O-360 engine upgrade for a C-172P

DKirkpatrick

Pre-takeoff checklist
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DKirkpatrick
Hi,
I hear-tell from my A&P that if we're gonna upgrade the engine (the O-320 D2J is ready for a major...) that I should buy the STC and Conversion/Engine from AirPlains.
Anybody know what this might cost me? Do we like this option or is there a better one?
(Don't really need to hear how I should buy something like a 182... I know that's probably right, but this is the airplane I want to keep and fly... thanks)
thanks
dan
 
I don't know how much they cost now (my 172N got the Air Plains conversion in 1997), but the 172/O-360 combination is excellent. Compared to a 182 you have lighter handling, better short-field performance, better fuel economy, fewer cylinders to feed and maintain (and they don't say "Continental" on them), and no constant-speed prop or cowl flaps to mess with. Useful load and speed will be not far behind many 182s.

A big plus of the O-360 in a 172 is that it lets you cruise-climb at higher airspeeds, keeping the engine cool.
 
I agree with @Pilawt . My 172n had the STC from PennYann. I don't know if that makes any difference though. It was a great upgrade.
You can expect all the benefits that he listed. My 172 had a useful load as good as most 182 and much better than my Bonanza.

The main thing you have to understand is that you don't get a cruise speed increase. But if you are happy with it now, you will be happier with it afterwards.
 
Flown one, amazing. Put a power flow exhaust on top of that and prepare to be impressed.
 
They put the wrong engine in it. IO-360-KB 220 horse smoother, IO no more icing..
 
They put the wrong engine in it. IO-360-KB 220 horse smoother, IO no more icing..
When did that become available? When I had had to replace the PennYan O360 in my 172n I was told there was no injected engine available. I don't have much of a problem with icing down here, but I'd have loved to try some GAMIs and see if I could go LOP and extend my engine life. (That was largely for @Salty ;) )
 
A friend had the 360 upgrade put on a 172N a year or two ago. It was 40 or 45 grand with labor and everything.
 
When did that become available? When I had had to replace the PennYan O360 in my 172n I was told there was no injected engine available. I don't have much of a problem with icing down here, but I'd have loved to try some GAMIs and see if I could go LOP and extend my engine life. (That was largely for @Salty ;) )

They came standard on the 172XP and Skymasters.

Those continental IO360 have a somewhat checkered history but from what I remember one of the best Brake Specific Fuel Consumption in its class.
 
Almost all of my time in 172's is in birds that have had the O360 conversion. Although none of them are ever going to win any performance competitions, I don't think I'd want to fly a 172 that didn't have the conversion.
 
possible to repitch the prop somehow to gain airspeed? I know it's a tradeoff, but ...
thanks
dan
 
possible to repitch the prop somehow to gain airspeed? I know it's a tradeoff, but ...
thanks
dan
Its a 172. Nothing you're ever going to do is going to make it fast. And climb performance is never anything to write home about under the best conditions. How much of that so so climb are you willing to give up to try to get an extra knot or two out of it?
 
My 172N/180 has a Power Flow, plus Maple Leaf exhaust fairing, factory wheel and brake fairings and flap gap seals. At 65% power it's a hair under 125 KTAS, at 75% closer to 130.
Lightly loaded that’s a very close to my own experiences. Really nice flexible arrangement. rate of climb is very impressive over the original engine.
 
I inquired about this very topic with a guy from G&N.
His comments were "it takes a considerable amount of modification, and it's not worth it in my opinion".
It's been some time ago so I don't remember all details, but possibly the entire motor mount structure has to be heavier duty or something, and also a cowl mod possibly.

Very subjective if it's worth it... and yes, easily into the 40's I'd bet.

What a great upgrade though.

Wondering if an IO-390 could squeeze in there?.. now that sounds expensive.
 
I have a '78 C172N with the Air Plains conversion and I think it's a great upgrade. You may get a knot or two more in cruise but it shines in the takeoff and climb performance. If you're willing to sacrifice a max of 30* of flaps you also get a 250 LB Gross increase to 2,550 LBS. It makes the Skyhawk a true 4-person aircraft.

The Air Plains conversion does require a new 76" prop and depending on where you are geographically it may not make any sense to re-pitch the prop. I'm around 2,700 MSL and at 5,000 MSL I can't redline the engine with the standard 60" pitch (you can increase the pitch to 62"). In any case I have found that my CHT's rapidly increase above 75% power, so while you CAN cruise at WOT it's not very gentle on the engine.

I think the Penn Yan conversion is pretty much the same as the Air Plains however if you have a O-320-E2D, O-320-D2J, or O-320-H2AD then they can turn that into an O-360-A4M and would make the most sense if it's time for overhaul. I know there are O-360 conversions that have a CS prop and those are nice too and allow a bit more performance than the fixed pitch prop, but IDK if the STC is active.

Good Luck!
 
however if you have a O-320-E2D, O-320-D2J, or O-320-H2AD then they can turn that into an O-360-A4M

That is interesting....I'm surprised the guy at G&N didn't mention it. Because I had spoken to him specifically about the 0-320 H2AD vs the 360 upgrade.
Any help to fnd more info about this?
 
Got a quote online.
There was a third option for a kit also at about 14k.

Option One: Conversion of your 0-320 to a Lycoming 0-360-A4M SuperHawk engine or provide an exchange converted engine (core deposit required).

Penn Yan Aero will overhaul and convert your O-320 engine to an FAA Approved 180 horsepower O-360-A4M engine.

Option One includes Penn Yan Aero’s warranty: Three years, 100% parts and labor or to Lycoming’s maximum recommended time between overhaul (TBO), whichever comes first; supported worldwide and transferable from one owner to another. Round-trip shipping and logistics within the contiguous United States are included in price below.

Penn Yan Aero overhaul and conversion to 180 horsepower O-360-A4M with Penn Yan Aero Overhauled Steel cylinders: $37,419
Penn Yan Aero overhaul and conversion to 180 horsepower O-360-A4M with Penn Yan Aero Overhauled Nickel cylinders: $37,958
Penn Yan Aero overhaul and conversion to 180 horsepower O-360-A4M with new Lycoming factory cylinders: $41,143

Option Two: New Lycoming SuperHawk 180 Horsepower Engine Exchange your 0-320 Lycoming engine for a Lycoming factory new, zero-time Lycoming 0-360-A4M SuperHawk specification engine with a zero time logbook. This option requires up to a 120 day lead time and includes the SuperHawk STC (everything needed including propeller) and Lycoming’s engine. Shipping is not included with this option.

New Lycoming O-360-A4M: $47,281 exchange

New Lycoming O-360-A4M: $51,567 outright


Great info... thanks @idahoflier
 
Our club's C-172N has the Penn Yan O-360 engine, along with the flaps being limited to 30 degrees. That flap change, along with the larger engine, doesn't do anything for speed, but it gives you an extra 250 pounds max gross. All at the cost of around 20-25 pounds. With full long range tanks (50 gallons useable, rather than 40 gallons) it will take over 100 pounds more in the cabin than the club's C-182P with full long range (75 gallons useable) tanks. As club rules require putting the plane away with full tanks I always plan that way. The C-172N is our champion load hauler. Somewhere around 755 pounds in the cabin with full tanks. Works great.
 
The Maple Leaf exhaust fairing helps CHT a lot.
I certainly wish I knew about that when I had my 172n/180. I always had high CHT problems and nothing any of the several A&P/IAs or engine specialists could do anything about it.
 
Power upgrades for this type of plane are certainly worthwhile. Almost all 4-seat light singles are underpowered in stock configuration. Even small changes in power have an enormous impact on excess power and lift, which dramatically increases climb rate. (This is a major safety and operational feature upgrade.) Overhaul is the time to do it

For my AA-5, there was a high-compression STC that upgrades the O-320-E2G engine from 150 hp to "160 hp". I did that at OH with no added cost except for the STC paperwork. With the stock propeller, my AA-5 will climb a solid 50% faster than with the stock engine. Or, you can affix a higher pitch STC propeller and cruise a little faster while still claiming much of the extra climb capability. Adding 30 hp to a C-172 will be dramatic. If you do go with Penn Yan, they do good work. I did all my cylinder work with them over the years using their overhauled cylinders with zero issues, with two different Grumman aircraft, and they did my MOH and STC conversion about a decade ago. The new engine is amazing compared to the one I inherited and ran out.
 
Steel cylinders I'm guessing?

My current engine has nitrided steel cylinders, but I've had cermichrome and channel chrome in the past. If you fly the engine frequently, steel is fine based on my ownership experience. I never wore out any of the cylinders I replaced prior to MOH. I'm a few hundred hours in on the new engine and I'm still getting 15-20 hours per quart. If it's more than that, I have a leak somewhere or I've filled it past 7 qt.
 
Many, many moons ago I used to rent a C172 with 180hp & CS prop. I still remember my initial reaction of 'this is what a Skyhawk should be'. Climb was great and being able to dial it back to 2300-2400rpm for cruise is really nice. Nose was a bit heavy, but replace that metal blade with a MT 2-blade would probably be a sweet set-up.

CH
 
180 HP 172s are slow enough. I have no idea why someone would put an O320 back in when they needed an overhaul, unless they were running a flight school and wanted to save gas.
 
180 HP 172s are slow enough. I have no idea why someone would put an O320 back in when they needed an overhaul, unless they were running a flight school and wanted to save gas.

I can think of 17K - 27K reasons why they might keep the O-320... ;-)
 
You're telling me a shop like LyCon would charge that big a difference, even with an STC?

I think Penn Yan is a pretty big shop and likely the cheapest option and @Skyrys62 posted the options and prices above.

I know when I was in the market for an O-360 C172 a few years ago I looked at buying a C172 with a run out engine and then converting it, but it was always cheaper to find an aircraft with the conversion already done, and that's the direction I went. I don't believe LyCon holds an STC for a C172 O-360 conversion so going a conversion route with them is likely more expensive.

The cheapest option is likely finding a C172 that already had the conversion done and was destroyed in a manner leaving the engine and prop undamaged and buying it and then transfer the STC to the C172 you want to convert. But that's like trying to find a needle in a haystack...
 
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