Neil - I'm partial to the 0235 or the 912ULS. I know that may be extreme but heres why. Both engines are designed and manufactured for aircraft. The 912ULS has a definite weight and fuel consumption advantage, but in comparison the 912 may present some heat (if operated to factory specs) and vibration issues. The reason I choose the 0235 over the 0200 is that the 0200 has an internal starter gear. If the starter gear is chipped or broken for any reason a full disassembly is necessary to insure no broken parts are in the rest of the engine (so I was told by A&P; not personal experience). Because of the lower RPMs the Lycoming and Continentals have a distinct advantage. You're developing your hp at a lower rpm less chance of heat issues if properly mounted and vented. The Rotax develops its hp at very high rpm better chance of the presence of heat. I do have a 912ULS on my 701; I got a really good deal and for the most part satisfied and comfortable flying. However, over 5200 rpms I start getting some EGT temp issues. The 0235 will take away from the payload capacity and have a SLIGHT increase in fuel consumption but in the long run will give you greater piece-of-mind in the air. One more, I like the specs on the Jabiru but some of the 601 guys have had and have issues. You may want to contact some of them. My two cents. Good Luck and Happy Flying.
This is a "Hot Button" discussion sure to draw fire from all camps. Built as an Advanced Ultra Light Aircraft in Canada I needed to keep the airframe weight (770lbs) as low as possible I chose the Rotax 912 ULS 100 hp engine. Properly installed on both my CH601HD and CH750 I have no engine issues, and over 1200+ hrs on the CH601HD Rotax that still runs 50hrs between oil changes with no oil consumption. Rotax designed the Rotax 912 series from the start to run at a high rpm using a gear box reduction to allow the use of larger diameter slow moving props. The Rotax 912 ULS 100 hp in my CH750 swings a 3-blade 72" dia. WARP prop and will cruise 5500 rpm all day with no heat/egt issues. Red line is 5800 rpm. Rotax has proven engine life in real world flying of 3000 hrs, which is why they advertise a 2000hr TBO.
The Jabiru 3300 engine is an excellent choice also, the CH750 Jabiru 3300 airframe weighs in at 810lbs. Be sure to get the 10 bar oil cooler the Zenith factory uses instead of the 7 bar cooler Jabiru supplies. Installation is simpler and the FWF pkg.is very well designed & complete. The Jabiru cruise rpm is 2900 with a red line of 3300rpm. It is a direct drive engine swinging a 64" dia. composite, ground adjustable prop...Zenith factory demo has a Sensinich 68" dia. wood prop painted to look like an aluminium prop? The Jabiru 3300 with FWF pkg.is priced lower than the Rotax with the FWF pkg.
The 0-200 Continetal & 0-235 Lycombings are old, proven designs...the 0-235 being the heaviest engine of the two. It results in a heavier airframe than requires more fuel (weight) and as a result the useful load is reduced along with the range. Because of the heavier engines you may have C of G issues when installed in the CH750 airframe. Just my 2 cents.
I'm going to wade into the fire on this one. My two cents worth, if I was to built a 750 I would go with a proven design 912 rotax and add a Bully Hawk performance package = 914 :>) There are lots of low time 80 hp 912 around for low $$$ and the $8500 for the Bully Hawk kit you can have a 914 for less than the cost of a 100 hp. This is the route that I am taking with my second 701.
My two cents. A William Wynne conversion of a Corvair. Direct drive, air cooled, about the same weight and power as an O-200, very affordable, and there is a completely engineered installation already worked out. William has the engine mount, cowl, intake and exhaust, all the detail work has been worked through already. Someone else also suggested a Corvair, but from a different supplier who just came on the scene recently. William developed the Corvair as a flight engine and some operators are taking his ideas and altering them just enough to say it is their idea and marketing the stuff. Some even worked in his shop for a while, then left and suddenly had the expertise to open a Corvair engine shop after zero development and research time. William spent decades, developed it all and, more importantly, has flight tested it before selling it to anyone. Stick with the original.
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