Re: N8WQ engine first start(s)

sanjay <Sanjay@...>

Congrats Jay

-------- Original message --------
From: "'Jay Scheevel SGT' jay@... [Q-LIST]" <Q-LIST@...>
Date: 4/15/18 2:04 PM (GMT-05:00)
To: Q-LIST@...
Subject: [Q-LIST] N8WQ engine first start(s)


I am pleased to announce that after 33.5 years build time, my baby, N8WQ has took her first breath yesterday and is very healthy!


The following 5 minute videos document the event(s). Outside air temp was about 55 deg. F, with a slight breeze into the nose of the plane. The engine is a (obviously much newer) Jabiru 3300A with liquid cooled heads, converted to solid lifters, with Rotec alternator and one electronic ignition and one magneto.


First video shows a couple starter cycles, first with ignition off to get oil into the gallery, then to pull some fuel into the manifold, after a couple more turns, it  starts up with the throttle too far open, so it startled me a bit, and I shut it down. After the second start it is clear that the throttle range is set too high overall, as the lowest possible RPM is around 800. (I fix this for the second set of videos, below)


This video picks up where the first left off in mid-run. The total run time for this first test is about 4+ minutes, and this video shows that after I shut her down, there is some smoke..uh oh!... but it turns out that it was just the exhaust manifold wrap “curing”. A one-time thing, so no problems.


During the first run, after checking vitals, I ran the mixture through its full range, watched pressures and temps and alternated both ignitions, all good. Oil pressure good, a little over 50 psi. Oil did not rise above 90 degrees F on this test (see second run description below for more on that).  After shut down, I checked for any coolant, oil or fuel leaks and none of those were to be seen. You can see me put my hand on the cylinder head just after the engine is shut down. It was about as warm as hot bath. During this run and the second run, the liquid cooling worked like a charm. CHT’s on all cylinders (under the plug, on the exhaust valve side of the cylinder) averaged around 200 degrees F, even after 10 minutes during the second run. Water temps were running at 145 degrees F and much cooler when I fully opened the exit door on the radiator plenum.


Prior to the second run, I had adjusted the throttle range, so minimum is more like 500 RPM. I don’t have the exact number because I have not calibrated the tach (EFIS) yet. May have to take my RPM off of a different source. Will see about this. Right now it comes off of the Hall sensor on the electronic side of the ignition. During this second run I ran up around 1800-1900 for about 6 or 7 minutes. Coolant temp stayed about the same as the first run (200-210 F) and oil temp reached up to a max of about 130 F.


In this second video between 3:30 and 4:00 you can see me cycling the exit door (cowl flap) on the near side. This makes about 20 F difference in water temp, with the high being 145 F.  CHT’s still a little over 200 F.


Final segment of second run.



I think I have wires reversed on #6 cylinder EGT, as it reads negative to start with and as the others heat up, it gets colder (like arctic cold), then goes off scale. The other 5 EGTs read around 700 F when idling and then at 1800-1900 RPM are in the 1100 F range (vary by about 20 F). 


The mixture control definitely affects the EGT, and engine gets a little rougher at full rich, so I know it is working, but it does not shut down the engine at full lean at idle. I can kill the engine by shutting off ignitions, or by moving fuel selector to OFF. I prefer the later, as it clears the engine of fuel. Starting, even hot, seems to be non-event (as long as I don’t leave the throttle wide open!).


I ran the engine using all combinations of fuel sourcing, gravity from header, header with boost pump, both tanks with both pumps and main only with main pump. All check out and will run the engine as expected. My fuel flow test using these methods a couple weeks ago, before mounting engine all yielded 200%+ of max possible engine consumption, but nice verify while running he engine. Also, whether fuel pumps were off or on and regardless of tank selection, there were no noticeable effects on the engine RPM richness etc., so the throttle body injector’s regulator seems to be working as advertised.


Compression appears to be very good. I will check after a couple more test runs.


Belt driven alternator, and internal B&C regulator working very well. Was kicking back about 30 amps after the start. Felt the battery boxes and main power cable after start and during charging, both cool to the touch, so that is good.


Will check prop torque again and maybe pull a rocker cover to check lash, then do some more test runs today.  All grins so far.



Jay Scheevel, Tri-Q still building



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