Diesel engines and JP-8 jet fuel.

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kd5byb

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Good evening all!

I work in a lab that tests turbo-shaft engines. As you'd imagine, we have a tank farm and always have JP-8 jet fuel readily available.

We run our Yanmar-powered diesel equipment on the JP-8 with seemingly no ill effects. It's handy, easy, and far cheaper than trucking in and maintaining a diesel tank/pump system.

Months ago, I read that JP-8 doesn't have the same lubricity as diesel, and therefore a lubricity additive is required to prevent early failure of injection pumps. We started using a very healthy dose of Power Service additive with the Slick Diesel additive. As usual, the equipment runs great.

Yet, a few weeks ago, I was reading that when the Army started using JP-8 in all turbo-shaft and recip diesels to lower logistics costs, they studied the lubricity issue and found no ill effects due to the lower lubricity of JP-8 vice diesel. The best I could tell, the test engines were 6.2L GM diesel V-8's.

Yanmar / John Deere recommend lubricity additive for "diesel fuel of unknown or low lubricity." They don't mention JP-8.

Looking for opinions from folks who may have experience running JP-8 in diesel engines. Any injection pump failures traceable to JP-8 usage? Think that the additive is required?

On one hand, the additive is cheap. Yet, on the other hand, we like to keep costs as low as we can.

thanks much,
ben
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The Army also runs DD 6V53 and DV92 engines and Cummins 903 V8s on JP8 with no problems that I'm aware of. I'm not aware of problems on other engines but have no experiance with them.

You do get about 5% less power and 5% more fuel consumption on JP8 compared to DF-2.
 
Every time I find myself around someone that is involved with army vehicle maintenance and repairs I ask how things are going with JP8. The answer has nearly always been the same, they run fine. One National Guard Maintenance Supervisor added that when in doubt, they add a little ATF to the mix as an emergency field measure. Some of the more knowledgeable feel they can tell the mixture is too dry from the sound of the injectors firing.

They did add that most technicians feel that the service life is somewhat compromised but no studies have shown service life to be statistically different from before the switch to JP8.

I also asked if they needed any modifications for the change and was told that no modifications were made.

You will have to admit that it is much easier to conduct a campaign when you only need to worry about two fuels. Bunker fuel for ships and JP8 for everything else. There are two exceptions. Does anyone know what they are?
 
Enriched uranium for nuclear powered ships.

Gasoline for small IC engine powered pilotless aircraft.

Or are those additional fuels 3 and 4
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I believe the USAF also uses special JP-8 so it would be another fuel.

Gasoline for some non-tactical vehicles.
 
I didn't consider enriched uranium because it doesn't need to be replenished often.

The two I had in mind are JP4 and gasoline. JP4 for the U2. Different fuel is needed for high altitude. Gasoline for small pilotless surveillance aircraft. Those are the two exceptions I was told about.
 
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I didn't consider enriched uranium because it doesn't need to be replenished often.

The two I had in mind are JP-4 and gasoline. JP-4 for the U-2. Different fuel is needed for high altitude. Gasoline for small pilotless surveillance aircraft. Those are the two exceptions I was told about.

Click to expand...


I believe the U-2 is using a variation of JP-8 now. Still a separate fuel because they can't depend on regular JP8 meeting their needs.

I also recall U-2s using something other than JP-4.

Aha, Mr Google says it was JPTS which cost 3 or 4 times what JP-8 costs which is why the modified the aircraft to be able to use JP-8.
 
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You will have to admit that it is much easier to conduct a campaign when you only need to worry about two fuels. Bunker fuel for ships and JP8 for everything else. There are two exceptions. Does anyone know what they are?

Click to expand...


I agree totally - one fuel for the Army makes a lot of sense.

I would never have guessed gasoline and JP-7 as the answer to your trivia question. I was going to say JP-4 for extreme cold climate aviation use but had no second guess. Don't think JP-8+100 ever got approved beyond research use so it was out.

Never would have thought gasoline, even though drones fly over my head on a regular basis. Doh!
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I know JP-4 is more volatile than JP-8; I seem to recall seeing a TM that required Chinooks to use JP-4 in arctic climates, else use JP-8. It may have been a very old TM - seem to recall it called for MIL-L-7808 instead of MIL-PRF-23699 for the engine oil...

Glad to hear that the big Army diesels do okay. Wonder if our little Yanmars will do okay without the additive.

I did see in another thread where folks were using TCW-III outboard 2-cycle oil as an additive - we may try that...

thanks much,
ben
patriot.gif
 
The military is testing, if not buying, outboards that run on JP fuel.
Nothing new, India and some other parts of Asia use outboards that run on kerosene.
 
The jet fuel the SR71 uses, JP7, is used ONLY in this aircraft. It is so modified that you can use it to extinguish a match; it will only burn in the SR-71's mammoth engines. JP-7 is unusual in that it is not a distillate fuel but is created from special blending stocks in order to have very low ( The very low volatility and relative unwillingness of JP-7 to be ignited required triethylborane (TEB) to be injected into the engine in order to light it up, and to light up the afterburner in flight
 
It sounds like there are people that know more about the needs of our high altitude planes than I do. I do clearly remember reading that it was the U2 in an article about using one fuel as much as possible in the US military. Those that I directly talked with probably don't know much about the needs of the U2. The SR71 has a much larger engine and flys much faster, but don't they both have a similar altitude ceiling?

Anyway if the U2 doesn't use JP7 I apologize. I'm not sure what publication the article was in, but it seems like it was the Los Angeles Times.
 
Originally Posted By: Big Jim
It sounds like there are people that know more about the needs of our high altitude planes than I do. I do clearly remember reading that it was the U2 in an article about using one fuel as much as possible in the US military. Those that I directly talked with probably don't know much about the needs of the U2. The SR71 has a much larger engine and flys much faster, but don't they both have a similar altitude ceiling?

Anyway if the U2 doesn't use JP7 I apologize. I'm not sure what publication the article was in, but it seems like it was the Los Angeles Times.


THREAD FROM THE DEAD NOTICE!

Forgive me, because I can't recall the spec, but the U2/TR1 does require a special fuel, other than JP8. I do recall that a few years ago, the AF was looking at developing an additive cocktail that they could use to supplement JP8, so that they could save money by no longer having to order very expensive one-off batches of special gas for the U2. Anyone else recall the U2/TR's special gas requirement?
 
Originally Posted By: Big Jim
I said JP4. I meant JP7. JP4 is an obsolete standard that is now filled by JP8.


JP-4 was replaced by JP-5 for at-sea uses. JP-5 is a high flashpoint navy-spec aviation fuel, whereas JP-8 has a lower flashpoint.

My biggest concern with using JP-8 is getting it on myself or breathing it. The additization of JP-8 is significantly different than regular diesel fuel, and some of these adds may be highly carcinogenic.
 
It might not mean anything but AFOSH (USAF version of OSHA) doesn't state anything extra scary about handling JP-8, you handle it as you would any other fuel or mogas.
 
Originally Posted By: JHZR2
Originally Posted By: Big Jim
I said JP4. I meant JP7. JP4 is an obsolete standard that is now filled by JP8.


JP-4 was replaced by JP-5 for at-sea uses. JP-5 is a high flashpoint navy-spec aviation fuel, whereas JP-8 has a lower flashpoint.

My biggest concern with using JP-8 is getting it on myself or breathing it. The additization of JP-8 is significantly different than regular diesel fuel, and some of these adds may be highly carcinogenic.


I don't think we ever had JP4 shipboard -- waaaaay too volatile. The Navy is so buggy about this stuff that it was a huge deal if you brought a jet aboard that had any JP4 in its tanks. The tank venting systems were simply not designed to deal with relatively ignitable JP4 fumes. {EDIT-2: even the possibility of defueling a few hundred lbs of JP4 freaked them out bad.} I recall having to go to some lengths to work around this when doing a CQ training det once. We ended up having to stop at an AFB (where JP4 used to be the standard stuff - this was 1986 IIRC) and refuel. I don't recall what the poor maintenance guys had to do to get us boat-ready, but they sure were excited about it (and not in a good way...).

Fully agree about JP hazards. Very nasty stuff.

EDIT: now that I think about it some more, there was a shipboard fuel that predated JP-5. I can only imagine how much fun it was when the carriers had to be loaded up gasoline!
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JP-8 + 100 is in use in the Air Force. +100 additive is used to help control the cokeing that occurs in the augmentor spray rings. This has been an issue with the Pratt & Whitney F100 series engines.

Also the engines are preserved with 1010 lubricating oil after they are ran on the test stand after maintenance. This preserves the fuel system and seals to keep them from drying out and leaking. 1010 oil also will work in a diesel engine. You might run up on some carbon build up over time running it straight.
 
JP-8 is close enough to regular diesel to be suitable for use as diesel. Army engines are going to be well maintained, and are built very rugged, so over their lifespans the additional wear from using a slightly off fuel is not an issue.
 
Originally Posted By: mojo
The jet fuel the SR71 uses, JP7, is used ONLY in this aircraft. It is so modified that you can use it to extinguish a match; it will only burn in the SR-71's mammoth engines. JP-7 is unusual in that it is not a distillate fuel but is created from special blending stocks in order to have very low ( The very low volatility and relative unwillingness of JP-7 to be ignited required triethylborane (TEB) to be injected into the engine in order to light it up, and to light up the afterburner in flight
Not your usual charcoal lighter fluid?
 
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