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Old 05-11-2009, 09:02 AM   #1
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Better combusion != more fuel

I've been looking around and notice that a lot of people think that getting a better burn means you get more fuel injected because of the computer compensating for the better burn because of oxygen sensor readings. This is especially true of people trying to sell HHO kits or EFIE units. When an engine begins to experience better combustion, all other things being the same, there is in fact less oxygen in the exhaust stream.

Lets take an example engine, any engine, it doesn't matter. Running stoich your sensor will read just as it always does. If you increase the amount of fuel in the engine, leaving intake volume and combustion efficiency alone you end up with a rich mixture, less oxygen in the exhaust. A computer will pull fuel to compensate for this. If fuel is removed there will be more oxygen in the exhaust stream and more fuel will be added to compensate for this.

Since it is an OXYGEN sensor and a better burn leads to less oxygen then you end up with an engine that is now reading rich, even if it isn't, and the computer will actually remove fuel as a result of the better burn trying to alleviate what it sees as a rich condition.
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Old 05-11-2009, 01:17 PM   #2
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Actually it is more complicated than that because the CAT is actually two stages and it breaks down the Nitrogen compounds containing oxygen and releases more O2 to combine with unburnt Hydrocarbons and Carbon Monoxide to form water and Carbon Dioxide and some left over oxygen in the process. The HHO pretty much just adds some heat to the process and combines to make more water if it burns completely.
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Old 05-11-2009, 01:28 PM   #3
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Yes, but that is read by the downstream O2 sensor that has nothing to do with air fuel mixtures.
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Old 05-11-2009, 01:42 PM   #4
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Better combustion is a product of maximum effective compression. By driving your conventional vehicle with the lowest possible engine on cycle, relative to engine off, you are creating more maximum effective compression for a shorter period of time, instead of lower compression in a constant mode.

This does not mean high revolutions or wide open throttle. It means more available oxygen packed into the same combustion chamber area.

This amplifies the leverage created by the expanding mixture as it heats up during combustion.

In most cases the mixture will be slightly more rich than under low load operation, but the real peak is at maximum BSFC which gives you the most power for a given amount of fuel. After that point unburned hydrocarbons will skyrocket if the mixture is enrichened, without substantial increases in power.

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Old 07-30-2009, 06:58 PM   #5
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Originally Posted by dkjones96 View Post
I've been looking around and notice that a lot of people think that getting a better burn means you get more fuel injected because of the computer compensating for the better burn because of oxygen sensor readings. This is especially true of people trying to sell HHO kits or EFIE units. When an engine begins to experience better combustion, all other things being the same, there is in fact less oxygen in the exhaust stream.

Lets take an example engine, any engine, it doesn't matter. Running stoich your sensor will read just as it always does. If you increase the amount of fuel in the engine, leaving intake volume and combustion efficiency alone you end up with a rich mixture, less oxygen in the exhaust. A computer will pull fuel to compensate for this. If fuel is removed there will be more oxygen in the exhaust stream and more fuel will be added to compensate for this.

Since it is an OXYGEN sensor and a better burn leads to less oxygen then you end up with an engine that is now reading rich, even if it isn't, and the computer will actually remove fuel as a result of the better burn trying to alleviate what it sees as a rich condition.
Don't forget that HHO generators also release Oxygen. and the raio of fuel to oxygen molecules actually goes up.
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Old 07-31-2009, 07:28 AM   #6
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Originally Posted by soda_pop503 View Post
Don't forget that HHO generators also release Oxygen. and the raio of fuel to oxygen molecules actually goes up.
Don't forget that HHO generators also release Hydrogen. It is a stoich mixture and unless HHO doesn't burn completely there will just be more water in the exhaust. No extra hydrogen and no extra oxygen.
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Old 07-31-2009, 07:59 AM   #7
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Yup...HHO generators split water into hydrogen and oxygen. Then, when you burn it in the engine, the combustion of it is a matter of recombining the oxygen with the hydrogen to make water again.
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Old 08-17-2009, 01:09 PM   #8
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Originally Posted by dkjones96 View Post
I've been looking around and notice that a lot of people think that getting a better burn means you get more fuel injected because of the computer compensating for the better burn because of oxygen sensor readings. This is especially true of people trying to sell HHO kits or EFIE units. When an engine begins to experience better combustion, all other things being the same, there is in fact less oxygen in the exhaust stream.

Lets take an example engine, any engine, it doesn't matter. Running stoich your sensor will read just as it always does. If you increase the amount of fuel in the engine, leaving intake volume and combustion efficiency alone you end up with a rich mixture, less oxygen in the exhaust. A computer will pull fuel to compensate for this. If fuel is removed there will be more oxygen in the exhaust stream and more fuel will be added to compensate for this.

Since it is an OXYGEN sensor and a better burn leads to less oxygen then you end up with an engine that is now reading rich, even if it isn't, and the computer will actually remove fuel as a result of the better burn trying to alleviate what it sees as a rich condition.
you state "If fuel is removed there will be more oxygen in the exhaust stream and more fuel will be added to compensate for this."
That much is true. but we are not just taking away fuel. better combustion means all the oxygen is being burnt up with fuel left over. Then the computer decreases fuel flow to where it should be.
So where does all this put you? now you dont have to ope the throttle quite as far to generate the same amount of power.
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Old 08-17-2009, 01:52 PM   #9
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Less throttle increases manifold vacuum which reduces the effective compression. Best engine efficiency is achieved when effective compression is highest.

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Old 08-17-2009, 07:33 PM   #10
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When an engine begins to experience better combustion, all other things being the same, there is in fact less oxygen in the exhaust stream.
How do you know for sure that there is less oxygen in the exhaust when you get better combustion?
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