Is 24# enough?

[smackmybutter535i]

My next dilema is deciding which injectors I'm gonna use. I'm afraid if I get the 30#ers I'll run too rich under normal driving conditions. I;m only gonna run 6psi but if I decide to step up how much boost can I run on 24# injectors? I need some expert advice please. Also the 24's are a little more in my price range right now. But if they won't be worth the hassle I'll go higher.

[Velocewest]

If you're going to run closed loop, does it really matter if the injectors have a larger capacity? The ECU will control the duration based on what it reads from the O2 sensor. Open loop would be a different story.

[russc]

For only 6psi, 24's are enough, but thats it. You'll need an FMU.

RussC

[FSAEracer03]

At a reasonable duty cycle (80-90%), and at a decent BSFC estimation (0.50), 24#ers will only support ~225hp. I'm not sure what you're planning on running, but I'd recommend searching for a set of 32# Ford Motorsport injectors on eBay. Many times you can find killer deals (8 for $120 or so) with low miles on them. For reference, 6 32# injectors under the same conditions will support about 300bhp. The 24# injectors will max out at just under 300, and the 32's will hit their ceiling around 400.

If you need any help, let me know. I'm in your area.

-Kevin-

[smackmybutter535i]

Thanks kevin, I was hoping to acheive around 300whp. I think this is reasonable since my last turbo project was very inefficent and I was only running my 20# injectors I'm surprised to get the results I did. After better planning and research of this project 300 seems pretty well in my range.
Kevin by the way check your PM

[Duke]

At a reasonable duty cycle (80-90%),
-Kevin-

I have learned/been advised that a 75% duty cycle is much more appropriate for a FI application. You will never "run out" of injector then. It’s all about safety.

[FSAEracer03]

At a reasonable duty cycle (80-90%),
-Kevin-

I have learned/been advised that a 75% duty cycle is much more appropriate for a FI application. You will never "run out" of injector then. It’s all about safety.

Well I agree there. The balance of injector choice has to do with having the lowest maximum duty cycle in your application while keeping enough to have a clean idle and throttle tip-in. If the range isn't all that wide between no-load idle and WOT high-rpm use, then the maximum duty cycle can be low.

The lower the duty cycle you use, the cooler the injectors. 90% isn't a wild range, though, but, yes, 75% would be better.

EDIT.... if you're looking for 300hp to the tires, I'd advise using something in the 40# range. That will give you room for estimation error and room for upgrades in the future.

[Duke]

The balance of injector choice has to do with having the lowest maximum duty cycle in your application while keeping enough to have a clean idle and throttle tip-in. If the range isn't all that wide between no-load idle and WOT high-rpm use, then the maximum duty cycle can be low.

I also agree. I have 78 lb injectors and due to the idle issues you stated above, I have had to wire my TEC3 for full sequential injection. This allows the TEC3 to use a much shorter duration signal to the injectors and thus a good idle with big injectors.