The scientific term HHO stands for oxyhydrogen, a mixture of hydrogen and oxygen with a concentration ratio of two parts hydrogen to one part oxygen. Oxyhydrogen is also used in welding torches, but has other uses in a vehicle engine. HHOs in automotive systems are oxyhydrogen gas generators that use water and a catalyst (known as an electrolyte solution) along with an electrical current to produce this gas.

Oxyhydrogen burns along with the main fuel in the engine (gasoline or diesel) and helps the main fuel burn completely, getting more power for the same amount of fuel used by the engine. This additional (gained) power is more than the engine load needs to run optimally, so the engine’s primary fuel can be weakened, while the engine delivers the same torque for that particular load.

When oxyhydrogen (also known as hydroxy gas) is burned, it returns to its original formation before electrolysis took place, which means that it turns into vapor, which is fine droplets of water.

Different types of HHO in automobile systems

There are mainly two types of HHO in automotive systems, comprising of wet HHO cell and dry HHO cell configurations. Both systems produce the resulting hydroxyl gas, but differ in their technical design. Originally, the experimental electrolysis process was carried out under the wet HHO cell design to produce hydrogen in laboratories. The wet cell configuration remains basically the same.

When experimenters began using this setup as a fuel saving device, word soon spread and many DIYers began trying to improve the design by using different materials, setup designs, and different catalysts. Wet cell design has improved significantly over the years and has also become more reliable. Through continual research and development, certain enthusiastic designers came up with an entirely new idea to reduce maintenance time associated with wet cell design. Fortunately, the latest design also became much more compact, which was a huge advantage with modern, cramped engine compartments. This became known as the HHO dry cell design.

Wet HHO cell vs. dry HHO cell

We have tested many different designs currently on the market and even ended up creating a HHO product reviews page for these HHO DIY tech guides. We have found that, in general, both designs have their own advantages and disadvantages.

Advantages of wet cell design:

• Easier to clean periodically as a preventative maintenance procedure
• Easier and faster to change corroded anode plates
• Does not have many seals that will eventually deteriorate or harden
• Cheaper to build compared to most dry cell designs
• No additional external pumps are needed for the electrolyte

Disadvantages of Wet Cell Design:

• Bulky design that can be a problem to install in modern engine compartments
• Frequent corrosion of the anode due to oxidation leading to increased cleanliness
• Anode plates will need to be replaced more frequently due to excessive corrosion.
• Wet cell design generates more heat in the electrolyte solution
• More current is needed compared to dry HHO cell design
• Electrolyte design needs more frequent flushing with fresh, clean electrolyte

Advantages of the dry cell design:

• Very compact in nature both in width and thickness.
• Needs less current to operate consistently
• Heat buildup in the HHO generator is almost non-existent
• Electrolyte stays cleaner for longer intervals
• Anode plates corrode much less
• Terminals do not corrode as they are isolated from the electrolyte
• Less periodic maintenance is generally needed

Disadvantages of the dry cell design:

• More expensive to produce or build one as a DIY project
• More precision is needed to build the design.
• Each cell is separated by a seal that will eventually harden and start to leak.
• Preventive maintenance procedures require disassembling the entire HHO generator to pieces
• An external electrolyte pump is required in most designs

As you’ve seen from above, both wet and dry HHO in car designs have their pros and cons. Depending on the space available in the engine compartment is an important factor to consider before attempting such an installation. Most modern vehicles that seem to have very little available space will probably need the dry cell design for two main reasons: less space required and less frequent maintenance. This allows installation to be placed in even the tightest and hardest to reach areas, if that is your only available option. A common option is to install the dry cell HHO generator in front of the radiator, just behind the bumper or behind the front fender, in the area of ​​the wheel that is covered by a factory plastic fender liner.