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Brian, I’m using this circuit to lower the CAS voltage that the EC2 see’s at high rpm. Might be worth testing. Bobby From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of bktrub@aol.com
Sent: Monday, February 06, 2012 11:40 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Upper end tuning Ok, I'll keep it in mind if I exhaust all other possiblities. -----Original Message-----
From: Tracy <rwstracy@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Mon, Feb 6, 2012 9:21 am
Subject: [FlyRotary] Re: Upper end tuning Not time enough for a technical discussion of the electrical / magnetic characteristics involved but it has to do with the fact that the EC2 was designed around the 2nd gen CAS which has very different characteristics than the 3rd gen. This is the same issue involved with the Renesis CAS (same type part as 3rd gen).
I am only guessing that your problem MIGHT have something to do with this. There is an EC2 modification that I've made for some Renesis users that solved similar problems. It may or may not help yours. If nothing else turns up, it might be worth trying the mod in your EC2 (not EM2)..
Tracy On Mon, Feb 6, 2012 at 11:49 AM, <bktrub@aol.com> wrote: I think we have. It seems interesting that it appears to be more rpm related than MP or fuel flow. I'll try going through all the other items I can think of- new spark plugs, mixture changes and a little more trial and error with the timing. What were your thoughts on the CAS incompatability with the EC2? And what would be your proposed fix? As you recall, I was having issues with really horrible and pants soiling backfiring which would commence about 200 feet agl after takeoff. That turned out to be a polarity reversal of the 360 degree sensing CAS. My engine was a JDM engine from a wreck. The only damage was to the CAS connector and a hole in the front housing. I did a rebuild and found the engine to be in excellent shape and fixed the front housing with a little tig welding. I wired the CAS with some miniature spade terminals, RTV and rescue tape. The only thing was, I had no way of telling what the polarity of the wiring was and had a 50% chance of getting it wrong, which of course I did. The CAS signal was of sufficient quality to run the engine up to all the speeds I could achieve on the ground, but once airborne, it quickly got into a range that was not achievable on the ground and the CAS signal was ambiguous enough where the engine would start backfiring violently. Lots of people would run out of their hangars to bear witness to the spectacle. The whole deal was a little outside my comfort zone. I"ve since obtained a proper connector from the dealership (for free!) and wired it in correctly. It was during this time that I recall your mentioning the possible CAS/EM2 incompatablity. So, if you would, could you let me know what your thoughts are on what you think a possible CAS/EM2 incompatabilty might arise from? Sent: Mon, Feb 6, 2012 8:26 am
Subject: [FlyRotary] Re: Upper end tuning Hmmm.... Hard RPM limit... Using the 13 BREW... Have we discussed the EC2 3rd gen crank sensor compatibility issue?
Tracy This was at any altitude- I'll take off at sea level and on climb out if the rpms get to 6100, the engine stumbles as if it were suddenly way too lean. So, what I'm saying is that this can happen at any altitude. It seems to be more of a RPM issue than of manifold pressure. As far as the EGT goes, it may be an instrumentation error. I've tried to richen up the mixture and then go up past 6100 rpm, but I still get the power drop. And yes, I have the EM2 set at the factory setting for engine max power, so all I'm seeing is just an arbitrary number. So, I'm going to change spark plugs and do some more flying. The weather is nice out here for the next few days so I have some opportunity to fully explore what's going on. Can't make an educated guess from the data given but here's a few questions & comments.
Can you clarify what you mean by "precipitous power drop"? Does the power go down at higher MP? (6100 at 22.6" aint bad on a FP prop. What was the airspeed & altitude? EVERYTHING MATTERS!)
Is the EGT imbalance only at high power? Are you sure it's not instrumentation error?
As Ed asked, what was the result of varying the mixture control at high power?
You say that engine is silky smooth below 6100. Does that imply it is rough above 6100?
The % power readout of the EM2 is meaningless if the fuel flow function isn't calibrated and you haven't plugged in a realistic value for your engine's max power.
Tracy
On Sun, Feb 5, 2012 at 10:01 PM, <bktrub@aol.com> wrote: I've got just over 20 hours on my plane today, all of the lower- end bugs have been worked out. Right now I'm having power drop off precipitously right at 6100 rpm- 22.6 inches of MP and around 70% power according to the EM2. This is around 130-140 mph IAS. The fuel injection Map shows a smooth graph at that point. I thought that there might be a timing issue so I tried advancing the timing about 2 degrees but that did not change a thing so I set the timing back where it was previously. I am seeing about a 180 f difference on the two rotors- I went to mode four to try to balance out the egts, but I could only effect about a 20 degree change. Rotor 2 consistently shows somewhere above 1800 F, which I tend to question. I'll re-check my calibration. I have had the injectors cleaned and tested so unless one of them got clogged, that should not be an issue. Still, I should pull them and have them re-checked. I may have an issue with the EGT probes themselves. Down below 6100 rpm the engine is smooth as silk, but obviously there is an issue above that .
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