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Hi Chris,
Are you picking up the tach signal from the injector? In a
conversation with Tracy a while back, he mentioned that there is a data
transfer over the serial link for rpm, but it hadn't worked very well.
If the injector signal is connected, the EM2 will use it and the
connection is needed for fuel calculations anyway.
There are some obvious differences between the operation of the car and
airplane as it relates to cooling. I basically agree with Bill
Schertz' comments but would also add that the whole system is fairly
complicated. At idle rpm, you don't have much heat to get rid of, but
the water pump is also running slow. The fan kicks in to provide some
air flow when you are stationary which does a pretty good job of
keeping the car cool. In the airplane, the prop blast helps, but I
don't think it's as effective as the fan in the car (just a guess).
You will definitely see an improvement when you get a 150 mph blast
through the system. Now you have the airplane producing a lot more
power most of the time but usually a lot more air available for cooling.
I guess my point is that there are several factors that need to be
balanced and there isn't a simple answer. One of the reasons I think
the electric water pump may work even though the electric motor uses
less power than the mechanical pump is that at low rpm the water flow
is greater for the electric than the mechanical. At higher power
(based on Bill Shertz data from way back) the flow seemed adequate but
marginal, and a higher water temperature would probably have to be
accepted for high power operations. Maybe 210 instead of 200.
All of my flight time was on 50F days and my oil cooler was not
installed in a very good location. Under those conditions my cooling
was marginal, and I saw oil and water temps of 220 on occasion. After
climbing to pattern altitude, I needed to pull back the power and temps
would stabilize at 190-200 with the oil being a little higher. Since
the oil cooler was not well placed, it confuses any conclusions I could
have drawn.
I think the warm start is just a matter of learning what the engine
needs. I had times when the engine would just kick right over and
other times when I didn't think it would ever start. You have mixture,
prime, cold start, throttle position and maybe some other factors to
fiddle with. I seem to remember having more luck with the throttle open
wider than I wanted it after it was running.
Bob W.
On Sun, 24 Feb 2008 21:29:20 -0600
"Christopher Barber" <CBarber@TexasAttorney.net> wrote:
I received my EC2/EM back from Tracy a week or so again and got it all installed (luckily my EC2 is in an easy access location on the cabin side firewall of my Velocity). After messin' with stuff and holding my tongue just right I have gotten my engine to fire up and run. Thank heavens, but now I have some questions for the collective regarding its running and some issues I am unsure about.
First, it seems if the stars are all aligned just right and Taurus is in sync with Venus, I have gotten the engine to start my last three trips to the hangar, however, I have not been able to get it to RE-start following the initial start-up. It comes close and it will cough and spew and fire but not quite start. So, it seems hard to start initially, even though it has started when cold but then does not want to start once run for several minutes. Thoughts?
Second, on the EM, I will advance the throttle and watch the RPM rise, but as I get to around 4500 rpm the rpm's start jumping around up to like 6500 then drops to 2000, then maybe to 4000 rpm every couple of seconds (I do not have NOP displayed though)....this is ONLY on the EM the engine is churning steadily at a high RPM, but I have no idea of what the rpm's really are. In the lower rpm's the monitor seems to be more consistent....but actually it will jump around a bit too, but still has a more realistically even display at what I believe the rpm's actually are. Thoughts?
Third, a bit more of a philosophical question. If we are using heat exchangers that are maybe about the same size as used in a car why do we seem to have cooling problems when the cars don't. Is it that when cars are stationary in traffic the rpm's remain pretty low and if they were revving at high rpm's they too would heat up faster? (also some seriously refined engineering from the auto manufacturers). I have not tweaked my cooling yet, but I have a pretty big radiator but I seem to be getting over 200 degree's F after only several minutes of running. It does take longer if it is running around 1000 rpm or below. I was just curious as to why it does not seem to transfer from cars to our use more directly. Would this be likely a non issue if I had 150 or so mph ram air being forced through the rad and oil cooler? But again, like I have said, my system has not been tweaked since I just got my computers back and just got it running again (also, being in Houston likely does not help any...even though it was a very pleasant 85 with low humidity today. Would colder weather make much of a difference?) How long should I expect to run the engine while stationary during engine testing and refinement before needing to shut down? Tracy mentioned in the manual that during "Auto Tune" mode, which may take about 10 minutes or so that if the engine gets too hot, to shut down and start where you left off after the engine cools. Is this about right, 10 minutes, or so, and the engine may start to approach red line. If so, I may be about right already. Thoughts?
Finally, for now anyway, the rear seal on my "B" redrive failed. and I was having oil spread out from the rear of the redrive I replaced the seal (9009 IIRC) per Tracy's phone instructions and checked to make sure the passages where clear, but low and behold, it is leaking again. Sorry, not much to go on. I will disassemble again and check when I get a chance though. Thoughts?
As always thanks for the insight. I know I can get too close to the issue and having a fresh perspective from y'all can be very helpful and give me a chance to step away and go "of course" once it is pointed out to me.
Thanks.
All the best,
Chris Barber
Houston
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