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Discussion Starter #1
just promise to tell them phil getchell sent you...

I'm not a TEC guy, so this may be really dumb..... I've read in places that the use of NO2 (nos) and propane are affective together... is this only with (diseal* sp) fuel only.... Something just doesn't add up... The nos I can see... being in Respiratory medicine... we use it all the time... Trust me, the high O2 concentration supports fire!!! But...porpane... (DRY.. of course...) seems like a good way to blow the pistons straight through the hood... Am I missing the boat?
 

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...and I'm just going to add to this post.
Do you think that if you added a leaf blower or something to an air intake and started it up when you drove your car it would be like an instant 'do-it-yourself turbocharger'? :lol:
 

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Yup, I saw that episode of Trucks!, too. The diesel truck in question went from 196 hp and 39x lb-ft at the wheels to about 460 hp and 800+ lb-ft. I think this kind of thing would only be "safe" with a diesel engine, which is designed for extremely high compression ratios and cylinder pressures.

I had never seen propane used before, either, but I do remember they had a pretty good explanation for why it wouldn't blow everything to pieces. It may have been something about diesels not using a direct spark to light the air/fuel mixture. The heat just comes from the extremely high compression; thus diesels have no spark plugs, which is why they can run under water as long as the air has a clear path (i.e. snorkel intakes, etc.).

If you try this with a sport compact 4-cylinder, however, you're in for an expensive surprise.
 

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Discussion Starter #5
Yup, "trucks" was the most recent time i've seen it... I've heard rumors of it in the jetta's too... diesel probably... It seems to me that it's psycho way to get hp... So... compression ratio? I can see what you mean when you talk about the use of glow plugs rather then spark plug... Let's just say... I won't be trying this on my Sti...(when I finally get one)
 

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Agent Chobos said:
It may have been something about diesels not using a direct spark to light the air/fuel mixture. The heat just comes from the extremely high compression; thus diesels have no spark plugs, which is why they can run under water as long as the air has a clear path (i.e. snorkel intakes, etc.)..
It's always been kinda funny to me that Diesel engines work off of a principle that one tries to avoid in a gas engine. The way I understand it Diesel's are just detonating, which could explains the noise they make as well.
 

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darwood said:
It's always been kinda funny to me that Diesel engines work off of a principle that one tries to avoid in a gas engine. The way I understand it Diesel's are just detonating, which could explains the noise they make as well.
From what I understand, that's exactly what they are doing. They don't have problems with early detonation, though, because there is no fuel in the cylinder until it's injected there at full compression.
 

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Discussion Starter #8
You guys really got your crap together... It all sounds right to me... The second you start talking diesel my undersatnding stops at glow plugs...lol... guess thats why I went into medicine... :oops: I could never be a mechanic!!! :lol:
 

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I don't know what you mean by "glow plugs". Diesel engines don't use any kind of plug to light things up. Just like darwood said, they operate on exactly the opposite principle of a gas engine. In a normal engine, you're trying to avoid detonation, which is the ignition of air/fuel before the spark plug fires. But diesels take advantage of the heat generated purely by compressing the mixture. There is no plug, just very high pressures and BAM!
 

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Glow plugs are indeed a feature of some, but not all, diesel engines. My attempt to explain further can, in no way, be any better than what can be found here.
 

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Actually, most diesels have glow plugs. It isn't a spark plug, it's really just a small heating element.

A diesel's primary way of creating combustion is compression only, but if you don't have a proper temperature, the compression isn't quite enough to light off the fuel. When it's cold out, the glow plugs are lit for a few seconds to create heat in the cylinders so that the engine will start. And then, of course once a few combustions have taken place, the heat is there already.
 

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Yes, if they don't have glow plugs then there is some preheating element in the air intake? or fuel line? that warms things up. I can't remember which it is. Diesels don't like the cold.
 

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In regards to the propane question - Propane is a catalist for diesel fuel. Your typical diesel engine only burns at about 75% efficiency. By adding propane to the mix, you get closer to 95% efficiency. More efficiency means more power. It'll work on any diesel engine, and won't blow up any GOOD diesel engine.
 

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jbhebert said:
It'll work on any diesel engine, and won't blow up any GOOD diesel engine.
So don't try this on a Chevy diesel engine? :p

Apparently there are reasons they don't make diesels anymore.
 

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Discussion Starter #16
Agent Chobos said:
I don't know what you mean by "glow plugs". Diesel engines don't use any kind of plug to light things up. Just like darwood said, they operate on exactly the opposite principle of a gas engine. In a normal engine, you're trying to avoid detonation, which is the ignition of air/fuel before the spark plug fires. But diesels take advantage of the heat generated purely by compressing the mixture. There is no plug, just very high pressures and BAM!
The glow plug allows a cold weather start.... as aforementioned... Remember, I know all about cold weather starts... I live in the coldest major city in North america ... at -50 not much starts :lol: but at -10 a diesel won't start without glow plugs...
 

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darwood said:
jbhebert said:
It'll work on any diesel engine, and won't blow up any GOOD diesel engine.
So don't try this on a Chevy diesel engine? :p

Apparently there are reasons they don't make diesels anymore.
None of the Big 3 make their own diesels; Ford gets theirs from International Harvester (Powerstroke), Dodge gets theirs from Cummins (since around 1981; before that they used Mitsubishi), and Chevy gets their new diesels from Isuzu (Duramax). The only Chevy diesels to avoid were the converted 350 gas engine ones that found their way into the Caddys and El Caminos in the 80's. Up until a year or two ago, the trucks all got Detroit Diesel engines, which weren't particularly powerful, but weren't nearly as bad as the converted 350s. The new Duramax is a SWEET diesel, especially since it comes hooked up to the Allison 5 speed auto or NV5600 6 speed manual.
 

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The noise that diesel engines make comes from the combustion process. Diesel engines inject fuel close to TDC, where the air is already pretty hot from compression. However, the fuel doesn't ignite as soon as it's injected; it goes through an ignition delay period where the chemistry of combustion is starting to break things up. The amount of fuel accumulates during the ignition delay, so when it finally starts burning, the pressure rises rapidly due to the burning of a large fraction of fuel. This stage is called the premixed-controlled burning phase. This pressure sends shock waves through the combustion chamber, making the block vibrate. This is where the diesel sound comes from.

Also, someone said that propane acts as a catalyst. That's a good way to put it. Diesels burn in a diffusion-controlled manner after the premixed-controlled phase (think of a candle and how it burns; diesels are similar). The added propane in the air adds a source of hydrogen. In combustion chemistry, the hydrogen radical, a single hydrogen atom, is a very important species. Adding it improves the flame speed, and thus burning rate. So, adding propane is a good thing in diesels.
 

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jbhebert said:
None of the Big 3 make their own diesels; Ford gets theirs from International Harvester (Powerstroke), Dodge gets theirs from Cummins (since around 1981; before that they used Mitsubishi), and Chevy gets their new diesels from Isuzu (Duramax). The only Chevy diesels to avoid were the converted 350 gas engine ones that found their way into the Caddys and El Caminos in the 80's. Up until a year or two ago, the trucks all got Detroit Diesel engines, which weren't particularly powerful, but weren't nearly as bad as the converted 350s. The new Duramax is a SWEET diesel, especially since it comes hooked up to the Allison 5 speed auto or NV5600 6 speed manual.
Exactly.
 
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