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Differing properties of fuel.

For the first half of my flying life I flew only piston engine aeroplanes, starting with the garden variety of flat horizontally opposed engines then as aeroplanes got bigger, radials engines which delivered more power. I first flew a turbine in ’93. A big step forward and a very expensive step too. Every pilot loves turbines, they start easy, no back firing or under or over priming, not prone to failure and free of vibration. But radials rumble and do have such a pleasing sound.
Turbines are made to burn Avtur or Jet A1 which is really a marketing term for kerosene. All of these 3 have a specific gravity of about 8, which is, in metric terms 0.8 kilograms per litre plus or minus about 4 grams.
Some ag.operators burn diesel which has a higher specific gravity of 0.9 kilograms per litre, plus or minus about 5 gms.
In Malaysia we burned exclusively diesel. Diesel gives off horrid and unpleasant fumes. The burn is, I understand, about 33% efficient (about the same as piston diesel engines) so much of the exhaust is unburned fuel. It’s hard on the eyes and lungs and I sometimes wonder if I and other pilots will succumb to lung cancer. I should mention we climb in and out of the aeroplane many times each day with engine running. Kerosene too is unpleasant but not as bad as diesel.
For takeoff we apply full power which is determined by going to the max of permitable torque or max permitted temperature or max engine rpm, which ever gets to the red line first. On a good engine this is torque. Now this is the interesting aspect. Full power on diesel burns less volume than kerosene. Here’s why. Diesel is heavier thus has more energy.
The reason for diesel being harder on the eyes is said to be the sulphur content. And this depends of course the location it is sourced and refined. It is also more corrosive on the engine. I once heard it said that if kero is more than 6c per litre more expensive than diesel, burn diesel.
As I said pilots climb in and out of an aeroplane many times each day. It is practice to shut down if a stop is to exceed 20 minutes. Here is the reasoning. The substantial part of wearing of a turbine is from rapid temperature changes. On start the temp climbs from ambient to about 400c and on final light up to about 650c very rapidly, about 12 seconds. On shutdown from 550c to about 150 even more rapidly. A startup/shutdown is what is known as a cycle and this along with running time determines the time/life of an engine so shut downs are kept to a minimum.
Now this is of interest to motorists with diesel burning motor cars. Here in Australia one fuel company sells high performance diesel. It is lighter specific gravity and I guess it would contain some kero or lighter fuel. This gives more power or performance but is not really necessary because most diesels have sufficient of both. I believe it is simply a marketing tool. Fuel is extracted from the earth and performance fuel is an extraction from my wallet. Most Model A readers who read this forum are in America and pay considerably less for you fuel than us down. For this reason we down under are more conscientious of fuel costs.
I acknowledge that lighter fuels are added to diesel during the winter months so as to stop waxing. I might also mention that those aeroplane operators who burn diesel must, in winter, fill with kero on the last refuelling of the day because a cold morning start fails or "hangs up" on this heavier fuel.

If any reader wishes to add to this or correct my figuring I will not be offended.