Injector size requirements

[randeez stable]

I have 52# injectors that came with my Procharger stage II kit on my 2011 GT.
Are they large enough to support 600 rwhp ?

 

[blownGTvert]

start with this http://fuelinjectorclinic.com/flow-calculator

 

[randeez stable]

start with this http://fuelinjectorclinic.com/flow-calculator

According to that chart. I got a 47# injector ( mine are 52#) at 90% duty cycle ( they recommended this) to achieve 600 rwhp at 54 # fuel pressure. ( from my gauge)

Can someone explain what duty cycle refers to here?

 

[dysan]

I believe duty cycle has to do with the amount of time the injector is open vs closed. You really don't want to be above 80-85% duty cycle.

 

[Greg Hazlett]

I believe duty cycle has to do with the amount of time the injector is open vs closed. You really don't want to be above 80-85% duty cycle.

This; you are playing with fire at 90%; for whatever reason people will spend XX amount of money on parts but never fuel and that is one of if not the most crucial part of the equation.

 

[beefcake]

This; you are playing with fire at 90%; for whatever reason people will spend XX amount of money on parts but never fuel and that is one of if not the most crucial part of the equation.

100% quoted for truth. Everyone wants to run on the ragged edge with injectors / bap's, etc..

Go with a good injector, we have the best deals on ID's, and even some great entry level fuel systems if you want to run e85

beef
513-478-1965

 

[s8v4o]

According to that chart. I got a 47# injector ( mine are 52#) at 90% duty cycle ( they recommended this) to achieve 600 rwhp at 54 # fuel pressure. ( from my gauge)

Can someone explain what duty cycle refers to here?

According to that same site with your information I get 56lb/hr injectors @ 90% duty cycle. IIRC fuel pressure in our vehicles is around 39 psi. At 85% duty cycle you'll want closer to 59lb/hr. So get some 60's.

 

[beefcake]

the 60's and 80's suck on these cars, you can tune them, but for the extra $ you spend tuning them, you could get a better injector and better drivability imo

 

[BruceH]

According to that same site with your information I get 56lb/hr injectors @ 90% duty cycle. IIRC fuel pressure in our vehicles is around 39 psi. At 85% duty cycle you'll want closer to 59lb/hr. So get some 60's.

The 5.0 is regulated to 54psi iirc. It's non adjustable. The 3v mostly runs at 39.15psi but it is adjustable in the tune so more psi can be commanded with different loads. IIRC the stock tune for a 3v commands as high as 72psi in the higher rpms.

 

[randeez stable]

Question. If I change the injectors to larger units, and do the long tube header install at the same time. Will it be safe to drive my car the 40 or so miles to get it retuned. I know I will have to keep it out of boost, but other than that, can I drive it ?

 

[05yellowgt]

Get a baseline tune from your tuner for the new injectors to drive to the dyno, or wait to change the injectors till you get there. If you run the bigger injectors with the tune for the smaller injectors you'll likely run into issues with running rich. The ECU will try to compensate, but it will fluctuate wildly since it thinks its injectors are smaller than they actually are.

 

[Greg Hazlett]

Get a baseline tune from your tuner for the new injectors to drive to the dyno, or wait to change the injectors till you get there. If you run the bigger injectors with the tune for the smaller injectors you'll likely run into issues with running rich. The ECU will try to compensate, but it will fluctuate wildly since it thinks its injectors are smaller than they actually are.

Good advice there!

 

[randeez stable]

Get a baseline tune from your tuner for the new injectors to drive to the dyno, or wait to change the injectors till you get there. If you run the bigger injectors with the tune for the smaller injectors you'll likely run into issues with running rich. The ECU will try to compensate, but it will fluctuate wildly since it thinks its injectors are smaller than they actually are.

That is what I thought. It common sense the larger injectors would run rich. And I wouldn't want to to damage my cats either.

Thanks for the advice !

 

[Weou09]

This; you are playing with fire at 90%; for whatever reason people will spend XX amount of money on parts but never fuel and that is one of if not the most crucial part of the equation.

Bosch 1000s and 2 465s and 1 255 pumps for me hehe let it drink I say!

 

[randeez stable]

I have been watching videos on 5.0 fast fords, and looked on the Brenspeed site. They made 600 rwhp with a Vortech kit , longtubes, catted X pipe and 52 pound injectors just like I have. They also added a BAP which Im planning. ( 5.0 Coyote)
I also went on the Kennedy dyno tune site and they said that 50 pound injectors were good to 600 rwhp.
I am getting some what confused as Im being told on here that 52 pound injectors will not be good enough for 600 rwhp on a Coyote.
Guess the next move is to call Donny Walsh, my tuner, and ask him.

 

[RocketcarX]

I have been watching videos on 5.0 fast fords, and looked on the Brenspeed site. They made 600 rwhp with a Vortech kit , longtubes, catted X pipe and 52 pound injectors just like I have. They also added a BAP which Im planning. ( 5.0 Coyote)
I also went on the Kennedy dyno tune site and they said that 50 pound injectors were good to 600 rwhp.
I am getting some what confused as Im being told on here that 52 pound injectors will not be good enough for 600 rwhp on a Coyote.
Guess the next move is to call Donny Walsh, my tuner, and ask him.

You could just keep asking the same question until you get the answer you want.

 

[randeez stable]

You could just keep asking the same question until you get the answer you want.

The correct accurate answer would be nicer.

 

[RocketcarX]

The correct accurate answer would be nicer.

You were given the answer. Is it possible? Yes. Is it either safe and or smart? No.

 

[skwerl]

The other thing to consider is how much time you expect to be putting out the full 100% output capability of your engine. If you have 52lb injectors and can squeeze 700hp out of them with a BAP and 100% duty cycle, what's it going to hurt if you only utilize all that capability once or twice per year? You're not going to be anywhere near 100% duty cycle driving around town 99.9% of the time.

 

[RocketcarX]

The other thing to consider is how much time you expect to be putting out the full 100% output capability of your engine. If you have 52lb injectors and can squeeze 700hp out of them with a BAP and 100% duty cycle, what's it going to hurt if you only utilize all that capability once or twice per year? You're not going to be anywhere near 100% duty cycle driving around town 99.9% of the time.

This is good logic until the one time it's not, and you have lean out of an injector hang. Why not just go to the limit of what a good tune and a factory bottom end can handle if you have to change the injectors anyway? Why let your injectors limit max power? Trade the injectors in the kit, or sell them, pay the difference for a good set of used injectors suitable for the power. Then, you can go past the 600 WHP mark into the safe zone of the correct, larger injectors.