Greetings, 

As before, I'm going to be lazy and just post my daily log.  I'm sure the turbo flame subject will make you read it :-)

Rusty

8-24-03  /  8 hours  /  1385 total

Finished up the top cowl tidbits, and tuned the engine.  The A controller was perfect, with Tracy’s default settings.  I did set the staging point at 18” MAP (12” vacuum, 14” vacuum indicated on my defective gauge), but it ran OK before I changed this too.  So much for the good news. 

The B controller was waaaaaaay rich across the board.  I couldn’t get the mixture lean enough, even with the mixture knob all the way CCW, so used mode 3 to reduce the flow rate several steps to bring the mixture down to the point where I could center the mixture knob.  I also set the staging point at 18” MAP on the B controller, but had to do lots of fiddling with the mixture to get the low power and staging area to behave.  It’s odd, the mixture indication on the AF gauge needs to be leaner with the B controller, than it does with the A.  In other words, on the A controller, two yellow bars rich of center is what seems to run best at low power, but on the B controller, it’s one yellow bar rich of center. If you try to get two, it just won’t run right, and can be improved by turning the mixture knob CCW.  Very strange.  Don’t understand this, but it works.

My theory, until proven wrong, is that the intake air temp at the throttle body is pretty darned hot.  Since it was 100 degrees on the ramp, and I’m running a turbo with no intercooler, I can imagine this to be true.  The A controller compensates for this by reducing the fuel flow to match the very hot air.  The B controller doesn’t have a temp sensor, so it assumes that the air isn’t so hot, and gives me far more fuel than I need.  Yep, that EM-2 would sure tell me how hot the air temp is :-) In the mean time, I’m going to take this as another reason to NOT boost the engine too much at low altitude, since the air is so hot already. 

Now, as for injector mismatch problems- it seems that the only operational problem appears when you turn off the primary injectors (wimpy over-rated MSD’s), and try to run at low power.  At higher powers, the engine seems to function OK, but I have to turn the mixture almost fully CCW to make the engine happy at low power.  I don’t see this as a no-go problem, but would like to match these up better at some point.  I’ll be sending all my unused injectors (2-MSD’s, and 4- Mazda 550’s) out to someone this week to find out what they really flow. 

While testing the engine, doing everything I could think of to throw it off, I was going from idle to full throttle, then back to idle.  A friend on the ground was shocked to see a nice flame appear at the turbo exhaust when I closed the throttle suddenly.  I hadn’t noticed this before, but I’m not surprised, or alarmed by it, because RX-7’s do it too if you take off the catalytic converters.  What was more entertaining/disturbing was when I accidentally left the cold start switch engaged while trying to start a hot engine.  The engine was too rich to fire, but the turbo ignited the fuel, and kept a continuous orange flame about a foot long flowing out of the exhaust pipe.  I can live without seeing that again :-)

For the record, both the tiny tach, and the new Equus 8068 worked perfectly.  Static rpm at 30” MAP was 4900, and at 36” MAP was 5400.  This is just a bit below the 5000 at sea level that I was looking for, but I think I’ll leave it hear for now.  I’m pretty sure I have enough power to fly :-)

Finally, I took the plane for a spin around the taxiway, and tried to clean the rest of the crud from the brake discs.  About half way around the airport, I noticed that the left brake pedal would sink if I held it.  Knowing what this meant, I took it back to the hanger and found that the flare fitting on the aluminum hose at the brake caliper just decided to start leaking.  After all the times I’ve tried to over-stress these lines by standing on the brakes, it just decided that now was the time to leak.  By the time I got back to the hanger, it was just dripping from gravity pressure.  Just amazing.  Of course now I have to pull the top skin again to get to the reservoir when I fix the connection.  Rats.