Hmmmm... I'll consider all this. I'm not getting a full compute on all the relationship the ALDA has. "Manifold vacuum"? seems to be a missing element on diesels in general, thus the persistent use of "vacuum pumps". I find a vacuum line going to the IP on my 300D but it only goes to the shutdown solenoid which seems to have the sole purpose of cutting off fuel to the IP.
BTW, thanks for teaching us how to spell "stoichiometric" correctly. I can finally sleep at night. It's one of those words you can speak but can't spell. While a diesel doesn't use a fuel/air externally mixed charge like gassers, and I concede discussions in the diesel world don't focus on "stoichiometirc ratio", it still factors into the "injected fuel charge/air mix ratio that happens in the cylinder. Since it happens in the cylinder it would be more difficult to measure, but I contend it still happens, as a necessity to even support combustion. To prove that point, take off the air intake and place a flat plate over it, cutting off air... engine stops... or cut off fuel... engine stops.. you need both, in a set ratio to sustain combustion. The better you do it.. the more power you extract per piston stroke and the smoother it runs. Since air that has been heated to the fuels flash point by compression is the "spark plug" in Rudolphs design, how much fuel injected strongly influences the flame generated. To little and you get a weak "bang", to much and it perhaps fails to light off because the droplet size reforms to liquid under pressure [as examples]. It seems the ALDA factors all those extremes into it's operation to keep engine load in match with fuel supplied by IP. Would be interesting to find some lab data or research data on diesels at low speed to support your comments about low speed running. I'll dig further. Thanks for stimulation of the old brain cells. Grant... AZ On Fri, Jul 15, 2011 at 11:29 PM, Jim Cathey <j...@windwireless.net> wrote: > So, if you would be so kind, "splain" to me just how the engine limits the >> fuel load based on the air charge? What, other than throttle position at >> the IP, limits fuel volume at the injector for each RPM of the engine? >> > > The ALDA, working in conjunction with the governor inside the IP > that also receives throttle position and RPM. (Or, as in the case of > the Frankenheap, manifold vacuum rather than throttle position.) > > Additional oxygen supports greater expansion and more >> complete burning of the fuel >> > > The combustion is already complete, or complete enough, if > there is no black smoke. Unused excess turbo air effectively > raises the compression ratio. > > More oxygen plus more fuel makes more heat energy, thus more power. >> To support combustion successful engine physics requires a stotsimetric >> (sp) >> ratio of 11.2 to 13.6 . Adding fuel or air outside that ratio band will >> fail combustion, or at least impact efficiency. >> > > Gassers (Otto) need a stoichiometric ratio, diesels do not. They don't > run with an even fuel mix to begin with. The fuel sprays in and > swirls and mixes and burns in-cylinder, a lot like a tiny high-speed > flamethrower. The uneven mixing is one of the reasons they have less > peak horsepower per displacement than a gasser. If you aimed at a > stoichiometric ratio it'd never mix quite well enough, and so you'd > get black smoke. > > On the other hand, the lack of requiring a stoichiometric ratio > means that at low loads they can be miserly with fuel. Diesels > run what would be 'lean', if it were evenly mixed, which it never > is, and which might even be bad if it were so. (Like an overlean > gasser.) > > Diesels are surprisingly different than gassers, in spite > of looking a lot the same. I don't know too much about the > stratified charge gassers, I think they might be stealing > part of a page from the diesel book. > > -- Jim > > > > ______________________________**_________ > http://www.okiebenz.com > For new and used parts go to www.okiebenz.com > To search list archives > http://www.okiebenz.com/**archive/<http://www.okiebenz.com/archive/> > > To Unsubscribe or change delivery options go to: > http://mail.okiebenz.com/**mailman/listinfo/mercedes_**okiebenz.com<http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com> > _______________________________________ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
