Staged Injection vs. 2 squirts per revolution

[WeezilUSA]

This may be kindof a stupid question, but I ordered some new injectors and it got me to thinking yesterday... Wasted Spark isn't a big deal cause when the spark is getting wasted, it does not really affect anything except for the coil firing an extra time... But I've got my fuel injectors setup (MSnSe 1 v2.29 etc etc) with just one bank to fire, so theoretically, they are all squirting simultaneously 2 times per revolution. Does fuel stay atomized long enough just sitting in the runners that are not on their intake stroke? I think MS1 can only do 2 banks max, but would the ideal be to have one squirt per injector right before that intake valve opened? Or am I thinking about this all backwards. I imagine at higher rpm it would be less of an issue, but I'm still interested to hear your thoughts.

[Sander]

The stock ECU also fires all the injectors at once. Should be fine I guess

[JohnMc]

If you think about the amount of time the fuel actually sits arond waiting patiently for the valve to open, you'll realize it doesn't really matter that much. It's not like a spark that has to happen at a precise time.

The most difference would be at idle. And there's not much of a difference, at least at the level of tuning most of us are doing with our cars.

Now for the OEM's, trying to hit those ultra squeeky clean emissions levels, it matters.

[WeezilUSA]

Ok cool. Out of curiosity, do some of the fancier setups stage the injector firing? I'm not trying to be over the top I guess this was just a bit more theoretical of a question in nature. Thanks for the input guys.

[Poik]

There are benefits to injecting both IVO and IVC. If you squirt twice then the fuel will hit the intake valve, which helps cool the valve, but also heats up the fuel which makes it atomize better.

[qwkswede]

You are talking about sequential electronic fuel injection. Lots of OEM systems do it, ever see the SEFI badge on the back of lots of GM products? Some of the fancier aftermarket EFI systems can do it too. VEMS can do it. The pros and cons are mentioned above. Its pretty subtle from what I have seen.

[qwkswede]

And yeah, you can time the injector opening at any desired time before the valve opens or after.

[Karl Buchka]

On something like a largely stock 8v redblock you're hardly going to find a quantifiable difference in power output by going from batch fire to sequential injection. What I really don't like about batch fire is since all the injectors are opening at the same time, you can get large pressure drops/oscillations in the fuel rail at higher RPM or with bigger injectors.

[the poi]

with 67lb injectors on my wagon, even with a fuel pulse damper and alternating fire, the knocking sound was annoying as hell all of the time