Hi All,

I've been fighting with a problem getting my EGT's to staying more or less equal but I'm running out of ideas of what might be wrong. At idle to about 4600 RPM the EGT's are +/- 20 deg. and go from 1100 to 1500 deg.  after that as power is increased rotor 1 will go up to 1820 or more and rotor 2 will max in the mid 1600's (my max static is about 5300rpm).  I've tried re-calibrated injectors in all four spots with no change.  I can disable either pair of injectors and run all the way to max static rpm of around 4300 with just one pair enabled and the temps stay in sync so I'm fairly sure the injector flow is reasonably well matched.  I've tried several times in flight to use EC2 modes 4 & 5 to balance the temps and I can get them fairly close  in my cruise settings of 4800-5600 rpm but the engine will then run real rough at lower throttle settings.   One thing I'm wondering about is with my exhaust system the length of the header pipes is about 3" longer on one pipe than the other, is it possible that one rotor  is coming into it's tuned band and causing it to go leaner and hence a 150 deg temp diff?  The tuned exhaust theory almost holds water except it's the rotor with the shorter pipe (rotor 1) that is running hotter and I would be expecting it to be the other pipe that would get to it's tuned length first.  Any one else seen this sort of thing?


Perry Casson
Glastar/13B  - 13 hours
http://eaa154.dhs.org/perry