flyrotary@lancaironline.net Mailing List Archive

Al Gietzen wrote: > > In order to get it to run well below the transition point, I had to put > in large mixture corrections (lean). I concluded that my problem was > aggravated by two factors, my fuel pressure regulator was not MAP > referenced, and my primary injectors have about 12% higher flow rating > than the secondary. I assume that since you are turbocharged you using > a MAP referenced fuel pressure regulator (FPR). > > > > I finally got it running OK below transition; at steady state, but > reducing throttle from higher loads would take the MAP values below > where I could get the big correction in, and the engine would flood out > and stall. I have since replaced the FPR with a MAP referenced version > and we'll see if that matches the default settings well enough. I > figure once airborn, and I can put it into a decent and have a chance to > set mixture corrections for very low MAP. > I see that we are in the same boat with mis-matched injectors. Because of this I was anticipating a transition problem. It really seems that the cure is to remove the transition and bring on those low flow injectors in the low RPM range. Maybe with a large syringe and someone spinning the CAS to make the EC2 think the engine is running . I do have a MAP referenced fuel flow regulator, but I don’t see any significant changes in fuel pressure at the MAPs I have run so far. I see that device as something to allow the fuel flow through the injectors to keep up when it is facing higher pressure in the manifold. I noticed that things leaned out quickly even at just 23” MAP. I’ll let you know if the syringe trick works. Dave Leonard

The biggest problem continues to be very rough running anywhere

under 18”MAP. It really won’t run any lower because of and bucks

and surges (but it runs really great above that MAP). I am thinking

that the problem is the injector transition.

Yes, pretty clearly that’s it. I had problems at low MAP as well during the 20B dyno testing. I noted the following in the test report:

“The other difficulty was that the mixture was much too rich at low MAP values. Setting the correction at steady state conditions did not get the MAP values as low as occur when throttle is pulled back from higher power; resulting in a very rich condition which causes the engine to stall.

(How do you set the mixture correction at very low MAP?).

In order to get it to run well below the transition point, I had to put in large mixture corrections (lean). I concluded that my problem was aggravated by two factors, my fuel pressure regulator was not MAP referenced, and my primary injectors have about 12% higher flow rating than the secondary. I assume that since you are turbocharged you using a MAP referenced fuel pressure regulator (FPR).

I finally got it running OK below transition; at steady state, but reducing throttle from higher loads would take the MAP values below where I could get the big correction in, and the engine would flood out and stall. I have since replaced the FPR with a MAP referenced version and we’ll see if that matches the default settings well enough. I figure once airborn, and I can put it into a decent and have a chance to set mixture corrections for very low MAP.

Best of luck,