Can I Increase Injector Size?

96chevy7.4L · May 16, 2008

I have a 96 7.4L vortec. I have done the following mods. 80mm throttle body, granatelli mass air sensor, 3 inch dual exhaust with x-pipe, throttle body spacer, hypertech III program. MY question would be can I go to like 1 size bigger injector. I seen those 5.0L motorsport injectors and the philosphy is sound with the wider band spray into the intake. But instead of the 19lb/hr injector I was thinking 20 or 21. Along with a wal-bro hi pressure fuel pump. will this help performance? am I not that advanced yet to require bigger injectors? Any ideas positive or negative appreciated.

Thanks

Texsrt4 · May 17, 2008

larger injectors than what you are tuned for or need to accomidate your air flow mods will not net you more power, but infact might hurt your driveability and power. my recomendation is to keep what you have (why spend hundreds on injectors when not needed) and spend the money on more airflow mods or a tune. more power and better driveability...whats not to love!!!!!

L29er · May 18, 2008

just so you know, those five O injectors are rated at 19lbs per hour at 43.5 psi (3bar) our 454s run at 4 bar (58psi) so they actually flow around 22llbs hour. like i`ve said i`ve got them and they work fine, no probs.

sablowme · May 19, 2008

i was honestly always under the impression that the mass air flows are bad and to stay away from them, usually they don't work well with tuners cuz the tuners are already set up to change air/fuel ratio, so if you have 2 items in the truck doing that it usually fowl up one of them to not perform as well. I would delete the mass air then add the injectors, maybe then go with a better tuner like Diablo or a SCT or maybe even a custom ordered tune. You have alot of mods for that hypertech. Those are usually for the little bolt on like exhaust,cia, and stuff like that.

Texsrt4 · May 19, 2008

youre almost spot on. the mass air flow only monitors its name sake. is is simply a sensor that measures airflow. the tune then tells the engine how to compensate for the air coming in. if you dont have a means of measuring the air coming in, you better be a good tuner to dial it in properly. an SD (speed density meaning using your MAP sensor) tune is not as accurate or as easy to set up.

his MAF is calibrated differently, so its not that its causing problems, the computer is just misreading the signal (imagine a sensor that is lying to the computer, so that the computer thinks its seeing something its not). the bigger MAF's can be tuned around and usually flow better

a proper tune will keep what he has and optimize it. i dont see that you have enough mods to justify the injectors. a custom tune will allow everything to be optimized and allow allow for the proper working of your aftermarket MAF

96chevy7.4L · May 25, 2008

Hi I have installed the granatelli sensor and everything seems to work well. my hi flow catalytic converters will be here the first of next week. Do you think I still need a better tuner or could I stay with the hypertech. Keep in mind that I do alot of heavy hauling. I have a D50 model john deere excavator that weighs 10500lbs. I haul it regularly. Will I run into probs as I haven't yet. Last week had it on my truck and towed over 150 miles to a job. Towed excellent and got almost 10mpg. Any recommendations greatly appreciated.

svensk · May 25, 2008

http://performancetrucks.net/forums/showthread.php?t=418455

96chevy7.4L · June 7, 2008

Well you guys were right the MAF from grantelli caused and excessive lean condition. I pulled it out and went back to stock on MAF sensor. Truck runs good and it isn't so lean. To all thinking of upgrading a mass air leave it alone.