Quote:
Originally Posted by Daox
At some point, you lean out the mixture so much that you end up lowering the combustion temperature so that detonation is no longer a problem. But, at this point your fuel charge is so diluted that you run into ignition problems because there isn't enough fuel to properly propagate the flame through the cylinder. This is why lean burn engines have specially designed heads or pistons or both, to increase swirl within the cylinder and more evenly disperse the fuel through the cylinder.
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You are absolutely correct
if you continue to use the combustion technology that we, as mechanics, have been taught for over 100 years.
I don't dispute one single statement or perception you say, as long as I qualify my agreement by saying that your statements only apply to fuel systems that put liquid fuel into the engine.
If you 'lean out' (as in cut back the liquid fuel) going into an engine
that has a conventional fuel system, you WILL increase exhaust temperatures because the combustion NEEDS that 'extra' fuel to quench the flame (as in make it so rich it cannot continue to burn) just as I explain in my blog. You are absolutely correct, and it's easily proven just by leaning the mixture in any engine.
It's also true that if you continue to lean out the fuel,
in a conventionally fueled engine, till there's barely enough fuel to burn, that the exhaust temperatures will be cooler, but you will also lose power.
I KNOW all this, you are not talking to a novice. I'm a mechanic with decades of experience working with fuel systems. These 'facts' are so easily proven that very few mechanics
even question that they are being duped! And some of them will fight to the death to defend the above facts, because their training and experience prove, to them, that the facts are right.
What the mechanics do not know is that there is a better way.
A way to
reduce fuel consumption by 90% while KEEPING full engine power and performance.
A way that resists detonation and preignition.
A way that reduces all pollutants (CO, NOx and hydrocarbons) to near zero.
A way that keeps the exhaust temperatures down without having to add 'quenching' fuel.
A way that has been proven and documented dozens of times (see Pogue and Ogle for high profile examples) and is well covered with hundreds of patents.
Most mechanics do know that only gasoline vapors, mixed with oxygen in a narrow air:fuel ratio, will burn.
What mechanics are NOT taught is that only the fuel that is vapor and mixed with oxygen when the spark plug fires actually powers the engine.
Mechanics are not taught that
the 14.7:1 air:fuel mixture, while true for open air combustion,
is NOT TRUE for internal combustion! And anyone with a scan gauge can prove it for themselves.
Mechanics are deliberately mislead by charts (like the one below),
that support conventional fuel system technology, so that they will not 'see' the truths that will prove they were/are being lied to.
Please remember I KNOW what mechanics are taught because I'm a certified automotive technician too.
Mechanics aren't taught that only about 10% of the fuel is vapor and mixed with oxygen when the spark plug fires; resulting in 90% of the fuel being wasted.
For engine power, it doesn't matter how much liquid fuel there is; (when it's liquid it might as well be water as far as the combustion is concerned) only the vapor fuel matters.
Mechanics are also not taught that if the engine were fed ONLY vapor fuel, that the chart below would look very different.
1. It wouldn't be based on bogus external combustion fuel ratios.
2. There would almost never be NOx, even on the lean' side of the chart, because combustion temperature high enough to create NOx would only exist for a few milliseconds after the spark plug fires. There would be no continued combustion that causes the overheating of the combustion constituents as they flow out past the exhaust valves.
3. There would be almost no CO for the whole range of 'normal' combustion.
4. The HC would loop like your chart, but it would go to near zero in the optimum range.
The chart below looks like it does because conventional fuel systems dump liquid fuel into the engine.
A small portion of the liquid fuel turns to vapor and explodes when the spark plug fires
but the rest of the liquid fuel needs to vaporize and mix with oxygen before it can burn. That vaporization and mixing takes far too long, even with 'swirl' technologies.
By the time this 'secondary' burning gets going (the primary burn was when the spark plug ignited the already existing vapor) the exhaust valves are opening and the flame is burning out past the exhaust valves.
You've likely seen race cars with the flames shooting out; that's all totally wasted fuel!
I believe in burning the fuel IN the engine, not in the exhaust. The KEY is to burn the fuel
completely within about 12 milliseconds after the spark plug fires.
At this time the engine geometry is exactly right to most efficiently convert the heat energy (pressure from expanding gasses) into mechanical energy. After these few milliseconds the piston is moving 'away' from the combustion faster than the combustion temperature/pressure can push on it (see combustion pressure charts) and the expanding the 'chamber area' is diluting the initial combustion pressure.
The problem with conventional combustion (that we mechanics are all taught to fix) is that when you have liquid fuel, the initial (vapor) combustion produced the heat needed to vaporize it; and it now mixes with oxygen and burns... WAY TO LATE! Now you'll have flames going out the exhaust, burning up your valves and creating high NOx.
But
we mechanics are taught there is a CURE!
Simply dump in more fuel, so when the initial (vapor) combustion vaporizes the liquid portion of the fuel, the resulting air:fuel ratio is too rich to burn and the flames are quenched.
But opps, there are now huge volumes of CO and HC. Well, there's a cure for that too. We'll add catalytic converters to the exhaust system and burn that excess fuel in the exhaust. There... all better now
Except for you ecomodders... YOU are burning 90% more fuel than you need to. Your engine is designed to run on gasoline vapors, it is running on gasoline vapors. It always has run on gasoline vapors.
The problem is the liquid fuel that is dumped into the engine with the gasoline vapors.
The ecomodder cure would be to stop putting liquid fuel into the engine; then you'd get the mileage already demonstrated by Pogue, Ogle and dozens of others.
So, to make my point clear, when you reduce the fuel in a conventional combustion, you are reducing the liquid fuel without a compensating rise in vapor fuel. This has two immediate and adverse effects.
1. You get 'lean burn' effects because the initial (spark plug fires) combustion has less vapor and
2. You get hot exhaust temperatures because you've cut back the 'quenching' fuel.
How does a person stop putting liquid fuel into the engine? That's what I've been researching and developing practical answers over the last 4 decades.
That's what I'll start to demonstrate here (if I'm allowed) over the next few months. I haven't got much spare time so I'll just be popping in from time to time, addressing comments like this one for now, and getting my projects into the garage later in the Spring.
I will show you simple, inexpensive ways, to reduce your liquid fuel while keeping your (initial) fuel vapors up and how to keep your exhaust temperatures down without needing quenching fuel. These techniques allow you to keep your power and dramatically reduce your harmful emissions.
Please have patience as I first answer the skeptics, hopefully providing enough information that they'll start to see that there is a better way.
After that it's only a matter of finding the most practical means to convert to the better (true ecomodder) way.
Quote:
Originally Posted by Daox
Here is a graph that represents things well. We know NOx is created at high cylinder temperatures. As you continue to lean things out, the temperature starts to go back down. However, as you continue, hydrocarbons increase as the fuel isn't completely burning anymore.
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All exactly true. Your graph is typical of what we are taught as mechanics.
Because we are taught liquid fuel combustion instead of vapor fuel combustion.
Quote:
Originally Posted by Daox
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