pure
fuel economy, you'd want to run oversquared as much as possible, too.

: On the big bore Continentals you need to be below 65% before you try
: that. Plus having a carbed engine makes LOP impractical.

LOP on a carb'd engine is difficult/unlikely. Running at peak (as long as
your CHT's aren't high) is fine as well... as long as your power is low.

-Cory

--

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

Max Conrad (ferried Pipers all over the world in the 40s and 50s) ran
fully leaned & with full carb heat when he was in his max range mode.
Do you know of any reason not to, assuming a low power setting? It
would improve the mixture distribution, something the O-470s are
notoriously poor at. It would also reduce the inlet air density,
allowing things to operate with less pumping loss.

nrp

In rec.aviation.owning nrp wrote:
: Max Conrad (ferried Pipers all over the world in the 40s and 50s) ran
: fully leaned & with full carb heat when he was in his max range mode.
: Do you know of any reason not to, assuming a low power setting? It
: would improve the mixture distribution, something the O-470s are
: notoriously poor at. It would also reduce the inlet air density,
: allowing things to operate with less pumping loss.

Unless the CHT's get too high in that configuration (causing poor valve
cooling and cylinder badness), there's not much that says it's bad except:
- No filtration of the air with carb heat. Shouldn't be a big deal in cruise (unless
you have a *really* dirty cowling).
- If flying in cold enough weather, you could get carb ice when normally ice crystals
would flow through unmelted. (I generally don't like to use carb heat until I know
it's necessary)
- Sudden power requirement will cause the engine to falter... get used to a quick red
knob, then throttle.

The real disadvantage of the arrangement on my fixed-pitch plane is 65% is
only obtainable at that mixture up to about 7000-8000'. "Best power" of 50 ROP will
get you 75% or so at that altitude.

-Cory

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

nrp wrote:

Max Conrad (ferried Pipers all over the world in the 40s and 50s) ran
fully leaned & with full carb heat when he was in his max range mode.
Do you know of any reason not to, assuming a low power setting? It
would improve the mixture distribution, something the O-470s are
notoriously poor at. It would also reduce the inlet air density,
allowing things to operate with less pumping loss.

On the 470's, in cruise, you give it whatever carb heat gets you a carb
temp of 40-45F. Running at full carb heat makes no sense whatsoever.

In rec.aviation.owning nrp wrote:
: Max Conrad (ferried Pipers all over the world in the 40s and 50s) ran
: fully leaned & with full carb heat when he was in his max range mode.
: Do you know of any reason not to, assuming a low power setting? It
: would improve the mixture distribution, something the O-470s are
: notoriously poor at. It would also reduce the inlet air density,
: allowing things to operate with less pumping loss.

I find that I can run my Cherokee's O-360 LOP quite effectively using full
carb heat. Attempts to do so without carb heat lead to unacceptable engine
roughness. With the carb heat on, I can reduce the RPM down several hundred
RPM from peak RPM with good smoothness. Without the carb heat, the RPM
peaks as the mixture gets leaner, then as the RPM begins to drop the engine
gets progressively rougher.

I have not run the engine LOP for any appreciable length of time as I have
no CHT or EGT instrumentation. I have done it for a minute or so to see if
it is possible.
--
Aaron C.