high pressure and cold temps = more power

[RFguy]

anyone finding that with all this high pressure and low temperatures, they are needing more right pedal  on TO climb that they usually do ? I am !   Cowra was 1000' below sea level yesterday mid morning..... (instead of 1000' above) 

[pmccarthy]

I reckon I did my best ever short take-off yesterday without trying.

[facthunter]

Of Course it's noticeably better when it's cold and a higher pressure. It's when it's the other way you have to exercise care.. Even hot air over the end of a sealed runway can reduce lift suddenly. Nev

[Area-51]

 

[facthunter]

I don't have your level of trust in the University of U tube.Nev

[Deano747]

Sort of similar in that it gave more air - but a LOT more fuel.

Yamaha's V-Max had a system that utilised 1 carb per cylinder up to about 4,000 rpm (don't recall exactly the rpm) and then 2 carbs per cylinder.

It gave quite a rush when the 2nd carb kicked in and the front wheel went skywards .........

[Area-51]

Many automobiles from late 60's to 90's had dual stage carburettors; Rochester, Holley, Stromberg, 2 or 4 barrel. Then there were multi stage multi valve cylinder heads to assist low end torque and high end power, and then variable induction plenum chambers... mechanically there really isn't anything new under the sun that wasn't tried by the 1940's.

 

The 3% +/-  power per 1000' air density rule is a good rule to remember for anyone flying behind a non boosted engine. Relative humidity also alters power and performance to a lesser degree.

[RFguy]

however some puzzles : 

What I also saw was higher than usual, for a given fuel flow , was slightly high (20F) EGT (single EGT readout) , (leaned to peak EGT at 65% power) ....despite the negative OATs.

- As usual , no difference on AVGAS or 98ULP.  

...have a single EGT readout. 

My 1st guess is that in these conditions, one or more cylinders  were going too lean (before engine stumble) later

IE , during the process of leaning for peak EGT / engine stumble, the monitored cylinder EGT got leaner (and hotter)  than ever before  when perhaps other cylinders were later getting leaner than usual, hence reading a overall leaner mixture onm the monitored EGT before stumble.

Usually, the monitored EGT cylinder when it just goes a touch beyond peak EGT, the engine stumbles.

Useful reason to have EGTs on all cylinders. Useful for troubleshooting/depuzzling the puzzle.

 

Edited August 2 by RFguy

[skippydiesel]

Area-51

 

Over compression engines are still with us - they are called diesels ( compression ignition) engines. 

[Red]

Video is showing is a higher compression than normal for the time  engine with a 2 stage induction system, never heard it called Over Compression before, seems like one of those terminology inventions Americans are fond of