Boll Aero 4.4

[bentprop]

Hi all,has anyone built this bigger Boll engine?
I've just got the plan for it,but ideally I'd like to convert it to glow operation.
Obviously,I would leave out the contra piston,and drill and tap the head for a glow plug.Do I need to change the ports in any way?Is there anything else that should be changed for glow?
I don't like that stinky diesel stuff. :fan:.
OK,you purists,I'll get me coat :big:

 

[modelmotor]

Hallo Bentprop,

Yes i built them all the Boll 1,8 the Boll 4,4 and the CICADA 1,4 cc model diesel engines.If you like to see and hear how they run go to: Gerard1modelengine or home built model engine by gerard or hand made model engine by gerard or to: my third hand made model engine.You can see different movies from some of the engines for example the Boll 4,4 and Cicada 1.4.cc.
I hope you enjoy the movies.The engines are running very rich and smokey because it's one of their first runs.The smell of diesel fuel is very intensive indeed ,but you need to get use to it certainly when the engine really runs well,but that's my opinion of course.

Regards,

Gerard.

 

[123RWO]

You need a compression ratio of at least 8:1 to run glow ignition with common moderate nitro fuels. I don't know how high you can go, but I think over 9:1 or so could result in preignition, so the head dimensions might need some modification.

RWO