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Differences between the 3.1L and the 3100??


jamhoney

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on 3.1s? I wrapped my 90 UB3, but I don't know how accurate the speedo was, in retrospect. floored my 90 non-ub3 lumina for a solid minute from a dead stop and never felt the engine retard. do you not feel it?

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Oh please, like I'd try to get my 25 year old 277k 2.8 over 85mph. I have no clue. I just THOUGHT it was 107, That's what it seems to be on a lot of early 90s stuff

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3.1 and 3100 FPR are WAY different from what i remember. same pressure(assuming you're referring to a 93-99 3100), but the design itself and location is different.

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Why are we bumping this? :think:

 

Because people are using the search function and are simply adding on to threads instead of making a new "what's the difference between a 3.1mpfi and a 3100sfi?" lol

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  • 2 weeks later...
  • 1 year later...

Can I use early 3100 injectors in my 3.1? If so, what else would I need? I have 3 bad injectors and I've been dealing with 3.1 injector issues since high school. Want to get this car together...thanks!

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Iirc, the newer injectors yield 4% more fuel, which can be fixed if so desired by tuning it. Otherwise, it's nearly unnoticeable. I just want to know if any other parts need swapped...for example, the rail...

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they flow a bit more, they're rated for roughly 17.5 lb/hr. if the 3.1 injectors are the 16.7 that GM implies in the calibration, that's 4.8% difference.

 

ideally, keeping it under 5% would be good, but even 10% would be acceptable if everything else is how it should be. the stock calibration will allow the long-term trim to remove up to 18.5% of the calculated fuel mass, so even 10% would give you a good range to work with.

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