Marty d's CH-701 build log

[skippydiesel]

3 hours ago, nomadpete said:

Thanks for a number, Skippy.

As a starting point I plan to put a air temp probe under the cowl. And in the exit stream.

That will give an idea of what is happening. Any other ideas?

Hot air leaving the cowl is not important. Heat around the ignition modules & the voltage regulator (VR) is. Put your thermocouples in these areas.

 

If possible either mount your VR in a known cool area or consider fitting dedicated outside air duct onto the VR.

 

You should also consider insulating all fuel lines /fittings in the engine bay, to minimise the chance of fuel vaporization/vapour lock.

 

Shield the underside of the carbys from exhaust pipe radiant heat. You can make shielding using ductile aluminium flashing, supplied by any good hardware/building supplier (even Bunnings Aerospace).  Fix in place with double wrap safety wire on exhaust and or cable ties on carbys (Alternatively purchase Rotax carby drip trays - they do little if anything about drops from the carbys but do act as good heat shields, better looking as well.).

 

I "Silastic" /glue exhaust wrap to one side of the flashing for extra insulation and safety wire it around a hose where it is in close proximity to the exhaust system .

 

If you are fitting an airbox (Rotax or other) consider ducting outside air in, more efficient combustion/power. The down side of this is greater chance of carby icing  - need carby heat or heated inlet manifold rings.😈