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Old 03-23-2005, 12:24 AM   #1
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Default a few qs about fuel injectors

I like my 42.5ers and they work good and all but damn, these things must be extrememly ineficient at lower duty cycles. I drove 86 miles on the innerstate and only used an eighth of a tank of gas, but then about 30 miles of city driving uses a little over that. I only have it richened up by 1 percent more in my mid and lower rpm bands. Could this be because maybe the bsfc is actually higher at lower rpms and it takes less fuel to run them at upper rpms? IF they dont take as much fuel to operate at higher duty cycles then maybe thats why leaning the fuel curve out at higher rpms can help give you more power. what do u all think
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Old 03-23-2005, 10:31 AM   #2
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I think you leaned your top end out because your injectors are ginormous and it was running really rich, robbing some power.
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Old 03-23-2005, 03:25 PM   #3
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Default Re: a few qs about fuel injectors

Quote:
Originally Posted by jachin
what do u all think
I don't think you need 42.5# injectors.

Cheers,
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Old 03-23-2005, 03:59 PM   #4
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You should sell them, even with a n20 kit on your SSEi you shouldn't be needing those...

50lb/fr injectors are run on SERIOUS v8'*... There'* no way you need those. Make some money on some GP guy going for 12'*..
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Old 03-23-2005, 06:47 PM   #5
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Yea, if you continue using them adjust it to about 84-85%. And no, at a higher rpm you'll burn more fuel. More air = more fuel.

Maybe I'm misunderstanding your question but the reason you get lower gas mileage in the city is because of stop and go. It takes more power (fuel) to get a car moving than to keep it moving. Thats why whenever you see EPA MPG estimates they give you city/highway numbers.
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Old 03-23-2005, 06:59 PM   #6
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The 42.5 injectors can only flow so little fuel as well. It is probably a tuning issue or something else, but there is a point where 42.5'* just won't flow less and are just too big. They are not needed in that application however, I think I would go with something a little closer to stock. My dad has 42.5'* in his GTP and didn't even put those in until he was running 12.7'*. They aren't even close to being maxed out now, so I can't see them being necessary in a mild application like that. Just to give you an idea of the size you need, I have 22lb. injectors in my STE...

Shawn
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Old 03-23-2005, 07:18 PM   #7
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What about after a cam, rockers and head work? then maybe nitrous? I know i dont need them right now, i got them a while back for future upgrades. At the time, i thought the stock injectors were weaker than what they really were. Anyway, dbtk pretty much answered my question, i was just wondering why leaning them out wont help my fuel economy.
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