Does anyone have any hard numbers on the real world economics -- purchase/operating/maintenance/overhaul costs -- of the available certified small engines for light aircraft? As far as I can tell, these are the currently available options around 100hp:

• Rotax 912 A/F (or new fuel-injected iSc)(100hp)
• Rotax 914 F (115hp)
• Continental O-200-D (100hp)
• Lycoming IO-233-LSA (116hp)

Thanks!

Matthew

I fly behind the Rotax 912A. Flying at 95-100 mph I burn 4-4.5 gph. 90-95 mph burn rate is 3.5-4 gph, variations depend on weight load.

Try looking here.
viewtopic.php?f=11&t=6573&hilit=shootout

The fuel burn of my continental C-85 is pretty much the same as what skysteve is reporting for his 912. I did a overhaul on my C-85: machined case halves, ground cam, new O-200 crank cylinders and pistons, new oil pump and new mags. Had somewhere between 12 and 14K into it when done. I imagine overhauling a O-200 would be close to the same.

Don't forget about the much higher oil consumption, I hear guys bragging about "only" using a qt every 25 hrs?? That sound about right (0-200)? I almost overfill at my oil change (75 hrs) and may add 1/3 a qt during that time, ending up at the next change with the tank lowish but still within specs. Then again if you got into a much less expensive engine then the Rotax costs, you could pay for a lot of oil!

Simply put, my 912S seems identical to my T-Crafts A-65, 3 1/4 to 3/ 3/4 GPH, I have not been over 4 GPH yet. REAL easy to get it below 3, even 2, when slow flying. Don't know if a 0-200 can do that? A buddy with a 0-200 in his t-Craft got about 5.5 GPH as I recall when we were flying together at similar speeds.

Kitplanes has a good article on alternative engines this month, Klaus Savier is doing some pretty amazing things with his electronic ignition and a fuel injection system on a 0-200, and getting some unreal numbers. But a good 70 lbs at least heavier then a 912S at least. Some small turbo diesels available only in European auto junkyards are pretty interesting also.

My C-85 uses 1 qt every 5-6 hours - but I believe most of the issues w/ the small contis is the design and placement of the crankcase breather. Lots of info on the web for fixes - but the oil consumption without mods is a significant issue.

Soy, do you always keep it full? When I change my oil I fill it then let it even out; typically it blows a lot out till just under 4 quarts then just a few dribbles after shutdown. I typically add a half quart between 25hr oil changes (when it gets to 3.5 quarts I fill it back up to 4 quarts, 4.5 it all the way full). I really don't think it burns much, instead it pukes it out the breather. Easy fix but can't do it on a certified engine.

There's a couple solutions on the oil-out-the-breather problem. First, turn the elbow that screws into the crankcase up at a steep angle-- then radius the breather hose aft-ward. This will allow oil that comes out the breather to run back into the engine instead of blowing on out. Second, remove the elbow itself & solder a piece of tubing to it that will slightly protrude into the engine. This keeps oil & stuff from running into the elbow and getting blown out-- only airborn stuff will go out the breather. I think they make a special part like this for aerobatics.

I've done tons of reasearch on this - and know the tricks. I don't keep the oil full - or it will blow more - the plane wants to be below 3 qts and I'm not really comfortable doing that on cross country. I've experimented and let it go down to 2 qts and still dropping. I agree it's not burning - it's blowing out the crankcase - but oil loss nonetheless at 1 qt per 20g of gas costs about an extra gallon of gas cost wise. It adds up.

My plane has the breather extension (according to prev. owner) but I've not pulled it to look at it. I need to re-route it and clock the elbow up and over the engine - but that's not how they come from the factory. It's on my todo list. 90% of the planes I've seen are flying this way. I've done a compression check (thanks lesuther) and the cylinders appear great so I'm not blowing by the rings.

The only cessna plane with an O200 to address this was the Aerobat - and the 90 degree elbow with the extension is $150 part. Hence all the homemade modifications.

My A&P (well the one who did my pre-buy) is a J3C owner too. He says TADT. I assumed everybody knows about it and lives with it or makes the mods to fix/manage/minimize.

BTW, Whee. Many cub owners have made crankcase breather extension mods on certified planes. You need the A&P to signoff - but many do as long as they understand what is being modified. It's grey area though. Technically you are silver soldering copper tubing inside the standard elbow and re-routing the breather up over and behind the engine instead of dropping it straight down. Lots of discussion on j3-cub.com and supercub.org about this sort of thing.

I have no data on the rotax 912 thing directly - but my brother flew a 912 powered kitfox for many years and I've talked to the local LSA flight school who run them and they claimed very reasonable cost of ownership for those engines. I don't think that helps much. But depending on what you are considering building, I would contact some of the more popular kit mfrs: kitfox, rans. See if they have data to share. I'd sure like to see it too.

I still contemplate building a Rans with the turbo 914. I can't stop thinking about going straight up and over the 13K pass that's right next to my house when the weather is good. My 85hp conti with no mixture control seems a little meek for the challenge regardless of how brave I might be on a good day.