Fuel on the intake valves

[MaxBoost at aol.com]

>They mentioned that the injectors have been repositioned and the intake has
>a small section cutout along the top of the port allowing the fuel to squirt
>more directly on or towards the intake valve.

>I thought this was interesting, especially considering we were just talking
>about the Hilburn systems. Coincidence????

>-Tom

FWIW, Nissan has been doing it since 1984 on their V6 engines.  I'm not sure
about some of the other makers though.  Actually, most of the fuel
atomization takes place through evaporation of the fuel on the hot intake
valve (at lower engine speeds).  Various people have tried open valve
injection timing in the past without major success.  I have heard it
described as "Making Oil" due to the large amounts of un evaporated fuel that
gets washed down the bore at lower rpms.  Supposedly the only way to make it
work is to aim the injector to hit the really hot exhaust valve.  Obviously
this requires a specific head and manifold setup to accomplish.

There was a thread about injection timing and batch vs sequential a while ago
on this list that may be archived somewhere.  The jist of it was that at WOT
and high rpm, injector timing had little effect, due to the limited time
available to inject fuel and the ability of the injector to flow fuel.  At
low engine speed and during transients, injector timing has a BIG effect on
response and torque.

On another note, I read somewhere that BMW's F1 engine had 4 injectors per
cylinder and timed the injection to wait until the exhaust valve closed to
start injecting fuel.  This was in the fuel economy runs in '85-'86 to save
blowing fuel through on overlap.

Max.