Required Fuel setting.

[107merc]

Hate to ask such a basic question but "search" didn't turn up anything.
"Required Fuel" setting. After I fill out the calculator, what is the unit of measure the answer given is in?? cc/min??
For example, mine is 10.3. Thanks.

[nathaninwa]

It's the theoretical pulse width in milliseconds that it takes to fuel the engine at 100%ve and 100kpa or 0 inches vacuum

[107merc]

Thanks, whats the box below it designated ms for then

[kjones6039]

Thanks, whats the box below it designated ms for then

The amount of fuel to be injected, in milliseconds, as nathan pointed out above......

Ken

[john.p.clegg]

Just take it as the amount of fuel required by the engine (RF) ....if you have two injectors firing the fuel in , the number in ms would be half the RF..

John

[107merc]

Sorry to be so slow, I understand that the ms box is the injector pulsewidth in milliseconds (in my case 5.15) required to supply the fuel for a single injection event. I assumed that the number in the larger box ( in my case 10.3)
was the actual amount of fuel required. If true, in what unit of measurement is the 10.3, being displayed?? lbs/hr, cc/min, or am I completely off. Or does it even matter. Thanks for responding, I am definitely on a learning curve.

[nathaninwa]

It's still in milliseconds. The larger number is the fuel required, but you must be using 2 squirts per cycle so it's cut in half then. So you see 5.15 per event and the total is 10.3 milliseconds

Edit, change your tune to 1 squirt per cycle and both numbers will match

[ashford]

in what unit of measurement is the 10.3, being displayed?? lbs/hr, cc/min, or am I completely off. Or does it even matter. Thanks for responding, I am definitely on a learning curve.

the measurement is in time, not volume. the volume the injector outputs affects what time it should be spraying.

the top box it the ms required to achieve a stoich ratio at 100% ve at 100 kpa per each engine cycle.
the lower box is the ms required " " " " " " " " per each injection event. ie if the injectors squirt twice per engine cycle it will be half of the box above it.

[107merc]

Thank you. now it's clear. I appreciate everyone taking the time to respond. Is there a formula that will let me calculate the actual amount of fuel
being dispersed at 10.3ms@...psi? plus injector size? Again thanks.

[nathaninwa]

Wouldn't that be the reverse of the inputs? So since it's 100ve at 100kpa based on the XX lb injector you put in, it would the injector size your using?

[107merc]

This is what I was looking for "injected fuel quantity is determined by pressure, flow rate and pulsewidth in ms" but I can't find a formula to plug the numbers into.
Any info appreciated.

[LT401Vette]

This is what I was looking for "injected fuel quantity is determined by pressure, flow rate and pulsewidth in ms" but I can't find a formula to plug the numbers into.
Any info appreciated.

Just multiply the injectors flow rating by the ms relative to the rated time period.

If the injector rating is in lb/hr, there are 3600000ms in an hour. So:
fuel per squirt = (sprayTimeInMs / 3600000) * flow rating.

your fuel per squirt will be in lbs.

If the injector rating is in cc/min:
There are 60000 ms in a min, so:
fuel per squirt = (sprayTimeInMs / 60000 ) * flow rating.
your fuel per squirt will be in cc's.

if you want your output units to be different correct from there.

If your flow rating is altered by running at a different fuel pressure than the injector was rated at, you can calculate the new flow rating using this:

new flow rating = Square Root (new fuel pressure/rated fuel pressure) x rated flow

[107merc]

Thank You.