Adding Diesel to gasoline
 

I've been running a 2005 Chevrolet 6.0L fuel injected van on diesel:gasoline mix at a ratio of between 30:70 & 40:60 successfully. 50:50 was too high when the ambient temperatures were -15 deg. F., but the lower ratios have worked well. Cold starting is OK, although it is necessary to allow the engine to warm a couple minutes before driving away to avoid stalling. There is no apparent misfire and fuel economy is improved. My experience using a blend in this range has been an increase in miles per gallon of 10-20% over straight gasoline. If the improvement were due only to the difference in specific heat, then the increase should be only slightly over 10%.

Hmm.
That's quite interesting.
I'v always wondered why Diesel wouldn't work in a Petrol engine, but knowing that it can work to some degree, is quite good.
So, just say, you had a 100 litre tank, filled up 70 litres of Petrol, then would you just go ahead and put 30 litres of Diesel in, or is there some way in which you have to mix it up for best results?
Thanks,
Tom.

Petrol + Diesel : Why do two-stroke engines come to mind? Didn't two-stroke engined cars from the 1960's run on a diesel/gas mix? I've never heard of it working in a four banger.

petrol diesel will clog your catolitic converter over time, this is due to the high sulfur content (50ppm in the US), I've run bio-diesel in my motorcycle at 10% without any issue at all, a very slight increase in mileage with a carburator but with fuel injection should be even better, at that 10% I had no decrease in power or top speed (it was on a 125cc Honda motorcycle) bio-diesel is sulfur free and acts not only as a fuel but as a top end lube, it's also a bio-fuel.

Did I read that right .... you can add biodiesel to gasoline and have it actually run in a gas engine ??

What's the catch ?

It gums up the exhaust valves, but not so much that you can't clean the engine once in awhile to keep it in check.

I've run straight diesel in a gas engine. You need gas to start it, but you can switch it over afterward. It requires some minor carb retuning sometimes, and FI ECU's don't really like it, but it can be done. I've never advocated doing it on a normal basis, though. I've done it in a pinch, where I had diesel fuel and no gasoline. If I knew I couldn't get anywhere without fueling up, I'd put the diesel fuel in the gas tank while I still had some gas enough to keep the engine running. Cold starting a gas engine on straight diesel isn't fun, and you should have 2 or 3 batteries and a can of ether on hand if you want to try it. It's a PITA.

I tried as much as 50% bio-diesel and at that point I didn't have full power, the fuel acted like it wasn't burning fully, or maybe fast enough, it smoked alot and sputtered at high revs, 20% bio-diesel it ran pretty well, a little smoke and a little sputtering at the highest revs, with 10% I couldn't tell the difference between the 1:9 mix of gas and the 100% gas other then a very faint Chinese food smell in the exhaust, the power was the same all the way up to redline, my top speed on the 125cc motorcycle was the same, the o2 sensor that I installed in the exhaust looked just fine, the spark plug looked perfect, I did not take any mixed with gas to see if it separated out weird or anything.
my gas mileage didn't change a great deal after adjusting for the extra 10% fuel in my tank, but it didn't drop either.

So, if gasoline costs $3.00 a gallon, and BD can be made for $1.00 per gallon, and you can use 9:1 gas/BD, your fuel costs will be $2.80/gallon on average. It's the same as getting a few more MPG, right? And potentially cleaner.

Well if it causes more smoke, then apparently the emissions are worse.
Cost isn't even a consideration.

It doesn't always cause more smoke, though. If you mix too much in, it doesn't have time to burn fully. The more you mix in, the higher you have to advance the timing. There's a break even point, like with everything, and there there's a point of diminishing returns.

Spark ignited diesel isn't a new concept, it can be executed cleanly, but requires proper tuning, as with any modification.

Straight gasoline = 15 mpg, 30% diesel blend = 18 mpg

Here at present low octane gasoline is $3.25/gal and Winter diesel is $3.55/gal

$3.25/15 miles = $0.2167 / mile

(3.25x.7) + (3.55x.3) = 2.275 + 1.06= $3.335 / gal blend

$3.335/18 miles = $0.1853 / mile

A saving of $31.40 per thousand miles in fuel cost.

I am experiencing no smoking or misfire. I discount all fears of filter clogging, injector clogging or valve stem depositions. If I've misjudged the fuel system seal compatibility I'll pay a hefty penalty. If there were misfiring then I'd be concerned about the cat., but absent the misfire I expect it to have a normal life.

I presume you've tested to a satisfactory extent and found that under your conditions, 30% is the most effective blend?

Have you noticed a change in engine running temps? I found that with diesel, my engines tend to "feel" a little bit hotter, but I haven't actually recorded temps to find out, since ABA testing would require drain/fill cycles, and I don't have time/patience for that.

When I am making bio diesel I usually burn one or two car tires, helps keep the world in check.

;)

It's a bit tough to get accurate test data with so many uncontrolled variables in actual driving conditions. 50% was definitely too much as indicated by poor cold temperature starting and idle as well as slight misfire under load. There were small incremental increases in mileage in the 10-30% range. My metering is not perfect, but I use the scan guage to judge consumption, then first add 1/3 diesel, move to the regular pump and complete the fill-up. Close enough to 30% for my purposes. Whether it is actually ideal..... can't say with certainty, but close enough for practical purposes.

Running temperatures are normal, riding on the thermostat at 190 whether straight gasoline or blended mix.

I deleted my last post I need to get some sleep.LOL

Anyway very informative. I just might have to try this on my company truck.

I don't suppose you have any data on the FE with straight diesel?

Does adding diesel fuel to gasoline in any proportion increase or decrease the overall octane rating for the fuel?

I don't, unfortunately, and I haven't had to do it enough to really have gotten any reputable data to begin with. TBH, I've only ever owned two cars that could use a SG, and I'm driving one of them now... the other is my wife's.

When I used to put diesel in my cars, I was like 16-18, always running out of fuel, etc. Right now, I don't think I'd be quite as willing to do it, but I'm not really sure why... probably because I have a gas station next door, and I actually pay attention to my fuel gauge now.

I've read in older Briggs and Stratton manuals that you could convert most of their gas only engines to diesel... they say to expect a power loss of about 20-30%, and an economy increase (run time on a metered tank at X load) of up to 30%, if that helps at all. I've never converted one, or tested the theory with a small engine, though.

I'll tell you what, though... I can give you a single tank reading when I pull the van off the road... I'll put 5 gallons of diesel in 15 of gas, fill the tank, and drive it out, then refill with gasoline. Its not accurate, but you've seen my average, so it'll be kinda obvious if there's a big increase that something worked.

I dunno, actually... Diesel's knock rating is in Cetane, not Octane... I dunno how to measure Octane levels on my own, and don't have a test block to do it with, so I couldn't honestly say.

Cetane and Octane are "made up" numbers, which give you an idea of the chemical composition of the fuel... Cetane, at higher numbers, gives a higher chance of autoignition, which is desirable in those type engines.

Octane, on the other hand, measures the resistance to compression ignition, a completely different beast.

Cetane is an alkaline molecule that ignites under very low compression situations. It has a Cetane number of 100. The higher your oil fuel's cetane number, the lower compression is required to ignite it.



Read more: cetane number - Comparison to Octane Rating, Chemical Relavance, Measuring Cetane Number, See Also, External Links cetane number - Comparison to Octane Rating, Chemical Relavance, Measuring Cetane Number, See Also, External Links

I'd imagine any gains from diesel fuel are from the higher Btu content.

I agree, it doesn't make sense any other way... The thermal efficiency of the engine doesn't change at all, so that doesn't add up unless it's from the higher BTU content.

Ya this doesn't add up. Every case I've seen of mixing diesel with gasoline has been a total disaster. There was a case recently where the nitwit at a local gas station filled up the 91 octane tank with diesel fuel. About a dozen cars unknowingly filled up with diesel, drove about a mile and broke down. Eventually the tow truck driver that was picking up all these cars off the side of the road put 2 and 2 together and called the gas station to turn off that pump.

http://www.youtube.com/watch?v=CvjrT5mRj_U

:confused: Wonder if there was something more to that story? Maybe it had something to do with FI vs Carb? I think every vehicle I've put it in was a Carb'd vehicle, so I can't vouch for FI... it could have clogged the fuel filter, etc... Diesel is useful as a spark ignited fuel, though, that's not to be questioned.

The vast majority of cars built in the last 25 years have EFI of one form or another.
Here is the original story.
Cars die after diesel flowed from high-octane pumps at San Rafael gas station - Marin Independent Journal

Can't say, really. I've done it on carb'd cars, and never with EFI, that I remember. At least not in full or large quantity. Maybe a gallon or so at a time, in my Sunbird (Pontiac 2.0OHC non-turbo).

I've run 2-cycle gas at 32:1 in my Civic, as well. Smoked a little bit, but it smoked normally, so I can't tell if it was from the fuel or just normal smoke.

As little regard as I normally have for my vehicles, I've added all sorts of things to the fuel, just to find out what would happen.

Of course, if you add diesel, the engine will run differently, and EFI fuel pumps aren't really designed to lift and pump diesel properly, nor are the injectors designed to flow it properly. Adding it to gasoline is a big difference from just using it straight.

I have to assume that those owners (of rather expensive cars, which normally means that they're not too up to date on their car knowledge) just noticed that it wasn't running like it normally did, and pulled over and called a dealer/mechanic etc. I'm sure they were more afraid than rational at that point.

I'd also never trust a dealer to tell me what's wrong, since they're usually known for including things that have nothing to do with the actual repair.

I would not try this blend in anything except a cylinder direct fuel injection system.

In an unmodified spark ignition engine designed for gasoline, which utilizes an unmodified carbureted fuel system or a manifold injection fuel system, the mixture will go too lean and likely result in explosive ignition. Explosive ignition will quickly and seriously damage the engine.

In the experiment underway, the engine has an unmodified cylinder direct injection fuel system and an unmodified OEM computer controlled ignition advance system utilizing a knock (preignition) sensor.

To date, there are no adverse affects.

My experience points otherwise, but your mileage, and opinion, may vary.

Point taken, see edit for clarification. I don't want anyone to try the wrong equipment set-up and damage their engine.

Hopefully your trial with your Caravan will result in an overall savings similar to mine. I look forward to reading your result.

If I do it in the Caravan, it will be just before I take it off the road to do a diesel conversion with my OM616.

The results will be inconclusive, at best, but a generous change should show that a difference can be made.

I've seen film of someone who filled their 911 with diesel instead of premium unleaded. Truly staggering amounts of smoke were coming out of the tailpipe...

Did anyone else notice the "takes several minutes of idling to warm up" statement? Sitting stationary with the engine running is generally very bad for fuel economy. For shorter trips, I imagine that would eat up all of your fuel savings, and then some.

-soD

I think my car gets diesel'd by accident as well. I have not figured which station...

Does anyone notice in the mixes, a gigantic low end increase? like a diesel?

that is a sign of fuel mixed...of course odor is another one.

if gas sits long enough, does what remains get thicker? towards diesel if allowed?

I'd love a 3 main boxer smacking around to diesel.

380 foot pounds at 200 rpm. :thumbup:

Gasoline will never turn into diesel. Diesel is basically a by-product (in this country) of gasoline production... it works the opposite way in other countries, where people follow the laws of nature. (Gasoline used to be a waste product, that was dumped in holes in the ground, streams, etc.)

Actually, I wrote: ""......when the ambient temperatures were -15 deg. F., ....... Cold starting is OK, although it is necessary to allow the engine to warm a couple minutes before driving away to avoid stalling." Not significantly different from the engine's behavior on straight gasoline when the temperatures are below -10 deg. F. A short period of idling to allow oil film to build and internal heat stresses to dissipate is good practice in extreme cold.

In this instance, there is no smoking. The exhaust appears the same as it does on straight gasoline, no change. The odor is slightly different, just a little odd.... one would be hard pressed to know the change is due to diesel.

Of course, that excessive idling always hurts economy is true. Be moderate, even in moderation.

So, running this on something with a carburetor, how far could I practically go before needing to re-adjust the carb? Keep in mind my car generally shifts at ~1100-1200rpm (yes, 1100, that's no typo), and cruises at ~1600rpm (40mph, my designated commute cruising speed)...

Technically, there is no correct answer. There is going to be a tradeoff of power for economy no matter what percent you use, and there will be differences of opinion on how much is too much.

Ultimately, it's up to you to just try it out and figure out where you're comfortable with your vehicle. There is really no correct answer here.

This is just a bad idea. I hope nobody pours diesel fuel into their gas tank because of this thread.

You have yet to actually make a point, other than posting an article about people who literally filled their cars with the wrong type of fuel, then complained about them running poorly, which is subjective at best.

I'm sorry but you're advocating something truly dangerous for most people's gasoline fueled engines without any quantifiable evidence that there is something to be gained here. I'm sure you like to make the point that that somebody used too much diesel fuel but how much is really safe in what engine? Do you know? I doubt it. The burden of proof is on the advocates of mixing gasoline and diesel in any proportion to show that:
1. Its safe for any gasoline engine
2. It doesn't negatively impact emissions or damage the emissions control devices
3. It works to improve fuel economy.

So far you've done none of those.
caveat emptor
cheers
Justin

I'm not advocating it at all, only adding my personal experience, having done it myself.

At least this time, you added a meaningful post. :thumbup:

And, by the way, evidence is (and has been) around that shows that gasoline carbureted engines can safely be run on kerosene variants with tuning. Those engines which I've seen and done work with aren't emissions controlled, though.

I did, however, make note that for each combination of engine/operator/fuel mixture, there is no right answer, it's for the operator to figure out on his own. That would be the nature of experimentation, in case you hadn't noticed.

You don't need to be insulting just because you think you're right. And yes, you are advocating for it.

You need to clearly specify:
There is NO evidence that there is any FE benefit here
This DOESN'T work on EFI engines which makes up 99% of the vehicles on the road today
It HAS NOT been tested on emissions controlled vehicles.
There are UNKNOWN long term consequences of putting diesel fuel into a gasoline engine in any proportion.