Adding Diesel to gasoline

[lindsayjim]

Diesel fuel and gasoline are miscible.

[The Atomic Ass]

Originally Posted by Christ

They're of differing viscosity, as well. Good question. I guess I'll have to get a glass jar and put equal amounts of both fuels in it and see if they stratify.

Hmm.. if fuel/water emulsion is good, and fuel/gas mix is good, is fuel/gas/water emulsion even better? We may never know...

PS - You're really going to try it on the Ninja? Don't get me wrong, I don't think it's a bad idea, but I just didn't see anyone wanting to try this on an exotic-type engine.

Well, water settles in gasoline, so, no.

I don't consider it particularly exotic. It was engineered in the mid-80's. It does run 87 well, and could probably run 85 at sea level, due to the low displacement.

I don't intend to start off with 30%, though. I'll try a 5/95 mix first, and see if there are any ill effects, if not, the following tank will be 10/90. And so on until I start seeing signs that I need to back off.

[The Atomic Ass]

Originally Posted by lindsayjim

Diesel fuel and gasoline are miscible.

That's good to know.

[lindsayjim]

A potential problem for this blend is extreme cold. Up here the diesel fuel is blended for cold temperatures during the Winter. I hypothesize that the addition of gasoline depresses the cloud point of the diesel fuel, but I don't know this for certain. I've only tested to -15 deg. F. so far. IF wax crystals were to form in the fuel, then without a heated filter there would be a problem...

Another potential problem is microbial growth, something straight gasoline does not have a problem with.

Time will tell....

[tasdrouille]

Just throw a bit a winter PowerService into the mix and you don't have to worry about gelling or any kind of growth.

[Christ]

Mr. BackSide -

Emulsions don't settle out when a surfactant is added to stabilize the interface between the continuous phase and the dispersed phase.

Soap emulsifies oils in water, and acts as a decent surfactant to stabilize the interface between oils and water.

[FourBinLabs]

I know this is an old post, but I couldn't come across another thread on this topic. I've seen many references to diesel lowering the octane rating of gasoline. My first instinct was to shout BS, but I'm at least smart enough to know that I know very little about this topic.

Originally Posted by Old Tele man

...octane is a figure of merit of the gasolines' resistance to detonation during compression buildup...diesel doesn't have this problem.

I'm confused as to how it's possible that a diesel engine may have double the compression of a gasoline engine, and not require more resistance to detonation. Many ignition advance curves ignite fuel as much as 30° - 40° BTDC at higher RPMS. If detonation was no big deal, you could continue to advance the timing to the point where ignition of the a/f mixture would actually be working against the motor more than working for it.

I thought that this was what would happen in a diesel engine if you used gasoline. The gasoline would ignite prematurely and cause the engine to work against itself. In the same regard, I thought that diesel fuel required more heat energy to get it going, which is why diesels have such high compression.

Help me out here. what am I missing.

[gone-ot]

...lookup the "auto-ignition" temperatures for gasoline (495ºF) and diesel (~600ºF).

• octane-rating is for gasoline...resistance to detonation
• cetane-number is for diesel...ignition delay or quality of combustion

[dcb]

Originally Posted by FourBinLabs

Help me out here. what am I missing.

in a compression ignition engine like a diesel the injection event IS the ignition event. There is no fuel to preignite

[FourBinLabs]

Originally Posted by Old Tele man

...lookup the "auto-ignition" temperatures for gasoline (495ºF) and diesel (~600ºF).

• octane-rating is for gasoline...resistance to detonation
• cetane-number is for diesel...ignition delay or quality of combustion

Being that a combustion chamber must be ~100°F hotter to "auto ignite" diesel, it would require more compression to achieve the necessary temperature to auto ignite diesel than gasoline.

about.com defines detonation as: "Definition: An unwanted explosion of the air/fuel mixture in the combustion chamber caused by excess heat and compression, advanced timing, or an overly lean mixture."

How can diesel fuel have a lower octane rating then regular gasoline then?

I hope I'm not pestering anyone, I really am trying to wrap my head around this.