[t vago]

Originally Posted by bazman

Guys - though we appreciate the science - it'd be more useful to discuss what might work in a car on the road.

Let's get back to that. This thread has potential if we make this all real.

Again - has anyone played with timing and lean burn while injecting high pressure water/meth?

I've never found anyone that has yet. I've come across meaningless experiments, and those that have tried injecting straight water without a custom tune hoping the water would do something magical. But who has actually tuned mappable water/meth injection under lean burn conditions?

I don't think anyone here has done so.

Originally Posted by bazman

To me, the obvious thing to do is try it if no one has. My tuner can change my timing and air fuel to anything the engine can take, and the potential lean limits go up if we drop the O2 sensors.

For straight gasoline, maximum fuel economy is seen at an AFR of 17:1.

Originally Posted by bazman

Will the increase be enough to justify the added cost of the meth? Hopefully. Would the increase justify the cost of the injection setup itself? likely not - but if you run boost then that cost is justified for other reasons.

Cost? If the water injection setup could be done cheaply enough, then it'll still be an attractive option.

It would help to quantify the fuel economy gains for this mod. If, for instance, the modification resulted in a 10% gain in fuel economy for my truck with a 19 MPG baseline, and my driving style (120 mile commute using mostly highway driving), I would consider it to be worthwhile.

Then again, for somebody who gets 30+ MPG, it might not be so attractive.

Originally Posted by bazman

I believe a 50/50 mix of water/meth MIGHT help and for me it is easy as I run that mix anyway and have a sizable tank in the trunk to store it. All I need is another water injection kit to supplement the one I have (or replace it if I can vary the flow from very low at cruise to very high at boost). I'd never run water all the time, only under boost or under lean burn conditions. My tune kicks lean burn in after 7-8 seconds of steady light throttle cruise, then off if I poke the throttle.

It definitely would help, but the key is to have an engine tune that takes advantage of water injection. The idea is the same as for boosted applications.

The trick is, as you have pointed out, how to vary the flow. I am assuming that you'd use a water pump variable controller to do this. Fuel injectors are reported to quickly corrode, except for those injectors with stainless steel internals.

Many years ago, when I was planning to install a turbocharger into my Sebring, I had bought a water injection kit, along with numerous solenoid valves and different sized water injection nozzles. Each nozzle was sized to allow roughly twice as much flow as the next smaller one. I was going to design a circuit that would have switched these nozzles on and off such that the engine under boost would have received roughly the same amount of water per cylinder for any given engine speed.