IFR Dropping at WOT

[cavy.417]

So I'm trying to figure out why my IFR is dropping at WOT and cant figure out why. Does anyone know? I'm running a 416 now but I looked at old logs from my cam only ls2 and the same thing happened with that setup. This one has ls9 injectors with correct data. Old setup was stock injectors with factory injector data. So by The Log I'm actually not getting all 54lbs out of my injectors. Is the IFR data in the scanner actually accurate?

[Eaglegoat]

It's the correct injector info. I don't know why you think they are 54lb injectors though. They are 52.5lb injectors, look at the 0kpa info.

That's why the IFR drops, there is less vacuum applied to the injector at WOT.

To be honest, if you don't know this you should stop tuning anything and learn sa little more about what's going on. This is basic stuff. I don't want to see you hurt your motor.

[cavy.417]

Ok I see I mis typed it but obviously they are 52lb. But still. I've been tuning for quite a while. I'm not an expert but I'm pretty sure my tune is fairly decent considering it's a SD tuned and did it myself. The data I got from someone on here. But from what I've always understood is that injectors flow a certain amount based on fuel pressure. And I'm pretty sure I'm not going to hurt my motor.

[Eaglegoat]

Ok I see I mis typed it but obviously they are 52lb. But still. I've been tuning for quite a while. I'm not an expert but I'm pretty sure my tune is fairly decent considering it's a SD tuned and did it myself. The data I got from someone on here. But from what I've always understood is that injectors flow a certain amount based on fuel pressure. And I'm pretty sure I'm not going to hurt my motor.

Injectors flow a certain amount based on pressure differently. 58psi rail pressure + 10psi manifold vacuum=68psi pressure differential across the injector.

[schpenxel]

Injector flow rate in the real world is dependent on the injectors themselves, fuel pressure and manifold pressure/vacuum.

At high vacuum levels (i.e. idle) effective injector flow rate is increased. The vacuum is literally sucking fuel out of the injectors. 5psi vacuum + 58psi fuel pressure = 63psi effective fuel pressure. I.e. injectors flow more.

When you get closer to 0 vacuum, that no longer happens and effective flow rate decreases. This is a larger problem on forced induction applications.. once you get into boost, manifold pressure pushes against fuel pressure.. so if you're running 10psi of boost and 58psi of fuel pressure, you effectively are only running 48 psi of fuel pressure. This, of course, reduces how much fuel the injectors can flow.

In your case.. I'm seeing yours go down to 50 lb/hr or so, which is slightly lower than shown in your flow rate table. I would guess there's a table somewhere (that we may not have access to) that is changing effective flow rate based on the conditions. On some OS's I've seen multipliers for injector temp for example, but do not see that in your tune. They reduce the injector flow rate as injector temp increases.

My point being.. I don't see a problem.