O320 in a 170B?

[zenpilot]

Just wondering who knows what about swapping out the old O-300 for an O-320 in a 170B. I've looked around quite a bit at the various O-360 mods (Stoots, Del, Avcon...), just wondering why I don't see or hear of more of the 150/160+ HP swapouts. Anybody flying one now? Field Approval? STC? Yankee Air Pirate?

Thanks, Karl

p.s. if this belongs in another topic area, it won't hurt my feelings to have it moved...

[Bruce Fenstermacher]

Karl there are a few out there but it just wasn't popular. The one I've seen was done with an STC.

Why wasn't it popular? I'm guessing because at the time lots of folks were seriously thinking of these engine mods in the late 60s and 70s the 0360 cost about the same as an 0320. The cost and work to do the change is the same. Today with the popularity of the 0360 for home builts there may be a greater difference in the price between an 0320 and 0360.

Another thing to consider regardless of the cost and that is benefit. Why spend lots of money to replace a good design engine rated at 145 hp for another rated for just 5 to 15 hp more. Basically there is no benefit unless the 0320 also has a constant speed prop in my opinion. And then the draw of the extra 35 hp of the 0360 over stock would still be just to much to overcome unless you happen to have a 0320 and prop laying around for free or nearly so.

[GAHorn]

I believe the chief attraction in the past was of the 4-cyl Lycoming over the 6-cyl Continental....at a time when new cylinders were prohibitively expensive for field overhauls. Everyone "repaired" or "overhauled' and "chromed" cylinders for Top overhauls/Field Overhauls and the cost of two-fewer cylinders seemed attractive, in times gone by.

These days, with the O-320 engines being rare-er than O-360's (which put out more power) has relegated them to lower status, since overhauling them costs the same or more than the O360's.

[toms170b]

There was an article in the 3rd quarter 2004 170 News on an IO-320-B1A lycoming conversion. the engine came from a twin Comanche with a constant speed prop. Pretty good article and explains the performance he got and all the plus and minuses he experienced. Bottom line, the writer got just about the same crusie performance of the lycopming 0-360, 180 HP conversion, not quite as good climb performance and about the same fuel burn. This was a fuel injected engine and he ended up with the same weight as the 0-360 but with less hp. I still have the article if anyone wants it.

[blueldr]

I'm a Continental guy!

Anyone who would trade a Continental for a Lycoming has to be missing something.

Actually, I used to have a Lycoming O-435-11, in my Stinson L-5, back in 1948, and thought highly of that engine.

I guess it's kind of like Fords and Chevvies.

[c170b53]

I've got the 0-320 in my plane and I've commented on it before as well. It seems the longer I've own it, the better I believe I can assess its performance. I thought I had increased my airspeed over the 0-300 airspeed but in fact, that's not correct. There's no real speed difference (my airspeed indicator plus the 175 wings makes me doubt my airspeed indications,) I may have gained 5 Knots which is no real mprovement. I'm at sea level and two days ago with outside temps around the freezing point my climb at 70 knots was bouncing around 1500-1600 ft/min. Climb has improved with the C/S prop and normally in summer I'll see at least a 1000 ft/min. The fuel burn averages at around 8.5 - 9 an hour at 2400 rpm. So the question is do you want to pay for a bit of climb performance.
I also have a Horton stall kit and two days ago I landed in a very strong wind (thankfully right down the pipe) during the roll out when I thought the action had stopped as I was about to turn off, I released the back pressure on the wheels. Mistake !!! My G/S had to be under 20 knots and yet I found myself back in the air in a flying attitude. So the Horton stall can lower your landing speed but also lowers your flying speed when you may not want it to.
Love the 170, just when I think I know it it shows me in another way how much fun it is.

[blueldr]

c170b53,

I would consider your average fuel burn a little high if you're flying the same speeds as a stock engined C-170except for climb.
The C-175 wings should make no difference except for the additional weight of the extra fuel, when carried, and that would be only 72 pounds. The faster climb rate requires a greater fuel burn for the extra power being used, but the reduced time in climb should average it out.
I think maybe you could use a more aggressive leaning program to bring that average down some.
A penny saved is a penny earned!

[c170b53]

You're correct, I do lean using a EI UB-16 but I'm not an aggressive leaner. I find the temp spreads in the four cylinders difficult to find a setting that makes everybody happy.

[blueldr]

c170b53,
Do you usualy use the leaning method of leaning back to where the engine starts to "stumble", and then enrichening just to where the engine barely "smoothes out"?
My curiousity is tweaked because a stock configured C-170, or any airplane, will require a certain amount of horsepower to attain a given speed. Since the specific fuel consumption of the Continental and Lycoming engines is almost exactly the same,
the fuel burn should be alike for the same speeds. My fuel burn, and that shown in the "owners manual", was a little lower than
what you report.

[c170b53]

No I lean rich of peak and watch my cylinder head temps. May not be the right way or most efficient way to squeeze out the endurance.

[blueldr]

Perhaps a good many pilots fail to realize that over leaning to the point of possible engine damage is not likely to occurr on a naturally aspirated engine at an altitude of seven thousand feet or more. Probably not above six thousand. The ambient atmospheric pressure at that altitude precludes the engine developing above about seventy percent power, which is about the break point for developing combustion temperatures high enough to damage the engine even on a stoichiometric mixture.

[Bruce Fenstermacher]

from the www:

Stoichiometric or Theoretical Combustion is the ideal combustion process where fuel is burned completely.

[GAHorn]

I thought stoichiometric was when someone was indifferent to the adoption of the metric system.

[blueldr]

You're absolutely correct, George, but it also produces the maximum combustion temperature. That's why it is usually shown in degrees Celsius. That guy, Celsius, was a Swede and only talked metric.

[GAHorn]

You're absolutely correct, George, but it also produces the maximum combustion temperature. That's why it is usually shown in degrees Celsius. That guy, Celsius, was a Swede and only talked metric.

So... did he and his Slovenic wife, Centigrade, get along well-enough to ever have kids?

Gradually, but only to a certain degree.

( "Hey Bob!..do you know how to convert Fahrenheit to Kelvin?"
"Absolutely!"
"Well, that's a relief, because I know absolutely zero about it!")