Water injection improves MPG?

[oil pan 4]

Just make sure it comes out of lean for anything more than light load. I did the IAT thing on a car back around 2000 to make it run leaner and it burned all the exhaust valves.
But last year I did a lean tune on my carbureted 7.4L suburban and got better fuel economy than the new suburbans that have fuel injection. Then when I tore the engine down the exhaust valves had no sign what so ever of burning. I attribute that to being able to richen the mix as I gave it more throttle.

[ar5boosted]

Originally Posted by oil pan 4

Just make sure it comes out of lean for anything more than light load. I did the IAT thing on a car back around 2000 to make it run leaner and it burned all the exhaust valves.

When I had water-injection running, there was no chance of burning anything. This was after running for over an hour. It never went up, unless you turned the water off.

https://plus.google.com/u/0/+DavidLy...ts/MW1qzbFfsDU

[teoman]

Aaa to the best of my knowledge (which is not much) lean burn doest really run hotter.

Because of the leaner conditions, the combustion is slower, so you have still burning gasses going out the exhaust hence the burning valves problem.

You can increase combustion speed with a warmr intake. Almost all chemical reactions are faster in higher temperatures.

Water will negate some of the fuel. But it could save the valves. Need to crunch some numbers if there can be any theoretical benefit.

[oil pan 4]

16.5 is said to be peak temperature, I ran 16.5 air fuel for cruise for almost a year and had no signs of burning valves.
Valves get burned at heavy throttle.
So no reason to run water.
The the heat is what gives you the better fuel economy, the water cools that combustion.

[teoman]

In the tuning video, the AFRs could be manipulated a bit. Does that mean that direct injection vw cars or diesels have a wideband o2 sensor?

I do not really have the facilities to play with mechanics but i am good with computers etc.

[cRiPpLe_rOoStEr]

Originally Posted by teoman

Aaa to the best of my knowledge (which is not much) lean burn doest really run hotter.

It does run hotter, since the lesser amount of fuel takes less latent evaporation heat from the intake air. Have you never seen that piston-engined aircraft pilots enrich the mixture when the engine starts overheating, in order to decrease the temperature?

[teoman]

Piston engined aircraft are a very luxurious hobby around here

As the excess fuel is not actually burned, water could be used in its place, in my opinion. I suppose having low RPM's would give the fuel more time to burn and would not kill the valves.

[ctmaybury@yahoo.com]

I would think that running hotter (short of burning valves and pistons) would be the goal for fe. Cool the fire = more unburned fuel.

[cRiPpLe_rOoStEr]

Replacing some of the fuel with a smaller amount of water won't increase unburnt HC emissions, it actually decreases them.

Originally Posted by teoman

Piston engined aircraft are a very luxurious hobby around here

Not just hobby, they're still widely used for commercial purposes here. Most of the cropdusting aircraft, which are common especially in rice, corn, soybean and sugarcane plantations, run ethanol on piston engines.

[teoman]

Rules regulations and not many people have such big lands for agriculture. So the are non existent over here.

And knowing the way the locals drive, I am perfectly happy none of them are airborne.