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Old 10-31-2011, 03:49 PM   #77 (permalink)
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Carbs are the choice of a racer?
Are you talking about NASCAR?
Indy cars have been EFI forever, at least 50 years.
Ask any early WW2 Sptifire pilot about the ME 109 on his arse with the DB 601 fuel injected inverted V12 engine. His only chance was a hard turn, to the right, that did not cause his fuel to slosh over to the side of the float chamber and starve his engine. The 109 had weak wings.
Ask any pilot of a B29 about the engine problems with that plane that were solved when they went to fuel injection on the exact same engine after the war.
Ask any Mercedes driver after 1955, or a Chrysler 300 after 1957.
Craig, I would suggest you find someone with a Honda CBR250R to try a similar configuration to the 250 Ninja that you are working with the owner on modifying. Mine (Honda) has averaged right at 84 MPG with no modifications. I would bet with your aero expertise it would easily top 100 MPG in your contest. With taller gearing it might get much higher.
Nissan went to EFI in their Z cars in 1975. The primitive Bosch derived FI allowed them to pass Federal emissions without any catalyst or even a EGR. Compared to the carburetors of the same era performance was outstanding.
Today everyone should look as Mazdas SkyActive fuel injection. Direct (into the combustion chamber) FI which actually has 5 separate injection pulses directly into the combustion chamber DURING THE COMBUSTION PORTION of the power stroke. By modulation of the fuel delivery while combustion pressures are at their peak, they can spread the power peak out over a much longer portion of the power stroke. This allows them to run 14 to 1 compression ratios on regular fuel.
None of that would ever be possible with a venturi controlled suction vaporization carburetor. The best bike carbs today are the constant velocity variable venturri setups. Based on the old SU types dating back to the 1930s they are very good at efficient delivery of fuel but when you add freezing temperatures they have serious icing problems that require preheating of the intake air for resolution. Lets not even consider the gross emissions problems from incomplete atomization of the fuel.
Not meant to be combative or a slam by any means, but fuel injection si the future. Carbs are history.

regards
Mech
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