Injector size 19/24

[87_LX_5.0]

I want to update the current injectors on my car which is a stock 87 5.0 speed density engine. Looking around, Ford Racing has a better price on the 24lb injectors than I can find on the OE 19lb injectors. Will the 24lb injectors run as a plug n play or will I need to update other fuel components?

Thanks

 

[HISSIN50]

How will the EEC know you added ~25% more injector?

 

[jrichker]

Changing the injector size on a stock or near stock engine will not increase the HP.

With the Speed Density computer, larger injectors will require you to either get a custom tune and have it retuned every time you add/change a component that changes the airflow through the engine. Components that change the airflow includes things like intake manifolds, cylinder heads and camshafts.

You will need to convert to Mass Air and either a custom tune or a MAF calibrated to match the injectors. Once installed, Mass Air adapts to changes in engine airflow due to changes in add-on equipment with no or minimal extra tuning.

Injector HP ratings: divide flow rating by.5 and multiply the result by the number of injectors. This uses a 100% duty cycle. These ratings are for naturally aspirated engines.

Example:
19/.5 = 38, 38 x 8 = 304 HP
24/.5 = 48, 48 x 8 = 384 HP
30/.5 = 60, 60 x 8 = 480 HP

The preferred duty cycle is about 85% maximum, so for a safety factor multiply the final figure times .85.

304 HP x .85 = 258 HP
385 HP x .85 = 326 HP
480 HP x .85 = 408 HP

Remember that the above ratings are at 39 PSI. Increasing the pressure will effectively increase the flow rating. Example: a 19 lb injector will flow 24 lbs at 63 PSI, and a 24 lb injector will flow 30 lbs at 63 PSI.

If you change the injectors, you will also need to change the fuel pump to provide sufficent fuel flow to keep from starving the injectors.

Safe “Horsepower Capacity” @ 40 PSI with 12 Volts
88 Liter Pump = 140 LB/HR X .9 = 126 LB/HR, Safe for 250 naturally aspirated Horsepower (stock pump size)
110 Liter Pump = 175 LB/HR X .9 = 157 LB/HR, Safe for 315 naturally aspirated Horsepower
155 Liter Pump = 246 LB/HR X .9 = 221 LB/HR, Safe for 440 naturally aspirated Horsepower
190 Liter Pump = 302 LB/HR X .9 = 271 LB/HR, Safe for 540 naturally aspirated Horsepower
255 Liter Pump = 405 LB/HR X .9 = 364 LB/HR, Safe for 700 naturally aspirated Horsepower

 

[wythors]

The short, concise answer to your question is "no".

When you say "update the current injectors", what is your goal? Unless there is something wrong with one of them, there is no need to do any more of an "update" than perhaps cleaning them if they're very high mileage.

 

[Mustang5L5]

Stick with 19's.

Why are you changing yours out?

 

[SMOKEDYA]

I agree stay with the 19's.My old combo 302 made 301/328 at the wheels and was fine on 19's.peace






john

 

[87_LX_5.0]

I'm not really looking for a performance increase with the larger injectors, just curious since the 24lb injectors were cheaper than 19lb. Thanks for all the input!

 

[DonMaximo]

You could probably head-fake the EEC if you change out the MAF for one that is calibrated for 24# injectors...but you will not gain power.

While I'm not certain, you could potentially introduce performance problems as your EEC does not have the flow characteristics (TPS v.s. Air Flow) for the combination you would install. While the EEC will adjust fuel trims to meet the optimal AFR, it could be quircky between (IIRC) the 9 values which the stock EEC was configured with at the factory.

And let's say you have DIY tuning software... the bottom line is that an injector change on a relatively stock motor, will not change your motors' (aka air-pump) ability to move more air.

A good/curious question... but I'd suggest you not go there.

Regards,

-D