I seem to recall hearing that another reason for favoring diesel vehicles over gasoline vehicles in a combat theater was because of the electrical noise emissions from the spark ignition system on a gasoline engine. These aren’t present on a diesel. It definitely matters for radio astronomy, but is it actually an issue for battlefield stealth?
I think, though, they leave a BIG heat signature. Not so good for infrared missles.
Aw, that’s a boring sign. I hoped you were going to post the one of a big spark plug with the red circle-slash over it.
I doubt that’s relevant for military vehicles, though, because they’re just not stealthy. There are lots of easier ways to detect an Army convoy.
From what I understand, it goes straight back, rather than out the side like most tanks, which is somewhat helpful for not immediately giving away where the tank is.
The newer ones are suprisingly efficient. I had a 2011 gas pickup (5.7L) which weighed 5800 lbs. and got 15 city, 19 highway. I now have a 2017 diesel (6.7L) which weighs 9200 lbs. and gets 16 city, 23 highway. Oddly enough, each truck gets the same mileage when towing my 8000 lb. trailer. FWIW: Weights are from the CAT scales with no load, just a full tank and me.
Back to the original question, I thought the main advantage of diesel was due to safer long term storage. That’s why I bought mine.
I do not have experience with the Honeywell AGT1500 used in the Abrams; but have experience with other gas turbines.
Gasoline engines have Octane numbers, Diesel engines have Cetane numbers and gas turbines have Wobbe numbers.
Although gas turbines have a wide range in Fuel, they do have limits. Now the army may have more flexibility, because their gas turbines do not need to meet emissions standards, but even then, their combustors (buckets) will need changeouts if the Wobbe index is out of envelope.
And then there is Vanadium. There is different amounts of Vanadium in different crudes. While gas turbines do not care about most things in fuel, Vanadium eats away turbine blades, and most turbines avoid using high vanadium fuels.
It’s true they’re built “stronger.” But as noted by @Napier, that’s because they have to be built stronger. This attribute doesn’t necessarily mean they’re more reliable unless a diesel is overbuilt for some reason.
While this does not relate directly to the OP this just popped up in my newsfeed and I thought it was relevant enough to share:
Interesting. I’m in California and fortunately we have Propel Diesel HPR (high performance renewable) available. It’s from Finland’s Neste Oil.
From their site,
An ultra-low carbon fuel (per CA CARB), Propel Diesel HPR is renewable diesel refined from recycled fats and oils.
Propel Diesel HPR —
is made from 98% renewable content (B20 biodiesel is 20% renewable and 80% petroleum)
is 75+ cetane, 40% higher than fossil diesel
is a significant reduction (up to 80%) in greenhouse gas emissions vs. fossil diesel
reduces NOx emissions by up to 14% and particulates (PM 2.5) by 29% vs. fossil diesel
is sulfur-free, aromatics-free and virtually odorless
The local station half a block from my office has three pumps – one gas, one road diesel, and one untaxed farm diesel (dyed red).
Although this is true, the taxes that really matter are the sales taxes on fuel. More than half the price of petrol or diesel at the pump is tax and car owners are obviously keen to keep mpg as high as possible.
A typical 2.0-litre diesel car can easily achieve more than 40mpg, while a petrol equivalent will do well to get 30 and often less.
Not related to engines but I recently came across a US Army use for gasoline that is sort of interesting: the USGI modular field kitchen (MFK).
Gasoline is used for kitchen cooking heat and lighting in an MFK. A bargain at $5k, reduced from $11k. It’s gotta be a fantastic deal for the right buyer who needs to dish up 750 meals a day and be gone in a week. Concert/festival promoter, remote logging/mineral exploration, seasonal recreation operator, etc.
Colemans.com surplus site:
U.S. G.I. Modular Field Kitchen Military | Colemans
you know what? you’re right, I forgot about that.
A little side note on military use of diesel fuel. During WW2 the Russians mostly had diesel engines in their tanks, while the Germans, British, and (mostly) American tanks ran on gasoline. This is often praised as a policy to make the tank less likely to burn, but it was actually to reduce the logistics burden on the overstretched Russian transport system, as diesel tanks burned less fuel per mile and didn’t need to be refueled as often.
One side effect was that, while diesel fuel was less likely to catch fire when a tank was hit, if it did catch it burned hotter and longer. A burnt-out Sherman was often hauled back to a rear area maintenance depot, refurbished, and sent back into action. A burnt-out T-34 usually had important bits melted and the armour integrity compromised by high temperatures.
(As for the difficulty of starting a diesel in cold weather, after the first Russian winter, German tanks were fitted with a port in the rear plate to insert a blowtorch to liquify the oil in the engine pan before trying to start them. This replaced the earlier practice of building a fire under the tank for this purpose!)
I first started driving trucks in the 1960s. After an especially cold winters night, I got up in the morning to a strange sight.
I had parked in a service area along with 20 or so other trucks. The temperature dropped to -10 or lower and because I was cold, I started my engine and left the heater running.
What I saw in the morning was the little fires that several other drivers had lit under their diesel tanks. Diesel has a waxing or cloud point. This is when the paraffin wax crystals solidify and clog up the fuel filter. Winter diesel has additives to help stop this but that night was in the autumn and many trucks would have still been running on summer fuel. Winter diesel fuel - Wikipedia
Having left my engine ticking over all night meant that I was okay - diesel engines pump fuel back into the tank and that was enough to keep it liquid.
@Bookkeeper, interesting! My daily driver is a diesel.
“Comparing the temperatures of burning gasoline and diesel and kerosene, diesel burns hotter than gasoline and hottest of the three. While gasoline barely surpasses 120,000 BTUs, diesel boasts over 137,000 BTUs per gallon! Kerosene falls a bit short of diesel, burning at almost 132,000 BTUs per gallon.”
I owned a couple of truck stops in an area where -30F was not unusual. We used to clean the filters on the dispensers every two or three days. Back then, filters were a simple mesh cylinder. You would pull out the old one, swap in a new. Then you took the old ones inside, let them thaw for a day and then scrape out all the paraffin so you could use them again. I was never so happy as when they came out with disposable filters.
For the last few decades, most 18 wheelers just run their trucks all night in the winter. Trying to restart a diesel that froze up was a miserable job.
The JLTV uses JP8, just like all the other US Army vehicles. The Abrams (tanks), Bradley (IFV), Stryker (ICV), MRAP, Humvee, HEMTT… they all use the same fuel–JP8.
I’ve often heard that airplanes have significant problems with being started cold.
I don’t know if it applies to modern aircraft engines and oils, but as I understand it, at least on older aircraft, you had to warm the engines up before starting the them. If you didn’t do so, you had a significant risk of the engine failing, possibly before you ever got off the ground.
Even starting a car engine in cold weather supposedly causes a lot more wear until the engine gets flowing. For this reason, I rarely start my car engine in cold weather. Instead, when it is cold enough I drive an older, less expensive, vehicle when it is much below freezing. I have known people who would plug their car into an electrical outlet at night to keep the oil warm whenever it was cold.
Nitpick:
Gasoline and diesel have roughly the same adiabatic flame temperature:
To be fair, diesel isn’t explictly listed in that table but, kerosene which has a similar carbon count - is probably a fair comparison.
To your point though, gasoline is more volatile and tends to get consumed in an open fire more quickly, so the high temperatures of a gasoline fire don’t persist as long as the high temps of a diesel fire.