I've had my Miata running on a megasquirt 2 for a little over a year at this point and have been very happy with every aspect of it other than the miles per gallon it's able to give. The particular type of megasquirt I have cannot handle sequential fuel for a v8. It's only capable of running 4 injectors so I have it set currently on batch fire which is killing my mileage below 2000 rpm's. In the city I get about 12 mpg and on the highway about 21. On top of this the engine's compression requires I run 91 octane.

I've been in the process of looking into water injection as a way too possibly at least give me the ability to run standard 87 octane. If it also gives me a few more mpg's and allows me to advance my ignition a bit more that would be nice as well. Since the ms2 can drive the system I don't need a controller which keeps the price down.

Has anyone had experience with water injection on ford engines? How much of the potential benefits are real and how much is snake oil. It almost seems to good to be true which makes me think oem's would be using it if it was really as good as it sounds.

Thanks for your thoughts everyone,

-Jason

 

I am in the process of installing a kit from Devilsown http://www.alcohol-injection.com/index.php. After about a year of research, they seemed to have the best options for my needs.They were very helpful on the phone. I am planning to increase boost & timing, & this will be a liquid intercooler to keep my IAC temps down. I am also switching to a 1995 ECU as suggested buy my dyno-tuner, Injected Engineering, who has performed this with great results.

 

It appears that Devilsown is working on their website at this time.
It's back up!

 

I looked at the three or four big names out there as well as Jegs and Summit and DevilsOwn seems to be the best suited to what I'm looking for. I need to contact them and see if they can sell me their $250 kit with the pressure switch deleted (I'm running it via the MS2 and as a NA setup) and the check valve and nozzle holder swapped for -4AN parts. Both of those parts are the same price as the kit's push-lock components so I hope they will be willing to work with me.

I'll use thier push lock from the tank to the pump but want to use PTFE stainless from the pump to the check valve to the nozzle. I'll use Summit PTFE line and hose ends since they are a bit more afordable. I'm planning to use my existing washer bottle as a tank since its pretty big and has a level sensor in it. I'll relocate the actual washer source to the cowl area so I can run mixes other than just washer fluid thorugh the injection system.

Other than having to relocate my oil cooler somewhere (it's currently in the washer tank location) the install looks to be pretty easy.

There are two ways I could have the MS2 trigger it from what I've been seeing. I could use one of the configurable output leads to trigger it which would give me two variable such as rpm's and load or I could use the table that is intended to operate the boost valve to give me a more progressive way of triggering it. What I really want to find out is if I can somehow use the level switch to activate table switching so I can have a "safe tune" setup that it can jump back to if I run out of water. I could easily do that by pulling over to the side of the road and loading another file with my laptop but it would be cool to be able to do it on the fly.

I had the MS2 built with an input for launch control which I'll doubt I'll ever use. I'm wondering if I can use that as an input to trigger the table switch.

I love armchair tuning.

-Jason

 

I couldn't sleep so I decided to attempt to tire my brain by drawing up a few designs I've been working on for the water injection system I'm planning on installing. Here they are:



Design one emulates the design of many of the available kits. The pressure is controlled by the pump’s internal pressure switch. The pump and the solenoid are triggered on and open by the same MS2 output. The line between the pump and the solenoid will hold 60 psi when the system is not operating but may have a lag as the pump “revs up” to speed when the system is turned on. The pump’s pressure switch also has an unknown degree of hystasis which could be 20 psi. This would mean the pump would only go on if the line pressure drops as low as 40 psi before pumping it back up to 60. Therefore pressure at the nozzle will fluctuate between 40 and 60 psi with no correlation between actual need (I would like higher psi at higher engine load).



Design two is identical to design one with the addition of a separate adjustable pressure switch which I’ll ramp up to 60psi on/80psi off (I’ll disable the pump’s own switch) between the pump and solenoid and a vacuum-referenced adjustable fuel regulator between the solenoid and the nozzle. In this design only the solenoid will be controlled by the MS2, the pump will be controlled by the pressure switch so that the line between the pump and solenoid always has at least 60 psi in it. The regulator will be set to 60 and will be able to use its vacuum reference to “ramp up” that pressure 20 psi as the manifold vacuum drops during WOT. Since the pressure switch is set to turn the pump on at 60 psi the pump should be operating most times during WOT operation and supplying a full 80 psi. As its currently designed there is a slight possibility that the extra 20 psi may not be available if the pump were to reach 80 while in WOT. If that were to happen the pressure would then drop to 60 psi even with the regulator allowing 80. If this becomes an issue (if the pump is powerful enough to sustain 80 psi immediately when the vacuum shots the regulator to 80) I can always install some type of WOT override relay that would bypass the pressure switch and lock the pump on after a certain throttle percentage (say 95% open). This could be easy enough to do with a nitrous actuator switch on the gas petal.

Thoughts?


-Jason

 

Water (alcohol) injection does have it's place. But it's not below 2,000 rpm. It's tough for water:air to stay in solution at those low intake velocities. It ends up falling out of solution, and running like a small stream into the open valve. as a liquid. It needs to be a vapor if it's going to help.

You might get away with using alcohol, which will stay in solution better. In the summer anyway.

But, lets do the math. Lets imagine that a water/meth kit will gain you 2mpg in town. That's a 17% improvement, so we're being really generous here. How much does it cost to install and run this system? And how many miles would it take to break even - IF it works?

From the practical stand point, you're usually better off just leaving it alone. OTOH, sometimes you just want to try stuff and see what happens.

Also, if you have enough cylinder pressure that you need premium fuel, then you probably shouldn't be lugging the engine below 2,000 rpm's. What's your dynamic compression, above 7.8? If it is, you'll end up breaking piston lands.