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.
Brian Trubee
-----Original Message-----
From: Tracy <rwstracy@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Mon, Feb 6, 2012 6:00 am
Subject: [FlyRotary] Re: Upper end tuning
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 .
Brian Trubee
RV-4 13 BREW