Water 4 Gas

[GreyICE]

Marine engines are big, well cared for, and run at optimal rpm.
46% is not unreasonable.
The rest of the energy leaves by the cooling water, chimney, or radiating into the engineroom.

Two strokes are by their nature less efficient than four strokes.

I'm asking because with steel you're usually limited to about 40% maximum theoretical efficiency. So 46% does seem unreasonably high.

The mechanical efficiency is a important indicator of engine status.

Theoretically its meaningless. Yes, practically its a good sign when your maintenance has been sucky.

You go to each cylinder in turn and measure the pressures during a stroke/cycle?.
The curve of difference between compression and max pressure give the effect of each cylinder. Divy the shaft effect with the sum of the cylinders and you have the mechanical effectivenes.

Such meassurements are done regulary to chek adjustment of injection timing and oil amounts.

They do not run on gasoline but marine heavyfuel, a bit like tar, must be heated to around 110-130C before the fuelpumps.

Which is cool and all, but I still have a feeling you're talking about carnot efficiency, not absolute efficiency.

 

[Freethinker]

Once an engine is running, it is producing 'surplus' electricity.

No it isn't. The alternator produces power on demand. No more than is required as determined by the voltage regulator. Turn the lights on and the alternator supplies more power. Turn them off and the output drops. As it produces more power in response to demand, the engine consumes more fuel.

 

[arthwollipot]

Hybrid cars do not strap the generators to the electrical engines, but ratter to the breaks (that instead of wasting the kinetic energy into heating the breaks, it is used to recharge a battery).

Actually, the Toyota Prius does both. It uses regenerative braking, but sometimes the battery is recharged by the engine as well.

 

[h.g.Whiz]

I don't think its a good idea to sustitute gas with water. The demand for water is high enough already.

 

[balrog666]

I tend to believe someone 'moreso', if and when they aren't trying to sell me something.

And "Yes, I DID hear a difference between the two idles."

While my sensory organs ARE imperfect, I have used then to successfuly navigate this world, avoid pitfalls, and even locate items, people, and places.

I heard a distinct difference in how that engine operated.

They guy claimed to witness a difference in fuel consumption, and while I did take him at his word, I am 'here' today to confirm my conclusions or have them be debunked.

I am certainly not emotionally connected my findings or conlcusions...

So ... are you really claiming that your ears can tell the difference in gasoline flow in a running car as opposed to a simple change in idle RPM?

BWAAAAAAAAAAAAAAHAHAHAHAHA!

GM should hire you with their $17 billion dollar bailout!

 

[Sherman Bay]

If the trick worked, why not run a gas powered electrical generator in you car, and run straight electrolysis-derived hydrogen through the motor?

The savings should be even greater, no?

Better yet, store all the hydrogen you generate while on the road and sell it at the next stop. Use the money you make to buy more gasoline for your tank, rinse & repeat. Think of all the wealth you will accumulate from New York to L.A.

 

[GreyICE]

Carnot efficiency gives you the maximum you could possibly get if your machine is technologically perfect. Since technologic perfection is technologically impossible, the real result will be quite lower (and more important).
Has far has I know (and was well pointed out), I personally never seen In my life a Carnot efficiency bigger then 80 something %, something whit 90% is a technological marble.

About your 20% efficiency for the cars, I have to tell the rest of the community that unfortunately “was” true (it is still true for some cars), although a bit outdated has today’s cars have improved to around 30 to 40% (and even so can still be outdated compared to the best efficient models).

http://www.fueleconomy.gov/FEG/atv.shtml

"Unfortunately was true" = is true for the majority of cars on the market.

Sure, many of the hybrids, which you apparently don't understand (they maximize fuel efficiency by running the car engine at its optimal efficiency point and generating electric power, you're confusing them with regenerative breaking) get high efficiencies, and many car engines have theoretically higher than the 15-20% efficiency they're getting, but the problem is the car only runs at optimal efficiency during near-full throttle conditions. ICEs lose efficiency as they throttle down, like most motors. Since we only achieve that when we're accelerating very, very quickly, the practical efficiency of your average car is in the 15-20% range.

Sorry, you're running on too much theory and too little knowledge.

 

[TMiguel]

Actually, the Toyota Prius does both. It uses regenerative braking, but sometimes the battery is recharged by the engine as well.

Like any other car in the market, but the gain is not in there.

 

[TMiguel]

http://www.fueleconomy.gov/FEG/atv.shtml

"Unfortunately was true" = is true for the majority of cars on the market.

Sure, many of the hybrids, which you apparently don't understand (they maximize fuel efficiency by running the car engine at its optimal efficiency point and generating electric power, you're confusing them with regenerative breaking) get high efficiencies, and many car engines have theoretically higher than the 15-20% efficiency they're getting, but the problem is the car only runs at optimal efficiency during near-full throttle conditions. ICEs lose efficiency as they throttle down, like most motors. Since we only achieve that when we're accelerating very, very quickly, the practical efficiency of your average car is in the 15-20% range.

Sorry, you're running on too much theory and too little knowledge.

Perhaps I'm running of top of the line data, I’m no automobile mechanic, I just run on the data that it is available to me.

 

[CFLarsen]

Devices like this don't work for one simple, brutal reason:

Exxon hasn't bought it.

 

[Boran]

Two strokes are by their nature less efficient than four strokes.
[...]

I doubt that this is the case for diesel two stroke engines, they do not expell unburned fuel-air mixture out of the exhaust since the fuel is injected in the cylinder once the air has already been compressed (and no exhaust or intake valves are available) I cannot link externally yet, but google "diesel two stroke" and you'll find the howstuffworks page explaining it.

And since a two stroke engine delivers power at a faster frquency (every two strokes rather than every four) I think efficiency would be higher since a lower RPM has to be used for a given power output (and a diesel likes a slow RPM since it has more time to burn that way)

I am by no means an expert I'm just making an educated guess with the knowledge I have.

As a sidenote, fuelsaving.info is an intresting site with lots of information about all kinds of fuelsaving contraptions and why they dont work and some real tips on how to save fuel (tip1: dont use your car if you dont have to)

 

[Rob Lister]

I'm willing to bet KotA is pulling our leg.

 

[Ladewig]

I tend to believe someone 'moreso', if and when they aren't trying to sell me something.

And "Yes, I DID hear a difference between the two idles."

I am not doubting that you did hear a difference. I and other posters are doubting that an engine idling at a different pitch is proof of improved gas mileage. It is not. To claim otherwise is absurd beyond belief.

They guy claimed to witness a difference in fuel consumption, and while I did take him at his word, I am 'here' today to confirm my conclusions or have them be debunked.

Post #15 seems to say otherwise:

The device works.

I am here today to learn how to make it work 'better'.

. . . . . . .

Everyone has said that there is no improvement. You insist that there is an improvement. Apparently there is nothing anyone here can say to convince you otherwise. Therefore the only thing left for us to recommend is for you to perform the experiment yourself. (1) Find a friend who will take your vehicle to a mechanic, (2) let the friend flip a coin and use the result to determine if the device should be installed or not, and then (3) drive the vehicle for a week making careful note of the mileage. Repeat steps two and three several times.

I am certainly not emotionally connected my findings or conlcusions...

 

[technoextreme]

ICEs lose efficiency as they throttle down, like most motors.

Electric motors efficiencies have a sweet spot in that you can rev the motor up or down it will start losing efficiency.

 

[Stout]

No it isn't. The alternator produces power on demand. No more than is required as determined by the voltage regulator. Turn the lights on and the alternator supplies more power. Turn them off and the output drops. As it produces more power in response to demand, the engine consumes more fuel.

That's exactly the thing I was wondering about after I'd read half of this thread and decided to step outside for a smoke..

With my old, skanky van, I could heat the the gas sucking V8 "rev down" when I turned on the lights, but with my newer. less skanky van I haven't noticed that effect.

I got to wondering whether turning on the lights didn't increase demand on the alternator ( and therefore didn't increase resistance and power demand on the motor ) or whether the computer system just compensated for the increased power demand and upped the fuel consumption a little.

I got to thinking that this might just be a plausible idea, assuming of course that the demand and resistance on the alternator *might* just be constant on my newer vehicle and started wondering whether I could tap into this "wasted" power.

Then I got to wondering, just how much power is output by that alternator, and would it even have an impact on my mileage at all. I mean, what sort of percentage energy output is generated by my alternator when held up to the power generated by my engine ? Is it even significant in the grand scheme of things ?

Quarky...that idea of running electrolysis-derived hydrogen through the motor....that's Stan Meyers isn't it ?

 

[Cuddles]

Look, I fancy myself a skeptic

Really?

http://www.internationalskeptics.com/forums/showthread.php?t=110976
http://www.internationalskeptics.com/forums/showthread.php?t=112728
http://www.internationalskeptics.com/forums/showthread.php?t=109260
http://www.internationalskeptics.com/forums/showthread.php?t=125950

I don't think that word means what you think it means.

Edit:

Then I got to wondering, just how much power is output by that alternator, and would it even have an impact on my mileage at all. I mean, what sort of percentage energy output is generated by my alternator when held up to the power generated by my engine ? Is it even significant in the grand scheme of things ?

That's something I've wondered before. I'm far from an expert on cars, but some rough calculations suggest that it's pretty much insignificant. Say an average car produces 100 horsepower of thrust, which seems representative enough. 1 horsepower = 746W, so that's around 75kW of actual mechanical power produced. According to a quick Google search, headlights are around 100W at most, with other lights presumably being a lot less. So turning your lights on will use maybe 250W, which is about 0.3% of the total power. I'd say that's pretty insignificant really.

Air conditioning and heating can certainly affect fuel consuption, but other than that the external lights wil be by far the biggest drain on power. Given that even that appears to be insignificant, I think you'll struggle to affect mileage by doing anything with electrical systems.

 

[technoextreme]

That's something I've wondered before. I'm far from an expert on cars, but some rough calculations suggest that it's pretty much insignificant. Say an average car produces 100 horsepower of thrust, which seems representative enough. 1 horsepower = 746W, so that's around 75kW of actual mechanical power produced. According to a quick Google search, headlights are around 100W at most, with other lights presumably being a lot less. So turning your lights on will use maybe 250W, which is about 0.3% of the total power. I'd say that's pretty insignificant really.

That's wrong. The math is dam annoying but I'm certain that straight power conversion is not correct. It tends to screw up where you are operating on the torque-rpm curve which then in turn affects efficiency. It's the exact antithesis of the reason why GreyICE described hybrids as being so efficient. Ahhhh... Yes. IEEE. The bastion of electrifying information. Lopping off 100 watts of power is the same exact fuel savings as loping of 110 pounds of a car. So yeah... 100 watts is a lot of waste.
http://www.spectrum.ieee.org/print/1420

 

[casebro]

Yes but Cudles, you are basing your calculations on full throttle horsepower. Do them again, only this time use the 15 hp that is all that is used in light cruise.

That's why air conditioning use is so bad on mileage. They suck only 3-4 horsepower, but that is 20% of the cruising out put.

 

[TjW]

I doubt that this is the case for diesel two stroke engines, they do not expell unburned fuel-air mixture out of the exhaust since the fuel is injected in the cylinder once the air has already been compressed (and no exhaust or intake valves are available) I cannot link externally yet, but google "diesel two stroke" and you'll find the howstuffworks page explaining it.

And since a two stroke engine delivers power at a faster frquency (every two strokes rather than every four) I think efficiency would be higher since a lower RPM has to be used for a given power output (and a diesel likes a slow RPM since it has more time to burn that way)

I am by no means an expert I'm just making an educated guess with the knowledge I have.

As a sidenote, fuelsaving.info is an intresting site with lots of information about all kinds of fuelsaving contraptions and why they dont work and some real tips on how to save fuel (tip1: dont use your car if you dont have to)

No. Efficiency isn't related to how fast you generate power pulses. It's a function of temperature differences. Essentially, that means the higher the compression ratio, the more efficient the engine can be. Google Carnot and "heat engine" for the theoretical explanation.

I've never heard of a two-stroke diesel that didn't have a turbo or super charger to increase the effective compression ratio, so I'd guess that the two strokes have a higher effective compression ratio than the four strokes they're being compared to.

 

[GreyICE]

I doubt that this is the case for diesel two stroke engines, they do not expell unburned fuel-air mixture out of the exhaust since the fuel is injected in the cylinder once the air has already been compressed (and no exhaust or intake valves are available) I cannot link externally yet, but google "diesel two stroke" and you'll find the howstuffworks page explaining it.

And since a two stroke engine delivers power at a faster frquency (every two strokes rather than every four) I think efficiency would be higher since a lower RPM has to be used for a given power output (and a diesel likes a slow RPM since it has more time to burn that way)

I am by no means an expert I'm just making an educated guess with the knowledge I have.

As a sidenote, fuelsaving.info is an intresting site with lots of information about all kinds of fuelsaving contraptions and why they dont work and some real tips on how to save fuel (tip1: dont use your car if you dont have to)

Fair enough, Diesel two-strokes aren't exactly my area of expertise, so I'll take your word for it. I guess a diesel engine could get that high, well maintained.