After what seems like years of testing (actual engine Hobbs time is only 6.8 hrs) I finally got a clean test run on the 20B. It ran flawlessly from idle to almost WOT (28.5" Hg. MAP) in today's run. Static RPM at this setting was 5950 which was higher than expected with a 72 x 104 3 blade prop. Blade stall could be a factor but the prop blast was enough to rip the hearing protectors off my head.
Bottom line is that the configuration I sent previously (in schematic jpg) is the tested and approved setup for the EC2 20B controller.
10-19-07
The problem with engine surge and roughness at around 3500 rpm turned out to be a failed diode on the rotor 2 secondary injector.
I believe this must have failed due to the high transient voltages that were present before adding the diode clamp and the solid state relay.
The schottky diodes only have a maximum reverse voltage rating of 100 volts. When replacing this part, I also installed diodes on the primary injectors.
After doing this, the engine ran perfectly in a previous test run until reaching the high rpm miss at 5150 rpm, at which point it ran very rough.
Today's test was to test the effect of reducing the Crank sensor to trigger wheel spacing to about .032" by removing the .062 washer which I had previously used to increase the spacing (~ .097").
(this engine installation has the Renesis Crank sensor setup) The theory was that the EC2 front end circuit was being overloaded and that a reduction of problem rpm threshold would confirm this when the spacing was reduced.
The test showed just the opposite effect. The high rpm miss was completely gone and I was able to run the engine at almost full throttle reaching an rpm over 5950 at about
28.5" Hg. WOT was not tested due to fears that the rail restraint might fail and nose the aircraft over. I am overjoyed with today's test results although I have not determined the exact phenomenon that caused the problem.
FBW throttle control continues to work well.
The only negative indications were oil pressure at high rpm which was about 59 PSI at 5900 with an oil temp of 190 F.
The oil pressure does not fall very much at lower rpm (2500 – 3500) where it is about 55 psi. Not sure if this is due to pressure drops in the system
(the sensor is at the lowest pressure point in the system) or instrument error. (the EM2 has not been calibrated for this function).
When first started, (oil cold) the pressure is 70 psi at any rpm above idle. I have installed a 70 psi pressure regulator so I assumed this was correct but maybe not.
The other problem is the engine's failure to hot start. I was unable to do it in spite of several attempts. It does not turn over very smartly when hot and the compression is not as good when hot.
I should take an instrument reading on this in a future test because it is difficult to feel the compression on a 3 rotor when pulling the prop through.
The very small battery and long cables (battery in tail cone for CG reasons) are contributing factors and I intend to install a larger battery (Odessy PC 680 currently used).