(I apologize for this and all my posts - I really over think things and often run down unproductive rabbit holes. No wonder my first plane (an Osprey2) took almost 20 years to build. I try to keep these ramblings to myself, but occasionally they creep out.)
Anyways... I've been tormented over engine selection ever since my son started his KR project (https://hugheskr2s.yolasite.com <https://hugheskr2s.yolasite.com/>). My guess is that the o-200 is probably the second best (and cheapest) engine for the KR. My vote for best would 100hp Rotax 912 for general general use and turbo 914 for high long cross country. On the “alternative” front, in my STOL flying, one of my buddies flies a Yamaha RX1 powered (140hp at 10,000rpm) Highlander. He (and now a lot of others have) had great experience with with the engine. Who knows, maybe it will be a viable alternative to the Rotax. There was just a Kitfox RX1 FWF package advertised locally on craigslist for $5200 - so pretty cheap. There’s something about the KR that just screams for the simplicity and grass roots of the VW. It seems like it should also be the cheapest, but after rebuilding it a few times costs add up. Unfortunately we now have 3 VWs and none of them were all that simple. Indeed all of them are very interesting, but all probably not what I’d like my son to fly behind. The project came with a Hapi Magnum engine (94mm bore x 69mm stoke and individual scat heads). Worries about cooling led me to sell the scat heads (to a fellow making 1/2 VWs) and purchase a home brew Great Plains. That engine was extremely interesting, having been built up by a retired Ford engine engineer with LN Engineering (Nickies) Aluminum cylinders, fuel injection, turbo charger, electronic ignition and injection control, etc. etc. Finally - to cap the rare and way too interesting VW engine saga, a Great Plains “Top Bug” 2600 Type 4 (103x78, also fuel injected and electric ignition, ForceOne crank/hub, alternator) Yikes! Yeah, my son is hooked on the VW’s. But I keep seeing things like the experiences of folks trying to push overloaded VW vans with the those ol engines and imagine we’d get similar reliability (or lack of it - have you ever seen this youtube series - https://youtu.be/7zfg-XJ99hg <https://youtu.be/7zfg-XJ99hg> ?). I've survived two engine outs (one a rotax 503 and the other a o-200 cont), and really would prefer not to see a third. Ironically, the engine I recommend is either a Rotax or a Continental o-200. However it is clear that the mean time between failures is far higher for the VW. Anyways, it is also clear that the KR can make great use of extra horsepower. With more HP, the KR goes faster. Obvious? Not really. Adding hp to a lot of airplanes mostly increases climb rate but has minimal effect on cruise speed. The reason for that weird phenomenon has a bit to do with the exponential increase of drag with speed, and a good bit to do with a more complex aspect of aerodynamics similar the the hull speed limitation of ships. With the realistic ~60hp a VW will pump out, they seem to see ~130mph. With 100hp from an o-200 a lot of folks are seeing something closer to 160mph. So your choice for reliably getting 100hp? Either a 165lb Rotax 912 that burns 4.5gph or a 225lb Continental o-200 burning 5.5gph. I think you could lighten the o-200 quite a bit (sub 200lbs) with a light weight starter, replacing the mags with EI, and using a Ellison carb, but you’ll never get it close to the 165lbs of the Rotax. All that said, my son intends to stick to the VW. He’s in a rush to get it finished and flying since he’s off to college next fall. Me, well I’m looking for a 912 ;-) Cheers, Owen https://sites.google.com/view/melbycavalier/home <https://sites.google.com/view/melbycavalier/home> https://youtu.be/uHGx25FIYDg <https://youtu.be/uHGx25FIYDg> - Oshkosh https://youtu.be/4aAJnWaqhUg <https://youtu.be/4aAJnWaqhUg> - Kitfox https://youtu.be/njuvkIEl_VQ <https://youtu.be/njuvkIEl_VQ> > On Dec 31, 2019, at 9:00 AM, [email protected] wrote: > > Message: 1 > Date: Mon, 30 Dec 2019 19:19:34 +0000 > From: G R Pickett <[email protected] <mailto:[email protected]>> > To: "[email protected] <mailto:[email protected]>" > <[email protected] <mailto:[email protected]>> > Subject: KR> Engine Selection > Message-ID: > > <dm6pr07mb4923ea6515c317fde0843f69ae...@dm6pr07mb4923.namprd07.prod.outlook.com > > <mailto:dm6pr07mb4923ea6515c317fde0843f69ae...@dm6pr07mb4923.namprd07.prod.outlook.com>> > > Content-Type: text/plain; charset="us-ascii" > > Just a reminder that today's VW engines was originally designed for flight > (target drones), and adapted to mass production for cars. There was even a > German-certified Limbach, that produced about 6000 of them. Their > performance in Beetles is legendary, but everyone who had one knows that they > do require different maintenance than American liquid cooled auto engines. > Properly assembling them with modern modifications really seems to extend > their TBO, but VeeDubs do need more attention to the valves than > Continentals. Additionally, VW valves are less expensive to repair. > The KRs were built around the VW engine, and LOTS of builders have great > success with them. If today's builders want to try newer, more powerful > engines in our KRs, we can do so - giving a little extra meaning to the > category of "Experimental." Names like Jabiru and Rotax sound like viable > options. Neither is That much cheaper than a Lycoming, and sometimes parts > are more difficult to find at reasonable prices. > Myself, I've often thought that liquid cooling might be a good alternative > for aircraft use, especially in the flight regimes use by most KR pilots. > Still, there haven't been so many liquid-cooled KRs flying for 10+ years that > I can think of. > Griff _______________________________________________ Search the KRnet Archives at https://www.mail-archive.com/[email protected]/. Please see LIST RULES and KRnet info at http://www.krnet.org/info.html. see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options. To UNsubscribe from KRnet, send a message to [email protected]
