big inch SBC EFI intake mainfold

[Phil Rickard]

Also keep in mind that as engine rpm increses, so does the air velocity in
the intake port, In other words, even though the intake valve in is a
closing than closed event, the air will still keep moving forward in the
runner and cause a turbulant effect as it collides with the backside of the
intake valve. This air turbulance at that point is what I was referring to
as aiding in fuel atomization and your point is valid and well taken.
Granted, this event happens in a very short time at high engine speeds and
it's effect becomes less and less of a factor as engine rpm's climb, but at
light to part throttle it definitely has an advantage over a setup that has
the injectors perpendicular to the intake runner floor. IMO.

Regards....

Phil Rickard- Engine builder/Tuner for Les Stanford-Pirate Racing Corvette
C5R......Formerly with L.P.E.
----- Original Message -----
From: Bruce Plecan <nacelp at bright.net>
To: <gmecm at diy-efi.org>
Sent: Tuesday, August 08, 2000 11:06 PM
Subject: Re: big inch SBC EFI intake mainfold


> Hmmm, well, just something that always gets me thinking
>
> Duty cycle WOT usually 85+%,  intake valve open, what 28% of the time.
> So most of the time the injector is shooting at a closed valve anyway.
> Most of the atomization takes place at the injector (OK, what 98%), and
the
> rest is vaporization, till the valve opens, and then some more atomization
> would take place again as the valve opens.  So as long as the injector is
> pointing at the general area does it really matter?.
> It looks like to me that the new tall narrow intakes, get the injector up
> high so as to spray on the hot back side if the intake valve.  Since the
> fuel is going to puddle there anyway
> Grumpy
>
>
> > 15* angle measured from the pintle to the face of the intake valve.
> > (backside) I prefer to follow the angle above due to the fact that the
> > portion of the spray pattern is at it's largest point there for better
> fuel
> > atomization. Also, the air velocity increases slightly at the bowl area
of
> > the valve pocket, furthermore enhancing fuel atomization. I have seen
many
> > other ways to do it also, but I believe the the ^ is the most efficient
> way
> > to deliver the incoming fuel in terms of power and keeping the BSFC
down.
> > Less fuel dropout means more energy released during a combustion
> event/gram
> > of fuel used.
> >
> > Regards....
> >
> > Phil Rickard- Engine builder/Tuner for Les Stanford-Pirate Racing
Corvette
> > C5R......Formerly with L.P.E.
> > ----- Original Message -----
> > From: <WEG1192 at aol.com>
> > To: <gmecm at diy-efi.org>
> > Sent: Tuesday, August 08, 2000 6:34 PM
> > Subject: Re: big inch SBC EFI intake mainfold
> >
> >
> > > Anyone know if the angle that an injector shoots into a ported
manifold
> > makes
> > > much difference? GM TPI is angled out toward the heads. Other systems
> seem
> > to
> > > be angled straight down. What's best?
> >
>
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