Power in the light

Attending the NHRA Drag Races tomorrow and I plan on taking a 300mm F2.8 and 17-55mm f2.8. What I was wonder is would it be effective I had a flash head set to full power either directly beside the starting line or ahead alittle on the fence line to light the cars at night? They would be fired wireless.

Tough to say without seeing the distance you have to work with, the light already there, & knowing the power settings of your flash. I'd expect that full power would be too much if you want to show the background, too.
One thing that might help is to know that power drops off less as the distance increases.
Fill light at sunset

If I was to place a strobe directly across from the starting line it is possible 15'. I will be shotting with 300mm (which I've never used before), but I figure I will have be around 50 to 100 yrds off the line to get a full frame of both cars aim at them or across the track.