what size injectors
- Thread starter 306man
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65ShelbyClone
Founding Member
My 302 is similar and when it was in my '89GT I ran it on 19s and raised the fuel pressure. It runs a lot harder with the better intake that's on it now, though(not EFI anymore, but it really liked the extra air regardless).
I would have to say the same stay with the 19's. I have GT40p's poted polished all bolt ons portd polished cobra intake. The car dyno'd 301/338 at the wheels with c&l 76 MM and stock 19's. The guy before me putt 24's and matching tube and it has a hiddious rich/fuel smell. peace
john
john
Stock fuel pump will run out before injectors IMO. Both are good for around 300fwhp.
i'd upgrade the fuel pump regardless. stock is like 50 lph, and i'd get at least a 190, a 190 will support pretty much anything, if you get real radical get a 255. on these cars you cant get to big of a pump, if your pump flows a load of fuel that the engine doesnt need it just returns it to the tank, if you have a 255 it just returns ALOT of fuel. no problems.
factory 19lbers go a long way, too many times do i see a pretty much stock mustang, maybe a CAI or headers you know. that has 24s or even bigger on them, NOT NEEDED!
personally if a person is going to make enough power to require larger injectors i would invest in a tune or tweecer or similar along with it. that way you can go into the EEC and tell it what injectors you have and set the flow to run perfect with the application.
i am not of a fan of the "calibrated" sensors and such. the modified sensors and sample tubes. once you upgrade past stock injectors the "calibrated" stuff will send out modified voltages (pro-m etc) or take less of sample of air ( C&L tubes) and the EEC will read this as less air, in turn it will dump in less fuel, BUT it will be the correct amount of fuel you need or pretty close. for ex. say you have an injector flowing exactly 2x the rate of the factory, the sensor would send HALF of the return signal back to the EEC, so the EEC only shoots out half the fuel, but since your injectors flow twice as much, your getting the same fuel as if you were running factory injectors with the MAF sending the full return signal.
sending out these modified signals back to the EEC isnt ideal. the EEC also uses the MAF signal to determine your load% when you run the engine, the MAF sending less signal back to the EEC is telling it "hey less air is coming in" so the EEC thinks its not running at as much of a load as it actually is. so for example you may be running only 70% load when your actually 100%, since the EEC thinks your at 70% it will utilize the spark advance/retard tables and such for a 70% rather than the 100% that you are ACTUALLY at. so you could have power left out on the table.
the aftermarket "calibrated" stuff is made to fool the factory computer, without any computer tuning of any sort, the EEC thinks its running 19lb injectors.
the IDEAL way to do it is get a tune or tweecer etc and go in and tell the EEC what injectors your running, so it knows, and you can mess with fuel tables for idle only, so you can get an awesome idle with HUGE injectors, and get the car to start alot easier.
people running LARGE injectors with no tune, a good amount of them seem to have a hard time starting the car and a horrid idle. rich and loading up, no good at all. with a tune you could make a bone stock mustang idle like factory and run good with huge ass injectors ( pointless but you could do it)
i'm no expert but this is what i have gathered on the MAF related stuff
factory 19lbers go a long way, too many times do i see a pretty much stock mustang, maybe a CAI or headers you know. that has 24s or even bigger on them, NOT NEEDED!
personally if a person is going to make enough power to require larger injectors i would invest in a tune or tweecer or similar along with it. that way you can go into the EEC and tell it what injectors you have and set the flow to run perfect with the application.
i am not of a fan of the "calibrated" sensors and such. the modified sensors and sample tubes. once you upgrade past stock injectors the "calibrated" stuff will send out modified voltages (pro-m etc) or take less of sample of air ( C&L tubes) and the EEC will read this as less air, in turn it will dump in less fuel, BUT it will be the correct amount of fuel you need or pretty close. for ex. say you have an injector flowing exactly 2x the rate of the factory, the sensor would send HALF of the return signal back to the EEC, so the EEC only shoots out half the fuel, but since your injectors flow twice as much, your getting the same fuel as if you were running factory injectors with the MAF sending the full return signal.
sending out these modified signals back to the EEC isnt ideal. the EEC also uses the MAF signal to determine your load% when you run the engine, the MAF sending less signal back to the EEC is telling it "hey less air is coming in" so the EEC thinks its not running at as much of a load as it actually is. so for example you may be running only 70% load when your actually 100%, since the EEC thinks your at 70% it will utilize the spark advance/retard tables and such for a 70% rather than the 100% that you are ACTUALLY at. so you could have power left out on the table.
the aftermarket "calibrated" stuff is made to fool the factory computer, without any computer tuning of any sort, the EEC thinks its running 19lb injectors.
the IDEAL way to do it is get a tune or tweecer etc and go in and tell the EEC what injectors your running, so it knows, and you can mess with fuel tables for idle only, so you can get an awesome idle with HUGE injectors, and get the car to start alot easier.
people running LARGE injectors with no tune, a good amount of them seem to have a hard time starting the car and a horrid idle. rich and loading up, no good at all. with a tune you could make a bone stock mustang idle like factory and run good with huge ass injectors ( pointless but you could do it)
i'm no expert but this is what i have gathered on the MAF related stuff
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