Injector sizing

[Greg Hermann]

At 11:40 AM 2/24/01, Tlsalt at aol.com wrote:
>Hello all,
>
>    I have a question about injector sizing.  Does anyone know of a torque
>based injector sizing formula ? All of the formulas I've seen use horsepower
>to determine injector size.  I am looking at a supercharged application and
>am a little puzzled about the torque output.  If maximum VE occurs at the
>torque peak, won't the highest fuel requirement be at peak torque?  I realize
>fuel consumption will be highest over time at higher rpm, but I'm interested
>in maximum pulsewidth.  For example, I have a 3.8 liter engine with 270cc
>injectors that has around 240 hp and 230 ft/lbs of torque.  I am looking at
>another 3.8 liter engine that is supercharged with 350 ft/lbs of torque and
>less horsepower ! (how do they do that ?)  Obviously it takes more fuel to
>make an additional 120 ft/lbs of torque.  Does the higher BSFC (0.55 lbs vs
>0.45lbs) in the formula enough for this difference?  Am I missing something?
>
the .55 bsfc does it. Try looking at the HP AT the torque peak to figure
out the pw (and duty cycle) you will need at the torque peak. HP is work
per unit time, and injector flow rate is a part of the determination of
fuel flow per unit time. They are consistent units. Torque has no time
factor in it.

Greg


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