Engine Testing:


As some of you know, my engine started for the first time in 2005. Since then I have made some major changes to the landing gear, propeller and engine control unit. So, I'm pretending like it will be the real "First Engine Start" once I get the new EFI controller installed.


The engine control unit is working.

Began engine testing today. I began by adding about one and a half gallons of fuel to the header tank. I switched on the main fuel pump and verified adequate fuel pressure. After shutting the pump down I inspected the fuel lines for leaks. A thorough inspection revealed none so I installed the cowl and pushed the plane outside for the initial test start. I set up my video camera and kept a fire extinguisher close by.

First start procedure:

  1. Fuel valve on
  2. Fuel pump on
  3. Main battery on
  4. Instruments on
  5. Verify fuel pressure
  6. Auxiliary battery on
  7. Throttle set just off idle
  8. "Clear"
  9. Start engine
  10. SURPRISE! That started quick!
  11. Monitor engine instruments
  12. Set throttle to 1150 rpms
  13. Instruments look good
  14. Let idle about 30 seconds while watching instruments
  15. Shut down

The first start went extremely well.

05-15-07 Second Start Video:


This time I recorded the event. Taking off my shoes was not for luck, my size 13's don't fit under the header tank. Also note that the passenger door blowing open was new to the procedure. I'll remove that step from all future starting sequences.

Third Start:

Time to start some serious testing. For this procedure I set out to monitor coolant temps, the Subaru engine ECU and alternator performance over a 20 minute event. For this I wanted the upper cowl off in case too much heat were to be developed in an overheat situation. To do this, I had to add some temporary ducting to the radiator inlets. I used duct tape to seal at the junctions to the radiator inlets and to hold the front of the tubes in place behind the prop. I reasoned that if this worked, it would prove the radiator size is adequate and that the ducting and cool-down would be the only issues with cooling once the cowl was reinstalled during subsequent testing.

The engine started as easy the third time as the first two. I set engine rpms to 1150 and monitored the instruments. After about a minute, I noticed that the alternator had stopped charging. I shut down the auxiliary battery so I could continue the test and have a fresh battery in case the main dropped below adequate voltage. Four minutes into the test I brought the engine rpms up to 3000 and continued monitoring the instruments. At this point the coolant temperature was near 150 deg f. I held this rpm for another four minutes with no change in the coolant temperature except some minor 2-4 deg up and down fluctuations. The battery was also hanging in there at 12.2 volts. At this point I brought the rpms back to 1150 and continued monitoring the instruments. Coolant temperature stayed stable at 145-150 deg f. Gear box temperature stabilized at 115 deg f. After 20 minutes total time I shut the engine down.

The engine ECU seemed to take everything in stride. The O2 sensors are mounted in tandem in the right header and the electronic speed sensor set at 85mph seemed to keep the ECU thinking everything was OK. I ran it long enough for the fuel tank tests to progress so I'll say for now that the Small Car work-around seems to do the trick.

After shut-down I investigated the alternator situation. I found the 5 amp fuse from the main switch was blown. I tested current draw on the wire to the alternator b-lead contactor. It measured .75 amps. I started the engine with a new fuse installed and the amps stayed the same. About 15 seconds into starting the engine the fuse blew again with no indication on the digital amp meter. I disconnected the IGN wire at the contactor and wired it directly to the B-lead and left the main switch, and fuse, connected to the b-lead contactor. With another new fuse installed I started the engine again and it blew the fuse in about 5 seconds. I removed the b-lead contactor and wire the alternator directly to the batteries and yet another new fuse to the main switch. This time nothing blew and the batteries charged for about 7 minutes before I shut the engine down. My conclusion is that I have a faulty contactor.

10-20-2007: Replaced the alternator b-lead contactor and tested alternator again. Upon engine start the alternator worked for about 30-40 seconds. Then the fuse blew. After some testing I found that something was shorting the b-lead contactor "on" signal wire. I ran out of time to do further investigating today.

11-03-2007: After some thinking at home on the alternator problem, I remembered that I had installed one of those "over-voltage" circuit protection goodies from Bob Nuckols a few years ago. I decided to remove it from the system and test the alternator again. The alternator performed flawlessly during this test.

Upon returning home I went to Bob's website and read up on this device to learn how to adjust it. From this reading I determined that it wasn't a good idea to pull the alternator off-line in this manner when using an internally-regulated alternator. I decided that I will leave this device out of my system.

11-17-2007: Performed more cooling system performance testing. The engine ran for approximately 30 minutes without exceeding 185 deg f. Outside temperature at the time was 60deg f.

All testing to be continued on Ground Testing page.