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Discussion Starter · #1 ·
For all y'all going with MegaSquirt or some other standalone fuel management system here is a pulsewidth calculator to help you get your base map set.

Injector Pulsewidth Calculator
 

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the calc is definately a base line. it says im suposed to have a req_ruel of almost 16 with my injectors, but its actually arround 8.5. it also says ill only make 120hp too.
 

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Discussion Starter · #3 ·
Well the closer you get your numbers to actual when you are imputting you'll get closer numbers coming out. Once again your BSFC was off so your end results were off. I fed in what I know about your car and this is what came out.


Max PW @80% duty @ Rev limit: (ms): 15.36
Max HP @ 80% duty: 162.46
Pulsewidth: 1.78
REQ_FUEL: 12.98

That assuming there is only one squirt for every 4 strokes. We probably have more like 2 squirts per 4 strokes so it would have said, REQ_FUEL: 6.49
 

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ya.. you have to set it to "speed dencity", 2 squirts, alternating. if yo uput it on 1 squirt itll run on 2 cyl. you can put it on simultaneous and itll fire all 4 injectors on every "event" my req fuel depends on the quality of petroleum distilates.
 

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Discussion Starter · #6 ·
Compression ratio would change the BSFC value so it is figured in but wou would need to have another calculator to determine how much that would change your BSFC. I admit it's not the most perfect tool but it would get someone closer to the values they need to get running than by guessing or by trial and error.
 

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script language="Javascript"

function calc_pw() {
var cfm, maxrpm, cid, cycles, fuelms, hpconst, squirtsec, maxpw, inj, cyls, bsfc, squirts, fuel, lbm, pwm, map, ve, pw, rpm, correction, slope;

rpm = document.form.rpm.value * 1;
maxrpm = document.form.maxrpm.value * 1;
ve = document.form.ve.value / 100;
slope = document.form.injopen.value * 1;
map = document.form.map.value / 100;
bsfc = document.form.bsfc.value * 1;
squirts = document.form.squirts.value * 1;
cid = document.form.cid.value * 1;
inj = document.form.inj.value * 1;
cyls = document.form.cyls.value * 1;
hpconst = 1.58;
cycles = document.form.cycles.value / 2;
cfm = (cid * rpm / (1728 * cycles)) * ve;
fuel = inj * cyls;
lbm = cfm / hpconst * bsfc;
fuelms = (fuel / 60000);
pwm = ((lbm / (rpm * squirts / cycles)) / fuelms);
correction = pwm * map;
pw = slope + correction;
squirtsec = (maxrpm / 60 / cycles * squirts);
maxpw = (1000 / squirtsec) * .8;
document.form.pw.value = pw;
document.form.reqfuel.value = (((pw - slope) / map) / ve);
document.form.maxhp.value = inj * cyls / bsfc * .8;
document.form.maxinj.value = cid * maxrpm / (1728 * cycles) / hpconst / cyls * bsfc * 1.2;
document.form.maxinjhp.value = document.form.maxinj.value * cyls / bsfc * .8;
document.form.maxpw.value = maxpw;
}

/script
 

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siragan said:
script language="Javascript"

function calc_pw() {
var cfm, maxrpm, cid, cycles, fuelms, hpconst, squirtsec, maxpw, inj, cyls, bsfc, squirts, fuel, lbm, pwm, map, ve, pw, rpm, correction, slope;

rpm = document.form.rpm.value * 1;
maxrpm = document.form.maxrpm.value * 1;
ve = document.form.ve.value / 100;
slope = document.form.injopen.value * 1;
map = document.form.map.value / 100;
bsfc = document.form.bsfc.value * 1;
squirts = document.form.squirts.value * 1;
cid = document.form.cid.value * 1;
inj = document.form.inj.value * 1;
cyls = document.form.cyls.value * 1;
hpconst = 1.58;
cycles = document.form.cycles.value / 2;
cfm = (cid * rpm / (1728 * cycles)) * ve;
fuel = inj * cyls;
lbm = cfm / hpconst * bsfc;
fuelms = (fuel / 60000);
pwm = ((lbm / (rpm * squirts / cycles)) / fuelms);
correction = pwm * map;
pw = slope + correction;
squirtsec = (maxrpm / 60 / cycles * squirts);
maxpw = (1000 / squirtsec) * .8;
document.form.pw.value = pw;
document.form.reqfuel.value = (((pw - slope) / map) / ve);
document.form.maxhp.value = inj * cyls / bsfc * .8;
document.form.maxinj.value = cid * maxrpm / (1728 * cycles) / hpconst / cyls * bsfc * 1.2;
document.form.maxinjhp.value = document.form.maxinj.value * cyls / bsfc * .8;
document.form.maxpw.value = maxpw;
}

/script
yeah, I was just about to say that to. :p
 

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Discussion Starter · #9 ·
Sure, speak Java why don't ya. I'm sure most of the guys on here can read it. LOL :lol:
 

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Not Java! Urg, headache :p

It's because of Java that I quit college ;)

But, that's simple programmation, just some calculation. Nothing too complicated
 

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Discussion Starter · #11 ·
Anyone else going to comment on this? Sticky worthy?
 
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