I will be running 9.6:1 compression on my 341w, MAF, gt40p heads, flat top pistons, and all the bolt on performance parts. hopefully gt40 lightning intake manifolds if i can find them.

should i think about upgrading from my EV6 injectors or are they ok with these modifications.

 

19 lb per hour injectors are good for close to 300 hp at the crank. A full GT40 set up on a 302 will run perfectly fine with stock injectors. But the question is, do you have a 302 or a 351?


Also, is your truck a MAF system or are you speed density? If you're SD, then you can't run bigger injectors without dyno tuning or MAF conversion. Also, can't run bigger injectors without either running a bigger fuel pump or much much higher fuel pressure. A 19 lb per hr injector will flow 24 lbs per hr at 63 PSI where as your stock fuel pressure should only be 39-41. So you'd either have to get an adjustable fuel pressure regulator or go with a bigger pump.

 

I have a 351w. Don't know why I didn't put that in the first post. Also Is MAF. I have no problem upgrading the fuel system. What do I need to do?

 

Why.. just put headers on it.

 

I meant intake manifolds sorry. I will be using headers.

 

What year truck is it?
If it's the dual fuel pump set up I have no clue how to upgrade them. But if it's just the high pressure pump in the tank, step up to like a 190 LPH fuel pump, 24 lb per hour injectors, 24 lb per hr calibrated mass air meter, and you probably still want an adjustable fuel pressure regulator to sort of dial in your set up a little. And I would definitely go bigger with the fuel system just in case. On a 302 you're fine, but a 351 I think you'd be cutting it close.

Also, here's some information I'm taking from stangnet, it's a post by Jrichker so the information I'm about to give you is not mine.
Fuel injector sizing & injector photos

Revised 07-May-2011 to add flywheel statement & improve injector table

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 at the flywheel.

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.

19/.5 = 38, 38 x 8 = 304 HP x .85 = 258 HP
24/.5 = 48, 48 x 8 = 384 HP x .85 = 326 HP
30/.5 = 60, 60 x 8 = 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.

See Automotive Performance Software / Interactive Calculators to get the calculators used in these examples.

Here's the duty cycle explanation. Duty cycle is how much of the time the intake is open the injectors are turned on. The 85% figure means that for 85% of the time the intake valve is open, the injectors are spraying. The idea is that you want some percentage of the duty cycle left over so that you have some room to grow the process.

If you are at 100% and you need more fuel, all you can do is turn up the fuel pressure. That means the whole fuel curve from idle to WOT is affected. Maybe you are already too rich at idle, and turning up the fuel pressure makes it worse. If you had some injector duty cycle left to play with, a custom tune could use that where it is needed. That would not over richen the whole range from idle to WOT.

Don't forget to increase the fuel pump size with you increase injector size or significantly increase the fuel pressure



http://www.veryuseful.com/mustang/te...ctor_Guide.jpg

 

wow some great info! i will try to find some 24lb injectors and corresponding MAF. any idea what vehicle i could rob them from?

also i have dual gas tanks with one pump in each.. so ill just have to double up when i buy the fuel pumps

 

The MAF will need to be aftermarket since Ford does all their injector sizing in the computer. 24 lb per hr injectors from a 460 will work fine. I also have heard of people using a 460 computer and running 24 lb injectors and it working out. But I don't know for sure if this would work and I don't know if those set ups were speed density or MAF.