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a really stupid question

Discussion in 'The Garage' started by stiches, Jan 31, 2006.

  1. stiches

    stiches Registered Member

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    I know what gas "petrol" is. and i semi know what diseal. and if you put gas in a diseal engine it will blow up...but my question is that what other good benefits of having a diseal engines. and what are some of the cons and anything i should be worried of? I am coming from a 78 blazer to a random beater untill i can get mine back on the road
     
  2. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    i'm not sure i really understand your post too well, but here's a shot. diesel requires much higher temperatures and compression to ignite. thus, if you put gasoline in, i believe it ignites before the piston reaches the top of its stroke, thereby the explosion creates a force against against which the piston has to push before it can come back down. i don't know, but i imagine a diesel engine couldn't run even a few seconds on gasoline. as far as benefits of diesel, you are looking at having all your torque at VERY low rpm (actually, everything is low rpm - the 6.2's are governed to i think 3600rpm), good fuel economy (geared properly, this can mean 20+ mpg). one benefit i plan to enjoy in my rig once i get it on the road is running veggie oil. it's an incredibly clean burning renewable fuel which you can make for yourself for 50 to 70 cents per gallon. there's tons of info on that online. many will claim that they are gutless, but they can also be built just like any other motor. i guess i'll leave it at that for now.
     
  3. dave_90_blazer

    dave_90_blazer 1/2 ton status

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    diesel fuel is also alot less volitile, so, safer fuel
     
  4. 79k20350

    79k20350 3/4 ton status

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    also no sparkplugs:D
     
  5. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    thus the reason for the higher compression and ignition temperatures.
     
  6. 79k20350

    79k20350 3/4 ton status

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    and why gas no worky. that would be a pretty high octane to work at
    20.0:1 + compression:D we could go on forever with differance, hell similaritys for that matter but we need more specific as to what you wana know
     
  7. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    this thread is turning into a lot of circular reasoning! :) wierd how things can prove themselves sometimes.
     
  8. stiches

    stiches Registered Member

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    just wondering because my g/f might be gettin a turbo diseal benz....and i want to know what are some things that are different then gas...i know the general concept...no plugs...there are coils...but like does anyone know anythin cause this board is one of the best for cars
     
  9. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    can't say i know much about mercedes, but the biggest difference is that you'll need to be familiar with the glow system (which i'm assuming it has) to start the vehicle. aside from that - you don't have plugs, like you said. you'll need to find out how much maintinence the turbo might require. that's about all i can think of for the mercedes. maybe consider priming the oil filter before you install it - but they may be small enough that thats not necessary. maybe that's helpful.
     
  10. Robert79K5

    Robert79K5 1/2 ton status

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    Well yes and no.....
    Gasoline is more volitile than diesel but it has a higher ignition temperature than diesel. I can see where if you had the right concentrations of diesel and gas in a diesel engine that the diesel could start to burn and the resulting flame could set off the gasoline and cause some serious engine issues, but if you run gasoline through your diesel what youll get basically is nothing, it just wont run because the diesel engine wont build enough heat to ignite the gasoline. I know it sounds weird but thats the reason gasoline engines have spark plugs because gasoline wont ignite under the temperatures created by the compression of a diesel engine.

    What makes diesel fuel safer than gas is its lower volatility. Gas will fume and achieve a nice near stoichiometric (sp) ratio in the air and if there is an ignition source the fumes will find it and Kaboom! Whereas diesel fuel just sits there, not evaporating.
     
  11. 79k20350

    79k20350 3/4 ton status

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    I forgot that diesels run cooler. i remember reading an article about some kind of deisel pump or generators, something of the sort in the artic that they have to idle up cause they would acutally freeze when it got cold enough. Even if the were running for god knows how long. it was just too cold and needed the higher rpms for the heat it created. never heard of that happening with a gas engine. :D

    Also a thing to look into is the fuel system, i magine its electric but theres alot to it my sure, then the injector pump, etc. other than that i dont know much about the mercedes diesel:o never had to bother with em, or woul i want too...;)
     
  12. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    hmmm. i thought that diesels ran alot hotter. one thing's for sure - oil out of a diesel truck is sure a he!! of alot hotter than a gas motor if you drain it while teh motor is still at operating temp!
     
  13. mr_blasto

    mr_blasto 1/2 ton status

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    Those old turbo diesel Benz' are pretty awesome. The one my three sisters drove all through high school was a '78, and was previously driven by a slew of kids in another family. We ended up giving it to my cousins who also drove it for a while.

    They last a long time and have horrible acceleration (even with the turbo). My sisters knew nothing about cars and managed to keep it alive for 8 years or so. My good friend's family had one nearly identical to ours at the same time - it was pretty funny to watch teenagers drive them.

    In the end, the diesel is not what you should be worried about. I would be more concerned with other things on the car breaking or needing replacement. German parts are really $$$.
     
  14. Robert79K5

    Robert79K5 1/2 ton status

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    Diesels do generate a whole lot of heat. There is actually more energy per unit volume of diesel fuel than in gasoline. The phenomenon he is talking about happens when diesels are left to idle for a long time. The spray of diesel fuel from the injector will actually cool the combustion chamber and cause incomplete combustion of the fuel. In some diesels oil and unburned diesel fuel will accumulate in the exhaust if left to idle too long. This is known as "wet stacking" My 6.2 will do it a little if I idle for a long time. Its kinda fun to romp on it and watch the cloud of smoke bellow from under my Blazer. :D
     
  15. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    Pros,

    better fuel economy
    heavier duty engine internally
    engine lasts twice as long
    builds way more torque at a lower RPM range
    smell better
    use a better and safer fuel
    much simpler for the most part, fuel and air, no spark to deal with.

    Cons,
    cost twice as much to rebuild
    are louder than a gas engine (this normally bothers women and yuppies)
    older designs are usually a little sluggish
     

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