http://www.onallcylinders.com/2012/07/11/injector-math-how-calculate-optimum-fuel-injector-size/

http://www.gtsparkplugs.com/InjectorSizeCalc.html

The online calculators work perfectly fine. For a little more detail you could google how injector calculations work, but the rule of thumb is that you want peak required fuel rate (driven by anticipated mass airflow and expected stoichiometry) of the injectors to correspond to an 80% injector duty cycle.

The way OEM's do it, however, for port injection anyway, is to ensure that you inject all the needed fuel at peak airflow while the intake valves are shut. This drives down brake specific fuel consumption by using the intake valve to drive a phase change of the fuel prior to introducing it into the cylinder.

But I digress, you probably just want to know how big to go; just use the calculators.

very well written iceguru1114 thanks for the help, i figure but looking at the calculators i need around 600 cc to 700cc injectors, i never knew there were injector calculators thanks for the help guys