Gen II with HHO kit anyone have this?

Hi Agape. Have you managed to find any solid evidence that such a kit can improve your fuel economy? Personally I'm doubtful. I don't see how using electricity to split water into hydrogen and oxygen, and then burning it for heat, could possibly be more efficient than using that electricity directly for motive power as the Prius already does.

 

The idea that has been put forth is that the introduction of HHO causes hydro-catalytic cracking, which causes a better burn. Steve @ AutoBeYours, who I would suspect as being reliable, seems to get a slight improvement in mileage. He shows how to use the rear defroster for the on/off function:

Prius Hydrogen Generator installation

I would be concerned with the corrosive nature of the vapors that the device would produce in the long term. The hydrogen content would probably not be enough to cause embrittlement, but that is also a concern.

 

Is there an award we can give in the new software for posts like this?

 

Don't be too hard on him. He's Irish, so English is not his native tongue.

Tom

 

HHO is snake oil, through and through, especially in the case of an optimized system like the Prius. Save your time and money.

Tom

 

Yeah 53 MPG at 70 MPG is pretty good, I agree. However a one way test, no mention of changes in elevation or wind speed/direction, anecdotal speed measurement "most notably is that this was mostly interstate at 71 mph. No cross check of whether the MFD fuel consumption was accurate (or altered by the change of fuel). Reliability of Steve as an honest person or not, it's hardly a conclusive test by any definition.

 

I was referring to him thinking that this was unknown Physics, not unknown Chemistry. (Alchemy?)
Minor difficulties with english do not bother me, English is my second language, I just wish I had a first language I could use as an excuse.

 

Ok that sounds good. I'd love to see a good comprehensive test of one of these rigs on a Prius. Like I said above, I'm skeptical, but I'd keep an open mind. The main claim for HHO is that it increases flame speed and therefore creates a closer to optimum pressure (/time) profile. I could be convinced if I saw a really well conducted study. It would have to include actual petrol station "hand calculations" to account for any influences on the cars MPG calculations.

Keep us updated on your progress with this Agape.

 

That makes sense. I was expressing dismay over his English. Being Irish, English should be his native tongue.

Tom

 

The energy required to break water down is not recovered by the burning process. If it were, power plants around the world would be using water to fuel their boilers.

 

I've spoken with one HHO installer that did it for about 2 years to a couple dozen cars. Unfortunately, the HHO is corrosive and eats away at the aluminum intake on most engines. After several of his customers came back to him for warranty repair he got out of the business.

I did some research on HHO and it does improve combustion when properly configured since it converts a little more of the waste heat into energy to move the car. If you do the research, you'll be shocked at how little energy from fuel actually goes into moving you in the vehicle. This is precisely why diesels are more efficient than petrol cars... they convert more of the energy stored in the fuel into forward motion.

-VR

 

Nonsense. First, changing combustion efficiency isn't going to do anything about waste heat losses. Second, any combustion energy gained by burning HHO is less than the energy required to split the water in the first place - it's a net loss, which is no surprise to anyone who has studied thermodynamics.

And speaking of thermodynamics, the comment about why diesels are more efficient than petrol is also incorrect. Diesels are more efficient for two reasons: 1) Diesel fuel has higher energy density, which really doesn't make the engine more efficient, but you do get more miles per gallon; and 2) Higher compression. Diesel engines run at higher compression, which makes for higher internal temperatures. As basic thermodynamics will tell you, the limit of engine efficiency is determined by the delta T between the hot side of the engine and the cold side of the engine. A diesel doesn't do any better with waste heat, but it does start at a higher temperature, allowing for higher efficiency.

If people would study physics, they wouldn't be misled by false and exaggerated marking claims.

Tom

 

Thanks for clarifying Tom. I don't want to start another HHO debate and I'm not a proponent of HHO and also am a believer in the laws of thermodynamics. (In hindsight, I probably shouldn't have commented on this thread on a hybrid vehicle forum)

I have some of the research but will send that to you in PM to get your take. (I don't want to post it here to start yet another debate on HHO when I don't consider it a good option or a viable type of transportation fuel such as biodiesel, methanol, biobutanol, etc.)

Here's a good video from a Stanford lecture series with Amory Lovins talking about the incredible inefficiency of internal combustion engines in transferring energy in fuel into forward motion with diagrams:

Amory Lovins Stanford Lecture on Energy Efficiency for Transportation | Efficiency Journal

I just did some research on HHO because I was curious. I found the math for the arguments pro and con and then met a former installer at an EV meeting and asked if I could talk with some of his customers.

-VR

 

Fair enough. The key to understanding the inefficiency of internal combustion engines is to look at the heat cycle. The Carnot Cycle defines the theoretical limit of efficiency for an internal combustion engine. It is directly related to the delta T between the hot and cold sides of the engine. Given current materials, there isn't a lot we can do to increase this delta T without melting the internal parts.

Adding to the losses is the need to cool an engine. Since our current materials have a limited resistance to heat, we end up discarding a fair amount of energy through the cooling system. It's less than ideal, but a necessary compromise with today's materials.

HHO addresses none of these fundamental limits. The efficiency figures are merely hand waving on the part of people who profit by selling quack devices. It's no better than magnets that clamp around the fuel line. In fact, magnets are better in that they are not likely to damage an engine, where HHO may do just that.

Tom

 

Hi Tom. Let me prefix this be saying that I am extremely skeptical of any HHO benefits, however if the OP is set on doing it I encourage him to do some accurate tank MPG measurements over a reasonable time and distance and post his results here.

The reason why I'm prepared to keep an open mind however, is because it is theoretically possible for a lossy sub-system (the HHO generation and subsequent combustion) to result in a net increase in efficiency of the overall system. Not that I've seen any evidence for it in the case of HHO, but in principle it is possible.

Take the example of the Prius's own synergy drive at low RPM. When the engine is under light load at highway speed the drive will often run in so called "heretical mode". Here energy is feed from the HV system into MG1, acting as a motor and supplementing the ICE to provide the input power to the power split device (PSD). However the mechanical output from the PSD is not used solely to drive the wheels, some of it goes to MG2 which acts as a generator to replace the energy consumed by MG1 on the input side. From a simplistic view of energy balance this makes no sense at all, feeding electrical energy into the PSD (obviously a lossy device) only to use the output power from that device to (re)generate that same electrical power. It works however to increase the overall efficiency, because it allows the ICE to turn at lower speed, a bit like an electric overdrive, and therefore to run at a more efficient operating point.

Now as to whether HHO could do something similar I'm skeptical, but remember that Carnot and Otto (and Atkinson) cycles are only idealized approximations to what actually happens in a combustion engine. And it is theoretically possible to alter the combustion pressure/time profile in such a way so as to increase efficiency. So while at this point I'm definitely still a skeptic, I do to some extent have an open mind on the matter.

 

Agreed. An optimized subsystem does not necessarily equate to overall optimization. I said something similar in a PM to the OP. I didn't repost it here, since I have made multiple similar posts in the past.

Like you, I don't expect HHO to provide any improvement, but I would like to see a fully repeatable scientific test. Slapping a kit on the old family truckster does not qualify as scientific or repeatable. A well designed test needs to be done on a dynamometer with controlled conditions. Likewise it would be good to see an engine tear-down after extensive HHO operation.

While general thermodynamics suggests that HHO is nothing more than snake oil, the matter is not firmly settled until we see real testing. There are too many subtle effects in ICE operation to completely rule out some sort of weird beneficial effect.

Tom