Engine upgrade recommendations for a J-3

Hector Parra

Pre-takeoff checklist
Feb 20, 2022
Montréal, Canada
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Hector Parra
Hi guys, the J-3 is one of my options as a first plane after my PPL is completed. I found one (1946) at TAP that currently has a Continental A-65-8F (65 HP, 1800hr TBO) + a McCauley 2 Blade. See pic below.
I'm planning to squeeze that engine until the end, but what will be a good engine option to install in the future? (New and/or refurbished). I won't mind adding more HP but I'm also aware of the airframe limitations.

Have you looked at available engine STCs for the J-3? They exist for the C-90 and O-200. I guess you could brew your own solution, but why?
Have you looked at available engine STCs for the J-3? They exist for the C-90 and O-200. I guess you could brew your own solution, but why?
Well, is a 46 bird and I will like to extend his life time for some more time. Engines can only last so much, even with overhauls. Honestly, my main concern with old engines is that spare parts will be harder and harder to get. That's why I was thinking on adding a new-ish engine. I'll take a look at the STCs, thanks for the tip
but what will be a good engine option to install in the future?
You have a number of options depending what level you want to upgrade to. On one end you have a C-75 or C-85 option listed on the TCDS that can be done on a logbook entry. There is also a C-90 option but requires a modification that is no longer available. As mentioned there are several STCs to include Univair's O-200 STC which is somewhat popular. There are also some O-235 powered J-3s which took the PA-11 TCDS option and had it field approved on a J3C. But it does take a bit more modifications. Plus there additional engine based performance upgrades on the C-85/O-200 like the Swords STC. May want to check with your APIA to see what they're comfort zone is and get more input. The Cub/Super Cub are some of my favorite aircraft.
My 2 cents is that a C-85 is the perfect engine for a J-3. I've flown 65, 85, and 90, and I can't tell the difference between 85 and 90. J3 is mostly weight limited, and the performance at max gross with an 85 is fine, to me anyway. The 65 is fine, but it doesn't climb as well. With any of them, again my 2 cents, it's important to realize that they'll easily land in a spot that's way too short to get out of, if there are any obstructions. I'd say the 65 climbs out with two people and full fuel *roughly* like that of a pa-28-150, and maybe the 85 like a -180 - roughly.

If you want better performance than that, then I'd look for another plane. Plenty of people are willing to pay a premium for a J-3 for sentimental reasons or just that they love them, and they're happy with them mostly as is.
There aren't really any "newer" engines you can slap on a cub. If you did I would guess the value would be ruined. C-85 is the sweet spot for a cub. Any more than that and you are just throwing gas money away. Honestly there is nothing wrong with the 65. Sure the climb at gross on a hot day is non existent but who wants to be folded up in the front seat of a cub anyway.
So far I have only flown C90 and O-200 powered J-3’. I agree the C90 or C85 is probably best engine with STC’s available. If you go O-200 then omit the electrical system and keep it as light as possible unless you want a single place airplane.
If you really want electrics get a lithium battery and charge it between flights we use 10ah Lithium's in our gliders for flights up to 8 hours long. You can even make it a removeable pack so the only permanent part of the airplane are the antenna’s.

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Suggest once you determine the J-3 is the “Forever Bird” that you build up your engine WELL before it is needed. Parts can be in short supply for all of the engines
you mentioned. Accessory Cases once were magnesium or aluminum but now they are gold. It could easily take a year to get it together.

Another advantage to this is you can sell the current engine while installed and running. That should be worth a few $$ more.
We mostly run C85, C85 Strokers, and O-200 engines in our J3C planes.
My personal preference is the O-200 (mounted by 337, not STC), but any of the three make a good choice.