Originally Posted by codprawn
The US forces did not convert their engines - they just use JP8 in them. In very hot countries they will sometimes add some extra lube but not always.
As far as biofuels are concerned remember that many countries including the EU are starting to add biodiesel wether you like it or not.
You mention HFFR tests - JP8 on it's own was pretty poor 700 micron - with 1% castor oil it achieved 185 micron - a hell of a difference - it was 285 with rapeseed oil - castor was the very best!!!
Yes it's an extremely complex subject but much research has gone into this - especially by the military,
And talking of the military it is quite common for small quantities of surplus jet fuel to go missing and end up powering all sorts of things..........
OK, so we agree that firstly, lubricity does not meet the diesel max spec of 460microns, so they need a lubricity additive in there, (different samples of JP8 will give different results depending on which crude oil they can from, so it could be 500, could be 900. The US Army will not wish to risk destroying it's engines in battle...
Secondly, cetane index/number, the fundamental for diesel fuel performance. Min spec for DERV is 46 and 51 respectively. Jet fuel is LOW cetane. Remember it comes off the distillation tower between diesel and naphtha (prime gasoline component), and gasoline is by definition very low cetane (high octane). Jet fuel (including JP8) has no cetane spec, and will be in the high 30's or low 40's (occassionally higher depending on crude). The US forces must be adding a cetane improver to their diesel engines or they would run rough and produce low power.
Of course, for their planes and tanks (M1 Abrams runs on a jet turbine), they need not touch the JP8, as it is being run in a turbine, where it was designed to be run. For the diesel engines, either they have modified them in some way (lower grade injectors, different compression ratios) or they apply additives to the JP8, either in vehicle or in delivery truck.
The process of going to this 'one-fuel' policy took many years, so it wasn't as simple as saying, hey, let's just run jet in all our vehicles.
And needless to say, standard JP8 is not going to run in any spark ignition (gasoline) engine, so these are being (have been?) phased out or converted to diesel.
So do yourself a favour - don't run heating oil or kero, pure, in your diesel car, unless it's an old, low tech one, (pre 1995 to be safe). Your new diesel would run yes, may sound fine.....but long term? Think about injectors at 1800 bar, your particulate filter blocked by heavier, higher sulphur fuel (jet fuel sulphur is 0.3% max, diesel is 0.005%)...........
As for biofuels, of course these have been in our DERV for ages, up to 5% in France, a bit less in the UK I think. Interestingly, noone seems brave enough yet to allow higher concentrations (above 10% say), due to doubts about long term performance. In any case, even at 10%, there wouldn't be enough biodiesel to go round, until the farmers ditch the wheat, etc and go for soya.......but that's another story.....