C90 vs. O200

[michael hz]

Good evening,

my name is Michael Harms and I'm new to the Cessna 120/140 Association. Thanks already for all the data you've collected on this homepage. Highly appreciated and helpful.
I currently live in Wichita Falls, Texas, and will go back to Germany soon after some awesome years over here in the US. Since I won't be able to take our 1956 Cessna 172 with me I'm thinking about buying a Cessna 140(A) as a commuter in Germany.

After some research I got to a point where I would like to know if it's more desirable to have an O-200 or a C-90 in a 140. The technical/performance differences between the two engines might be marginal, but I would like to know if you see some advantages between both engines, especially in regard to maintenance and obtaining parts.

Thanks a lot for any advice.

Regards from Texoma

Michael

[6183]

Welcome Michael,

C-90 or 0-200, hmmm. Some folks will no doubt say the C-90 is the best engine while others will chime in that the 0-200 is a good selection. From personal experience I can say that a 140 with fabric covered wings equipped with a C-90 will outrun and out climb a C140A with an 0-200 (I can see Randy Thompson and Tom Julian both smiling on that subject). Let's look at the some of the differences:
- C-140 with fabric wings is lighter and has a cleaner wing meaning with a good smooth fabric job, the surface is slick compared to the all metal 140A wing that has rivet heads protruding.
- The C-90 is certificated to use a longer propeller(71 - 74 inch) than the 0-200 which is limited to 69 inches per the engine type certificate. You'll notice some better performance in aircraft equipped with the longer propeller over those with the 69" propeller as used on the 0-200. Additionally when you're pulling 2,450 to 2,500 rpms out of an 0-200 your fuel burn is going to be more than that from a C-90.
- Some C-90 parts are becoming more difficult to obtain than those of an 0-200. For starters the engine case and crankshaft are getting harder to locate; however, there is an STC to allow the 0-200 crankshaft to be installed in the C-90, but that's another subject. Bottom line quite a few 0-200 parts are still being manufactured, and some of those are also used in the C-90.

What's all this amount to, I wouldn't hesitate to purchase any good airworthy 140 or 140A with a C-90 or an 0-200 upgrade. Both engines will fit anything you're wanting to accomplish unless speed is an issue then I would opt for the C-140 with the C-90. Both airplanes are great performers, you will not be disappointed. My 140A came with an 0-200 when I purchased the airplane 21 years ago, and I've never regretted that installation. If the aircraft still had a C90 as originally installed that would have been okay too. Just my 2 cents.

[michael hz]

Good morning,

thanks a lot for the thorough response. Highly appreciated.
The things you mentioned check with what I have been able to collect on the internet with the help of google, especially in regard to the O-200 crankshaft put in a C-90 engine. So thanks for the sanity check on that.

Your statements about the performance sound reasonable. Thanks for that! However, I'm looking for a whole metalized aircraft since I'm going to use it for a 1:45h commute between my airbase (Military brought me to the Us) and my home field/family on weekends. My family hangar at home is already full so the 140(A) will be parked outside occasionally which is the reason that I'd favor a non-fabric aircraft.
Therefore performance is not too much of a factor for me rather than serviceability.

The aircraft I have my hands on in is a 140A with a high time C-90 (1800h on it) for a reasonable price. I'm just thinking about equipping it with the O-200 once I bought it.

Does anybody have experience with using Thompson's O-200 STC on a 140A?

Thanks again already for any response.

Regards from Texoma

Michael

[6643]

Actually, the C90 crank and the O200 crank are the same. In fact, since the C90 came first, the proper statement is the O200 uses a C90 crankshaft...

There is an STC (actually, at least 2 STCs) that allow use of the O200 crankshaft (bowing to common terminology) in the C85 as C85 cranks are not in production and getting harder to find.

The C90 turns slower and swings a bigger prop.

[6183]

Actually, the C90 crank and the O200 crank are the same. In fact, since the C90 came first, the proper statement is the O200 uses a C90 crankshaft...

There is an STC (actually, at least 2 STCs) that allow use of the O200 crankshaft (bowing to common terminology) in the C85 as C85 cranks are not in production and getting harder to find.

The C90 turns slower and swings a bigger prop.

Thanks John for clearing that up.

Mike