Too much intake throttle body airflow?
07-03-2007, 10:36 PM
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Too much intake throttle body airflow? I have often heard of sbc builders talking of "over carbing" a motor. Is this possible on a efi setup? I know that fueling is more defined but is it possible to have too much airflow from the intake or will it only cause a lack of low end vacuum? What other affects would having lets say a intake/tb setup that flows for say 1300cfm when your engine only requires 1050 cfm?
Thanks,
..RJ..
Thanks,
..RJ..
07-03-2007, 11:07 PM
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Fuel injection is alot more forgiving than carbs...did I just say that outloud lol(Im actually a carb fan deep down). The main thing on carbs is volumetric effeciency, size of engine and the operating rpm range. A 350 at 100% effeciency reving at 6000rpm is pulling 607cfm and a 406 reving at 6000rpm that has 100% effeciency is pulling 704cfm. So on a street engine situation I would run a 650 on the 350 and a 750 on the 406. The thing about fuel injection is its almost constantly adjusting itself in closed loop and like the 6.0 with the 90mm TB form the factory...its right at home.
07-03-2007, 11:20 PM
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so if i put a gmpp single plane on a 383 lsx with good heads big cam and a 1550cfm or a 1300cfm carb style tb would it be over kill or is it ok just because it is fuel injected?
07-03-2007, 11:27 PM
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Depending on how radical the 383 is. If you have a 13:1, solid roller cammed, LS7 headed 383 that you rev to 7500 then it would probably run pretty good with a 1300cfm TB.
07-04-2007, 04:43 PM
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so basically what you are saying is yes your intake tb can flow too much for a given setup. If i dont have a motor of that magnitude what happens when you put to much air to it if anything? Does it just run like crap and you never get it tuned or what? Can you elaborate on this please?
..RJ..
..RJ..
07-04-2007, 06:48 PM
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About the only negative I've ever encountered when using a tb thats "too big"(which is a theory I don't subscribe to)is some strange tip in/light throttle driveability. Even that can be tuned out most of the time. I say the bigger the better if your intake will accept it. These are just my thoughts and some will disagree.
