MSefi.com read only forum (Jan.15,2018)

I'm not sure where to put this but I'm going to try and explain everything (the important parts) in as much detail as possible.

I'm an Engineering student at the University of Houston and my senior design project consists of a 6 stroke diesel/steam engine. Basically we're using the waste heat from the diesel exhaust and heat sinks to heat water and inject into the combustion chamber where it turns to steam to create another power stroke to help efficiency. Instead of getting a new camshaft made, we're going to open the valves with solenoids/actuators so we can switch between 4 stroke and 6 stroke fairly easily.

Here's the main question, I need a way to control the injectors (both diesel and water). Since the engine is a diesel (single cylinder 250 cc) I don't need control over ignition. I was wondering if there was anyway that I could use a crank trigger with megasquirt to fire the injectors only. And also I need to have precise control since I need the diesel and water to inject at a exact moment to a max of 3000 RPMs. I know there are going to be a problem with injectors since they will be diesel injectors and some require more amps and the MS injector driver may not be able to handle it, but I'm looking into small injectors. Any help would be greatly appreciated.

Jason

Jason,

You can certainly fire only the injectors. MegaSquirt was originally designed for injector only control.

MS-II (v2.873+) allows you to set the 'Injection Timing Delay'. Normally MegaSquirt injects when it gets a tach signal. However, this value lets you set a delay (as a percentage of crank degrees) to wait after the tach signal (i.e. the crank wheel signal) before starting injection. So that might do what you need. There is more here: http://www.megamanual.com/mt28.htm#s

Whether it is accurate enough for your purposes, and whether MegaSquirt can handle the injectors you use is something you will have to determine.

Lance.

Thank you Lance for your quick reply. I do have a few further questions though.

It looks like I'll be making some sort of crank trigger system (haven't really looked into it but I'm guessing something like the missing tooth trigger?) Will MS have enough data to be able to run the injectors with just a trigger system? Will it enrich some when it calculates the RPM going up? More than likely this engine will be run at a set RPM, 3000 RPM's or less. Since this is a little diesel, it doesn't have any sort of throttle body.

Do you have any information on how accurate the injector firing system is? I read that pulse width is exact but I couldn't find much on the accuracy of the injectors.

Also, since the water and diesel need to be injected at different times, how is the trigger system going to distinguish between when to fire the diesel injector and the water injector. Will I need to make 2 different crank triggers and run them apart?

Sorry for so many questions.

Jason