Jabiru engines on the brink ??

[birdy]

The machining of the engine is so neat I would"nt mind having a clean engine mounted on a frame in my house as a piece of art. Dam shame. Aint that the truth. If its profesionaly finnished, polished, has pretty paint or stupid bells n wisls, fair chance all its good for is a wall ornament.

[gyroo]

That"s true, Birdy, they are neatly machined. But, as a matter of common sense the dramatic reduction in cylinder fin cooling area the further out you go has always mystified me (see Picture 1 for the Jab setup). If you look at WWII engines from 60 and 70 years ago, as a matter of routine the designers and builders of air cooled engines gave them enormous amounts of cooling fin area right AT the head (see Picture 2 showing the cylinders of a Pratt and Whitney R2800 - an 80 year old design).

[RossM]

Another air cooled engine.Don"t forget, I know nothing about engines.http://www.corvusaero.com.au/UL-Powe...power.com/they recommend CHT and EGT sensors, CHT on every cylinder, and a lot of warnings about never exceeding max temp.

[Russell]

Many owners have no problems at all, many have lots of problems.The " regulations" make it near on impossible to make changes no matter how better that change has proven to be.Guys that build from kits, can make changes, prove them, but factory built machines are hamstrung by regs.Heat control is the prime factor to most problems. There are mechanical issues as well, but heat is the killer.Maybe, just maybe, with casa threatening jab, finally jab will be forced to address issues, if they do, then jabs will be brilliant, as a flying machine they are faultless. Mine 100kts true cruise, 15L per hr.........not badStill love them gyros tho, really do. .......one of each is the ultimate indulgence.

[tonydenton]

I agree russ, I have friends that have a jab and never had a problem. not even a tiny fault. they have been around Australia and all.

[WEST OZ FLYER]

Ross, that ul engine you posted has the same mounting bolt pattern as the Jabiru engine although slightly heavier. I was told that if the registration number has an E in front the 24 means that it can"t be used at a flight school, aero club etc ( hire and reward ) and you could do what ever you wanted to it as it was now experimental. Put in a proper engine and would have a decent airplane.

[birdy]

I reckon it"s blindingly obvious why Jabs burn out their exhaust valves and deform their heads.Ex valves can burn even in new petrol engines that show no sign of heat problems.Incorrect geometary of intake will create lean mixs on sum cylinders.These pots will continuously burn the ex valves, no matter how much cooling it has.

[MadMuz]

Here is a link to Rotec..... wow, they seem awesomeEdit: So you did Mark, sorry about that ... I wondered where I had found it

[gyroo]

Gee Mad Muz Thanks for reposting the link I posted on page 1 of this thread. Duh.