For Scott and Cody

[redcagepatrol]

Originally posted by Chadnutz
Sigh... The motor is made more efficient at the cost of some pollution. The chip just allows for more fuel when it is needed....

If there is more pollution, the motor is LESS efficient. Stochimetric(sp) combustion is where all the fuel/O2 is burned, leaving realitivly small amounts of NOx and CO in the exhaust. Stock combustion is about 15% extra air (the reason for the NOx is because we have to combust air and not O2). The extra air in the combustion chamber is used for cooling and scavaging of the exhaust. When you add more fuel, without getting enough boost, the engine gets LESS efficient because not all of the fuel is burnt and you are no-where-near a stoich mixture.

Hey Nutz, read an engine book - preferably one dealing with combustion and emissions, it will help you better understand how your engine runs.

I will try to round up some graphs when the emission folks come into work...

[Chadnutz]

So why does the truck come from the factory with the timing retarded? How can you explain that even thought a chip pumps in more fuel the economy goes up 1-2 mpg given the same driving style... There is more AVAILABLE power, but it also becomes more efficient.

[eight]

What I hear is that a diesel makes 3 kinds of emissions and cannot be over on any of them. They retard the timing to keep the NOx low but that raises the other two. So by advancing the timing it makes less pollution over all, but the NOx is out of limits. And supposedly advancing the timing makes better mileage. I've never had a chip in anything that made the mileage improve. And I've got 3 brothers and my dad who have chips or programmers in their strokes and mileage never improved for them. I'll soon see if this Edge EZ my dad's got laying around will help my dodge any, but I doubt it.

[uglyota]

Originally posted by Chadnutz
How can you explain that even thought a chip pumps in more fuel the economy goes up 1-2 mpg given the same driving style...

Because of exactly what Scott said...the engine comes out of the factory pumping in more air than it should (more than is stoichiometrically correct). To achieve a stoichiometric (perfectly efficient) mixture you would need either less air or more fuel, and since clogging your air filter would be stupid, people pump in more fuel.

But the bottom line is that none of it makes any difference in fuel economy (nevermind enough of a difference to pay for the mod itself), as I know from gas engines and as Scott and Kopecki confirmed for diesels.

Oh yeah,

[eight]

There isn't actually a stoichiometric ratio for a diesel. They burn as much diesel as is put in as long as there's enough air. Ever notice how they don't have throttle bodies? They cannot make a lean, hot flame like a gas motor can. Now running too much air through with a turbo is done as a way to dilute the emissions and EGTs, but it takes extra power to compress that extra air. Oh, and I remembered the reason why advancing the timing supposedly increases mileage, it allows the fuel to more completely combust in the cylinder.

[redcagepatrol]

Originally posted by eight
There isn't actually a stoichiometric ratio for a diesel.

are you kidding? Did you fall asleep in Chemistry? Of course there is but Turbocharged engines don't run that mixture.

I will attach a few graphs to help ya'll understand combustion. If you don't know, BSFC is Brake Specific Fuel Consumption and HC is hydracarbons

[uglyota]

Not that I know anything about diesels, but if put in just enough air to burn all the fuel, you've got a stoichiometric mix.

Am I wrong?

If advancing timing allows the fuel to more completely combust in the cylinder, isn't that getting closer to a stoichiometric mix?

[redcagepatrol]

more

[uglyota]

Originally posted by redcagepatrol
are you kidding? Did you fall asleep in Chemistry? Of course there is but Turbocharged engines don't run that mixture.
I will attach a few graphs to help ya'll understand combustion

This must be why you's gradjiated!

[redcagepatrol]

an interesting side not on this one deals with the speed limits and Houston. As the engine RPM slows, the residence time increases and the NOx emissions gets worse (NOx causes Ozone). This is why Houston raised the speed limit back up after the polititions (sp) dropped the limit to "reduce emissions" Some people are just mis-informed or just plain stupid - they can convince the public of anything. They were wondering why the emissions went up - go figure

[redcagepatrol]

last one

[redcagepatrol]

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[Broncocustom]

Those are just a few of the graphs from 2 books out of many we have in our office. The group Scott and myself work for does emmision testing on industrial engines that can run on natural gas or diesel. All our coworkers talk about is NOx, CO and fuel consumption.

[jerryg79]

But, but the guys on my internet site said.....

[redcagepatrol]

I guess everyone understands how diesels work now? Let me know if you need some more graphs or some more understanding.