two questions.

[tx_swordguy]

I have about 12hrs on a new to me sonex with a jabiru 3300 and have a couple of question about running and flying it.
1. I have been concerned (possibly overly so) about my cyl temps during hot Texas temps. I have increased the exit holes generously and increased the size of the lip on the bottom of the cowl to get as much exit pressure as I can. I also put in th coke bottle baffles designed by Jeff. I flew for the first time today with the mods and feel my temps were good but OAT was only about 87f so a long way from HOT outside. My CHT at 2700-2800 cruise were #1 270+/-, #2 279+/-, #3 235-250ish, #4 285-295, #5 275-285, #6 275-285. These appear good and in WOT climb all were under 300 except 4 would sometimes go to about 308 . I could keep my EGT below 1300 depending on how I leaned. My method of leaning is to set my cruise at 2700ishrpm level flight and pull my mix until it runs rough. I then richen a turn or two until it smooths out and fine tune until EGT is below 1300. It purrs like a kitten but I am only burning somewhere in the neighborhood of 5-5.5 gph. Thats awesome as long as I am not doing damage to the Jabiru by running too lean. I am about 7 hrs from a 25 hr service on it when I will change out the plugs to see what they look like. It just came of a condition inspection when I bought it with 321 hrs on it. It is a solid lifter 3300 running on premium ethenol free MO gas with Marvels Mystery oil added at 4 oz/10gallons. field elevation is 800' OATs will hit 100 routinely and I flew in that a month ago getting 350ish on #4 on climbout which worried me. CHT prob is under plugs. Am I ok or should I richen it up a bit? The Mike Busch article I read seemed to be aimed at LOP was safer than ROP if you were running close to peak.
?#2 . I tried my hand at some aileron rolls this morning (maybe 6,need practice) upon landing I noticed I had oil all over underside. I lost approx 1/4-1/3 qt of oil that appeared to exit the breather tube when I was inverted. I have the breather cylinder tube sitting on the right side of the engine attatched to oil filler tube that is supposed to catch and return the oil. Obviously this is not going to work for acrobatics. is there a different set up I need to make or just deal with dumping oil all over the place and make sure I don't do enough to run out of oil? Sorry for the long post
Mark Whiddon

[DCASonex]

Mark,

Your numbers look pretty good. With a Jabiru, you do want to keep CHT comfortably under 350. If when re-torquing your head bolts, they move much at all you are running too hot. The top of the cylinder is being pressed into the head. (Not Good.) Be sure to check the bottom head bolt that is hidden behind a plug between the rocker arms. When climbing out on hot days, may need to step climb. I try to climb out at over 100 MPH to improve cooling. Your 87 deg day would be a warm one for us here in the hills of the NE (45°F this morning) so not a lot of experience with hotter temps, but sounds like you have a good handle on the situation and doing things right..

Oil loss when doing rolls: Engine is not designed for negative Gs. I have done rolls with no noted oil loss. Best way to keep oil in a Jabiru is to run the vent line up alongside the filler box all the way to the cowl before turning down to your catch can. Also do not fill past half full mark on dip stick or oil will foam and over heat. (CAMit dip sticks show full at this level)

David A. Sonex TD, CAMit 3300 (#0004)

[tx_swordguy]

Thanks David.
I was concerned about the lower fuel consumption damaging the engine somehow. I thought all my numbers "looked" ok but I am a full gallon or more from what I hear a lot of guys running in gph. I will look into a different way to run the breather and see if that can be changed some how