Is 24lb Injectors Good Enough Or Do I Need 30s?

[MikeH686]

Im about to get my 347 stroker back from mekeown motorsports and before i gave it to him the more had 24 lb injectors on it.

My setup includes:
Edelbrock performer heads
Holley upper and lower
Trickflow track max stage one cam
I had the maf calibrated for 24lb injectors but i would like to know will 24s be enough with the added cubic inches or will i need to go 30s. Right now im going naturally aspirated but i had the motor built for boost ... compression is 9:1

 

[Gearbanger 101]

It'll be close. You ideally want them running below 80% duty cycle and with the power you could potentially make, you might be a little above that.

If you're going to replace them and plan on adding forced induction, don't waste your time on 30's, or you'll just have to upgrade again. Go with a set of 42's from a second Gen Lightning and they should supply all the fuel you'll need.

 

[MikeH686]

So should i go 42s then or stay 24s for now until i add forced induction then go 42s

 

[Gearbanger 101]

You'll probably be OK with the 24lb/hr injectors for now. They'll handle about 320-325hp within their safest operational range. You should be pretty close to that with your set up. If not, you can always dial back the ignition timing levels a few degree's to soften your horsepower levels a little.

I'd get it on a dyno after the build to know for sure. If you start maxing out the injectors, your dyno operator will let you know. You can make the decison to upgrade them at that time if you want. All it's going to cost you is another hours dyno time.

 

[MikeH686]

Oh ok yeah my motor should be back in the car the middle of june so ill probably be asking tons of questions especially with connectors and all sjnce i gutted the car for paint

 

[jrichker]

Oh ok yeah my motor should be back in the car the middle of june so ill probably be asking tons of questions especially with connectors and all sjnce i gutted the car for paint

What year car do you have? I have wiring diagrams for several different years of EFI MUstangs that might be useful.

 

[MikeH686]

91 efi

 

[Markus]

I run 24lbs with my 331. The duty cycle is 80-85 % with 50 psi fuel pressure.
I´m change to 30 pounders. So i think the 24 lbs injectores are not sufficent for your application.

Markus

 

[MikeH686]

hmm so should i go thirties then or 42s? cus if i go 30's i will be fine til i turbo it then i will need 42's but if i get 42's now will i run into any issues?

 

[Gearbanger 101]

I run 24lbs with my 331. The duty cycle is 80-85 % with 50 psi fuel pressure.
I´m change to 30 pounders. So i think the 24 lbs injectores are not sufficent for your application.

Markus

Your engine is probably making a good 30hp more than his will with your AFR 185's vs. his Edelbrock Performers. That 30hp difference may be what's putting you over the edge and what may keep him in the safe zone?

I still think he'll be close, but passable if he pulls a little engine timing and takes a little steam out of the sales.

hmm so should i go thirties then or 42s? cus if i go 30's i will be fine til i turbo it then i will need 42's but if i get 42's now will i run into any issues?

Either injector (the 30's or the 42's) is going to require a tune or MAF calibraion in order to run properly, so go with the 42's. They'll idle and run just fine for the time being.....if they're needed.

Again, we can throw all the guesses out you'd like, but you won't know for certain until you get it on the dyno.

 

[MikeH686]

true im gonna get the engine dynoed as soon as i get it finished and everything, if i need more fuel i know ill then need to get new injectors as well as maf. Brands? is ford racing good brand or any other suggestions or does ford racing even sell injectors?

 

[Gearbanger 101]

There are tonnes of used ones floating around out there. As I said earlier, they came standard on all 2nd Gen Lightnings "99-'04. I don't know if Ford Racing still carries them, but there are still companies that sell them new. Their part number is M-9593-f302

 

[MikeH686]

True ill take a look at this more tomorriw but will i be good when i go to dyno it? Then ill know if i need more fuel after the engine dyno

 

[Hoytster]

If I were you, I'd upgrade to the 42's and get a proper tune to support them. I was maxing out 24's on my TFS headed stock bottom 302 with stock fuel pressure. With 30's I was in the 85-88% range. You're running decent heads with more cubes than I was so I would assume your setup is going to max the 24's out quicker than you think with stock fuel pressure.