Teach me fuel injectors…

[Daryl]

Always been curious but never understood the when, why and how of the different “lb injectors” for a fuel system. How do you know if you need 24lb, 30lb, 42lb, or ??? I assume they’re scheduled for different levels of performance that your engine has and the tune?

Can someone give me a “Layman’s Version” or better yet, “Fuel injectors for Dummies” version so someone like me can understand (or at least get a Novice’s level of understanding)?

Thanks in advance!

 

[joemomma]

From my limited understanding, each injector is rated to support a certain HP with a desired duty cycle. For example, 19lb/hr injectors will support xxx HP at 80% duty cycle. Meaning, they'll support xxx power running at 80% of "full" capacity. You don't want your injectors maxed out for safety and longevity reasons. Once you hit a certain number (or duty cycle), you need to step up to the next size. I'm sure there's a chart somewhere.

 

[Daryl]

Ok, that’s a good start. Gives me a basis to start learning and understanding.

Anyone else???

 

[lwarrior1016]

That’s pretty much it. The engine uses a certain amount of fuel, as power goes up fuel demand goes up. If your injector can’t supply the engine with enough fuel, then you need a bigger one. The tuner would tell you when you needed bigger injectors as that is all seen in the calibration information.

 

[ttocs]

Unless someone corrects me you would be better off getting a tune for the specific injector size rather than trying to run a MAF that says it is calibrated to the injectors. So figure that into the price.

 

[lwarrior1016]

Unless someone corrects me you would be better off getting a tune for the specific injector size rather than trying to run a MAF that says it is calibrated to the injectors. So figure that into the price.

That’s right. The “calibrated” MAF is kind of a band aid fix for needing a tune. They just skew the load reading to reflect the injector flow rate. Daryl was already tuned, so I think he’s just looking for info now.

 

[95opal]

 

[Daryl]

Looks like I have some homework to do! Thanks everyone ++

 

[ttocs]

I can't remember how far into your motor you are but until you get into the heads/cam it isn't going to do anything but get ready for future upgrades. like I said you should get a tune for the new injectors and then if you did do more later you would need to tune it again. Wait till you need the injectors and pay for one tune and save some cash

 

[Daryl]

I can't remember how far into your motor you are but until you get into the heads/cam it isn't going to do anything but get ready for future upgrades. like I said you should get a tune for the new injectors and then if you did do more later you would need to tune it again. Wait till you need the injectors and pay for one tune and save some cash

Yes, the car was tuned after the rotating assembly, cam and heads were installed. “If” memory serves, I believe Accel 24lb injectors.

And yes, I’m strictly after an education here. The car is running great and strong, so I’m not going to change anything.

 

[ttocs]

unless you were to get into boost the 24s should be plenty.

 

[94IndyPace]

I had my HCI fox on the dyno and tuned with 30lb injectors I was at 80%. Put down 329/330 if I remember correctly. Really not fond of those charts.