Depends on setup and gearing. Like any electric. The taller the gearing, the shorter the run time. I am thinking of using a 15t pinion.

See I have an advantage. I already have the brushless motors and ESC's and batteries. All I need are the correct pinions and make a motor mount on my CNC Mill. I will most likely make my own chassis. I do now want all the extra holes left over from the nitro chassis and want to save the original chassis incase later I want to go back to nitro.

On average expect anywhere from 10 - 20 minute run times. Even though they are very dangerous because cars draw more amps from batteries than planes. LiPos will give you longer run times.