DIY_EFI Digest V5 #45

Hunt David huntd at
Mon Jan 31 15:34:48 GMT 2000

Just lettin' Grumpy relax--

You have pretty well defined the hydraulic system necessary to squirt about
0.06 grams of diesel fuel into a chamber in each cylinder of the Navistar
V-8 26 times a second. And--remember, it only has to squirt the diesel in
one direction.

Now--double the frequency (suspecting that you want to do this on an engine
that turns more than 3200 rpm). Then, increase the mass that you have to
move by a factor of at least three thousand (for a 180 gram valve?), and
last of all, actuate it in both directions. For a little extra fun, realize
that no impact at the end of the stroke is acceptable. Last of all,
consider the amount of work Navistar did to develop the injection system!

Be kind of a fun problem, I would think!


Yeah, but since the diesel fires each revolution the frequency is the
same...right? And, .06 * 3200 is about 192 grams/ second.  Pretty
impressive, eh!

Also, I don't thing that atomizing .06 grams of diesel fuel (pushing it
through a small orifice) is necessarily less work than accelerating (and
decelerating) a 180 gram valve.  I say this because of the size of the pump.
Can anyone do the math?  I may have the numbers for the viscosity, but don't
know how to do the math.

P.S. Anything Navistar can do in production we should be able to do better
as one-off projects.  Never underestimate the amount of engineering that is
necessary to create a product that can be made on a production line!

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