Hi,

Does anyone know of an STC to fit a Lycoming O-320 in a 1958 C172 ?
I know of all the other engine options out there, but this one fits my mission profile the best.
As far as I know none of these STC holders have one (Av-Con, Del-Air, Air plains, Stoots or Penn Yan).

Thanks,
Jaime

It’s a known gap, probably because…why? Few want to spend the money for essentially the same power when they could upgrade to a 360.

You might be able to get a field approval using later Cessna 172 models for which the 320 is on the TCDS as a basis.

JD_WFC wrote:Hi,

Does anyone know of an STC to fit a Lycoming O-320 in a 1958 C172 ?
I know of all the other engine options out there, but this one fits my mission profile the best.
As far as I know none of these STC holders have one (Av-Con, Del-Air, Air plains, Stoots or Penn Yan).

Thanks,
Jaime

I think for the money you'd spend on a O-320 conversion you should just Send your O-300 to airworx and have them work their magic on it. That way you keep your stock motor, but he gets them bumped up to 170HP. If I had an O-300 powered aircraft that is what I would be doing.

A1Skinner wrote:I think for the money you'd spend on a O-320 conversion you should just Send your O-300 to airplanes and have them work their magic on it. That way you keep your stock motor, but he gets them bumped up to 170HP. If I had an O-300 powered aircraft that is what I would be doing.

I think that's "Airworx", not airplanes.

hotrod180 wrote:

A1Skinner wrote:I think for the money you'd spend on a O-320 conversion you should just Send your O-300 to airplanes and have them work their magic on it. That way you keep your stock motor, but he gets them bumped up to 170HP. If I had an O-300 powered aircraft that is what I would be doing.

I think that's "Airworx", not airplanes.

Dang auto correct. that'll teach me for not proof reading my post.

I thnk there was one (for170s at least) O-320 called Doyne?

Having owned a similar older 172, there is no way I would go through all that effort to install an O-320 when cost wise, the afore mentioned O-360 would be a much better option. You can always pull the throttle back and get similar fuel burn if that's your concern. Or full throttle to get that awesome TO performance. Resale with the O-360 will also be a huge plus. Yes, I realize many say they are never going to sell their plane. LOL, well, I had my 172 for just shy of 40 years before I sold it.

As mentioned, the cheapest route would probably be the already mentioned Airworx O-300 option. They have a FB page with dyno results. You retain that smooth running 6 cylinder and no issues with engine mount scrounging and other issues. I visited their operation a couple of years ago and had planned the conversion before deciding to sell my 172. If memory serves me, I'm thinking they dynod the engine at 174 HP. Only other requirement is a pitch change for the prop.

I did know of a guy that put an O-320 in exactly like you are asking. I say, did know, as I lost touch with him. He was a canadian that was living in New Mexico at the time.
Took him quite a while to scrounge the parts and in the end, he wished he had gone with the O-360 as the performance was minimal. He only did it because he already had the engine. He told me that he should have just sold it and used the 360.