flyrotary@lancaironline.net Mailing List Archive

The solution Lynn is the hot wire mass flow sensor. I'm not sure if Tracy could incorporate one in place of the map sensor. The circuitry may be more complicated. There are comercial versions available fro use with many of the throttle bodies. A single P-port inlet tube without an air box poses a real problem. Some of the older mechanical systems are easier to work with on single tube openings. Many of the bikes used an alpha-n system measuring only throttle opening RPM and had a sensor for speed, usually at the rear sprocket. The needed injector map was VERY complex and hard to modify. True mass flow would be better. I wonder what the LeMans 26B used?

Bill Jepson

No doubt that Tracy could design a injection system that uses a mass flow sensor - after all, as you know, the system only wants to know (and doesn't care how) how much air mass is in the combustion chamber in order to determine the fuel to meet your desired A/F ratio.

However, unless there was some significant market demand for such, I doubt it would be worth his investment to do so. I have not given it any thought, but there might be reliability/safety issues using a air mass flow sensor vice a manifold pressure sensor in aircraft application.

For one thing it would be a bit more of a hassle to have two air flow sensors (for redundancy) spacewise and perhaps plumbing wise (air) than with the two pressure sensor. -The pressure sensor can be stuck any place including inside the EC2 box in the cockpit area with just two small hoses running to them - not so with two air mass flow sensors.

The Alpha-N system based on Throttle position and rpm might be more suitable, but as Bill indicated the fuel map might be more complex as there would be no direct indication of engine load such as manifold pressure or air flow would give. Another challenge would be to have a Throttle position sensor which would be compatible with all the variety of TB that folks use.

So it certainly could be done, but unless there was some market demand for it, I don't foresee it coming.

Just my 0.02 worth and I certainly don't speak for Tracy

Ed

Ed