Gasoline as a Diesel Stablizer

[DefinitelyMe]

Originally Posted by TheBestAnchor

Repost from a google search,



"Just so happens I am a marine diesel engineer :-)

Basically, you could run a diesel engine on a mixture of petrol (gasoline) and diesel at a ratio of 10:90 max. In areas where it's VERY cold, you can use either Kerosene or Petrol to help improve the operation of the engine.

The problem is NOT with damage to injectors, pumps or seals, it's damage caused by the shock waves from the very sharp rise in pressure when the petrol is injected into the cylinder. Petrol doesn't particularly like being subjected to the resulting temperatures and pressures of a compression ratio of 25:1 (for example)! The resulting damage will most likely damage the bearings, the piston, and you may even blow a head gasket (which is designed to be the weak point so that it blows rather than anything else) Modern cars won't like it because they quite often utilise multi-shot injection. This means that prior to the main fuel charge, a smaller charge is injected to prepare the cylinder (raising the temperature and reducing the ignition delay). If you consider the advanced injection timing, and what will essentially a 'rich' fuel mixture... You can probably tell it's not going to be good!

However, if you get the mixture of petrol and diesel right, it does actually have it's benefits."

Very interesting. So it seems that a small amount of petrol is not damaging to the engine. It doesn't say anything about the dangers of having the mixture in your tank though, which is an entirely separate issue.

[TheBestAnchor]

Originally Posted by DefinitelyMe

Very interesting. So it seems that a small amount of petrol is not damaging to the engine. It doesn't say anything about the dangers of having the mixture in your tank though, which is an entirely separate issue.

"Could", and "VERY cold" seem to be qualifiers in his opinion?

Most trucking analogies so far don't seem relievant to tank, or bilge concerns in a marine environment.

[GrahamHO]

Originally Posted by weavis

I burned a boat down once. To be fair, it was intentional. 3 of us and an old duck punt with cover.
We were testing an Uzi fully automatic machine gun. Put half a gallon of petrol in a plastic petrol 'can' on board. Fired 300 rounds.

Nothing happened. I waded out and got the petrol can off and gave it to someone to test if it was petrol............. he threw it on the fire.

It was petrol. The explosion was spectacular.

So we ended up lobbing flares into the punt. Eventually it started to burn.

Then we had to pull the boat out after it melted.

Somehow, it wasnt worth the effort.

Dont know why I shared this really.........

That sounds fun! I'll have to try that.

Seriously though I'm speculating that the can of petrol was probably full and there was not much if any vapour present in it. Perhaps of it had been 1/4 full it would have exploded

An almost empty fuel tank which is full of fumes is more dangerous than a full fuel tank.

Check out the findings for the TWA 747 flight 800 explosion when climbing out of JFK. The center wing tank was almost empty. The tank was over air conditioning units which must have heated the remaining fuel while on the ground. A spark from one of about 3 possibilities probably caused the explosion.

The recommendations included maintaining a recommended minimum level of fuel in tanks as well as installing fuel tank temperature gauges etc etc.

On the other hand some suggest a CIA missile.

[model 10]

Originally Posted by Trim50

Each species has its own characteristics. Gasoline is known to kill most of them and that is why they use it.

There is something that grows in avgas. You find in fuel strainers all the time. It's white and accumulates at the bottom of the strainer. I suppose there could be some water it's living on but it would not be much.

[a64pilot]

Some of you have how a Diesel operates a little incorrect.
Diesel is NOT sprayed into the combustion chamber while the piston is coming up mixing with the air until the pressure is enough to ignite the air / fuel mixture.
The Diesel begins to burn the instant it become present in the combustion chamber, this is why injections pressures are so high, and the biggest reason why Diesels are low RPM engines, there isn't time to get enough fuel in the engine at high RPM.
A Diesel cannot either suffer from pre-ignition or detonation, the octane of diesel fuel I believe is very low, it's very difficult to get a spark ignition engine to operate on Diesel due to this low octane.


Sent from my iPad using Cruisers Sailing Forum

[Dockhead]

To the OP:

I was always taught that mixing petrol (gasoline) with diesel creates an explosion hazard in the tank.

It was explained to me this way:

"It is dangerous to mix gasoline into diesel, kerosene, fuel oils etc. because the vapour space above the liquid fuel in the tank becomes explosive at normal ambient temperature. Normally, the vapour space in a diesel tank is mostly air, and the mixture is too lean (not enough fuel) to burn. Gasoline is the other way around. It is very volatile,
and the vapour space is mostly fuel vapour and is too rich to burn or explode. These are the only two conditions under which it is safe to handle either fuels. If you mix gasoline and diesel fuels together, the vapour space becomes explosive, and any ignition source such as static,
wiring etc. could cause the tank to explode. "

Diesel/gasoline mix explosion danger (Bob Falkiner)

I've heard it many times over the years and from different sources. Nigel Calder also cautions against this. I'm surprised that, with your engineering background, you haven't heard this. Perhaps you know better? But if you're not even aware of the standard arguments about it, I doubt it. Before doing this again, you might want to study the question.

[Cadence]

Originally Posted by a64pilot

Some of you have how a Diesel operates a little incorrect.
Diesel is NOT sprayed into the combustion chamber while the piston is coming up mixing with the air until the pressure is enough to ignite the air / fuel mixture.
The Diesel begins to burn the instant it become present in the combustion chamber, this is why injections pressures are so high, and the biggest reason why Diesels are low RPM engines, there isn't time to get enough fuel in the engine at high RPM.
A Diesel cannot either suffer from pre-ignition or detonation, the octane of diesel fuel I believe is very low, it's very difficult to get a spark ignition engine to operate on Diesel due to this low octane.


Sent from my iPad using Cruisers Sailing Forum

I would take issue with the injector putting it in at the last moment. Any fuel doesn't work unless atomizes and under pressure. Hell, an open bucket of gas you can snuff a cigarette in. Not advised however.

[DefinitelyMe]

Originally Posted by TheBestAnchor

"Could", and "VERY cold" seem to be qualifiers in his opinion?

Most trucking analogies so far don't seem relievant to tank, or bilge concerns in a marine environment.

Agreed on the tank/bilge/etc. concerns. I read the 'very cold' bit as applying to the use of kerosene rather than petrol, and i think the 'could' bit refers to something that is, at least from a mechanical perspective, viable. I think the most interesting bit about the post is that he (whoever 'he' is!) appears to dispel the argument that the petrol would be damaging to injectors, pumps etc. Rather he is saying that the limiting factor (above 10%) is the potential for preignition and the damage that could cause to the engine.

I'm at risk of drawing lots of negative feedback with this next statement...... but it seems to me that if what people on here are saying is more or less accurate, one [B]could[B] mix petrol into diesel at, say, a percentage of about 0.1%, or even 0.01% and the resulting mixture would have negligibly greater safety risks associated with it, would not cause any damage to the engine and would effectively control growth in the tank.

[valhalla360]

Originally Posted by SniperSailor

Actually, before the advent of better products, long haul truckers used to add a bit of gasoline to their diesel to keep things clean. But that was something like a pint to 20 gallons. That would work out to about 10 pints (2.5 gallons) to 200 gallons of diesel. Not nearly the same ratio, and as I said before, today there are better, and more important, safer products....see... AMSOIL - Synthetic Oil, Motor and Engine Oil, Lubricants, Air Filters, Oil Filters and Greases

People do dumb stuff all the time. Doesn't mean it's smart.

Long haul truckers really don't have much of an issue with bugs because they drain and fill thier tanks 2-3 times per week. Cruising boats have problems because many don't train and fill thier tank more than once per year.

Also with the saddle hung tanks any fumes that get out of the tank just drift away on the wind, so even if there was an issue, it's unlikely to create a fire hazard.

And finally, as you pointed out, they are looking at less than 1/10th what the OP suggested.

[thinwater]

Originally Posted by Guy

There is something that grows in avgas. You find in fuel strainers all the time. It's white and accumulates at the bottom of the strainer. I suppose there could be some water it's living on but it would not be much.

Most likely this is aluminum hydroxide gel, which might look a bit like biomass to some. The cure is low water and an effective aluminum corrosion inhibitor (Biobor EB, Merc Quick Store, and Seafoam are good for this as determined by specific 3rd party testing, many are snake oil).

[Cadence]

You would think if adding gas solved the bug problems the refinery would do it. Advertise bug free diesel. Oh and did we mention a significant lower flash point.


Engines are built around that flash point I haven't seen regular, high test and premium at the diesel pump.

[MarkSF]

Originally Posted by DefinitelyMe

Very interesting. So it seems that a small amount of petrol is not damaging to the engine. It doesn't say anything about the dangers of having the mixture in your tank though, which is an entirely separate issue.

Even 1% gasoline in diesel will cause a significant reduction in lubricity. The effect of this reduction will be most pronounced on modern high-pressure fuel injection engines. They can run at up to 20-25K PSI, and the pump is lubricated entirely by the fuel.

The lubricity of US ultra low sulphur diesel is already right on the edge of acceptability.

There's a VW document on the internet discussing diesel lubricity.

US ULSD has a lower lubricity spec (520u) than European (460u). Some samples failed to pass even the US standard, VW used one for testing which has 570u wear scar. Just 1% gasoline contamination raised this number to 700u, which is pretty appalling, and this number rose slowly at higher gasoline contaminations.

Even older diesel engines like my Universal 5424 were designed to be run on higher-sulphur fuel with lubricity that is much higher than these numbers.

[TheBestAnchor]

Originally Posted by DefinitelyMe

Agreed on the tank/bilge/etc. concerns. I read the 'very cold' bit as applying to the use of kerosene rather than petrol, and i think the 'could' bit refers to something that is, at least from a mechanical perspective, viable. I think the most interesting bit about the post is that he (whoever 'he' is!) appears to dispel the argument that the petrol would be damaging to injectors, pumps etc. Rather he is saying that the limiting factor (above 10%) is the potential for preignition and the damage that could cause to the engine.

I'm at risk of drawing lots of negative feedback with this next statement...... but it seems to me that if what people on here are saying is more or less accurate, one [B]could[B] mix petrol into diesel at, say, a percentage of about 0.1%, or even 0.01% and the resulting mixture would have negligibly greater safety risks associated with it, would not cause any damage to the engine and would effectively control growth in the tank.

"In areas where it's VERY cold, you can use either Kerosene or Petrol to help improve the operation of the engine."

There is an "or"? "could", "can", I didn't take this as a recommendation "should" to use gasoline. Mastery of english? is not one of my strenghts tho...

"The problem is NOT with damage to injectors, pumps or seals"* seems broad to me? Id be interested to hear from someone who designs injectors, cavitation?

The effects of gasolines on bugs that may be present in diesel is hardly an Otto Rohwedder moment at this point. Good discussion on the possible pitfalls tho.

Lets just hope Trim doesnt have a mishap that requires a hull, or machinery claim. Due to this tread, I'm pretty sure his insurance company just got a hall pass...

[Cadence]

Originally Posted by TheBestAnchor

"In areas where it's VERY cold, you can use either Kerosene or Petrol to help improve the operation of the engine."

There is an "or"? "could", "can", I didn't take this as a recommendation "should" to use gasoline. Mastery of english? is not one of my strenghts tho...

"The problem is NOT with damage to injectors, pumps or seals"* seems broad to me? Id be interested to hear from someone who designs injectors, cavitation?

The effects of gasolines on bugs that may be present in diesel is hardly an Otto Rohwedder moment at this point. Good discussion on the possible pitfalls tho.

Lets just hope Trim doesnt have a mishap that requires a hull, or machinery claim. Due to this tread, I'm pretty sure his insurance company just got a hall pass...

I believe the artic truckers do it to keep the diesel from jelling. Not a thing to do with bugs since they suck down one hell of a lot of fuel.