Fuel injection plugs

Gary Derian gderian at oh.verio.com
Tue Apr 27 19:23:33 GMT 1999


What is the point of direct injection?  All it does is make the operating
conditions on the injector more severe.  Direct injection requires injecting
only during the intake stroke.  This provides some time for mixing during
compression.  That would be a lot of gas injected in a very short time.
Less than 180 degrees of crank, probably less than 100 deg.  The gaseous
fuel would take up volume the same as if it were carbureted.  If you mean to
inject at TDC, you now have a diesel.  Gaseous fuels have way too much
octane rating to be useful in a diesel.  I guess that's why you need the
spark plug, sort of like the old Texaco and Ford stratified charge engines
from the 60's.  But if you're doing that, you need to change the piston
shape and move the spark plug into the rich zone.

Gary Derian <gderian at oh.verio.com>
> >
> ><< Has anyone heard of or seen a combination injector/spark plug for
> >conversion
> > to direct fuel injection without changing heads?
> >
> > If not, would you like one?
> >
> > Charlie Springer >>
> >
> >It has been tried.  Most of the problems are electrical interference
> between
> >the injector coil and spark energy. Plus the fact that the fuel
> concentration
> >next to the plug may be too rich to fire the plug without fouling over
> >time.
> >
> >James
> >
>
> It looks like an engineering challenge to me.  Perhaps a puff of air
> after the fuel has been injected.
>
> Actually, I would like a set that will inject a gas.  That would remove
> the power disadvantage of propane and methane.
>
> Ray Drouillard
>
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