Adding Diesel to gasoline

[darcane]

Originally Posted by FourBinLabs

If you go on to read further, it does state that it does not hurt to use lower octane fuel in a vehicle than what is specified if the vehicle does not knock (although a knock sensor would prevent you from knowing this). High elevation and low temperatures also allow the use of lower octane. If the vehicle is not knocking, then lowering the octane is no problem.

If you can advance your timing with the same octane you used before, you decreased your margin for error and reap the rewards of better mileage & torque. Buying lower octane for cheaper saves $, and causes no harm if it isn't making the vehicle knock. So diesel lowering the octane rating isn't necessarily bad.

It does state you can go lower, but the specific quote here is:

Once you have identified the fuel that keeps the engine at optimum settings,
there is no advantage in moving to an even higher octane fuel. The
manufacturer's recommendation is conservative, so you may be able to
carefully reduce the fuel octane. The penalty for getting it badly wrong,
and not realising that you have, could be expensive engine damage.

I think most of the people warning against adding Diesel know this and are trying to inform you of the possible results. If you get your mix wrong, you will destroy your engine. If you know the dangers and still go for it, more power to you. I, for one, don't plan on giving this one a try and would still recommend others not to do it either.

Mike

[UFO]

Originally Posted by tim3058

Let's be open minded please.

The OP has a gas/EFI van and is running 30% diesel and reporting a noticeable 10-20% mpg boost. Worth looking into. I'm struck by the genius involved in such an out-of-the-box concept. Many questions surround how much is ok, and what long-term effects may be, but this might have potential for the serious experimental-type of ecomodder.

Good idea lindsayjim!

Any thoughts on what this would do in a lean-burn Honda VX engine?

I am open minded, but substituting one petroleum product for another with higher energy density is not an mpg boost to me. If you want to burn a diesel fuel, use it in a diesel engine, and use a renewable one if possible.

Gasoline and diesel both come from the same filthy hole in the ground. But keep looking for that holy grail.

[FourBinLabs]

Originally Posted by darcane

I think most of the people warning against adding Diesel know this and are trying to inform you of the possible results. If you get your mix wrong, you will destroy your engine. If you know the dangers and still go for it, more power to you. I, for one, don't plan on giving this one a try and would still recommend others not to do it either.

As per the quote from the article, it's pretty hard to miss a knock, if you've heard one before. If not, look up engine knock or spark knock on youtube. I think in most people's case, the real danger is worse fuel economy and lost power due to the computer compensating.

Not that I'm one to shrug of a good warning, but my observations of the trend here was the most members warning not to do it have not done it. There were a few who mentioned smoke problems or even included a vid.

Originally Posted by UFO

I am open minded, but substituting one petroleum product for another with higher energy density is not an mpg boost to me. If you want to burn a diesel fuel, use it in a diesel engine, and use a renewable one if possible.

I agree with you here. Using higher BTU density fuel is not a real increase in economy. Also, renewable fuel makes more sense that swapping for another fossil fuel.

But from what I've learned here, there is a lot more then meets the eye when it comes to the complicated array of reactions that go on in an ICE. I'm not expecting magic here. If there were incredible results to be found here, I'm sure it would long ago have become common practice.

If I find that mile economy goes down by 50%, I'll still consider the experiment a success, because of what I've learned. This turns into a great jumping off point to find out where the extra energy went and why, which can in turn spark more ideas.

[darcane]

Originally Posted by FourBinLabs

As per the quote from the article, it's pretty hard to miss a knock, if you've heard one before. If not, look up engine knock or spark knock on youtube. I think in most people's case, the real danger is worse fuel economy and lost power due to the computer compensating.

Not that I'm one to shrug of a good warning, but my observations of the trend here was the most members warning not to do it have not done it. There were a few who mentioned smoke problems or even included a vid.

Actually, it's quite easy to miss a knock. I know just what it sounds like, I've heard it plenty of times over the years in the older vehicles I own. But knock can be damaging even when it's not audible inside the car; especially with all the soundproofing in modern cars.

And, I actually do have experience with diesel in a gasoline tank. I used to work at a place that rents U-Hauls. The gasoline powered trucks periodically came in topped off with diesel and usually barely ran or had to be towed back. I have no way of knowing what the percentage of the mix was though.

That said, I don't believe that you always need to try things personally to figure out it's a bad idea. For example, I also recommend against putting sand in your oil even though I have never tried it.

Mike

[FourBinLabs]

Originally Posted by darcane

And, I actually do have experience with diesel in a gasoline tank. I used to work at a place that rents U-Hauls. The gasoline powered trucks periodically came in topped off with diesel and usually barely ran or had to be towed back. I have no way of knowing what the percentage of the mix was though.

That said, I don't believe that you always need to try things personally to figure out it's a bad idea. For example, I also recommend against putting sand in your oil even though I have never tried it.

Sorry Mike, I wasn't directing the comment about experience on diesel in gas tank at you. It was more referring to the general trend on this tread as a whole. The trend being, many of the users that were more more against it, not mentioning any experience. Thank you for finally mentioning yours

As per the sand in oil situation, it actually really helped my gas mileage. I never had to put more gas in that vehicle again . I know what your saying here, and your right, sometimes common sense telling you something is a bad idea should be enough to keep you from doing it. However, it seems unlikely that there could be any sort of perceived benefit to trying something like that.

Gotta get to work, Cheers.

[lindsayjim]

Update: 30K miles since beginning this trial. Highway mileage ranges from 17.8 to 18.2 using approx 1/3 diesel at fill-up. Changed original OEM spark plugs out at 102,000 miles and one oxygen sensor (Bank1 Sensor1) at the same time. The rest of the oxygen sensors are still original. Should probably change the others also, based on age and mileage but have not been sufficiently motivated to go out in the cold and do it. No smoke, no odor. I do revert to straight gasoline when the temperature drops below -30F if I have to let the vehicle sit outside and cold soak. Nothing bad to report other than it's a bit of a pain to pay at two pumps. Fortunately the pumps are at the same island so moving the vehicle is not necessary. I use a Scan Gauge II in order to know how much diesel will be needed and pump it first. Figure I've saved about a grand in fuel costs this year.

[tim3058]

Originally Posted by lindsayjim

Update: ... Figure I've saved about a grand in fuel costs this year.

Pretty real holy grail right there, well worth chasing

Please keep us posted on how the van does long-term... cool stuff

Do you see a noticeable power loss lindsayjim?

[lindsayjim]

I have a pretty soft foot and don't notice any power difference at all. Theoretically there should be a little bit more power due to the increase in specific heat of the fuels. Doubt anyone would be able to tell short of using a dyno however.

[UFO]

Originally Posted by lindsayjim

I have a pretty soft foot and don't notice any power difference at all. Theoretically there should be a little bit more power due to the increase in specific heat of the fuels. Doubt anyone would be able to tell short of using a dyno however.

You won't get more power unless you get in more air. A mileage change is probably the only result from this type of mod (other than a mileage drop or damage from too much octane loss).

[mort]

I have another reason I'm not going to mix diesel into my gas tank. For a sealed tank, like a gas tank in a car, if there is any liquid fuel present the high partial pressure of gasoline saturates the vapor volume of the container. The saturated vapor is too rich to burn (above the upper explosive limit, UEL). Essentially a sealed gas tank with gas in it is safe. A diesel tank is also safe, but diesel has such a low vapor pressure the vapor is too lean to burn (below the lower explosive limit, LEL). But a mixture of the 2, for a wide range of concentrations of gasoline and diesel, allows explosive mixtures in the vapor volume of the canister. For extreme concentrations the mixture is safe, but at about 5% diesel the amount of gasoline that evaporates into a closed container drops below its UEL, and above about 50% diesel - 50% gasoline, the diesel vapor concentration rises above its LEL. A bad idea to mix in the same tank.

-mort