The following information is the result of my own research and testing.
This subject is open for discussion.
Like everyone, I have poured additives in my fuel tank in the past to try and give me better economy and make the engine run better. The manufacturers of these commercial products available at every Auto Parts store claim that "A clean and carbon free engine will give you better economy and reduce engine wear"
I do not dispute their claims, but the way these products work is only temporary. For the benefits to continuously be there, you need to use their products on an ongoing basis. As soon as you stop using them, the carbon returns and economy decreases.
Most of these products are a "Hydrocarbon" based detergent that marginally increases combustion to loosen and remove carbon deposits in the cylinder. Remove the carbon and you have better seating valves and combustion that happens only when the spark plug ignites (residual carbon holds heat and could ignite the fuel before it is supposed to be ignited)Octane Boosters
are just that - They increase the Octane rating of the fuel that you are using. If the fuel you put in your car is rated at 92% Octane, the amount of booster you put in your tank will give you varying increases up to the 100% mark.
The problem here is that the cost of most additives negates the savings you receive in increased milage and less fuel purchased.
Around 30 years ago, enterprising Auto Engineers decided to analyse the exhaust of cars and found that there was a great deal of unburned fuel coming out the exhaust as "Unburned Hydrocarbons" and they decided to try making products that made the fuel burn completely within the cylinder. They did and many people started using them. There was an added benefit to using these products, they also nearly eliminated damaging exhaust emissions.
The fuel companies refused to include these products at the refinery due to the fact that they did not want a 10% to 20% reduction in fuel sales, so the use of the products remained in the promoting hands of the faithful minority.
About 10 to 12 years ago these products became ineffective to the majority of users. The reason was that engine technology advanced to include a fuel management computer with a regulating feed from Oxygen Sensors. The products used all the Oxygen in the cylinder to burn the fuel, and the O2 sensor told the computer there was not enough O2 so it increased the amount of fuel poured into the cylinder. This did not happen with all cars, just those with advanced fuel management computers.
The manufacturers of these products started adding Octane boosters to their product to help with sales and this allowed marginal economy increases in late model cars.
Before getting into HHO, I was one of the minority using these additives with mixed results.
I have three cars - My own with around 5% increase in economy (I have an on-board fuel computer), My wife's with around 10% economy (she has an earlier car with one of the earlier computers), and an old clunker that my kids use that gets around 21% (this car has a carburettor and no computer).
To increase the effectiveness of these products I had a HHO enthusiast undertake a controlled field test. You can see the results at http://reduceyourfuelbill.com.au/forum/index.php?topic=76.0
The conclusion of my findings:
I get around 2 ltr / min from my HHO gen in my car with around 28% economy. Fuel Catalyst Products are no benefit in my car, I am already using all the fuel poured into the cylinder.
My wife has a 3/4 ltr / min HHO gen in her car, uses a fuel catalyst product as well and gets around the same percentage (I am not sure exactly, she keeps lousy records). This because of the EFIE for the HHO gen.
My kids car does not have a HHO gen (I am going to send it to car heaven soon). I just use the Fuel Catalyst Product with no EFIE and get 14% increase in economy.
If you have a HHO unit with around 2 ltrs / min, a Fuel Catalyst Product will be of no significant advantage to you. - If you have a HHO gen with less than 2 ltrs / min output and you find a reputable Fuel Catalyst Product that claims to use 100% of the fuel, it will probably be beneficial with an EFIE.
Keep on experimenting with your HHO gen - you will need nothing else if you get the production up around the 2 ltr / min.Caution:
Watch out for products that make outlandish claims (eg. realign the petrol molecules with magnets, or encourages aliens to visit your car during the night to give you their fuel saving technology)