4.9 Fuel injector upgrade.

But you got rid of all those pretty ridges and lumps! :LOL:

Nice bowl work indeed.

As for the injector upgrade... that head is going to flow way better than stock for sure and with the intake work and the bigger T/B you may flow enough to where the bigger injectors will benefit you. If you add a cam at this point then the bigger injectors are the proverbial no brainer.

The stock injectors will support 164 HP @ a BSFC of 0.5 lbs/HP-Hr and 80% duty cycle. If you push the BSFC to .48 and the duty cycle to 90% the HP peak becomes 192. I'd guess that you will begin to see a benefit from the larger injectors somewhere around 180 HP. Remember that on a 300 19# injectors flow something like 23# because of the higher pressure drop so they're good for something in excess of 220 HP.

Have you found someone who can re-flash your PCM? The stock unit may have some drivability issues with the bigger injectors and is going to get "confused" somewhere around 170 HP.
 
ive heard of several people who can reflash the computer, but i am trying to go around that... I do have to smog my truck (California crap), so im shooting for things that are easy to remove (if needed) and real life gains.

On the injector swap - Now, as i hear it, the factory injectors on my truck are 12# injectors (rated by ford at 35-40psi?). Since the 6 runs at 55-60 psi, the injectors are running somewhere around 15 psi? Anyway, with an adjustable fuel pressure regulator, and some 19# injectors, i could tune it anywhere from factory, all the way up to the 19#s limit, no?

Ive also been reading around that the mid 90s taurus has 14-15# injectors, with the newer style spray pattern. The local guys (our fuel injection shop) told me about the 14-15s, and said they may do a little better in my app. Any thoughts?


Thanks for the good words on the head work. I think it turned out very nice. No problems yet, other than a couple IAC issues (but i havent really touched it...). I am also going to do the cam swap. Ive heard good things about it, and im looking forward to it. Several people on here have had the cam and passed smog if i remember correctly?

Thanks again guys, i love this site.
:D
 
Your injectors are rated for 14 lbs/hr. @ 39 PSI. At the pressure on a 300 (55-58 PSI) they flow more like 17#.

Most AFPRs adjust up to a max number of about 60 PSI or less so there's little or nothing to be gained by using one with the stock injectors. If you use one with the 19s and turn it down, it will solve the excess fuel flow issues but it may vapor lock the fuel rail. One of the reasons Ford went to the higher pressure rail on the300s was because exhaust heat was boiling the fuel in the rail
 
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