I just inherited a 172H with an O-300. I ferry'd it to Idaho this week and whew.... it does NOT like altitude; it REALLY doesn't like altitude and some weight to carry.

I've looked into this in the past and only found Air Plains ($96k), Pen Yan ($90k) and Stoots ($100k+) options to upgrade to 180hp+. I've heard about the Del Air and Avcon in the past but can't find any way to get those today. Am I missing any options? I need more than 145hp! (or whatever that little 300 is still pushing....)

Thanks!

(pic for attention)

Firstly, I'd say to try to remember it's a 172. Silly to say, but time and time again, folks seem to miss this simple fact. This forum alone is fraught with the bones of dreamers asking questions on how to make their thing into the other thing. (this includes me.) No one can sit with the fact that their thing is just their thing... If you want the other thing, you have to BUY the other thing.

I'd say enjoy the 172 for what it is... a 172.

To answer your question: Big HP conversions on 170s have gotten so stupidly expensive… at the end of the day, the cost pushes an owner so far upside down one would have to be insane to go down that route. (172s even worse)

With a sold C170B fetching $100k, and the big motor/prop/install damn near $125k, the smart move is obviously the C180.

That said, and for your 172, Chris and I at Airworx got the approval for the high HP O-300. My test bed motor dyno’d at 174hp, which is impressive. It’s lighter, smoother, and needs NO “kit!” Same everything… and no STC to buy.

Yes folks have been doing this kinda thing for years, but this is the "legal" route. Best part… it’s only a couple of bucks more than a regular O-300 overhaul.

This is (IMHO) the way to go.

Bird will be slightly slower than with the Lyc, no C/S prop, but MUCH lighter and will give you like $75k in gas money. Oh… and at the end of your time with the bird, you will actually sell it for more than you have into it.

Call Airworx in AL for deets.

Bigrenna wrote:remember it's a 172.

Yep.
The 172 I get to help take care of came up with a flat cylinder at annual a week ago(150hp O-320). Cracked head, and another cylinder showed some cracking - 2100 hours SMOH. Knock on wood, bottom end is still in great shape. Decided to swap 4 new superior cylinders, if we can get another 400 hours out of them we're money ahead. With a little luck we'll get 1000 hours out of them then go for overhaul.
Ram air has an stc for engine and airframe 150-160hp conversion with 8:1 cylinders. Also would require repitching or new prop, and carb rejet. $1k just for the 2 sheets of paper.
Decided to bag that until overhaul when it might make more sense.
Sometimes simple is best.

First, define "Just inherited". If this implies literally that you just received the airplane as a gift......that's one thing. If that IS the case, one of the big engine mods may well be the way to go. You'll probably have an airplane that's actually worth what you have in it.

If that's not the case, why did you puchase it in the first place....with the intent to convert it? If so, any of those conversions will work. First task I would address is who's going to do the work, and sign it off? That person MAY have some experience with one particular engine conversion......or not.

But, as Greg noted, this is a big project, make certain you have ALL your ducks in a row before committing.

I believe that the Air Plains and Penn Yann conversions use a fixed pitch prop, while Stoots uses CS. If you're going that far dollar-wise, I'd go with a constant speed prop conversion.....otherwise, you're giving up some of that hp at takeoff.

And, living at 4500 msl, I totally understand your frustration with performance. That said, I flew a 90 hp Cub out of here and around much of Idaho and western Montana.

Good luck.

MTV

I went with an 0-360 upgrade under the hood of my 170B.

The Airworx Big Balls 0-300 is a very serious contender that was still only a twinkle in Bigrenna eyes at the time I upgrade. It's the route I would have taken had it been an available option if for no other reason than the simplicity of it, that's a huge consideration.

Thanks all.

Yes, I actually inherited it. It was my step-father's airplane. I had promised him I would take care of it "till the grandkids need it to learn on" - at the time I thought that was many years in the future. This past November, he fell, smacked his skull and never woke up. You just never know when it's your day.

So.... I can't really sell it. But, I would like more power to make it more useful. I have a Supercub that I'm partners in as well as my T-6 and Bonanza (it's for sale) and I'm building a Murphy Moose. If I could get this thing to have a bit more HP, I think it'd be a great run-around bird and I could teach some of my friend's kids in it.

I hadn't heard about the big balls 300. That sounds like my wheelhouse, thanks for the info!