Why inconsistant engineering units

[wrench]

Why does my originally equipped J's cylinder head temp gauge read in Fº (Fahrenheit) and the Exhaust Gas / OAT temperature in Cº (Celsius). I don't know about you but I like the finer resolution of Fº especially when the outside air temperature gets close to the freezing point.

Then I will read a LOP or ROP post and sometimes engineering units are included with the numbers stated but mostly not. Now what? I guess just keep looking out for traffic, birds, altitude, heading, etc. etc. then lean until rough then enrich until smooth, and it can even be done by ear. Seems to have worked in the old days but I'm not sure about now after reading the posts.

Is it just a plot so I have to buy an engine analyzer and then I can pick my own engineering units to display? If so, which analyzer? Can't disable the original equipment because its part of the operating instructions who knows what hoops you'd have to jump through to change it and don't forget all the official government permissions. God knows you wouldn't want to have the same temperature units on the panel to avoid any confusion without the governments superior input and direction on the subject. I'm told I can't even just put a new STC'd gauge with new Fº calibrated probes in place of the original because the op manual would still refer to the Cº readings.

Lets not even start with Knots or MPH displayed on the different model year airspeed indicators. “Don't approach at more than 81 or 85 or whatever for “X” condition” I see similar numbers like that from time to time for approach speed guidance when a new driver may ask...... 81? ….. eighty one WHAT? Mach would have worked all along but everybody except SR71 drivers just hate decimals, “my approach speed is 0.1563467 and I cruise at 0.2850539 but I just round it up to 0.2851 what's yours in your Mooney”?

Oh well just a rant because the planes down for maintenance and I have this free time to think about improvements in equipment and operation........damn.

But seriously, what has been in your experience the least painful path to a modern engine analyzer installation for a 1978 J?

 

[Parker_Woodruff]

Quote: flyingwrench

But seriously, what has been in your experience the least painful path to a modern engine analyzer installation for a 1978 J?

 

[carusoam]

Bill, your rant is well taken..

It is snowing where I am and therefore no flying.

Fortunately, old airplanes never go away, and we are stuck with whatever leading edge technology they were built with in their time.

My 65C had an EGT that had no calibration, accept the lines were spaced 25 deg F apart.  No idea what peak value was.

I like Parker's JPI recomendation.  Complete data set in one place with alarms.  Legally replaces the old junk that is scattered across the panel.

Best regards,

-a-

[danb35]

I've had good experience with EI, so if you were interested in the glass, all-in-one, replace-all-the-engine-instruments idea I'd probably suggest the EI MVP-50.  I'd expect that any digital instrument would be able to read in F or C.

[robert7467]

Man, Bill echo's my thoughts exactly. I've always been frustrated by the mixture of Celsius and Fahrenheit and recently got all of my instrumentation to the point of where they read Fahrenheit, including an OAT probe for the JPI-700. Simply thumbing through the POH one will see the two units of measurement intertwined on the same page. Add to the mix that the Cylinder Head temperature gauge is calibrated in Fahrenheit yet the EGT gauge is Celsius. In this respect the plane is absolutely schizoid.