Comment

Comment by Tracy Buttles on November 30, 2011 at 6:42pm

ok Bob

thanks

Comment by Bob McDonald on November 30, 2011 at 6:14pm

Tracey - This is Conrad Watters Rotax 912S install in his CH750. I was at Can-Zac to conduct the 1st test flight of Conrad's CH750. My installation is different than this one. Contact Conrad or Mark Townsend for the information you want.

Comment by Tracy Buttles on November 30, 2011 at 5:15pm

Bob  what  did you use for the fuel pressure sending unit thread adaptor?

i have the stock dynon one and it NPT and the rotax fitting is metric , just wondering where you got the fitting?

found one at MCaster carr but they want 35 bucks for that little adaptor!!!

 

Comment by Bob McDonald on November 28, 2011 at 7:43pm

Tat is a Tanis engine preheater on Conrad's engine. I have a Reiffe heater on my CH750. The Reiffe has a 100 watt element expoxied to the bottom of engine block, and 50 watt gear clamp style heater around the oil tank on the firewall (dry sump engine). The red cube is a fuel flow sensor and round grey sensor is a manifold pressure sensor.

Comment by Mike Hammond on November 28, 2011 at 7:24pm

Tracy, those are heating elements that are part of an engine preheating system.

Comment by Tracy Buttles on November 28, 2011 at 5:27pm

Bob ,what are the sensors on the intake bolt just above the heads?

and where did you get a adaptor for the fuel pressure guage   metric to NPT?

 

Comment by Bob McDonald on November 27, 2011 at 4:50pm

Just as important as the horse power numbers is the ability of the Rotax 912S to swing a 72 inch dia. prop for STOL performance. Other engine manufactures claim more horse power, but their crank shafts can only swing a 64 inch dia prop, and must spin it at faster rpm. I have Rotax 912 engines... never had any issues with either of them. 

Comment by Mike Hammond on November 27, 2011 at 4:05pm

It may make 105 HP on the dyno sucking cold air without being confined in a cowling, but I bet you loose some power by not having a cold air induction, then there is the issue of always having carb heat with the coolant heated carbs, not to mention having more hoses and clamps to possibly leak coolant.

Comment by Bob McDonald on November 27, 2011 at 3:42pm

Allan

This is Conrad Watters engine setup. I fly as an Advanced Ultra Light Aircraft in Canada, and do not have either the Rotax 912 intake pipe or this type of carb heat. If registered as Experiment or Amatuer Built in Canada you can fly with a higher gross weight, but MUST have carb heat regardless of weather the engine / cowl configuration. I watched the engine install with the 1st Rotax 912S in a CH750 "Catnip" built at Can-Zac and that is where I observed the Rotax intake having to be cut apart , rotated and re-welded to fit under the cowls. Is your intake pipe Rotax supplied or after market via Zenith? Its funny that Rotax "tuned intake pipe" guarantees a full 100 hp when used with the Rotax stainless exhaust, but what Rotax does not say is that the use of K&N conical air filters instead of the intake of the $1,200 pipe actually dynos at 105 hp. Its mis-representation through omission to sell the pipe.

Comment by Mike Hammond on November 27, 2011 at 3:37pm

I met Bill Alexander and got to see and fly his CH750 this weekend.  His 912s installation is first class and includes the Rotax intake manifold.  He did not have to cut or modify the manifold to fit his aircraft, and he also has the manifold set up to use cold filtered air from a NACA scoop that he grafted into the left side of the cowl.  Bill also welded a lightweight shrould that straddles the muffler and supplies warm air to the carb heat valve on the Rotax tubular intake manifold.  Bill's set up is great because his engine is breathing cool ambient temp air which helps make full power, it also runs much quiter because the intake manifold is a great intake noise silencer, and he has carb heat when he needs it, and can turn it off when it is not required.  Did I mention that his set up looked as good as any factory installation that I have ever seen?

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