On Sun, Jun 14, 2009 at 10:47 PM, Don Wallker
<drwalker@gbis.com> wrote:
Now that I have the cooling problem well on the way to being solved. It's time to ask you guys about not developing full power. The RV-8 flys great,but is only producing what feels like 150 hp or so. At this point in the engine development, I'm not feeling confidant enough to take it much outside of the traffic pattern. Running strong as long as a don't take off on B controller. I'm only getting 6400 RPM or so in flight
That really is low if using C drive. What was airspeed? That affects things a lot.
and the throttle won't give any more power past the 2/3rds point.
There must be something more restrictive than the TB in the intake tract. Or, the manifold design is bad (turbulent flow ?)
66mm ford TB
I spent this morning running it on the ground and have some data that my shed some light on the situation.
R1 EGT R2 EGT prop RPM manifold pressure EM-2
Both inj on 1570 1589 5850 at midrange O2 25.0
Both, rich 1710 1450 5890 27.8
Sec only 1530 1570 5900 at midrange O2 26.5 Pri only 1606 1587 5443 at midrange O2 27.9
Always report airport altitude when reporting MP. Otherwise we can't tell if this is normal or not. At sea level, these numbers would suck. The fact that WOT MPs are different suggests that your MP data is bogus. Is midrange O2 best power point? If so, the reading may not be normal for unknown reasons. Usually about 70 - 80 % is best power. Only odd reading was "Both Rich" numbers. I suspect this is not valid data since others were normal.
What size secondary injectors are you using? Stock?
The interesting thing is that I am getting about the same power using one or the other set of injectors.
Normal.
What I am doing is tying off the plane to my truck, running it to full throttle and then turning off one set of injectors and then the other and recording the info. Could it be that I am flooding on rotor 2 with both sets on?
Don't see indication of this but then O2 reading may be suspect.
I'm not seeing it on the O2 mixture graph. I'm running with the cowl off for better cooling and have temporarily added a radiator fan. This gives me 2 or 3 mins more run time. It also cools things down faster for the next run. Unfortunately, the manifold reading don't mean anything. The numbers jump around on the EM-2 from 19 to28. I just took down the ones that seem to be displayed the most. Hummm?
Major instrumentation problem and must be fixed before making any hard conclusions. See Al's comments. Could be causing EC2 problems.
Engine running smooth. This jumping around has been like this from the beginning. I have lines running to ports on the front of the manifold and rear and have them teed together and then to the EC-2. Yes, the lines are tight on the EC-2. My mechanical gauge is smooth. I doubt the pressure is fluxuating. I think the signal is being distorted somewhere.
Always use the PLENUM for MP tap unless there is a VERY good reason not to (like you haven't got one)
Additionally, When I switch off one of the Injector banks, the RPM display on the EM-2 goes to 0. Not NOP. This happen with both the Primary and secondary injectors banks.
If you switch off the primaries the reading will go to zero and FF also. These readings are sensed by the connection to the rotor 1 primary injector. This is normal. NOT normal if it happens on secondaries.
I have always had a problem with Controlled B. It does not seem to copy from A. I have tried this many times, with all other power in the plane off. It is quite different running on B than A and I have to adjust the mixture a lot as I advance the throttle.
Possibilities include not really copying for some reason. (wiring, procedure, etc)
Temp sensor on A not mounted or connected properly. B will always look a little different if the air conditions are not median (temp at 75 F). B has no temp or voltage compensation so it may require some adjustment to mixture control. Remember, B is just to get you home in case of controller A failure. Would it?
These engine running conditions are also happening when I turn everything but the essential buss off.
I've tried some of the things you all have suggested. Disconnecting the Hushpower 2. Louder but no real RPM diffferance. It's about the same loudness as an unmuffled O-540. For those of you that don't know, I have a tangential muffler in series and acting as a manifold. I even turboed it this morning by attaching the shop blower to the intake to pressurize the intake to make sure there is not an 'eddie' in the intake manifold that is preventing air to flow to rotor 2. All I got was about 50 more RPM and the same EGTs. Didn't record the manifold pressure. I've switched the injectors, no difference. Some possible solutions would be to weld on a bung to each rotor exhaust and add a switch to see where the individual rotor are as far as O2 is concerned. Another solution is to swap out someone else's EC-2 that is set up for Renesis and the small primary injectors and the large secondary. Anybody? The fact that B controller won't copy makes me think there may be a problem here. Another possible solution it to rewire using Joe's suggestion from yesterday of using twisted pairs, although if this is the problem, it is happening on the power wires and not the signal ones. Another is to use Tracy's suggestion from his post today to put the EM-2 and EC-2 on it's own breaker. My setup now as per Tracy's original diagram, a non critical buss that has the EM-2, instruments, radios, flaps,etc. on it and a critical buss with coils, injectors, fuel pumps and EC-2 on it. I'm thinking there is one common cause. Well, at least hoping!
Could be but most cases I see are a variety of details.
Tracy Crook
Your thoughts, suggestions, admonitions
Don Walker
N113BR
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