HHO – Mercury Capri


All the information on this website is based on my personal experience. I am not a licensed car mechanic, nor am I a physician or chemist. I do not take any responsibility and/or liability for whatever outcome a person or company might experience based on information found on this website. Read and use this information completely at your own risk.


After I tested the HHO kit in the Capri in 2012, I tried it in my Scirocco as well in 2014. Click HERE if you want to see how the kit performed in the Scirocco.


A HHO Booster is a kit that can be installed in your car’s engine compartment and can give several benefits. The most import ones are:
– increases fuel efficiency with 10-60%
– increases engine power
– reduces harmful emission
– cleans out built-up carbon deposits in engine
These kits are sold under names like H2O car kit, H2O booster kit, HHO car kit etc. and are priced between 300 and 1100USD. When I found one of these kits for around 400USD I decided to buy one and put it to the test.

Flow diagram-s

How does it work?

Basically power is drawn from the car’s battery to split demineralised water into hydrogen (H2) and oxygen (O2), via electrolysis. This H2/O2 mixture is then led into into the air intake of the throttle body, into the engine’s fuel mixture.Click and see the schematic diagrams on the right to get an idea of how this works in practice. For more detailed information and theoretical background, see any of these links:

Wiring Diagram-s

Increased O2 value

With a HHO kit, H2 + O2 will be fed into the air intake of the car and hence the O2 value in the exhaust gas will increase as well. Most cars with fuel injection will have an O2 sensor/lambda sensor to measure the amount of O2 in the exhaust gas. If the measured O2 value is higher than the factory set value, the ECU/PCM thinks the fuel+air mixture is too lean and will increase the amount of injected fuel. So without some sort of remedy for this, when using a HHO kit, the mileage of the car will decrease for most fuel injected engines. This issue is normally not applicable for carbureted engines.

Remedy 1: Install EFIE chip to adjust the ECU/PCM signals to the injectors
These chips are standard supplied with some HHO kit suppliers. If you want want to buy the chip loose you can get these at Volo Performance Inc.
These chips are not compatible with all cars. The Volo chips for example only work with OBD2 compatible cars. To learn more about OBD2 click HERE.

Remedy 2: Reset factory default O2 value in ECU/PCM
By disconnecting the car’s battery and draining the capacitors, a vehicle can reset the stored O2 reference value. After reconnecting the battery, the ECU/PCM will build up a new O2 reference value. This remedy is not a 100% sure to work either, since this reset procedure does not work on all cars.

The opinions regarding whether you need a chip or not depends strongly on which supplier you ask:

Global Energy Devices -> No you do not! E.F.I.E’s are a mess to work with….
source: www.globalenergydevices.com/faq

Green Fuel H2O -> Absolutely YES you do !…
source: www.greenfuelh2o.com/FAQ_s/25.htm

TIP: Do your research before deciding to by a kit, ask the supplier first if your car is compatible. If you have a car that is OBD2 compatible, you’re pretty safe I think since you can try to either reset the default O2 value or a chip.

Break even point

See chart on the right (example: with a 10% fuel efficiency increase, you need approx. 60 full fuel tanks in the USA to save the equal amount of money on fuel that the kit purchase would would cost. After that you’re saving money compared to having no kit. For Western Europe this is approx. 30 full fuel tanks).
Not included in these costs since they have very little impact are:
– costs of demineralised water: approx 2.5 USD/Gallon
(I use approx. 200ml on 600km)
– costs of electrolyte: approx. 25USD/kg
(I don’t think I will use the full 1 kg in the next 2 years)
Kit comes supplied with a small bottle of electrolyte (KOH).

Break Even-s

The Capri Conversion

Although I have known about HHO kits for a while, I mainly drove motorcycles in the past which are not really suitable for a HHO kit. But when I saw the Capri for 1200 dollars it was love at first sight. Besides this seemed to me like the perfect opportunity to try one of these HHO kits, since the mileage of this old Capri was pretty bad. I looked on the internet for a kit supplier and found Global Energy Devices and decided to give their kit a try. At that point I assumed that it anticipated a huge difference in mileage and proposed to GED to make a movie about the installation and compare mileage & performance results before and after. In exchange I would get the kit money refunded once done. They tentatively accepted; it depended how good the movie would be. And so it began…

The HHO Kit

– Supplier: Global Energy Devices
– Kit Type: Solo/single kit for engine size up to 5.5L
(not for sale anymore, comparable with current 250 S model)
– Price: 350-450 USD
– Increased O2 in exhaust remedy: Default O2 value reset
– Ampere/current meter: optional
– Current control for HHO cell: Current can only be adjusted indirectly
by diluting or adding electrolyte.

The Car

– Make/Brand: Mercury Capri GS
– Year: 1986
– Mileage at time of kit install: +/- 165.000km
– Engine: 3.8L gasoline (benzine), V6, 12 valves, Indirect Injection
– Other info: O2/Lambda sensor (with 3-way cat)


The HHO kit from Global Energy Devices did not yield any results in My mercury Capri. In fact the  mileage got worse, click HERE for the full sheet of measurements:
-Reference Point = before HHO kit installation, average of 6 fuel tanks
-12.3% = after HHO kit installation, before flushing the kit, average of 4 fuel tanks
-11.4% = after HHO kit installation, after flushing the kit, average of 5 fuel tanks
This might be due to the fact that the procedure to reset the default O2 value stored in the ECU/PCM didn’t work. Since this car is from before the introduction of OBD2, I did not have the option to see if installing a EFIE chip would make a difference.


Increased Mileage
To see the full measurement chart with detailed results, click HERE.

– Reference Point = before HHO kit installation, average of 6 fuel tanks
-12.3% = after HHO kit installation, before flushing the kit, average of 4 fuel tanks

-11.4%= after HHO kit installation, after flushing the kit, average of 5 fuel tanks
Explanation: The HHO kit manual instructs to flush the kit and refill it after 1000km have been driven with the kit switched ON. This has to due with some protective layers wearing off and contaminating the water mixture in the kit, during the initial use of the kit.

-9.5% = after HHO kit installation, air intake restricted, average of 2 fuel tanks
Explanation: Since the lid of the air filter housing didn’t seal perfectly on the housing, I wanted to eliminate any kind of doubt that the H2 + O2 mixture would not be sucked in by the engine and fly out trough the area’s where the lid did not seal off properly. This would be unlikely to happen since the connecting elbow to the H2 + O2 hose was right above the throttle body, and besides the elbow was placed on the inner part of the lid; this part sealed already on the rubber seating of the round air filter. Anyhow, to eliminate any doubt I completely taped the lid to the air filter housing and in addition restricted the air flow of the normal air. See picture.

Increased engine power
To see the Dyno run report before installation of the kit, click HERE.
Since I did not measure an increase mileage, I did not spent money on a second Dyno run after kit installation.
I did not feel a difference in power myself with the kit switched ON or OFF

Reduced Emissions
To see the Air-Care report before installation of the kit, click HERE.
Since I did not measure an increase mileage, I did not spent money on a second Air-Care report after kit installation.

Conclusion & Personal Opinion

Instead of a mileage increase, the mileage got worse after installing the HHO kit from Global Energy Devices. This is probably due to the problem described above under “Increased O2 value”: the increased O2 in the exhaust gas triggered the ECU/PCM to inject more fuel. The supplier’s procedure to reset the default O2 value probably didn’t work on my car (if this was indeed the problem). Since this car is from before the introduction of OBD2, I did not have the option to see if installing a EFIE chip would make a difference.
Further more I did not experience any difference in engine power between driving with the kit ON or OFF. Since I was primary aiming at an increased mileage, the 100 USD spent on the Dyno run was wasted on top of the cost of the kit itself.
If I buy another kit in the future, I would contact the supplier first to:
-let them comment on my current measurements
-discuss if in their opinion my car is compatible
-see if there is a “money back guarantee” in case it doesn’t yield any increased mileage

Contact with Global Energy Devices (GED) regarding the Capri

Especially during the initial installation of the kit in the Capri I’ve had a lot of contact with GED. They have been very responsive and did in my opinion all what could be expected when you’re hundreds of miles away from each other: we did a lot of e-mail communication, looked at installation pictures and movies about the performance of the gas production of the kit.
However, when after all the correspondence with GED I still didn’t get any results with the Capri and I asked if I could return the kit for a refund, GED refused this. Even though we both agreed that I did all the steps as per manual. Their opinion was that the kit performed as it should; created the correct amount of  H2/O2 gas and therefore the problem was in my car, not their product. Although the problem could indeed be my car (assuming that the problem stems from the increased O2 value as described above), in my opinion GED should warn more clearly about that on their website. What also surprised me, was that on their website they state in very clear terms that a EFIE chip is not necessary, but during our correspondence they said that if my car was OBD2 compatible I could have tried a chip. Finally, as described above, I proposed GED to make a movie about the kit installation and test results. In this proposal I stated that the car would be a Mercury Capri 3.8L V6. With GED being the experts on their product, they could have asked more questions regarding the specifics of the car in case of any doubt. Taking all this into account, including the money I spent on shipping, importing/border costs (Canada) and the Dyno run, I lost a lot of money on the kit and I would have found it appropriate if GED refunded it.

Install Pictures AirInt Capri-s

Install Pictures Capri 6-s

Install Pictures Capri 5-s

Install Pictures Capri 4-s

Install Pictures Capri 3-s

Install Pictures Capri 1-s

Tips & Notes

Below are some of my personal notes based on my own experience:

For an extensive list of frequently asked questions with answers, see any of these links:

Amperage Meter
Initially I bought this kit without an amperage meter to save money, but I bought one separately after reading the manual: you cannot see what you’re doing without one. I highly advise to buy a kit which has an amperage meter included, unless you have one yourself already.

Amperage reading, quantity of electrolyte
Note that when you read the amperage that the kit draws when you add the electrolyte, to determine the right quantity, is very dependent on how long the kit has been ON:
When you’ve been driving for an hour, the amperage (current) reading can be 2x as high as when you just start your engine.

Can I install the kit myself?
The kit is supplied with a clear manual. Anybody who is a little bit handy and knows about basic car mechanics can install the kit. If you have it installed by a professional car mechanic, I guess it would take them less than 4 hours to install.

Is this kit for everybody?
In my opinion NO. If you’re the person who never checks the fluid levels of you car, then my advice is not to buy this kit. But if you’re a little bit handy and interested in this technology, go for it.

Install Pictures Capri 2-s

Hose Clamps
The hoses connecting the reservoir and the HHO cell kept leaking over and over again with the original hose clamps supplied with the kit: I replaced them at least 3 times. This can create a mess, since the KOH solution is corrosive. I advise to use fully round hose clamps. After my last replacement with these fully round ones, they haven’t leaked (so far). I suggested this to the supplier of my kit as well. They said to take this into consideration.

If you have any more specific questions regarding the kit for which the answers cannot be found on the website of the supplier, you can always send me an e-mail. If I can answer it, I will post the answer on this page or reply via e-mail.


Hose Clamps-s