SonexBuilders.net

Attached is a report of my efforts/results of my installation of liquid cooled heads for those considering doing so.

Hi all, robert,
Thanks for the time to post this report. Interesting reading. We have a jab 3300 w the sonex baffles. Works well with a few small mods. We have alum blast tubes inside the baffles running to the back out to cool the coils. A good idea for jab or aerovee coils.
Contact with rotec seems to be universal. Spotty. Paul is a nice guy at oshkosh. Maybe they need to hire another person for the communications side of the house. Seems to be a problem everywhere these days. Lack of staffing.
Will you be at oshkosh again this year? Would like to see the install in person. Have fun flight testing. Be safe!

WaiexN143NM
Michael

What an excellent write up Robert, well done. Although I have no intention of fitting water cooled heads, the information is helpful. Interestingly, in Australia if we were to fit water cooled heads onto a Jabiru engine, we would automatically place restrictions on the aircraft such as where we can fly and taking passengers.
I have the Jabiru supplied ram air ducts on my 2.2 Jab, they work well, cooling as never been an issue 260 degF being the highest I have ever seen one in summer time.

Phil

Hi Robert, interesting report. I also have the early engine with thick fin heads. I probably don't run it as hard, usually cruise at around 2800 and it runs cool so it will be interesting to see how well it lasts - only 321 hours so far.
Jabiru also sell a quick-start coil option. I was a bit fed up with difficult cold starting so contacted them and surprisingly the guy I talked to suggested instead that I just make a small mod to the Bing carb. I seem to recall it was drilling out the starter jet to a larger size. It didn't make much difference to starting but I eventually fixed the hard starting almost by accident in a totally different way. I put a little solar panel (about a foot square) on the roof of the hangar and whenever the Sonex is parked it is connected to it via a charging regulator. The battery is always fully charged so spins the engine just that bit faster and starts easily.

Peter
Sonex 894

My CHTs were not high by normal standards, and had easily within spec temps as a general rule. Depending on ambient air temps, I saw CHTs from 255-300 F normally in cruise (at altitude~6000+ ft). But the spot right between the valve seats is the vulnerable spot. Since the Rotec Heads have the same design, I am unsure if the lower CHT will help with this flaw. Only time will tell...(not the ideal way to find problems in an aircraft engine).

R.
Robert E. Barber
N157SX, Sexy Hexy
S/N 271