Injector timing qns.

[Craig Pugsley]

Hi there,

A few days ago I asked this:

>I've got a few questions regarding injector timing:
>
>i/  Does the timing of the injector relative to the timing of
>    the intake opening matter much?. IE if you've got the same
>    injector on time, but change the 'phase angle' relative to the
>    cam, will the power output vary much?
>
>    Rewording, will power output change much between full sequential
>    and simultaneous injection, if you assume (as with L-Jetronic)
>    that the fuel can "Hang around" in the intake while the valve
>    is shut, or for optimum power should the fuel injector only be
>    turned on while air is flowing into the engine

I did a bit of digging (actually, I was trying to find those SAE
papers Dale was speaking of - with no luck).

I found an SAE-like organisation's year book on automotive electronics.
There was an article from the mid 80's (I lost the bit of paper that
I wrote the exact reference on).

Anyway, in a paper by J.H. Francis from Lucas, U.K. titled
'Electronic engine management for high speed competition engines'
It is written about the Lucas '468' as used on a V6 rally car.

It's got a few graphs which look like this:

   Peak torque (Nm) at 6000 RPM
        338.0 |
              |
        334.5 |                  **
              |                *   **
        331.0 |****          **      ***
              |    ******  **       
        327.5 |          **
              |
        324.0 |
              |_________________________   Injector valve closing angle.
             BDC         |TDC      |  BDC 
                         |<------->|
                      intake valve open.

IE what they are saying is that they got max torque with the injector
firing finishing about 2/3 of the way through the intake cycle.
Conclusion: Timing IS critical for maximum performance. (Even though
it's only 2-3% difference)

There is also another graph showing fuel consumption. Above 6000 rpm,
sequential and grouped injection use the same amount of fuel.
Below 6000 rpm, the sequential uses about 3/4 of the fuel that grouped
injection uses (According to the graph).

Can someone please tell me what they think of my HEGO probe idea posted
the other day? I might try it and let you know anyway.

Cheers,
Craig.

pugsley at trl.oz.au