Another injector question

[Steve Ruse]

>Right now, we are still debating MAP vs. MAF, maybe somebody could give me
>some info to help in that area also. What are the benefits of each?
>
>Gets right back to what exactly do you want to accomlipce?.
>Steady state anything will work.
>Transistions, MAP take an edge over MAF.
>MAF has to have some *sense* time in the equation, where MAP is just kinda
>looking at waves.
>Again, just TPS and RPM, with enough feedback can be a simple functional
>setup.
>Is this for *day to day* driving, and need to be *emission* conscience?.
Or
>just for HP.


This is mostly just for HP. HP is about 45% of our competition, and 5% is
fuel mileage. Right now I'm mostly looking at HP, and once I get that down I
will start designing for mileage. This is my school's first experience with
this competition, but I want to be competitive the first time out. Luckily
we have almost a year and a half to get things together.

> Also, what is a cheap source for MAF sensors, or could we just take a MAS
>from a car and use it? How much does the shape & size of the intake ducting
>affect the accuracy of a MAS?
>
>Intake ducting for a MAF system can make or break it in a minute.
Reversion
>is a very real problem.  Though min with a MAP.


>Right now I am leaning towards (mostly) software control, via either a 68
>series Motorola processor or through a PC/parallel port. Is there an easy &
>accurate way to implement EFI through hardware only?
>
>Using a bunch of comparators, you can do about anything.  Just gets to be
>clumbersome.
>
>What kind of feedback could we use other than O2 sensors, and exactly how
do
>O2s figure into your fuel calculations? I know my car's PCM just uses long
>term fuel "trims" to compensate for variances in O2 readings. Are O2
numbers
>ever used in immediate fuel calculations?
>
>O2 numbers are meaningless.
>It's about recovering heat energy, that is usually the concern.
>you want HP, or Fuel Economy.
>If going for HP, then you run for an optimime mixture, but you have to
>experiment to find what that mixture is for your combination, and then
shoot
>for that.   you can't forecast what AFR (air fuel ratio) is optimime for
>your engine.
>Bruce


Thanks a lot for the help Bruce! Luckily, my team has an engine dyno that we
will be rebuilding this semester. So what you are saying is that we could
monitor our O2 #s to make sure we are making our max HP? That shouldn't be a
lot easier to determine once we get the dyno going.

Steve Ravet - Sorry for the HTML mail, I'll watch that from now on.

Thanks guys!
Steve Ruse

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