My major argument is this: The engine throw off lots of waste energy in the form of heat. Using the heat to vaporize water inside the combustion chamber should generate power. Cool engine, generate power.
Yes, the flow rate is critical, and it probably doesn't work until the engine is completely warmed up and opening the thermostat (which mine does often due to the grille block). My system will feature a needle valve to control the flow precisely. A soon as I get a few minutes, I will write an update on my experimental system's progress in the Water Injection thread below.
Jim, that's my thought exactly, but remember just because you're absorbing heat does neccessarily mean you're increasing the efficiency. You could have some water become water vapor and lower the temp of the exhaust from 1000F to 800F but if it's 800F with 20% steam that's the same energy content because of the latent heat of the steam versus the latent heat of normal air, etc.
But yes, the 6 cycle engine and use of a LOT of water to generate a LOT of steam will move a piston, but timing it right and using the right amount of water will be very hard. Having 5-10% water vapor in the charge will not generate enough steam to move a piston at all.
So I would love to see your experiment, I cannot see it hurting beyond lowering your intake charge too much or causing the fuel to burn to slowly. I really think the only way water injection will prove useful is by using direct injection and injecting a LOT.
And lastly, to comment on higher octane, it is slower burning and resists ignition. Some of my cars improved slightly with it and some decreased MPG with it. Some didn't seem to make a difference but ran hotter, exhaust headers glowed brighter at night, etc. What others have been trying to say is that if your ignition is timed perfectly so that just before BDC (bottom dead center) of the power stroke it fully completes burning the entire charge and then you put in fuel that will not have enough time to fully complete burning before BDC, you will lose efficiency. You will lose power anyway (assuming higher octane/race fuels really have less energy content as stated above), but you'll lose efficiency too because you're not even capturing all that energy for work, it's burning slower and burning in the tailpipe instead of the cylinder.
Yeah the water adds cooling to the combustion so it in effect cools the engine and the burning of the fuel at a lower temperature - it should also provide about a 600 to 1 expansion of water to steam which is supposed to add to the cylinder pressure and improve efficiency since water expands more than air when heated up to steam temperatures. It also cleans carbon which is why I ran it in my 65 Rambler American with a flat head 6 which used to carbon up a lot in the squish area of the combustion chambers. Too much water injected will put the flame out - water at too low an engine temperature will make rust form in the engine - you also run a little risk of getting more water in the oil from blowby. The MAF (Mass Air FLow) sensor is usually a electrically heated wire or chip (ceramic) that is cooled by air flow - more air flow more cooling and that indicates more fuel needs to be injected - HOWEVER if doused with water it also cools the wire/chip and results in excessive fuel being injected and you get rich mixture and O2 sensor feedback which will generate a CEL.
So the trick is to inject water at the proper engine operating modes where it does good and not when it is not needed like idle - engine braking - light throttle - cold engine temps - just before shutting off the engine.
And here are plans for a nice little controller which will wait two minutes to turn the system on after startup, turn it off at idle, and then wait two seconds to turn it back on again when you take off:
- Welding baffles to bottom of PE/PP feed tank w/ old soldering iron
- Attaching Suction Diptube, Vent Filter, and Recycle Bulkheads to top of tank
- Welding top of tank back onto body of tank. Hydrotesting revealed one small hairline leak, which I repaired.
- Attaching redundant pump suction strainers to assembly.
- Hooking up pump, needle valve, and nozzle with temporary tubing for wet testing. $4 hardware store 1/8" FPT needle valve did not reduce flow through nozzle noticably (even at 1/2 turn above 0% open), so I bit the bullet and bought the $19 panel mount precision needle valve from McMaster-Carr. This valve is intended for Pneumatics but we'll give it a go.
- integrate universal fuel line filter (paper media)
- test precision needle valve control
- mimic plumbing setup (as it would be in the car, minus vacuum) as closely as possible, to duplicate pressure drops
- characterize system by catching discharge in a 1-gallon milk jug, i.e. "at 1 turn above 0% open needle valve, the system dispenses 0.1 GPH", "at 2 turns above 0% open needle valve , the system dispenses 0.2 GPM". That way I can have a calibration curve without resorting to expensive Rotameters to see the flow rate in realitime.
i'm still struggling to put together a far more basic system...
initially i'll have a pe tank with a bubbler and a line to a vacuum port of the carb above the throttle valve...
i'm considdering useing a bicicle tire valve as a one way valve to keep the bubbler working for a while after the intake cacuum has disapeared. it that works i might try to advance timeing a little.
second setup will be similar but will relocate the bubbler to a copper boiler tube that is heated by the exhaust...
the goal is to have a simple reliable system that allows me to run lower octane fuel and advance timeing
Jim Dunlop: what's the best way to weld pe? just put the bits together and heat them or use a 3d scrap as welding substance? seems like a very usefull technique, but i'd hate to waste all my good containers finding out how to do it.
That's exactly how to do it. Put the piece you want to join together, and use a strip as a "weld rod" to add material. This is necessary to fill in the cracks and make up for the slight deformation that occurs to the pieces you are joining.
The key is to make sure you use EXACTLY the same material. As I learned in college, polymers DO NOT like to mix with each other -- even if they're both commonly called the same thing such as PE or PP. Make sure, at minimum, the materials have the same recycling code number, unless it's 7 (like the red gas can I am using)...then you need to buy a duplicate product to cut up for construction pieces / weld rod.
Also, don't dwell too short or you won't get fusion...and don't dwell too long or you'll get too much deformation and potentially thermal decomposition (burning).
thanks, also for the waring of the different pe kinds.... i assumed this would not be the case... i've seen white pe containers with a transparent fine running the length of the bottle to check fluid level... but obviously mixing different bottles won't be that easy...
i'm one more part (t-junction for the vacuum hose), and some spare time away from testing my first primitive setup, so hopefully i can get this working soon.