rob x38 got closest.

Manifold pressure is simply an indication of how much air is available for combustion...how much fuel you put with it dictates how much power is produced.

High wing drifter my Bonanza is sitting in a hangar in Australia undergoing it's annual with the prop off being overhauled....actually it should be finished by now but you know what LAMEs are like, but I digress...it's MP gauge is reading 29.5in...but it's developing no power.

Yes the fuel flow in GPH x 14.5 (memory ?) will give you HP when lean of peak EGT.

Nothing in a typical piston powered aircraft indicates how much power is being produced...a combination of MP/RPM/FF have been worked out by the manufacturers for a range of density altitudes but no one gauge, or combination actually indicate HP or % power.

The throttle controls the air side of the fuel/air ratio and the mixture and RPM control the fuel side....RPM? You bet...when you adjust the RPM you also change the speed of rotation of the engine driven fuel pump thereby leaning (lower RPM) or enrichening (higher RPM)...in my A36 it equates very roughly to 1 liter /100rpm....and is instantly shown as a change of EGT followed shortly by the CHT either increasing or decreasing on the EDM 700.

In my aircraft the throttle stays wide open from the start of the takeoff roll until very late in the descent...In cruise I make small adjustments in power with the rpm or large ones with the mixture. Less power required= less rpm or leaner mixture and more power is the opposite.

Note that this only works lean of peak EGT. ROP leaner is more power and heat until just before peak EGT and then the leaner you go the less power/heat you produce.

Fascinating stuff really.

The Manifold Pressure gauge reads barametic pressure.
For those who have seen vacuum gauges attached to automotive engines, it is essentially the same thing, but the gauge reads 'backwards', ie. with a MP gauge, Full load will read high manifold barametic pressure, a vaccum gauge will read low vacuum at high loads.
Regards,
White Bear.

I seem to remember that engine oil has five main uses - forgetting that it can be used to actuate ancillary services like CSU, etc.

1. Clean
2. Lubricate
3. Cool
4. Seal

5. Protect - specifically protect from corrosion.

Anyone confirm/deny?

For me the topic has now become a question of who is interested in what they do......

For example the majority of people here have a genuine interest in GA and strive to learn a lot, however, there is a group (growing) who do enough to pass the tests. It's a bit like the driving test but moved on.

Question: how many 20 hours learner drivers can go straight to the M1 at 70+MPH
Answer: all
Reasoning: Doesn't make it right