Tri-Power TBI

[Gary Derian]

With a speed density system, each computer is responding to the actual
engine conditions MAP and rpm.  During the transition from single to triple,
the air flow is split in some unknown proportion between the primary and
secondary TBIs.  The fuel flow must also be split in that same proportion to
distribute fuel evenly among all 8 cylinders.  With two speed density
systems, each will fuel the entire engine since the inputs are the same.
There is no way to split the fuel flow in proportion since the air flow
split is constantly changing.  Two MAS systems would work, one for the
primary and one for the secondaries.

The whole reason for tri-power is to get around the limitations of a carb.
Why build a TPI the same way?  The easiest way I see is to run three equal
size TBIs together.  Gee, just add one more for an IR setup.

Gary Derian <gderian at cybergate.net>



>Gary Derian wrote:
>>
>> It seems to me that a tri-power TBI setup would work OK at WOT or center
>> unit only but getting a good fuel distribution during the transition
would
>> be very difficult.  How is the ECM to know what the air flow distribution
is
>> between the three TBIs?  A small change in throttle linkage would throw
it
>> off.  If all 3 were the same size and worked together at all times, a
>> reasonable approximation would be to inject an equal amount of fuel into
>> each.


Clive wrote:

>Use 3 TBI units, including 3 computers. Each one would then respond like
>a carb. Actually, 2 computers would do the job. One to run the "primary"
>and one to run the 2 secondaries .