Injector post for nine5flareside (moved)

[nine5flareside]

Originally Posted by cleatus12r

Here's the deal with a gasser and larger injectors.....bear with me

The short answer is "no" and this is why.

A gasoline engine relies on a constant 12.5:1 (very rich) and 15.5:1 (very lean) with 14.7:1 being considered "stoichiometric" (perfect) air/fuel ratio to run. Air and fuel are both metered to always arrive at this number no matter the load, RPM, or temperature. Slightly richer mixtures are going to produce more power, run cooler, and occur under load. Leaner mixtures are going to be hotter, more prone to detonation, and occur under light loads (cruise).

One would think that putting larger injectors would get more fuel out and make more power. This is absolutely almost never the case because.........

The stock injectors will be able to deliver enough fuel to maintain the air/fuel ratio on an engine that has quite a few modifications without retuning the PCM to compensate. By compensate, I am referring to the fact that a "19 lb." injector will put out less fuel than a "24 lb." injector given the same fuel pressure, same injector on-time, and same firing frequency. To compensate for this, the PCM would have to be programmed to command the injectors on for far less time at idle and through the midrange. It is also very certain that with a near stock engine that the ENTIRE range of operation be "pulled-back" because there is simply too much fuel across the board.

You mentioned a MAF/injector combo. Ok. Well, that includes a MAF sensor that is calibrated to send a signal back to the PCM indicating that there is not as much load on the engine (not as much mass air flow through it) so the PCM automatically cuts back the injector on-time anyway. Can I ask what the point is? It's like giving a kid a Snickers bar and then getting mad that he starts eating it.

It's almost certainly something I wouldn't spend my money on.

I figured as much and that is why I quoted you when you said "injectors", larger high pressure oil pump, and tunes to run them. From my understanding the guy really didnt have mods that required bigger injectors I just didnt understand why you put "injectors", larger high pressure oil pump, and tunes to run them" as things for him to upgrade.

Being that you know so much about injectors, when is a good time to upgrade your injectors. When you upgrade what parts exactly should you be looking into more fuel delivery?