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Diesel Truck for hunting
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<blockquote data-quote="steve smith" data-source="post: 41132" data-attributes="member: 110"><p>Sorry DC</p><p>I'd have to disagree with you there. Diesel engines have a much higher compression ratio than gasoline engines. Most gas engines have a compression ratio somewhere around 9:1 where as a true diesel (like the Cummins) has somewhere around 16.5-17:1.</p><p></p><p>Though I do agree with you on the flash point of diesel being much higher than gas. And that it remains constant at any pressure. But I still believe that the amount of compression (and the amount of heat generated during compression) has a lot to do with starting troubles in cold weather. Diesel engines with low comression would have trouble starting in cold weather with or without glow plugs. The Onan generator I mentioned earlier has much lower compression and will not start in 101 degree weather without running the glowplugs through the heating cycle. I know be cause I tried. </p><p>Looking back at the various gas laws used in chemistry, If you take a given volume of air (the number of molecules is fixed, we'll say one cubic liter)at atmospheric pressure, and ambient temperature. If the volume of air is compressed to half of it's orininal volume (now .5 cu liters, but the mass remaining constant (1cu lt @ 1ATM) the temperature increases accordingly. Now if you compress the air even more (lets say down to .25cu liters, (a 4:1 compression ratio) the temperature increase in a predictable path. The final temperature is entirely dependant upon the initial temp and the amount of compression. So with my experience in my truck @28 degrees F a 17.1:1 compression ratio is enough to raise the air temperature to the flash point of #2 diesel fuel with out the use of the fuel preheat. With the onan generator in 101 degree F the compression ratio is not high enough to raise the temp to the flash point of diesel. Hit the plug heating button for 30sec and it fires right up. The generator is a diesel engine but it is not a true diese engine, in that it requires an external heat source to fire. The Cummins engine is a true diesel in that it requires only the heat generated during compression to fire.</p><p></p><p>[ 02-09-2004: Message edited by: txhunter ]</p></blockquote><p></p>
[QUOTE="steve smith, post: 41132, member: 110"] Sorry DC I'd have to disagree with you there. Diesel engines have a much higher compression ratio than gasoline engines. Most gas engines have a compression ratio somewhere around 9:1 where as a true diesel (like the Cummins) has somewhere around 16.5-17:1. Though I do agree with you on the flash point of diesel being much higher than gas. And that it remains constant at any pressure. But I still believe that the amount of compression (and the amount of heat generated during compression) has a lot to do with starting troubles in cold weather. Diesel engines with low comression would have trouble starting in cold weather with or without glow plugs. The Onan generator I mentioned earlier has much lower compression and will not start in 101 degree weather without running the glowplugs through the heating cycle. I know be cause I tried. Looking back at the various gas laws used in chemistry, If you take a given volume of air (the number of molecules is fixed, we'll say one cubic liter)at atmospheric pressure, and ambient temperature. If the volume of air is compressed to half of it's orininal volume (now .5 cu liters, but the mass remaining constant (1cu lt @ 1ATM) the temperature increases accordingly. Now if you compress the air even more (lets say down to .25cu liters, (a 4:1 compression ratio) the temperature increase in a predictable path. The final temperature is entirely dependant upon the initial temp and the amount of compression. So with my experience in my truck @28 degrees F a 17.1:1 compression ratio is enough to raise the air temperature to the flash point of #2 diesel fuel with out the use of the fuel preheat. With the onan generator in 101 degree F the compression ratio is not high enough to raise the temp to the flash point of diesel. Hit the plug heating button for 30sec and it fires right up. The generator is a diesel engine but it is not a true diese engine, in that it requires an external heat source to fire. The Cummins engine is a true diesel in that it requires only the heat generated during compression to fire. [ 02-09-2004: Message edited by: txhunter ] [/QUOTE]
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