flyrotary@lancaironline.net Mailing List Archive

Yeah; I’m sure my experience isn’t much different than others on the first runs. I guess I had higher expectations since I’ve run on the dyno, and had things pretty well dialed in. The other is that; except where I was using different sensors, I expected to have hard data from the EM2, and it seems there are enough surprises that it cast a shadow on much of the data. Makes for some anxiety.

First fuel pressure is key. You want it lower. I have the same TWM fuel pressure regulator that you do. Make sure that it is hooked up to the manifold. You should be seeing pressures closer to 32psi at idle. I opened up the tension screw on the pressure regulator all the way. That gives me about 41 PSI with the engine off, up near 50 when running boost, and 32 at idle. Any test I made with higher fuel pressures made the situation much worse.

I understand that the EM2 is preset for a VDO 0-100 fuel pressure sender. Mine is a 0 -80, so I adjusted the scale factor from 10.23 to 12.8, and the low level offset just a bit to get 0 at zero pressure. But is the reading now correct? I guess I’ll believe it when I have another gauge to verify it.

Try different configurations with the manifold pressure lines. Make SURE that each line is connected to all the runners/rotors. In my set up controller A samples both rotors right at the port, while controller B samples the pressure (from both runners T'd) just downstream of the throttle body. I find that A runs a little better on the ground and B seem to be a little smoother at altitude (though both work very well above 2000 RPM.

The TWM MAP port is connected to two of the three barrels (one per rotor) so it is averaging rotors 2 & 3. Worked fine in the dyno runs. I added a port at the rotor 1 intake, which I’m using for the controller B and the fuel pressure regulator.

Keep playing with the MAP and work very hard to make sure there are no gaps. Use a wide Mode 2 band at first, then fine tune with a narrow one.

I had the mixture correction table mapped out pretty well on the dyno, except at very low MAP, I think around 12-13 is as low as we saw on the dyno. Two things have changed since then – the pressure regulator I had then was not MAP referenced (fixed at 40 psi); and, when I sent the EC2 back to Tracy for updating earlier this year, he made some adjustment (I know not what) to compensate for the two injector sizes that I have (570 cc.min primaries and 500 secondary). I intended to star over with the default, but following the directions to reset did not change the correction values. I then decided it best to work off the mixture mapping I had done. I have made no attempt to change the mixture table yet, and viewing it on the EM2 it seems OK. I adjusted the mixture with the EC2 mixture knob at 2000 rpm from about 10:00 oclock (rough - too lean) to 5:00 (rough - too rich), and it was smoothest at about 2:00, but still rough.

I finally got my to idle pretty good down to about 1200 or 1300 (sometimes 1000). It actually seems to run a little better when cold. Sometimes it runs exceedingly well and sounds like music. Sometimes not. But if it runs rough all I have to do lately is get it back above 1600 and it settles down.

Keep at it. If you want I will be working on mine all weekend and you can come down to MYF and hear it idle if interested.

Did I know you were at Montgomery? I thought you were somewhere up around LA. I might like to get down there and chat, but don’t know when right now. Maybe you could send me a number where I can get in touch. Alg3@cox.net.

Thanks,

Dave Leonard

> I guess I have now done what I’d consider the first serious runs of the

> engine on the plane, and I have so many question marks in my head, it’s hard

> to know what to address next.

> The biggest issue is; I cannot get smooth running up to about 2200 rpm;

> which is as far as I went. At about 2000 I adjusted mixture from too lean

> to too rich, and nowhere does it smooth out completely – some roughness,

> mild surging. At lower rpm, 1000 – 1500 it is quite rough and unsteady,

> which is disconcerting in itself, but worrisome when it goes through periods

> of torsional vibration with the reduction gear backlash, which is noisy and

> shakes the plane.

> Of course it brings back the recent discussions of you other guys with the

> 550 injectors in the primary. I kind of glossed over that because I

> recalled smooth running on the dyno. In hindsight now, I think the operator

> figured out early-on that to keep it smooth he needed to keep some load on –

> just turn the load knob a little and it was fine. And on the dyno when it

> wasn’t running smooth, no big deal – no redrive to backlash, and the engine

> is bolted down in the next room. You could just hear that it wasn’t running

> smooth.

> Still, I suspect something is different now; and perhaps you’ll indulge my

> dumping, and pass on a clue or two.

> At 2000 I’m seeing a 13.1 MAP reading. Seems low to me. Is it? That puts

> it below the stage point, yet when I turned off the primary injectors, it

> continued to run; just rougher. Same effect turning off the secondaries.

> Hotest EGT was at about 1100, lowest about 980. Bigger spread than I ever

> saw on the dyno runs, but the data we took there was always under higher

> load.

> Fuel pressure reads 50 psi, TWM tells me it came to me preset at 43.5. When

> the coolant temp read 125 when the pipes and rad tanks were just about too

> hot to touch, which I guessed to be more like 140. I’m suspicious of just

> about every readout. Later when the WT read 140, the CHT TC that measure

> temps in and out of the rads were reading about 85. I believed backup

> gauges were unnecessary.

> Oh yeah; the mixture bar reads just about full scale all the time, even when

> the engine is about to die from being too lean. I have a different heated

> Bosch sensor, which I assumed would have the same 0-1volt range. Maybe not.

> Is the sensor output voltage low when lean or rich? With the engine off and

> sensor heated I measured .052 volts. I tried to get a reading with the

> engine running, but all I got was about .025 and I can’t be certain I had

> contact with the lead – and with the prop spinning so close by I didn’t

> spend too much time trying.

> One other major concern. With hot oil (150) at the filter block where the

> feed goes to the redrive, the ¼” Al line to the redrive was hardly above

> ambient temp a minute or two after shutdown; suggesting little or no flow

> was going there. Oil pressure was in the 90’s. I’m not aware that there is

> an orifice in there. This has me a bit baffled.

> Oil pressure, coolant pressure, Oil temp seem fine.

> Maybe I should go to a movie.

> Al (not ecstatic)

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