FI idea using TBI throttle body

[Joe Boucher]

It's very gratifying when you have the same idea as someone who you
consider smarter or better.  Edelbrock has honored me by producing a
system similar to something I was thinking of.

Edelbrock has released a fuel injection system using a throttle body
minus the injectors as the metering system, a MAP sensor and a regular
manifold with individual injectors for each valve.  I'm resonably sure
the injectors are ganged fired one way or another.

I had been thinking for a few months about a system similar to this.  My
Camaro has large intake passages making for slow velocities at idle and
low engine speeds resulting in the possibilty of fuel dropping out of
suspension in the intake stream.  So, a throttle body fuel injection
system scheme would not improve this.  TPI would give you individual
injectors which would help this situation by at least spraying the fuel
in the vacinity of the valves but is expensive compared to the TBI.
Also, stock TBI manifolds don't like RPM's over 4500 to 5000 unless you
buy the big siamesed runners.  Part of this mental game was to leave the
engine internally in the same configuration as it is now. The power band
now is from about 2500 to 6500 RPM.  I was playing with the idea of
combining individual injectors at each valve with the TBI throttle body
as the metering device and holder of the throttle position sensor when I
saw Edelbrocks ad.  And the over $1000 price.

My afore mentioned electron challenged knowledge has a hole in relation
to this idea.  How would the impedance of firing four injectors a side
effect the TBI ECM designed for one per side?  Not knowing the impedance
for the TBI injectors is a problem.  I have seen references for the
Bosch type injectors listing the impedance. Could a combination of
parallel and series ganging of the individual injectors get the
impedance close to the one TBI injector?  Will driving four instead of
one overpower the power output of the ECM resulting in burned out
components regardless of matching impedance?

Before anyone spends alot of time on this, it's a mental exercise for
now.

I have another question about FI and cams with lots of overlap, but I'll
post that later.

Joe Boucher
'70 Camaro '81 TBI Suburban