How does Avgas differ from the standard Unleaded and Diesal (and old 4*) available from petrol forecourts? :confused:
Why don’t aircraft use the 2 fuels that power car engines as surely there isn’t that much difference between, for example, an SA Bulldog engine and a Ford Mondeo engine?
By: wessex boy - 18th December 2006 at 17:27
Unleaded is gently rising on Octane at the moment, standard is 95, BP offer Unltimate at 97, and now Tescos super is 99. Avgas is 100
It makes a huge difference to my Wife’s Honda CRV, but hardly noticable in my Impreza:D
By: BlueRobin - 17th December 2006 at 12:31
isn’t that much difference between, for example, an SA Bulldog engine and a Ford Mondeo engine?
I just saw this.
Bulldog engine is made by Lycoming, horinzontally-opposed cylinders (boxer). The technology dates back to WW2 and hasn’t changed much since.
Mondeo petrol engine, e.g. Duratec, with inline cylinder arrangement. Mass-produced, computer-aided design to high tolerances. Roots are probably about 10-15 years old.
By: BlueRobin - 17th December 2006 at 12:19
AVGAS is a higher octane rating and also contains lots of lead, so not much use for your car compared to standard forecourt unleaded. Using forecourt unleaded in aero piston engines runs a higher risk of vapour lock and detonation. You can use UL on certain aero engines, in fact some prefer it, with lots of research has be done in the US, but it acknowledged to be of little use for higher-powered, supercharged or turbocharged engines.
Diesel is a kerosene/paraffin-based oil fuel so is totally incompatible with AVGAS. Just like you don’t go sticking unleaded in your diesel car and vice versa! However there are some diesel-based aero engines that run on diesel and Jet Fuel. Jet Fuel is also a kerosene/paraffin-based oil fuel so the two are generally compatible. However Jet Fuel has less lubricating properties so in the case of the Thielert engine fitted to aircraft like the Diamond DA40/42, certain parts have to be toughened to cope. Jet Fuel also has additional chemicals to allow operation in lower temperatures, disel does not so will wax and solidify.
There was an article on AVGAS in the AOPA UK mag recently so might answer your questions in greater detail.
http://www.iaopa-eur.org/mediaServlet/storage/gamag/oct06/Avgas.pdf
from
http://www.iaopa-eur.org/contentServlet/oct06.htm
Also read through the following Wiki articles.
http://en.wikipedia.org/wiki/Petrol
http://en.wikipedia.org/wiki/Avgas
http://en.wikipedia.org/wiki/Jet_fuel
http://en.wikipedia.org/wiki/Diesel
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December 17, 2006 at 11:10 am