Injector Sizing: not dumb questions at all

[Greg Hermann]

>Thanks for your comments Greg,
>
>The Hilborn and Enderle injection systems had very poor metering at anything
>other than full throttle, they went way rich.  They were replaced not
>because they had constant flow but because they had poor metering.  Both
>Rochester and Bosch had very good constant flow FI systems.  Earlier this
>year in "Automotive Engineering", SAE's magazine, there was an article
>examining fuel droplet size vs. injection timing.  The researchers found
>that droplet size was smaller when the fuel was injected onto a closed valve
>and the exhaust backflow hit it than it was when injected during the intake
>stroke.  Backflow is a fact of life and can be useful to atomize fuel.
>
>The Lucas timed injection was indeed mechanical but at high rpm it was
>practically constant flow, similar to an EFI.
>
>Your comment about using cylinder turbulence to cover sins is a bit strong.
>I'm not bent on committing sins, I just want to have an effective FI system
>that works and that I can afford.  Do you have any real evidence that
>injection timed to inject only during intake flow provides better torque and
>fuel consumption at anything other that light throttle and low rpm?  As
>intake dynamics change with rpm and intake pressure, how do you vary the
>injection stroke start and stop time to inject only while air is flowing
>into the cylinder?  You must vary fuel flow rate quite a lot, either with
>pressure, a variable flow injector or multiple injectors.  If air is allowed
>to enter the cylinder without fuel, you still need to use cylinder
>turbulence to mix it up, the same sin you accuse me of.
>
>I agree with low compression/hot exhaust.  Its basic thermodynamics.
>
>Gary Derian <gderian at cybergate.net>

For something that impressed me as very much as being a peek into the
future, take a peek at the web site that Stuart Baly called our attention
to over the weekend, amid the smoke. "www.orbeng.com.au". Their stuff would
appear to offer the best yet. Their financial data appear to indicate that
people like Siemens, Daimler, and Bosch agree with this assessment. The
neatest thing about it is that I see no reason not to stab the Orbital air
assisted injectors (the actual fuel injectors, which, in turn, plug into
them,  are standard stuff) into the existing bungs on an existing TPI
engine and go from there. One would have twice as many drivers, (one for
fuel injectors, one for air valves) but hey--I hear Sandy already has some
grey hairs! Orbital claims maximum droplet size of 8 microns coming out of
the injector. Obviously, if these units can direct inject, they are quick
enough to match injection with inhale in a TPI system without resorting to
staged injectors. The Orbital air injectors are in production in Michigan,
and available through the Mercury Marine parts system, as (that) Merc has
had engines (their DFI-200) in production using them for two years!!!!!
(All I know SO FAR!!)

Anybody out there care to place a wager on how much improvement in: torque,
power, and BSFC would be seen with this type of a conversion on an
otherwise same TPI engine???? (Tom--I've got first dibs on any bets against
improvements.)

Regards, Greg