Been a long time since I posted. Flying 421C and TBM850 (TBM professionally) … definitely miss the B58! Training a student who owns a nice A36 though so get to get on the controls sometimes.

I own a 1974 172M, 3800hrs TT. Owned 5 years. I put in GTN650, G500A/P, GI275’s including engine monitor. All this so I could teach in it. Teach on the side, my students are older, accomplished, want to learn to fly GA. This way, I prepare them fully for capable planes.

Only my students and friends rent the plane. One highly experienced buddy (GA/ATP) left tow bar and prop struck. Now I need to rebuild. Engine has 1800hrs. Figured no one is hurt, so it is what it is.

Thinking I might just stop/pause teaching for a couple of years b/c Im flying 450+hrs/yr.

Got me thinking…should I upgrade? I’ll probably never sell the plane. It’s got 38 gallons useable. Anyone have experience on this 172 upgrade? PenYan or plains? Others? The cost may run me off but I have a short window to decide.

The local club has a stock 172P which is, I think 160hp. It's a great flyer.

Two of the other 172s have Penn Yann 180hp STCs

They're noticeably more powerful - power on stalls take a bit more attention, and take off distances are shorter. We have a fair amount of grass to play on locally and the power helps there, and with passengers.

I like both versions and both experiences - but you've already invested in a panel that probably tilts the character of the plane to something the 180hp STC and upgross would be at home in.

If you aren't on the grass, or short runways, or loaded up (or high DA), you may not miss it, but if you get it, you'll immediately feel the difference...

I would say definitely yes, but the cost will be high. Finding a used engine will be a challenge - thousands of RV & supercub homebuilders are on the prowl for the same 180hp 360. I sold one a couple of years ago (the spare engine I had for my travel air). Listed it on barnstormers just as I was headed off to meet my wife for lunch. It was sold before we finished eating. I dropped the ad within a few hours but the phone kept ringing for weeks.

I have flown my friends 175 which has an O-360 and a constant speed prop upgrade. I would upgrade just for the constant speed prop because it made the airplane a pleasure to fly.

If the 180hp turns out to be cost prohibitive then the Ram 160hp (STC SA2375SW-D/SE3692SW-D) might make sense. Basically modify your existing engine by replacement of pistons with higher compression and I think maybe a repitch of your prop assuming it's repairable.

This is what we did with our M model. 180 hp conversions are very expensive and cost you the use of Flaps 40. STC limits to Flaps 30, I believe. They do give a 100-lb MTOW increase though. Ours has a pretty good useful load as is, so we didn't really need that. We also operate off of grass and keeping Flaps 40 was more important.

The RAM 160 hp conversion trades the O-320-E2D for -D2J, which was designed to run on 100LL. If you need still more power there's Powerflow exhaust and/or an E-mag. Honestly, the C172 is such a bug-smacker that increasing cruise speed is tough but takeoff and climb are easily enhanced.

Here's a piece I wrote about our project: https://www.aopa.org/news-and-media/all-news/2019/february/pilot/ownership-heart-transplant

This is what we did with our M model. 180 hp conversions are very expensive and cost you the use of Flaps 40. STC limits to Flaps 30, I believe. They do give a 100-lb MTOW increase though. Ours has a pretty good useful load as is, so we didn't really need that. We also operate off of grass and keeping Flaps 40 was more important.

The RAM 160 hp conversion trades the O-320-E2D for -D2J, which was designed to run on 100LL. If you need still more power there's Powerflow exhaust and/or an E-mag. Honestly, the C172 is such a bug-smacker that increasing cruise speed is tough but takeoff and climb are easily enhanced.

Here's a piece I wrote about our project: https://www.aopa.org/news-and-media/all-news/2019/february/pilot/ownership-heart-transplant

The 180hp was a game changer giving dual to an adult in SoCal. I think you’ll really appreciate the difference flying two-up in the Houston heat.

Compared to the 150hp, there is a material difference in altitude AGL crossing the airport boundary on departure. I felt this gave me meaningfully better options if I had lost the engine.

Also much faster climb to altitude (or back to altitude) if working on private maneuvers.

I don't often disagree with Paul, but in this case I don't think the CS prop weight penalty is worth it.

Not to mention the initial cost of the prop, spinner, control and governor along with the increased maintenance and amortization costs, future AD exposure etc.

That's a draggy airframe, so you wouldn't gain much in speed to comensate for the higher fuel flow.

Primary benefit IMO would be rate of climb. You'd have a shorter takeoff roll but landing distance would be unchanged.

There will be moments where 180 hp would be nice to have. I chased a friend in a 150hp 172 while he flew a 180hp 172 . He outclimbed and outran me by enough to be frustrating.

On the other hand - Isn't the 150 hp engine one of the most reliable engines in GA?
Are the few less minutes of climbing and few extra kts really worth the additional AMUs?

If this 172 is still used for training not having extra power available forces the student to work with what they have. There may be a time where powering the way out of a situation isn't available to someone and they will be better off if they have learned to use finesse instead.

Thanks Jeff

My favorite fixed gear Cessna is the T-41C I did my instrument training in. It had a Continental IO-360 210hp with a constant speed prop. It had great performance even on a hot day in Albuquerque.

I like the constant speed prop in turbulence. I agree there is a weight penalty.

Power Flow exhaust might be a good intermediate addition, way less than 5he 180hp upgrade.

I regularly fly a 172 with this 180hp Air Plains mod, https://www.airplains.com/cessna172-180hp

It retains a fixed pitch prop and performs quite well.

If I had to overhaul a 150 or 160hp 172, this is what I would do.

Just another option to consider.

George