Quote:
Originally Posted by bbraden
You'll have to machine a pre-combustion chamber into the head in order for the IDI injectors to work. They're not built to take the hammering that a DI injector will. Plus, you'll have to have a glow plug. I'm betting that with a loose engine and all the WD-40 in the world, it's still not going to start under 30 degrees. I've never actually seen how air injection works... never heard of it before.
Either way, I'm not trying to say it can't be done at all. You can probably do it with enough time and enough money. I guess it's just the German Farmer in me that wants to over-engineer everything. If I build something it's because it's going to be better than I could buy it or so much cheaper that I can deal with all of it's crap that I'll have to put up with.
Anyways, it sounds like you have a pretty good idea of what you want out of this engine, so I'll just leave it at that. Have fun!
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I'll have to drill out the spark plug holes anyway, and I thought about drilling them out, tapping them, and screwing in a sort of precombustion chamber. The OEM spark plug holes are way too small to screw in any diesel injector I've ever seen. I'm going to have to check clearances on that anyway, to make sure it won't interfere with the two-valves-per-cylinder.
Basically, the thing I had in mind for the pre-combustion chamber was just a threaded bulb fitting with holes in it that stuck down into the combustion chamber only slightly, and the injector screws into the top of it. If you need, I can make a crappy MS Paint rendition of it and upload it, so you can get a better idea of what I'm talking about.
Air injection seems to be out of the question - its' used on slow-speed diesel engines, I can't find an example used on a high-speed engine. (slow speed = 60-200RPM operational speed).
I don't know how well the engine will start in temps below 30 degrees, but my GM 6.2 Diesel started with a single spray of WD40 in sub-0 temps as long as I warmed up the block for about an hour. It would only take about 10 rotations to start it up, with a quick spray of WD-40 in the intake.
I know what you mean about over-engineering things, it's normally a fault of mine too. I overdo it until it doesn't work, usually.
You have to remember, though. This is a TINKER project. I'm not taking it too seriously, I just want to see what will and won't work, first hand, and WHY it won't work. If, in the end, it works, I might build a few of them and sell them.
I've got small (briggs engines, Kohler engines, etc.. ) that I've also been considering similar projects with... I have one specifically that I don't have a use for, so I was thinking about doing a carb'd spark ignited diesel with it. Again, just to see what happens.