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Old 05-06-2023, 09:27 AM
Duncannon Duncannon is offline
Join Date: Jun 2021
Location: Georgia
Posts: 38
Default Upgrade from o235 to o360

Most RV9’s are built equipped with o320 engines or better (and rightfully so), but occasionally I have seen some 9’s for sale with o235 equipped, and for a pretty low price. Would it be a super difficult task to upgrade engines? Or perhaps find a shop to do an upgrade for me? Of course, after paying for the o320, plus the labor hours of removing the old engine and installing the new, it could be financial disaster.

And I wouldn’t necessarily have the upgrade done immediately. If I got a very good deal, I may fly it for a few years, or perhaps even wait until the o235 needs an overhaul before doing the upgrade. I realize the rule of thumb is to buy the aircraft that’s already equipped with what you want, instead of upgrading. I also realize that swapping a different engine is NOT a small task, especially when changing brands (cont. to lyc., going to or from an auto engine, etc.)
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Old 05-06-2023, 10:43 AM
Avanza Avanza is offline
Join Date: Jul 2020
Location: Vastervik Sweden
Posts: 355
Smile Engine Mount

Lycoming engines have three types of engine mounts. (not the rubber ones).
- Conical, straight mount configuration mounts parallel to the crankshaft.
- Dynafocal 1, angle to the crankshaft with Type 1 being 30°.
- Dynafocal 2, angle to the crankshaft with Type 2 being 18°.
Most O-360 are configured as Dynafocal 1.
Your engine is likely the Conical mount and may be to weak for 180 hp.
Is the nose gear integrated with the engine mount ? Taildragger ?
You will most likely need a new engine mount, probably custom made.
A new custom cowling is required.
Yes it will be expensive and it will take some time to overcome all obstacles.
If you have the time and money, it can be done.

Good luck
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Old 05-06-2023, 07:55 PM
rmarshall234 rmarshall234 is offline
Join Date: Jun 2008
Location: San Diego, CA
Posts: 518

I'll bet those O-235 equipped -9s are light and fly really nice with that long, efficient wing. Might want to fly one of each before making a big move.

I had an RV-3 with a 185 HP Lycon engine. If I were to get another one, I'd look for the lightest available and with a small engine. But that's just me. Good luck.
Robert Marshall
RV-3 - 500hrs
A&P / IA
Parachute Rigger
Acroduster SA750 - finished!
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Old 05-06-2023, 08:02 PM
rvbuilder2002 rvbuilder2002 is offline
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 10,199

The O-235L2C that has commonly been used uses an engine mount that is different from the normal conical or dynafocal used for O-320 or O-360, so the engine mount would have to change and the cowl as well if you installed a O-360.
Opinions, information, and comments, are my own unless stated otherwise.
You are personally responsible for determining the suitability of any tips, ideas, etc. obtained from any post I have made in this forum.

Scott McDaniels
Hubbard, Oregon
Formerly of Van's Aircraft Engineering Prototype Shop
FAA/DAR, A&P, EAA Technical Councelor
RV-6A (aka "Junkyard Special ")
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Old 05-07-2023, 12:54 AM
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Phyrcooler Phyrcooler is offline
Join Date: Feb 2006
Posts: 503

O-235’s came in various flavors from 100 to 125 hp. (I think most common were 108 - 115). So, it is possible with a rebuild, you could add a few more hp via parts selection if you were starting at the lower end.

If you got a steal of a buy on an aircraft with a run out engine that needed a lot of upgrades, it might be worth getting the new engine mount/gear leg/O-320… but unless you are a builder type, you’d probably be dollars ahead buying what you want.
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