I am writing a spreadsheet that uses an interesting method of calculating power output for Lycoming engines. I acquired an old Lycoming document that explains how to calculate power based on fuel flow and the amount the EGT is rich or lean of peak EGT. The method is apparently based on a bunch of runs in the test cell, where fuel flow, EGT, rpm and power output were measured. Lycoming determined that for a given rpm and manifold pressure that peak power was achieved with the mixture set to give an EGT of about 115 deg F rich of peak EGT. They used the test cell data to determine relationships between EGT delta from peak, specific fuel consumption, horsepower, friction horsepower etc.I am looking for some data from aircraft with Lycoming engines of 235, 320, 360 and 540 cubic inch displacement and constant-speed props. Read on for more.I am writing a spreadsheet that uses an interesting method of calculating power output for Lycoming engines. I acquired an old Lycoming document that explains how to calculate power based on fuel flow and the amount the EGT is rich or lean of peak EGT. The method is apparently based on a bunch of runs in the test cell, where fuel flow, EGT, rpm and power output were measured. Lycoming determined that for a given rpm and manifold pressure that peak power was achieved with the mixture set to give an EGT of about 115 deg F rich of peak EGT. They used the test cell data to determine relationships between EGT delta from peak, specific fuel consumption, horsepower, friction horsepower etc.So, in theory, with inputs of engine displacement, rpm, EGT delta from peak EGT and fuel flow, it should be possible to calculate the power output. I crafted a spreadsheet that uses this method, and now I want to get some data to see whether this method appears to give reasonable results in the real world. I am concerned that variations in the accuracy of fuel flow systems, variations in EGT probe locations, etc may mean that this method is not useable outside the test cell.If this method works, it would be useable by aircraft with EGT and fuel flow indicators. Manifold pressure is not required, so this may be especially useful for aircraft with fixed-pitch props, as many of them do not have manifold pressure gauges.I am looking for some data from aircraft with Lycoming engines of 235, 320, 360 and 540 cubic inch displacement and constant-speed props. Read on for more. In order to assess the usefulness of this method, I am looking for data from aircraft with Lycoming engines of 235, 320, 360 and 540 cubic inch displacement and constant-speed props (the CS prop is needed to get data at consistent MP and rpm combinations). I intend to compare power calculations with this method, vs the more traditional power chart method using rpm, MP, altitude and temperature. I need the following data at a range of altitudes and power settings:For each test point record the following data:1. Altitude,2. air temperature,3. rpm,4. manifold pressure,5. how many degrees the EGT is rich or lean of peak and6. fuel flow.Ideally, I would like to get several sets of fuel flow vs EGT at each altitude and power condition. If possible, it would be good to get some points at peak EGT, one point lean of peak EGT and several conditions rich of peak EGT, including at about 115 deg F rich of peak EGT (or 64 deg C rich of peak). The peak EGT and lean of peak EGT are probably only possible at lower power, and may not be a good idea for many engines. Be cautious - don't hurt your engine.Also indicate:1. the engine model,2. type of ignition system,3. carburetor, fuel injection, or Ellison throttle body injector,4. any engine mods,5. EGT units (F or C),6. fuel flow units,7. whether the fuel flow and tachometer have been checked for accuracy (and if so, roughly how long ago).8. If you know the spread in fuel flow between when the first and last cylinder hits peak EGT I would like to get this data too.To check your manifold pressure gauge accuracy, please go to an airfield that issues an altimeter setting, and has a known field elevation. With the engine stopped, record the manifold pressure, altimeter setting and field elevation.Once I get a few sets of data, I will crunch it to see whether this method seems to be useful. If I judge it useful I will publish the spreadsheet.Please send the data direct to me at This email address is being protected from spambots. You need JavaScript enabled to view it.