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Greg Ward wrote:
Y'know, not meaning to offend anyone, but I am trying to mate a 400 hp 20B to a 250 knot+ Lancair, and after hearing how successful some of these installations have been, I am getting a little nervous. Are these firing/grounding/running problems common? What am I missing here? How about some straight answers from some people in the know? My life depends on this stuff. Although my budget isn't unlimited, I am willing to spend what is necessary to guarantee that at least I can get on the ground if something goes wrong, but what do I buy???? I could sure use some input from Tracy, and guys like Tom Parkes, etc. (who won't return a query), about what they are experiencing with this genesis of rotary installations. I just want to get to 18,000 feet, cut back to 70%, and relax. Again, if I offend, I apologize.
Greg Ward
650-766-1480
Greg, I can see what is going on here from 18,000 feet, because I'm mixed up in it every day. In my case it is with networking, but it is the same type of work, trying to get a complex system running.
I'm not trying to disparage anyone. I'll state again for the record, I do this nearly every day. The tendency (if not the driving force) is to assemble the dozens of parts and hope that it all works. The good news is that this sometimes works. The bad news is that this rarely works. When it doesn't work, we're left wondering which of the dozens of parts is at fault. That's when the headaches begin.
Luckily, there is another method. Assemble sub-systems and verify each before adding another. This is a long, tedious process, resulting in an anti-climatic engine start ("Of course it ran. All the sub-systems checked out.") Most people, including myself, want to skip the sub-system testing, because it is SO easy to tell yourself that the particular system is so simple to be foolproof, and there is no guarantee that your test will catch every possible fault with that system anyway. Better to put it all together and see what happens. I'm trying hard to resist that temptation, so here is my engine game plan (so far):
I - Disassemble engine completely. A - Clean each part
B - Verify published tolerances
C - Prepare for re-assembly (paint/oil/ceramic coat as necessary)
II - Re-assemble engine with aid of 'expert'
Expert being defined as someone who has done it several times. I have someone who has agreed to help, and I'd like to let him know that I've been making steady progress.
III - Verify mechanical operation to the extent possible.
A - Turning torque test
B - Compression check
C - ??
IV - Add electronic ignition.
A - Mount VR sensors and timing wheel on a lathe and verify signal integrity to 6000 RPM with oscilloscope.
B - Install VR sensors, turn engine with starter, and verify VR sensor output with oscilloscope.
C - Verify oil flow at the same time, using the procedure outlined by Lynn where you verify flow into a container at each connection point.
D - Connect each VR sensor to its corresponding EDIS module, and verify proper ignition advance with a timing light.
E - Connect EDIS modules to Megasquirt computer and verify ignition advance, by manipulating the advance and checking while cranking.
V - At this point, I can feel confident that I have the mechanical, oil pump and ignition sub-systems operating properly. Test engine operation with the backup fuel system, a manual fuel valve.
A - Verify clean signal from VR sensors with oscilloscope
B - Verify wide-band fuel-air sensor follows fuel/throttle adjustments
C - Verify timing advances with RPM.
D - Verify electric water pump flow.
E - Verify generator output.
F - ??
VI - Add injectors.
A - Verify fuel flow of individual injectors. Timed flow into beaker. Match injectors as close as possible into each bank.
B - Run engine with injectors connected to Megasquirt, but fuel delivered to engine with backup fuel system. Injectors flow into measured volumes. Verify fuel flow follows engine speed.
C - Install injectors. Verify engine operation on primary fuel system up to 6000 RPM.
VII - Test cooling system.
A - Instrument ducts for both oil and water cooler with multiple manometers.
B - Instrument all heat exchangers with input and output temperature measurements.
C - Instrument engine with input and output temperature measurements.
D - Record temperature data, in parallel with data from Megaquirt during several heating cycles.
VIII - Cross my fingers and hope the engine works.
Now, the question is, "Will I have the patience to follow the plan?"
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