auto diesel vs. jet fuel

[CMN]

I could'nt find anything on this with the search function, so here goes:

I know from my previous VW diesel, that it ran nicely on Jet A1. And the manual for my current turboprop (PT6A-67b) states, that autodielsel can be used for a limited period. 50 hrs I think.

So my question is; what are the differences between autodiesel and jet fuel in general ?

[hetfield]

Originally Posted by CMN

So my question is; what are the differences between autodiesel and jet fuel in general ?

The way to the gas-station.....

[john_tullamarine]

.. good to see this question as I have a number of diesel units to operate and one of the jobs on my list is to investigate precisely this problem ..

To start, I understand that the fractions are reasonably close and, in essence, diesel has a bit more heavy oil content that kero.

My interest is to find out what I need to add to slops Jet A kero to end up something pretty close to diesel ...

Next ?

[Piltdown Man]

Some years ago, the cunning members of the RAFGSA at Bicester used to put brake fluid in their "waste" JP1 (Jet A1 equivalent I belive) so that they could run certain diesel devices on this non-dyed fuel. A bit smoky, but it worked.

PM

[chevvron]

Duty payable (in the UK anyway)

[CMN]

'Non-dyed'; what does that mean ?

[Jetstream Rider]

Diesel is dyed to indicate duty has been paid on it. If you use non-dyed fuel in your motor vehicle, you are breaking the law, as no duty has been paid.

I would hazard a guess that water content is more tightly controlled with Jet A1 than with Diesel.

[Basil]

Red diesel

JR,

I think it's the other way round.

http://www.ybw.com/mbm/redalert/pdf/...l_campaign.pdf

http://www.ybw.com/mbm/redalert/index.html

have a lot of info and are important reading for anyone who runs a diesel boat.

They really are out to get us you know!

[XPMorten]

When producing fuel from raw oil, one heats up the oil in a destilation
tower. This process is called cracking. The "cracking" wil crack
the huge hydrocarbon atom chains in raw oil into smaller and lighter chains.
So, at the top of the tower you will get the lighter fuels, heavier fuels further down;

Gas
Kerosine
Gasoline
Diesel
Heavy oils (for big diesel engines)

The higher up you go in the tower the LESS self-ignitable the fuels are.
Or higher octane number if you like. Kerosine and gasoline need a spark
to ignite. Actually you don't ignite the fuel itself, but the wapor mixed with air.
Lower down (diesel etc) they self-ignite easier and only need high pressure to ignite.
These have what we call a high cetan number.

To get to your question, using the wrong fuel will cause the fuel to ignite
at the wrong TIME. Either too early or late. This causes a bad combustion,
detonating combustion, hotspots with uncombusted fuel, poor air/fuel mix etc.
It will damage your engine over time.

Combustion engines (on the ground) are all about thermodynamic effieciency. So using the right
fuel is essential. In the air there are other important factors as well like reliablity, weight/power ratio etc.

Cheers,

M

[Intruder]

Diesel has higher lubricity and higher energy content than Jet A. It will also not have the low freezing point that Jet A has, so fuel icing will be a problem.

[javelin]

1 to 2 % engine oil or clear two stroke oil in Jet A1 or heating oil will provide the lubricity needed to help a diesel engine along it's way on roads outside the United Kingdom. Within our shores, I have no idea what ratio you need

[mustafagander]

XPM, just for the sake of accuracy, the process you described is FRACTIONATING or distilling. It's not dissimilar to making whisky!!

CRACKING is another thing altogether. Cracking is all about "cracking" the longer (heavier) molecules of the petroleum feedstock to get more shorter (lighter) molecules petrol/kero/diesel). It normally uses a catalyst to facilitate the process, hence the term "cat cracking" - not a cruel process to torture pussy cats!!

[Loose rivets]

No mention of 'the cut'?

[XPMorten]

mustafagander,

Well, tried to keep it simple
Look here for a good explenation.

http://www.infoplease.com/ce6/sci/A0860338.html

M

[CMN]

So to put it short; jet fuel is less ignitable than diesel, and diesel contains lubrication. Right ?

And jet fuel is of another color, so the greedy people in customs can check your fuel filter to see if you have been robbing them....

[RatherBeFlying]

Avgas

When I bought my R5 in '76, the manual called for premium gas, just as unleaded gas became the norm and the premium pumps were switched over to unleaded.

The detonation was prominent with unleaded; so took to mixing in 100 octane and carrying an Explosafe container of 100 to mix in when buying gas off airport.

Trips were planned with gas stops at airports. Sadly the authorities put the screws to the FBOs and the number of airports I could buy from diminished.

Ended up stuck one trip; so put in standard leaded gas and did NOT get detonation. Drove car until rust termites stopped holding hands in '86.

[compressor stall]

Diesel (at least in Oz) contains more oil, and this is used for lubriating oil pumps in Landcruiser (and no doubt other engines). Older landcruisers (like mine!) don't need the oil (in the fuel) for lubrication of the oilpump so work just fine on JETA1. At least that what I believe!

Oh, and we run Haggulunds perfectly well on the leftovers of our Garretts' Antarctic Type Kerosene; both Cummins and Merc Engines!

[snips]

Used a 1:50 ratio Two stroke to Jet A1 mix for Snocats,Tractors etc . 4 Litre Bottles into a barrel of avtur
Works a treat and never had any problems.
Diesel has a higher Calorific value so more grunt for going up hill!