Is there anyone old enough to remember when water injection was often recommended as the fix for detonation. What ever happened to that. Early 80's I think.

 

Yes I do remember reading about that back in my 1/4 mile days.
I think there set it up was with a windshield washer bottle and a switch either on the shifter or gas pedel that when you hit wide open it sprayed a lite mist of water into the carb. to help cool down the cylinders to stop the Detonation from happening. and seeing as water is 2 parts Oxygen you'd get the added boost of air too.

Now for the draw backs to this set up.

Water when sprayed on open flames will expaned 1600 times it's mass into steam. And I don't know if you know it or not but water makes Cast Iron rust really fast. and what are your cylinder walls made of ?
Ring life wouldn't last very long and you'd have to change your oil alot too due to condensation. Not to mention the thermo shock you'd be laying on your pistons and valves.


Cool Idiea hook it up and play with it for a while and let us all know how it goes ....

ShaZam

 

That's what I remembered too, basically a windsheild wiper squirter shooting into the carb. The water didn't increase power, it's 1 part oxygen. They used to add alcohol to the reservoir.
It was very popular for a couple years. I wasn't seriously considering water injection, I thought there must have been some draw backs or we would still be using it.

 

Water injection was used back in the 60's as a mileage trick. You could buy the setup from JC Whitney back then. It was still around in the 70's.

 

...If you seach through the net for supercharger manufactuers or water injection you can still find these units. Usually they are triggered by a Hobbs switch that senses pressure. To use one on a carb equiped engine you would need a vacuume operated switch.

I have studied this before but don't seem to need it at this time.

The water seems to keep the pistons and cylinder heads very clean, sort of a steam cleaning action. That in itself reduces preignition by eliminating carbon. The other effect is of slowing down the burn rate of the fuel which is what octane additives do.

 

There is one draw back. Each water droplet makes kind of a tiny explosion instead of the burning action like gasoline. The result is pitting of the top of the piston and hence the lack of carbon buildup on piston tops. They look kind of like they were sand blasted. Water injection was used in WW2 as a high altitude boost for fighter aircraft engines.

 

I don't think water was a WWII power booster, I think it was to control detonation on supercharged engines.

Side note; the Germans were using nitrous to get their fighter planes up faster.

I wonder if the requirement of refilling a water or water/alcohol bottle is the main drawback to water injection; one more thing to fiddle with. Also, there must be distribution problems with it; the back cylinders would probably get more than the front cylinders.

EGR has much of the same benefits as water injection.

 

I'm having a hard time believing some of this. I remember hearing that a small stream of water would help reduce the carbon build up in the chambers. I used to do this for about 15 min, right before changing spark plugs.
Water is in the chambers for the brief period. I can't believe it's there long enough to cause oxidation.
I doubt it would be used more than 5% of the time under normal driving conditions so I doubt it will improve mileage.
Water and EGR slow the burn rate and do nothing for power. Using alcohol with the water, helped restore some power.
You could also use a micro switch that was triggered by throttle position.
I think people got tired of refilling the water resevior at every fuel stop.

 

Brian S,

Water injection has a very limited and specific application: to control detonation at high boost when the fuel supply can't be enriched enough for the level of boost. In some applications, water injection acted as just a temporary stop-gap to prevent lean-out detonation until the fuel supply could catch up to the demand.

When used in aviation engines, water injection coincides with very high boost, very high fuel consumption, and much higher than normal power output (up to 200-250% of normal max power, in some cases) for a brief period.

The only cases I've ever heard of where water injection was used successfully on road engines involved the same problem, i.e., lean-out detonation under excessive boost.

Alcohol was originally mixed with water for injection in aviation engines simply because alcohol lowers the freezing point of the water, not for any caloric benefit in the combustion process (which would probably be insignificant anyway).

As you and Paul observed correctly, if you introduce anything other than fuel and oxidant (e.g., air, nitrous oxide, more air, etc.) into the intake airstream, it will reduce the power output.

Of course, I'm not surprised that water injection would have been marketed as a fuel mileage gimmick, much like magnets are now.

 

What I was talking about is not corrosion. It is pitting that occurs when the water 'burns' during the combustion. Compare it to a very tiny localized lean condition that actually burns little pits in the top of the piston. Just relating what I have actually seen.