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MFI question

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  • MFI question

    So it seems that MFI is now legal in U6SA is that correct? Other that the possible reliability/maintenance issues what are the advantages or disadvantages?

  • #2
    From what I gather it's never not been legal, just had to use the stock throttle bodies, and I think The water pump had to remain untouched, I think they were going off the camshaft for the fuel pump drive....
    The biggest advantage in my eyes is the fact there's no wiring required for the injection and tuning is simple once you get your head around it all, the downside that I can see with it is a few things. The amount of plumbing required is crazy, it can get pretty expensive with all the fittings required, other thing is it's really easy to hydro lock the engine on start up, you need a really good ignition system or a voltage booster (16v) to fire the sucker up, I always hear the mfi cars in the pits next to me when I'm getting my belts and everything done up sitting there cranking for 30 seconds to a minute trying to get going, I have seen a few guys miss races because there battery has dropped below 12 volts from cranking so much to get going, realistically a good set of well tuned set of keihin flatslides will do close to the same job without all the extra plumbing etc, the one area the mfi cars have it over efi and carbs is the torque and throttle response it has down low in the rev range, if your running tight little stop start tracks then mfi is the way to go, but if your running on big wide tracks that run full throttle for the entire lap after lap then carbs are the way to go, flatslides do not have a butterfly restricting the throttle body, plus the short intake track is great for top end horses, not to mention its less weight, and very easy to tune, a simple plug check tells you if your on the money on the main jet, and car feel and drivability tell you where you need to be at on the needles, its foolproof
    Last edited by AussieQ73; 01-09-2015, 09:35 AM.
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    • #3
      yes I understood the throttle body issue and from what I understood nobody making mfi used the stock throttle body etc, in affect making them illegal. thanks for the reply


      • #4
        actually guhl has and had for a few years mfi with stock throttle bodies and he couldn't get anyone to run it