Vapor vs Atomization, and the winner is

[Bruce Plecan]

I'm not to sure I beleive all of what's been said about this lately.

A carb., while offering better atomization for metering might be good,
but alot of what gets metered winds up on the floor of the manifold
where it lays long enough to pick up some heat, and thus is vapor.
The exception being side drafts (and then mostly at higher rpms).

Also, On some manifolds, I've noticed clean trails of where the fuel
formed runners, or little streams of fuel going to the runners.

At low engine speeds, the fuel from a TPI might have time to just
fall on the floor of the runner, and trickle on down to the intake valve.
But, as rpm increase the air speed will help some in keeping it
atomized.

I wish someone had the time/energy to fire a couple injectors
horizontially, and say 45d off vertical, and see what the patterns
are really like, at like normally installed distance from injector to
opposite port wall, and just one shoot, say 1.7msec long like what
an idle pulse would be.  That might answer some questions.

If Harry Ricardo's statements about how fuel burns are true then the
vap/atm issue would just boil down to a couple degrees difference in
timing in actual practice.

One universal truth (for high performance)that I've noticed, and that works
for me, is keeping the intake manifold as cool as possible.
Trouble is a dual plane the distribution goes out the window.

One thing I'd like to do, is eliminate the Water cross over in the front
of the intake, and use a Y with remote thermostat housing (SBC),
and come up with a good recirculating themostat.

Then the comment about it not mattering since the injector wasn't
pointed directly at the valve head anyway.  Well, the inertia of the
fuel is going to carry the fuel till it hits something anyway since the
distances are so short, and the gravity will help it get to the head of
the valve anyway (at idle, low rpm).

For high peforkmance,  vapor isn't too good, since it would be more
prone to compression ignition, detonation.  Also, with these tendencies,
would be more touchy about fuel.

Nomex CSH, with chin strap, on
Bruce