Join Date: Dec 2008
Location: California Central Coast
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There are many theoretical advantages of FI, but they may or may not be implemented in a particular vehicle.
1. Modifications for the mechanically challenged will be easier as fuel changes will be part of a plug and play black box instead of having to be done separately to a carburetor.
2. Compared to a carburetor, FI allows use of a more radical camshaft to get higher HP without a rough idle, fouled plugs, and loss of torque at low to mid RPM. Of course, the manufacturer may or may not spec a different cam to take advantage of changing to FI.
3. I don't know squat about motorcycle carburetors, but most car carbs use a fuel bowl and a float actuated valve to control the fuel level, which influences how lean or rich the carb runs. Bouncing over rough terrain bounces the float and results in less control over fuel metering. Climbing or descending steep hills affects the fuel level and can result in the engine quitting.
4. Carburetors have evolved different ways of dealing with the problem of opening the throttle too fast, but nothing works as well as FI in eliminating bogging. It's nice to simply floor it and not worry.
5. All carburetors require some restriction of airflow in order to generate a vacuum signal to pull fuel from the bowl, thru the jets and into the venturi. Carburetor sizing is critical, thus a carb for racing is very poor for street use.
FI is much more flexible. You can have a 600 HP Viper engine that has a smooth idle, doesn't foul plugs and even gets some sort of mileage. This could never be done with high air flow carburetors and lumpy cams. So with FI you should be able to expect a much better compromise between power, mileage, and drivability. Not to mention automatically compensating for altitude and temperature.
Of course, the manufacturer can elect to use low compression, mild timing, and mild cams together with FI. Such a FI setup might have a relatively small throttle body, limiting the benefits that could be obtained from greater displacement or more radical cams. We won't really know what the potential of the '09 FI is until someone like Todd starts testing. It may or may not be equal to what a modified carbureted '08 can achieve.
Last edited by TCSF; 02-06-2009 at 12:30 AM.