RE: Test stands for break in (not good)
"I have installed a eagle tree system on my ZDZ 210. I have data but I am no expert in this field yet. The things I have learned is you can through out the lazer temp gun to check temps after you land. My experiance tells me (maybe just my airplane setup) that in the air at WOT my head temps (2nd fin down from the top of the cyl) are 95-110 deg. When you land the plane the temps climb to 160-180 before you can get to it with a temp gun (my lo end is a little lean). My exhaust temps (I have egts about 2 inches from the piston) are Idle 450-550, wot one cyl. will be around 950 max the other about 910 (that is extended upline wot runs). Vertical rpms around 5400 with a 31X12 three blade Mej.
It will turn about 6400 flat out and starts to rip slightly. I have leaned the motor twice on the top end (about 1/32) and saw about 20 degree jump in exhaust temp the first time and no change the second time. I run mtw tuned pipes on the motor and have not tuned the length yet.
I have started by extending the headers 2 1/2 inches. I am very interested in comments on what I am seeing.
Pat are these exhaust temp. close to optimum or not? I have a friend who runs a car dyno and he said temps around 1200 are common and 1300-1400 for brief seconds are ok. Those are 4 stroke car engines. I would like to know approximate exhaust temps to look for with a 2 stroke.
Very interesting thread and I am not trying to step on toes just want to get others opinions (and thats what they are). "
************************************************** *******************************************
800 to 1,000 for egt's is pretty common, and imo is near the peak as it stands. Much over that and things start to melt. Changing the header lengths most certainly effect the egt's since you will be changing the fuel charge that entes and exits the engine. Nice to hear your monitoring using egt instead of cht. Cht is slow to react to changes while egt is immediate and notes the true state of the fuel charge used. Unfortunately manufactuers don't provide max egt ranges for their engines so you're in a trial and error game where the errors require replacing the piston and ring assembly.
If anyone has egt info that could help you prevent cylinder melt downs it would be nice to post it for reference. Note that due to large differences in metalurgical composition there will be a large spread between what is acceptable and what will be over the top with different engines.