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Author Topic: Arduino as an engine control module?  (Read 2855 times)
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where the spirit leads
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It takes heat to turn water into steam.    If you inject cold water at the top of a compression stroke, some may turn into steam, but the process of turning cold water into steam absorbs the heat from the compressed air, and the pressure will DROP, not rise.  It will consume mechanical power to do this.   As the piston starts down, the cooled air cools even more as the pressure drops, which can cause water to condense, further reducing the pressure against the piston going down.   It will take far more power to push the piston up, inject the water, than will be recovered on the way down.   

There is nothing to gain here.  NOTHING.   It will consume water, fuel, and time, and you'll have a severe loss in fuel economy.  You could, in theory, inject superheated water under high pressure, but that consumes large amoutns of fuel to heat the water and keep it compressed (not flash to steam).   There is no efficiency to be gained here.  None. 
 

How does the pressure drop as water expands into steam?  I agree that the pressure will decrease as the piston travels down, but it does with burning fuel as well.  The water would not condense, as the piston and cylinder walls will still be hot.  Water expanding into steam can create extremely high pressure.  Are you telling me that steam engines don't work?  The only difference here is that I will be using the heat from the previous combustion to make the steam.

Ok, think carefully about this.  What turns the water into steam?  Heat.  How much heat is in the air?  How much steam can you create with the heat contained in the small amount of air that's compressed inside the cylinder?  At what pressure?  You can figure all this out by calculating the amount of air that's in the cylinder, and how much you compress it.  From this, you can determine the btu's of heat that the air contains, and how much water you can evaporate with the btu's avialable.  At this point, it's  a downhill slope. 

What I suggest you do, is to figure out the pressure / temperature slope for water turning into steam, remember, the ONLY thing steam is, is evaporated water.  And, the heat from the air compressed in the cylinder is absorbed evaporating the water.  The only other heat that's available, is to suck the heat out of the pistons and cylinders and combustion chamber, heat that will have to be absorbed the next combustion stroke, instead of being converted to pressure to drive the piston. 

The efficiency loss involved in a cold engine is NOT just from "running rich".   It's from large amounts of heat absorption from the combustion, and it is from reduced combustion efficiency, as the lesser amount of heat vaporizes the fuel less well.  The reason it runs rich is because it is difficult to ignite the mixture - and that's becuase there's not enough heat to vaporize the fuel well. 

Now, as your air is cooled by evaporating water, you now have the piston begin to travel downward, relieving the pressure, but as your pressure falls, so does the temperature.  As the temperature falls, the steam reconverts back to liquid.  You may not see it like fog, or vapor, but it has recondensed, dropping the pressure even faster. 

I'm sorry, if there was a "magical perpetual motion" machine, it might work.  But there is no energy created by shoving water into the cylinder.  There is simple physics of heat being absorbed by water.   This can't possibly produce MORE mechanical energy than you put into the system = the only energy input is going to be the force requird to shove the water in and the generated kenetic energy from the previous combustion stroke shoving the piston up due to the  flywheel effect.  There has to be an energy input, and that energy input is GOING to be the fuel you burn. 

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5 of every 4 people have math issues.  

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The MegaSquirt is not open source, I had looked at that as a possibility for another vehicle at one time, had it been open source, I may have used it.

It's open source. The circuit design, PCB layout and source code are all freely available.
The MegaSquirt® EFI Controller microprocessor code is available, and you are encouraged to make and share modifications (for use on B&G boards) to suit your installation. Several modified versions have been developed for particular applications/features already. Other people have developed and shared helpful freeware for MegaSquirt® EFI Controller, including:

    TunerStudioMS - for tuning and datalogging the MegaSquirt® EFI Controller with a laptop computer, (Phil Tobin)
    MegaTune - for tuning and datalogging the MegaSquirt® EFI Controller with a laptop computer running Windows 9x/ME/XP, (Eric Fahlgren)
    EasyTherm - to simplify the substitution of non-standard temperature sensors and to upload software revisions (MegaSquirt-I only, MS-II™ can be recalibrated in MegaTune). (Roger Enns)
    MS Palm - to tune and datalog with a Palm (Roger Enns)

In addition, ancillary hardware has been developed, or is being developed, for your MegaSquirt. These include:

    MegaStimulator - to test your completed MegaSquirt® EFI controller unit prior to installing it. (Jeff Clarke)
    Relay board - to simplify wiring of the MegaSquirt. (Bowling and Grippo)
    MegaView - to provide a dedicated display for the MegaSquirt - available NOW!. (Bowling and Grippo)
    MegaSquirt-II™, which has ignition control, available now (hardware). (Bowling and Grippo)

As well, Jim Willette has developed the Willette programmer - for programming blank or corrupted MegaSquirt-I™ processors, and a MegaProgrammer(.ZIP file) is also available for the same purpose.

The best feature of some MegaSquirt® controllers is that you build them yourself! Since you assemble the controller, and all information about the design is available to you, you are able to troubleshoot the board if a problem arises, and, in almost all cases, repair the unit yourself. The system as it exists today is a complete “turn-key” solution. You solder it together, install in the vehicle or boat, tune, and use it. The complete source code is available for those who want to understand or even modify the control algorithms.
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I know what you're saying and I know that the steam (or anything else) does not create energy.  The heat used to make the steam is mostly heat that would normally be lost into the radiator.  By having a water control valve instead of a traditional thermostat, I can keep that heat in the engine and use it to make the steam.  There is a great deal of heat dissipated by the radiator, and using that energy to push the piston down is better than losing it in the radiator.  Even if there is less force acting on the piston than a regular power stroke.  I would also modify the exhaust manifold to heat the water to a bit above boiling (it will be pressurized) before injecting it into the cylinder, saving some of the heat that is lost into the exhaust as well.  The steam could not possibly condense back into water; the water will be injected already above it's atmospheric boiling point, and be inside a cast iron cylinder which would be no less than 250ºF with aluminum on both ends of the cylinder at a similar temperature.  If I find that the engine does cool down using an every-other power stroke using steam, I can just increase the number of regular power strokes to keep the engine in the ideal range.  I could even redo the cooling system to heat the engine using heat from the exhaust if the temperature drops below 250ºF.

I know this will be a complicated system, but taking heat that normally disappears into thin air and using it to push the pistons down just a little bit is better than letting it go without using it at all.  It may not be as good as a power stroke from gasoline/petrol, but some force from energy that is otherwise lost is force that's not really directly from fossil-fuels.  It is, but it isn't. 

Good to know MegaSquirt is open source.


I appreciate all the comments from everyone.  I just wanted to know if the Arduino would be capable of controlling this system, whether it works or not.  I have some time to spend at an auto repair shop I'm starting, and until we get going, I'm often there with nothing to do for a few hours at a time.  I've got all the parts but the injectors, I may as well try to use them for something.  I'd rather do this than nothing, and hey, I get to play with electronics and engines at the same time smiley
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  Do any of the posters to this thread know of a programming solution for GM ECMs "computers"? I know of flash boxes but, not of any programmers that let me choose the tune.

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