Factors to consider..
injector placement
rpm
airspeed in manifold and heads
typically the standard maps supplied with the M8 or M48 are close enough to be
of little concern for the baseline tuning. While on the dyno and the baseline
established. Air fuel ratio reasonable approx. 13.0 to 13.5 for a NA engine and
the ign timing set for best power and no more, move the injector timing around.
If it makes the air fuel ratio richer you are going in the right direction. just
trim the fuel up as you go along. Also leave the default setting for setting the
timing for the injector closing. A rpm only based map is fine as well as we are
not concerned with mileage only peak power at WOT. At 80 or 90 % duty cycle the
ECU is no longer sequential either and there is very little to gain.
Dave
Nigel Shaw wrote:
>
> List,
> A question from a 'back ground lurker' who intends to me more active
> this year.
> Injection timing as applied to a sequential efi setup. Is there some 'rule
> of thumb' as to how much before the inlet valve closes to where the 'End Of
> Injection' point should be set? I guess there's no simple answer as I suppose
> it's related to piston speed, piston area, inlet port area, distance from
> injector to inlet valve.
> At low duty cycles when all of the fuel can be injected when the inlet
> valve is open seems kinda straight forward but my max duty cycle is around 80%
> so the 'Start Of Injection' has to be such that I'm shooting at the back of a
> closed valve in order to get all the fuel in before the valve shuts. This is
> with a MoTeC M8 ECU. Not afraid to crunch some numbers here....just need a
> starting point.
> I promise to try and keep future posts a little more concise.
>
> Nigel S.....Down in NZ and doing it hard on the first day back at work for the
> year.
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