Why only two runners? Runners are like rocks. They NEVER fail :-)
You are not using the intake manifold shown in this picture
are you? :-)

You will have to ask Tracy. I would say the dynamic range of
the TBI injectors might be a problem but I could be wrong.

I know Tracy stages two of the four injectors. That kind of
provides a fail safe system and a wide dynamic range with two
injectors per rotor. If one of yours fails you will be at least
half down on power for sure.

Dynamic range when applied to a fuel injector needs some
explanation. Fuel injectors have some minimum pulse width
where they stop working. If the squirt hole in the injector is
big enough to pass fuel for full power too much fuel
may come out for smooth running at low power and at the minimum
pulse width. So it is better to use smaller squirt holes and two
injectors per rotor. One per rotor is used at low power and two
per rotor for full power. Plus I suspect the spray pattern
with a smaller injector is better at the minimum pulse
width.

Paul Lamar

Martin Orro wrote:

Paul,

 Two rotor 13B with PERIPHERAL PORTS = two runners....correct?  Each
runner in a peripheral port replaces two or three in a 4/6 side port,
less weight, joints and parts count, simpler manifolds, cleaner
installation. Jeff's post echoes my concept.

 What is the reliability of injectors?  Is it dependent on wattage, fuel
pressure, ambient heat, vibration, all of these?  What is the MTBF of
these devices?  Redundancy is great, I agree, but where is the
experiential evidence for requiring double to triple the plumbing,
wiring and compromises multiple injectors require?

 I'm trying to simplify the system, not sacrifice reliability.  I'm
willing to compromise idle characteristics (minimum pulse width,
peripheral port design) for better power and BSFC.

Tracy, what is your take on TPI vs TBI injectors in this application?

                Thanx,          Martin

OK Now I under stand. Peripheral ports. Ah so.

I have no idea on reliability numbers but I think you see very few 
cars pulled over with failed injectors. I have one car that has gone 
150K and another that has gone 90K with no injector problems.
Other problems yes but no injector problems.

I had a VW Square Back back in the 1969 or so that ran about 100K with
no injector problems. Bosch injectors.

I have no experience with TBI systems.

Paul Lamar
 
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