differences between diesel and gasoline fuel

hi.

I was wondering what will happen if we will try to run diesel cycle engine on gasoline?

I know how both otto and diesel cycle works, but I gues that main difference between diesel and gasoline (beside other physical properties) fuel is its speed of burning.
I am guesing that diesel has longer carbon-hydrogen molecules than gasoline, so it is burning slower, that is why diesels have longer stroke and slower rpm.

So hypoteticaly (or from experience if enywhone has try it), what will happen if we run diesel engine on gasoline. I'll say that gasoline will burn when injected to the cylinder, but propably the explosion and temperature will be to high and the peak pressure will eventualy damage the egine.

On the other hand what will happen if we run gasoline engine on diesel. Probably nothing as there will be misfires and even egnited diesel won't burn efficently, so I'll say engine won't even run.

(But once by mistake I fill the lawn mowe with the diesel and it ran for about few seconds or so - there was however no gasoline in the delivering system as it surely evaporated durring the winter pause).

If you put gas in your diesel engine it will not start due to the major fact that diesel engines run on compression alone and have no ignition source. Gasoline requires a spark to ignite the fuel/air mix when it's been compressed to cause the combustion. Diesel combusts from the compression of the piston and uses no spark plugs. Gasoline engines can run on diesel but will produce so much smoke from the exhaust that you will not even be able to see the car.

If you put gas in your diesel engine it will not start due to the major fact that diesel engines run on compression alone and have no ignition source. Gasoline requires a spark to ignite the fuel/air mix when it's been compressed to cause the combustion. Diesel combusts from the compression of the piston and uses no spark plugs. Gasoline engines can run on diesel but will produce so much smoke from the exhaust that you will not even be able to see the car.

ok I don't know if you are some kind of expert but I do know that you don't know much about engines and surely you don't know thermodynamics equations, according to your statetment.

Gasoline autoignition point is even lower that diesel. For normal gasoline it is 257 deg C for diesel it is 316.

So if the compression temperature ignites diesel it sure will the gasoline!!!!

I think the problem will be as I allready wrote, too high peak pressure and temperature, thus destroying the engine!!!!

yes. and a couple of companies, notably mercedes benz, are working on a new motor they call the diesotto. compression ignition, gasoline engine with variable valve timing, direct injection, turbocharging, and variable compression. their working prototype has made something like 230hp and 295 lbft from a 1.8 liter 4 cylinder. oh yeah with around 30-40 mpg too.

yes. and a couple of companies, notably mercedes benz, are working on a new motor they call the diesotto. compression ignition, gasoline engine with variable valve timing, direct injection, turbocharging, and variable compression. their working prototype has made something like 230hp and 295 lbft from a 1.8 liter 4 cylinder. oh yeah with around 30-40 mpg too.

30-40mpg and 230hp! well if that is true, it is some hiiiiiiiiiiiiiighly efficient engine.

with variabile compresion you mean miller cylce wich can be attained with variabile valve lift or hydraulic haead inclination system like found on some saabs?

If you put gas in your diesel engine it will not start due to the major fact that diesel engines run on compression alone and have no ignition source. Gasoline requires a spark to ignite the fuel/air mix when it's been compressed to cause the combustion. Diesel combusts from the compression of the piston and uses no spark plugs. Gasoline engines can run on diesel but will produce so much smoke from the exhaust that you will not even be able to see the car.

Actually, that's not quite true. If you fill your tank there will be enough fuel in the lines to start the engine. After that runs out the cylinder temps are hot enough to detonate gasoline. That that point the diesel engine blows up.

I know it happened to two diesel trucks that filled up at a station I worked at. The guy put diesel in the 89 tank and 89 in the diesel tank. I made a lot of unhappy customers. A lot of people needed fuel systems flushed while two guys needed engines.

It depends on the ratio of the two fuels. I seen a diesel run on a gas mixture, the owner said it had no power, smoked bad and had an extra knock. I accidently put kerosene in my motorcycle. (who expects k1 in a gas container?) I made it about 7 miles then it ran bad and I could feel the extra heat. (air cooled) It died and wouldn't restart, I didn't even make it to the gas station. The bike never did run the same afterwards.

Actually, that's not quite true. If you fill your tank there will be enough fuel in the lines to start the engine. After that runs out the cylinder temps are hot enough to detonate gasoline. That that point the diesel engine blows up.
I know several people who've had their diesel vehicles filled with petrol. The above did not happen. The engine simply either ran very badly on the diesel/petrol mix in the lines or didn't run at all.

In very cold climates petrol is often mixed in with diesel to prevent the diesel turning into wax.

30-40mpg and 230hp! well if that is true, it is some hiiiiiiiiiiiiiighly efficient engine.

I have a dually with a cummins diesel making 27 mpg while moving a 7500-lb truck and putting 500 hp to the ground. Its pretty common with the big diesel trucks to get 25+ even with some pretty crazy modifications

Its pretty common with the big diesel trucks to get 25+ even with some pretty crazy modifications Diesel pick-up trucks you mean. 18 wheelers actually only adverage 3 to 7.5 mpg depending on horsepower, how much weight they are pulling, the driver and so on..

Right. I shouldn't have said "big". I should have said pickup.

30-40mpg and 230hp! well if that is true, it is some hiiiiiiiiiiiiiighly efficient engine.

Of course you're not getting 30-40mpg while producing 230hp. But you can get 30-40mpg from an engine which can produce 230hp.

Assuming 90km/h
Assume 35 USmpg = roughly 15km/l
Your vehicle would be drinking 6 litres per hour. (5.4kg)
With a BSFC of 200g/kwh that is 27 kilowatts continuous output.

Roughly 36.5 hp.

Of course you're not getting 30-40mpg while producing 230hp. But you can get 30-40mpg from an engine which can produce 230hp.


exactly. the compression ignition part only happens at certain times to improve efficiency. tnstaafl. oh and i believe the variable compression is like saab's but im not 100% sure. i do know its not miller cycle.

The only reason I can see for the spark plugs is improved cold-start emissions.

Funnily enough that's how many old tractors and bulldozers used to run, have a valve which opens to reveal a sparkplug and lower the compression. Start on petrol, once the engine is warm switch to diesel and close the valve over the spark plug.

Funnily enough that's how many old tractors and bulldozers used to run, have a valve which opens to reveal a sparkplug and lower the compression. Start on petrol, once the engine is warm switch to diesel and close the valve over the spark plug. I have a 1921 Farmall Regular tractor that starts on gas then you switch it to kerosene when warm. Before you shut it off you switch it back gas and let it run for a little while so it will start next time. It smokes like freight train and used about 11 gallons on a 20 minute run. I don't have it all the way restored yet so it needs tuned in still.

My two observations are spark ignited low compression oil burners are real dogs for power and mileage. Very high compression self-ignition gasoline engines are far higher in power and mileage than either the original gas or oil engine.

It can also be stated like this : The diesel engine itself is far superior and the gasoline fuel is superior. Convert diesel engines to gas and "try not to use spark plugs"

My two observations are spark ignited low compression oil burners are real dogs for power and mileage. Very high compression self-ignition gasoline engines are far higher in power and mileage than either the original gas or oil engine.

It can also be stated like this : The diesel engine itself is far superior and the gasoline fuel is superior. Convert diesel engines to gas and "try not to use spark plugs"

Scania have created what could be IMO the perfect engine. It's a high compression (28:1 static plus boost) diesel engine which runs on ethanol. The high compression numbers are needed to cause the high octane ethanol to self-ignite but they also result in very high efficiency. Scania report around 50% which has previously only been acheived in very large and low revving ship engines.

A VW 1.9tdi is one of the most efficient road going engines, it works out around 42% efficient at best point.

Diesel fuel has a higher BTU content than gasoline, so I'm not sure that using gasoline in a diesel compression ignition engine is the way to go. About its only benefit would be that it burns faster and would allow for higher revs. Ethanol (although nicer to the environment) has only about 2/3 the BTUs of gasoline, so all of the benefits might be more than lost with mileage and energy consumption.

I like diesel how it is. If we can find decent and sustainable ways to keep diesel emissions in check, I think its a better fuel. Not to mention its a much safer fuel from a flammability standpoint. Its less damaging in a spill, and is less likely to ignite if spilled.

The primary benefits of ethanol is the ease of production (distll anything) and the complete lack of soot.
Basically it's the first compression ignition engine to run on a traditional spark ignition fuel.

Brewing biodiesel or running plant oils is a much easier option for the rest of the diesel vehicles out there.

If we can find decent and sustainable ways to keep diesel emissions in check.. 2007 U.S. emissions for on-highway trucks (18 wheelers) state "no black smoke." If the truck meets '07 emissions, it should have NO soot in the stack. (tailpipe you car guys) 2010 emissions are to have cleaner air out the exhaust then being ingested, makeing the engine an air cleaner, literally. Detroit Diesel and Cummins are going to inject a solution (urea? you-ree-uh) to achive this. check out thier sites curtis, I know you'll like it, intresting stuff! :)

Yup, urea injection. It does wonders, and the new diesels will exhaust cleaner air than they ingest... but I think it will take a while until we find the optimal setup. Urea injection works well, but there are better ways to accomplish it without that complication.

Biofuels are a great way to eliminate those requirements, but there is no way to support even 1/10th of our country's energy demands on biofuel at our current consumption.

I know several people who've had their diesel vehicles filled with petrol. The above did not happen. The engine simply either ran very badly on the diesel/petrol mix in the lines or didn't run at all.

In very cold climates petrol is often mixed in with diesel to prevent the diesel turning into wax.

Perhaps that's not a definite, but I know for a fact it has happened.

some Paccar trucks (DAF LFs and CFs) arleady run with urea injection. called AdBlue, i believe.

i think people in the US will at some point come to the realisation that Diesels are the way forward, like Europe has. we have loads of diesels, and not just light commercials and shopping trolleys. for example, the guy who lives next to me has an '07 BMW 735 diesel. and diesels are everywhere in Europe, mostly because they're so economical ad many are as clean as their petrol counterparts.

two things are holding the US back in terms of getting more diesels on the road, the first being the memories of 80s diesels, which were slow/noisy/pollutant and left clouds of black smoke in their wake.

the second is that there aren't many diesel techs over there and there aren't enough people who know enough about diesels. so advancement is being held back by the market more than the manufacturers.

the second is that there aren't many diesel techs over there and there aren't enough people who know enough about diesels. so advancement is being held back by the market more than the manufacturers. By 2010 they are predicting a shortage of over 9 thousand diesel engine techs in the U.S. Thats according to the Detriot Diesel class I went to this past December. I believe it! Kids now want to work with computers and make 100k a year. I work nights, my shift is was down to me, a foreman/service writer, and another tech. Now we have a trainee, who I believe can screw up ANYTHING. So, not only finding techs, but finding good techs.
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By 2010 they are predicting a shortage of over 9 thousand diesel engine techs in the U.S. Thats according to the Detriot Diesel class I went to this past December. I believe it! Kids now want to work with computers and make 100k a year. I work nights, my shift is was down to me, a foreman/service writer, and another tech. Now we have a trainee, who I believe can screw up ANYTHING. So, not only finding techs, but finding good techs.
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I'd come work for you if I didn't kinda burn myself out on it. I worked 60-70 hour weeks and was still horrifically behind. I was noticing health effects from all the chemicals, and my back and knees were complaining. When the week was done, there was so much work left that I didn't feel like I accomplished anything.

The money is there for the right person. Just wasn't me.

i've done the 60-70 hour weeks and enjoyed it because i was doing nearly what i wanted to do. (i was running a tyre shop)

ready to do it all over again with diesels this time.