do i need injectors

[teej281]

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[cliffyk]

Originally Posted by Black_GT_02

Cliff, is there anything I can do with 95% fuel duty cycle to prevent me from replacing my fuel injectors to 60lbs? I'm a college student and ....welll... don't have too much money haha. I'm getting the internals really cheap and the main reason is so I dont have to constantly worry about throwing a rod? Obviously now fuel rails won't work but is there anything else you can think of? My fuel pump will hold 550rwhp but i see now that my injectors (42) will not.

Boosting the fuel pressure via the tune (the Returnless Fuel Rail Pressure Drop scalar) is the only real option¹, unless you go to a return style system and use an vacuum/boost controlled AFPR.

Unfortunately the EEC-V tune for the 2V engine does not support the PIDs for either direct monitoring of injector duty cycle, or injector pulse width (mode $22 PIDs 1141 and 1142) so that it might be calculated. This means there is no convenient way to really know what the duty cycle is. You can measure the pulse width and rpm with an oscilloscope and do the math, but that's a real PITA.

Monitor the crap out of the AFR (it will go lean very fast once the injectors go static and airflow continues to increase)--the best bet would be to dial-down the boost until you can get the 60 lb/h injectors.

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¹ - If this path is chosen you will also need to change the high and low injector slope scalars to represent the new injector capacity (at the higher pressure). For example, 42 lb/h injectors (rated at 43.5 psi) operated at 75 psi become 55 lb/h injectors--the formula is"

sqrt(new psi/43.5) * old lb/h = sqrt(75/43.5) * 42 = 55 lb/h

I have never played with bumping the returnless f/p in the tune, however it should work within a reasonable pressure range--I have no idea what that range might be however.

[Black_GT_02]

Originally Posted by cliffyk

Boosting the fuel pressure via the tune (the Returnless Fuel Rail Pressure Drop scalar) is the only real option¹, unless you go to a return style system and use an vacuum/boost controlled AFPR.

Unfortunately the EEC-V tune for the 2V engine does not support the PIDs for either direct monitoring of injector duty cycle, or injector pulse width (mode $22 PIDs 1141 and 1142) so that it might be calculated. This means there is no convenient way to really know what the duty cycle is. You can measure the pulse width and rpm with an oscilloscope and do the math, but that's a real PITA.

Monitor the crap out of the AFR (it will go lean very fast once the injectors go static and airflow continues to increase)--the best bet would be to dial-down the boost until you can get the 60 lb/h injectors.

-----------------------------------------------
¹ - If this path is chosen you will also need to change the high and low injector slope scalars to represent the new injector capacity (at the higher pressure). For example, 42 lb/h injectors (rated at 43.5 psi) operated at 75 psi become 55 lb/h injectors--the formula is"

sqrt(new psi/43.5) * old lb/h = sqrt(75/43.5) * 42 = 55 lb/h

I have never played with bumping the returnless f/p in the tune, however it should work within a reasonable pressure range--I have no idea what that range might be however.

thank you. much appreciated.

[teej281]

What about me?!

[cliffyk]

Originally Posted by teej281

So ive been reading one of two things around...ford switched to 21lb injectors at the end of 2002 and that they just switched for 2002 in general. So just a question, do you think that my engine more than likely has 21lbs or 19lbs injectors??? Cus i fear that i keep hearing some pinging and i think that it is detonation. I mean with a slipping clutch, i put down 250rwhp and 263rwtq...and i heard if youre running lean your torque will be down. The a/f wasnt working at the time because it just read 15 the whole way through. But Im kinda worried now because I get valve noise when i go wot sometimes. So do you think that upping to 24's would give me enough room to be good for some longtubes or something??? And cliffy, is that chart for rear wheel horsepower or flywheel?

Ford switched to the pink (21 lb/h, they call it lavender) injectors because the orange (19 lb/h) injectors turned out to be slightly undersized for the PI engine. If you have pink injectors they are the 21 lb/h units.

As for AFR, you need to find a dyno shop that has a working wide band O2 sensor, or better yet buy your own. I am surprised that operator did not stop the run, I've never been to a dyno shop that would do a pull without monitoring AFR. You can't tune a modern engine, optimally, without a WB system.

In the last, the HP numbers in the chart represent the total HP production capacity for a given injector size, I.e. they are total engine output, "flywheel/crank" ratings. Also, they are based upon the assumptions of 0.5 BSFC (Brake Specific Fuel Consumption) for n/a; and 0.6 BSFC for f/i.

Both of these are "rule of thumb" assumptions that could vary by as much as +/- 0.05 for any real world application.

If you want to really get into this, John Heywood's Internal Combustion Engine Fundamentals, published in 1988, contains all you will ever need to know about engines. I studied under Professor Heywood in the early 70's, a staggeringly intelligent man who has forgotten more about engines than I will ever know...

[teej281]

i just checked out that book the other day for a paper im writing on internal combustion engines. lol So that book will help me with a lot??? And can anyone suggest any books that is specifically on mustang engines??? I was looking at sean hyland's books and was wondering if they would be accurate enough to write papers from???

[Mustang_NTriangle]

Originally Posted by sainthk

Sxynerd,
So let say you buy 60lb injectors, you only use what you need and not the whole 60lbs? and i'm guessing thats why you need a re-tune so the comp knows what to support?

if you go with 60s for injectors but are only running 290-low 300 rwhp it is going to be a bitch to tune. I won't go that big unless you are looking for more than 400 rwhp...