Injector sizing

[Tlsalt at aol.com]

Greg Hermann wrote:

>Pulsewidth is calculated from duty cycle TIMES maximum available cycle
time.

Hello Greg,

    Thanks for your response.  I've never focused on duty cycle, other than 
to ensure that the injectors are large enough to avoid going over 85% and 
that the pulsewidth at maximum rpm is within the time window.  I've never 
seen pulsewidth calculated from duty cycle.  What is this formula ?  The VE 
based maximum pulsewidth formula has always worked for me.

>in these numbers, BSFC is assumed to be CONSTANT from 1500 through 4500 rpm.)

I managed to find a BSFC chart for my engine and it relatively flat from 
1500-3500 pm (0.44-0.46) but it begins to rise at 3500 and peaks at 0.55 at 
5000 rpm (hp peak).  I assume you use the BSFC at the hp peak and 80-85% duty 
cycle to size the injectors.

Paul 
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