Ed,
Attached is my map table as of today after I tuned it tied down on the ground. I have a 93 13BREW that is normally aspirated, it has 9.1/1 compression, swinging a catto 74 dia x 88 pitch prop through a 2.85/1 PSRU. This EC2 is set up to accomodate turbo engines, so I have addresses that go up to 38 inHg. They are not used.
I generally idle at MAP address 11 mp of 14.9 inHg. at around 1600rpm. This is a 60 degree day at barometer setting of 30.3. Advancing the throttle, the EC2 switches over to the high RPM table at MAP address 17 (mp 17.2), going straight to address 80. My staging point is 84 (mp 19.1) from there up to full throttle, MAP address 106 mp 29.1, the transition is smooth. At full throttle on the ground I'm getting 5200 RPM. When I go much past that RPM on takeoff, that's when the missing starts. I'm still guessing that I need to richen up the mixture in the addresses above 106.
Any input from anyone on this would be appreciated.
Brian Trubee
-----Original Message-----
From: Ed Anderson <eanderson@carolina.rr.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Fri, May 13, 2011 3:18 pm
Subject: [FlyRotary] Re: Engine Tuning
Brian, what values do you have in your fuel map around 90-105? I have values of 172 for WOT and at times (cool OAT) I have to enrichen the mixture beyond that with the manual mixture control
Ed
Sent: Friday, May 13, 2011 5:35 PM
Subject: [FlyRotary] Engine Tuning
Since the weather has been cooperating lately, I've had the opportunity to put a few more hours on the airplane. On the ground, I can go from an idle up to full throttle and the engine will be smooth. But when I take off, it seems that as soon as I'm up a few hundred feet off the runway, I get hellacious backfiring at full throttle. I can mitigate it a bit by throttling back to about 5100 rpm, and turning the mixture knob to near full rich. It's getting to be a bit nerve wracking to take off thinking I've got it smoothed out and then get a series of hand grenades going off under my butt. I'm thinking that I'm still running too lean up at map address 106 or so. So, I go into the edit page and richen up the mixture around those addresses. I think I'm creeping up on smooth full throttle running.
The good news is that my coolant runs at 175 degrees and oil at less- so the cooling is more than effective, I just need to close up my air inlet a bit or restrict the outflow.
Brian Trubee