Are Jabiru engines really that bad?

[Icarus]

You didn't mention the piston crown's temperature. You aren't monitoring that. The design of the Jabiru piston is not optimal for getting the heat out of the crown. "W" slot and skirt relieved pistons are designed for a Holden car or cars generally. IF you spray a lot of oil on the bottom of it you will improve the situation. This is done on turbo charged air cooled aero engines. Nev

I see , so the pistons are designed for a water cooled engine , the air cooled jabs are running too hot for the pistons to effectively dissipate enough heat at times?

The oil squirters cant hurt .

 

Are the turbos oil cooled only.? do they suffer from oil coking ?

 

 

[facthunter]

That piston is designed to have a high heat gradient from crown to skirt, and the heat only transfers through the area of the gudgeon pin boss. This is to reduce initial (cold) clearance skirt to bore by a controlled distortion process.

 

Oil jets use energy as the oil pumped volume is greater. This controls piston temps, as that is the aim of it. Sometimes the engines have heavier (thicker) cyl head sections than the standard engine. Unless the piston overheats there is no problem with ring land coking. The rings and bores are designed for the extra load and the oil consumption is much the same. (sometimes the bore is nitrided, where the lower power one isn't). Nev