Myth Busters SUCKS! (HHO mod, does it work?)

[shovel]

I don't think the "well manufacturers of cars aren't doing it so that means it doesn't work" argument - which is valid elsewhere, applies to HHO simply because an enormous demographic of end users can barely be bothered to keep air inside their tires or take action beyond "turn up the radio" when their car starts malfunctioning. This demographic would be utterly mystified and boggled by an idea like "wait I have to put distilled water in this hole and gas in that hole?" ... what happens when they put gas in the water tank? What happens when SnakeOleum Ltd. releases their "MAGIC HORSEPOWER IN A BOTTLE HHO ADDITIVE!"...

I doubt a manufacturer wants to get within 100 yards of that mess. Even if HHO would kick ass in practice.. on which I have too little hard data to form an opinion.

[Nerys]

I disagree. cruising is where I already get the best fuel economy. I would get close to 60mpg if I never had to slow down or accelerate.

its the accelerating that ruins your fuel economy. this is WHY the prius gets such good mpg (well for its kind 46mpg is not very good)

cruising it would have the least impact AND be the most difficult since now you need an electric motor wheel gear combo that can handle the higher speeds. ie more expensive.

[dcb]

best fuel economy and best bsfc peak are two different things, and the electrical demands (equipment costs) will go up very much if you expect to accelerate anything car sized up to 35mph.

If you accelerate and shift properly (centered around bsfc parameters) your engine will be extracting the most energy from the fuel you give it. Whereas with cruise you are probably far from bsfc peak already.

So with your limited battery capacity/money mode I think that is your best bet is to try to help the engine when it is not running efficiently. The batteries you have will run longer too if you only maintain a given output rather than peak them with acceleration demands, and you can optimize (gear) the system for a target speed. plus the controller then only really needs to be an on-off switch, basically.

So for keeping the engine in it's most efficient mode and the electric (with limited capacity) in its most efficient mode, add electric power to cruise, IMHO (and freewheel AND braking regen if you can swing it).

[dcb]

Or just lug a battery or two around and get rid of the alternator

[Nerys]

Cruise costs more money. The small motors I can afford can not effectively attain 50mph with enough torque to make a difference. When dealing with electric motors from cars believe it or not the 0-35 is a lot easier than the 35-55 mph bracket. Torque is easier and cheaper than SPEED. speed requires a bigger motor and a higher voltage pack.

I only need enough power for about 11 or 12 accelerations to make a huge difference in fuel economy.

Adding power to 30 minutes of my 90 minute commute won't really have much of an effect on over all mpg since its adding power where I LEAST need it.

Your talking about efficiency in extracting power from the engine. I am not. I am talking about using at little gasoline as possible. These are completely different things.

There is a reason the Prius uses the EV system for UNDER 35mph usage. This is because under 35mph usage is where you waste all your fuel.

If I can carry enough power to eliminate the motor for coast stop wait and accelerate to 30-35mph I could probably hit 70mpg which would have a significant effect on my gas savings.

using an electric motor for just cruising is a DOUBLE penalty. I am now using the ICE to still accelerate the car its LEAST efficient mode AND now I am adding on 1000 that I need to accelerate of "dead weight" in the battery and electric drive train until I get to cruise speed.

On top of that I would be seriously maxing out the electric drive train to get it to spin at 50mph on my budget and on top of that the additional energy would be "minimal" at best especially once you subtract the dead weight acceleration penalty imposed on the ICE.

no if I can't use it to accelerate there is no real point in trying the gain will be too small and never "pay" for the cost of installing it.

IF I were to install a drive pack the first thing I would do is remove the alternator and replace the water pump with an electric water pump. this way the engine does NOTHING but move the car.

[dcb]

I guess you didn't get what I was saying then. you throw a switch at cruise and you get to lift your foot a tiny bit for some period of time. Engine stays running, just uses a little less fuel.

If it's contribution is minimal when it has been so optimized to maximize motor efficiency and battery energy extraction during cruise, how do you expect your $200 in batteries to get you up to 35mph a dozen times when you are completely flogging the batteries and motor?!?

I think you need to do some more serious figguring.

[Nerys]

Its not about flogging the batteries. If they let me accelerate 11-12 times I will save MORE GAS than I will using them to ease up on the throttle at 55mph.

Your just not understanding the efficiencies of these cars. They are MOST efficient while cruising. its the acceleration that is the worst possible time to use the ICE not the cruise.

for acceleration I only need to use the batteries at full power for maybe 15 minutes TOTAL for the whole trip.

they MIGHT last 30 minutes at "cruise" if I was really lucky (probably more like 25 minutes)

in that 15 minutes of acceleration I will save MANY TIMES more gasoline than in the 30 minutes of cruise.

On top of that its even WORSE since now I have to use EVEN MORE fuel in the ICE at the worst possible points in time to ACCELERATE this larger mass of batteries and motor to speed.

with the 0-35 mode the batteries are moving themselves. once AT speed mass is a minor penalty.

its all about the inertia. thats the part your missing.

when your at a stop your fighting inertia. when your cruising inertia is HELPING you.

PLUS by using the ice for acceleration this means I can NOT turn it off at every light I have to leave it running. eating up even MORE fuel.

while the motor will only be used 11-12 minutes for acceleration BECAUSE I CAN DO THIS I actually get to keep the motor off for close to 18 minutes (I will have to time it to nail down more accurate numbers)

each light is 3 minutes of ZERO gas usage plus the coast down time. since I would have the electric motor to get me back to 30 or so I would not have to worry about light timing or anything like that. Light goes red TURN off the ice and coast. Stop wait start up the EV motor to 30mph and then and only then restart the ICE.

there really is no point in using an ev motor to "enhance" cruise especially on a car this small which is already silly efficient at cruise. The gains would be SO SMALL that I am not sure if it would be reliably measurable. Unless I was able to SHUT DOWN the ice at cruise which the setup you describe would NOT permit me to do.

"If it's contribution is minimal when it has been so optimized to maximize motor efficiency and battery energy extraction during cruise,"

thats the part your missing. what you describe is the OPPOSITE of maximizing motor efficiency. your saying use the EV at its LEAST efficient point in the process and use it at the ICE's MOST efficiency point in the process both of which are the OPPOSITE of what you want to do.

you want to use the EV when "IT" is most efficiency IE acceleration and you want to NOT use the ICE when it is LEAST efficient ie Acceleration.

[dcb]

As you said, if you had the money you would get lots more battery and motor and etc.

You don't. It's all about getting the most energy out of what you have, though I expect you will come back with "no it isn't" or somesuch oversimplification.


A couple questions (hint, there is only one answer)

Do you agree that you get the most energy out of a given amount of fuel at BSFC peak?


Do you agree that there is an optimal discharge rate for a battery to get the most energy out of it? (unfortunately lower is almost always better) and that you only have $200 of battery to work with currently?

Do you agree that you can typically approximate bsfc peak while accelerating a stick shift? i.e. hold 70% throttle and center shifts @ 3k in your case?

Do you agree that the load will typically be much less than %70 while cruising, and thus even though you are getting "great mpg", your engine is not extracting the most energy it can out of the fuel?

Still with me?

ok, so we have established:
1. Your engine DOESN'T need any help at being efficient during acceleration. (cus you know how to accelerate most efficiently)

2. Your engine DOES need help at cruise.

3. You have a fairly small amount of electric energy to contribute to your drive on the current budget. If you hope to see the most return at the pump (putting energy back in the car not via the wall outlet) you had better optimize.

So lets say you have 4 trolling batteries already, and they can make 3hp for an hour (just a swag), and your car needs 9hp at cruise, and you cruise for an hour daily. The effect would be like cutting your drag by a third.

Lets say you happen to be around the 3k rpm mark, the first problem you should notice is that reducing load increases bsfc. Well like with an aeromod, you will have to regear (get a trans out of a 1.3 or an xfi) to get your engine load back up to an efficient place (and fully realize your mpg going up by 50% maybe).

FYI, If you glide properly, the extra weight isn't a huge deal on acceleration, just takes you longer to glide to a stop.

[user removed]

Nerys.

Maybe you should consider investing your time, which you can afford, in learning the hypermiling techniques of those on this forum who drive the same car you have.

I am averaging 50 MPG in my Echo which is rated at 32 combined.

Your car is averaging 43 MPG. The combined EPA for your car is 46 MPG.

I am averaging 65 MPG in my Insight. The current EPA combined is 47 MPG, just 1 MPG better than your Metro.

Driving your car the same way I drive mine 60 MPG should be fairly easy to achieve, as long as everything is is good shape on your car.

I think most of us here do understand the ways to maximise the efficiency of our cars, and when the engine is most efficient. That is why we use pulse and glide as well as many other tactics, especially DFCO and situational awareness (in my case) to extract every foot of distance travelled for every drop of fuel consumed.

Your goal of 60 MPG is totally achievable without any additional expense of capital, if you carefully study the proven techniques and apply them to your situation. The only reason you should not be getting 60 MPG is is you live in an area where you have to climb steep grades in your normal driving situation.

If your trips are very short, then you might consider a block heater to reduce the high fuel consumption on cold starts.

No engine is highly efficient at cruising speeds, because it is barely doing any more work than it would if you just ran it at the same RPM with no load.

My Insight shuts off when you are not moving, and uses the battery to boost the engines power on acceleration. The return on battery energy regeneration is about 30%, so I try to avoid all situations where I would encounter regeneration.

Light timing, avoiding any brake use, maximising DFCO, which means using no fuel slowing down when you must stop (for any reason) and maybe even shutting the engine off at those 3 minute lights (none that long here) will achieve your goals without having to redesign your car, and it doesn't cost you a dime.

You have one of the best hypermiling cars around. Don't take this the wrong way, but wouldn't it be a lot easier to just emulate the tactics of those here who freely offer their techniques to others so we all can minimise our consumption.

Instead of arguing with others here I would suggest you forget any assumptions about their understanding of engine efficiency and instead studying their proven techniques.
Relax and absorb the vast amount of empirical data that proves beyond any doubt that they indeed understand completely the limitations of their individual vehicles in every respect.

The end result will be your goals are achieved and in doing so you will better understand what is really wrong with the ways cars are designed. Maybe some day that knowledge will lead everyone on this planet to demand better designs which incorporate efficiency into the vehicle itself and relieve the driver of the work load necessary due to the poor designs.

regards
Mech

[dcb]

FYI, I just looked at Nerys metro page Details: Ryo-Oki - 1994 Geo Metro Xfi Fuel Economy - EcoModder.com

he/she does claim to schlep 1300 lbs around (4 people and some gear), so definite kudos for being efficient in that regard (and already owns an xfi).

But it is a good point. Nerys, it would be good to have a baseline though, do you always have 1300lbs of payload? or do you know what average mpg you get with just a driver and no gear? If you are using good technique and can't beat 45mpg in an xfi by a wide margin then you may very well have some mechanical issues.

Originally Posted by Old Mechanic

My Insight shuts off when you are not moving, and uses the battery to boost the engines power on acceleration.

The insight is a good example of a mild hybrid, and has lean burn provisions for cruise. I'm sure the power management could be improved upon with some human intervention though, and a bit of wall plug.