Reply to "Stroker Motor Questions by Dave F #5972"

> What are the controls this setup?

The computer choice is up to the user. Dennis at PPC used to use the
Haltech but may have switched when Haltech pulled their U.S. distributor.
I forget what Kelly chose (FAST?). I suppose you could run a Megasquirt
or hacked GM if you wanted. I'm leaning towards Electromotive because I
want to blend speed density and Alpha-N control approaches and also want
spark timing control. Many of the aftermarket ECU's are speed-density or
Alpha-N. Speed-density (alone) does not work well on highly modified engines
that lose manifold vacuum upon any throttle opening. With independent runner
throttle bodies, once off idle, throttle position is a better indication of
load than a MAP sensor. This is because a small opening in the throttle
body will cause manifold vacuum to go to atmospheric. Beyond say 10-15%
throttle opening, there is little response to a MAP. Alpha-N is the way to
go with naturally-aspirated independent runner but it doesn't do much for
part load/part throttle fuel economy. That's where it's beneficial to blend
in the MAP. Mike Trusty has been running IR EFI for many years. It's been his
experience that MAP dependant ECU's don't handle IR systems (with or without
big cams) well. The MAP changes so rapidly, even with a mild cam, that at
just off throttle the MAP goes almost to atmosphere which makes the ECU think
the throttle is wide open even though the throttle position doesn't verify
that. Add in the hard to get rid of pulsations even with manifolded vacuum.
In his experience what works best is a system that can look at both throttle
position and MAP and allow you to give one or the other more authority in
different power ranges. I know some guys give throttle position all of the
authority. That works but doesn't do anything for part load/throttle economy.
Electromotive has a blend mode in their software which is a function that
allows you to blend the authority between the throttle position and MAP.
John Meaney (the guy behind most of the aftermarket EFI systems like FAST
and Big Stuff3) says his latest and greatest Big Stuff3 unit allows the user
to tailor the cell width for both rpm and load (MAP or TPS%) and that by
increasing the resolution you can get the sensitivity I'm after. Still not
sure if I buy that yet.

Dan Jones