Adding Diesel to gasoline

[NachtRitter]

Originally Posted by Old Tele man

...from that same source:

"Knock and preignition are both favoured by high temperatures, so one may lead to the other. Under high-speed conditions knock can lead to preignition, which then accelerates engine destruction
[27,28]."

...bold emphasis is mine, not the author.

Correct... knock can lead to preignition. Knock is not the same as preignition.

Thanks for clarifiying.

[FourBinLabs]

Well, I read the whole thing. I'd say you were spot on Mr. NachtRitter. Thanks for the link and re recommending it after I skipped over it the first time.

Octane rating is not related to when a fuel preignites or auto ignites (per se), it's actually measuring the probability of molecules being broken down into other molecules that are more likely to auto ignite.

it takes more heat to auto ignite diesel fuel than gasoline, however diesel fuel either A) breaks down into readily auto ignited compounds easier/faster than gasoline when exposed to high heat and pressure or B) breaks down into compounds that are more auto ignitable than what gasoline breaks down into.

It makes sense now. I think a lot of the confusion here was many terms that were being used in a less than 100% accurate manner.

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.

[FourBinLabs]

Originally Posted by UFO

Oh very good. And how is my statement "The engine was designed for gasoline - use it." an opinion?

Most vehicles we not designed to have the tops chopped or boat tails attached, but people still do it. It's your opinion that everyone should use gasoline in the cars designed for gasoline.

Originally Posted by UFO

Come on now, what sort of benefit is expected or documented? Diesel reduces the octane, so you will now knock when you compress this brew, so you either damage your engine or your ECM reduces timing for poor mileage.

I don't know if there is any expected result, but you cannot document results without testing/experimenting, it's one of those "cause and affect things". If one were to try and and document poor fuel economy or no gain, then it's knowledge gained.

Originally Posted by UFO

This forum usually sticks to sound experimentation looking for effective ways to reduce petroleum consumption, but this thread is almost as far into the weeds as HHO. Sorry to have to be the one to point it out, but now the rest is up to you.

What classifies sound and unsound experimentation?

[NachtRitter]

Originally Posted by FourBinLabs

Well, I read the whole thing. I'd say you were spot on Mr. NachtRitter. Thanks for the link and re recommending it after I skipped over it the first time.

Octane rating is not related to when a fuel preignites or auto ignites (per se), it's actually measuring the probability of molecules being broken down into other molecules that are more likely to auto ignite.

it takes more heat to auto ignite diesel fuel than gasoline, however diesel fuel either A) breaks down into readily auto ignited compounds easier/faster than gasoline when exposed to high heat and pressure or B) breaks down into compounds that are more auto ignitable than what gasoline breaks down into.

It makes sense now. I think a lot of the confusion here was many terms that were being used in a less than 100% accurate manner.

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.

Good summary.... and I definitely agree that the terms are often not being used correctly.

Back to the original discussion...

[UFO]

Originally Posted by FourBinLabs

Most vehicles we not designed to have the tops chopped or boat tails attached, but people still do it. It's your opinion that everyone should use gasoline in the cars designed for gasoline.

That analogy doesn't make sense. Let's stick to engines.

Originally Posted by FourBinLabs

I don't know if there is any expected result, but you cannot document results without testing/experimenting, it's one of those "cause and affect things". If one were to try and and document poor fuel economy or no gain, then it's knowledge gained.

I'll let you re-invent the wheel. I already know what happens when I reduce the octane of my fuel.

Originally Posted by FourBinLabs

What classifies sound and unsound experimentation?

Maybe you should read a few more threads, and judge for yourself.

[FourBinLabs]

Originally Posted by UFO

That analogy doesn't make sense. Let's stick to engines.

I fail to see how it does not apply. Making modifications to your vehicle is somehow more or less justifiable depending on what part you are working on? Just replace adding a boat tail with advancing the timing if that helps you understand.

Originally Posted by UFO

I'll let you re-invent the wheel. I already know what happens when I reduce the octane of my fuel.

I'm sorry to hear you have those kind of problems with your vehicle.

Originally Posted by UFO

Maybe you should read a few more threads, and judge for yourself.

I plan to do just that.

[tim3058]

Originally Posted by UFO

That analogy doesn't make sense. Let's stick to engines... I'll let you re-invent the wheel. I already know what happens when I reduce the octane of my fuel. ...Maybe you should read a few more threads, and judge for yourself.

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?

[gone-ot]

...is the OP remembering to "include" the quantity of diesel fuel being added into the gasoline in his "total" fuel used calculations?

...ironically, both gasoline and diesel fuel both have the same stoichiometric A/F (by weight) combustion ratios -- 14.7-to-1 -- although rather differing energy content values:

• gasoline = 114,000 BTU/gal
• ..diesel = 129,500 BTU/gal

[FourBinLabs]

Originally Posted by tim3058

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.

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

My guess is that a lean-burn situation would increase the chance of running into engine knock. It would seem that whatever affect you see most gasoline engines, you would see on a lean burn. This is purely speculation though. I've already learned from this thread that there is a lot more to what happens in the combustion chamber then meets the eye.

Also, just to let you know, I started a test on this back on Tuesday. I am running ~10% mix in my vehicle. I put in 2.5 gallons of diesel and 22 gallons of gasoline. I would have gone to 22.5 but ran out of room in the tank. Then again, I'm sure there was more than .5 gallons of gasoline in the tank, so maybe that's a good thing.

If someone secretly put 10% diesel into my tank, I would have no idea. Power seems unaffected, or has changed in such a small way that I can not tell. There is no change in exhaust look or odor.

I haven't been putting many miles on this week, and I have been letting my vehicle idle more than usual because of the recent cold temps. I am driving round trip to chicago this weekend (over 100mi each way), so I'll be able to get a good idea what the highway mileage is.

The bad news, I haven't been checking my mileage in this vehicle for a couple years because I only drive it in the winter. After running through a few tanks and switching back to gasoline, I can show some results. It's just going to take a long time.

[tim3058]

Cool, I'm looking forward to hearing what you discover FourBinlabs. Increased chance of knock was the only thing that I could come up with right offhand too, but I'd think the ECM should pull back the timing to compensate. Any of the chemical engineers/combustion experts care to theorize on mixing in diesel for lean-burn engines? Same effect as in lindsayjim's van or no?