XRAY - Model racing cars

To get a particular FDR you can for example use a small spur or a large spur. I recall reading an article some years back on the pros and cons of smaller spurs vs larger spurs but it has not been retained in my memory banks.

Is one better than the other?

A larger Spur is always going to be slower but less strain on the drive ( less heat)

Do you know why that is? Also when you say slower do you mean acceleration or top speed or both?

More Spur (driven) teeth longer distance to travel but greater acceleration. Bicycle gearing always springs to mind when talking acceleration/top speed. If you try to start in the lowest gearing it's hard work so you use higher gearing to improve acceleration but rather than pedal like mad you change gears

Im running in the 17.5 blinky class.

Would 64dp be any better than 48dp when it comes to acceleration and speed?

Admittedly more teeth but as they are smaller there is less theoretical resistance (quieter) but the difference for most is negligible, but it does give a lot more options

Ive heard that you get better acceleration and pull out of a corner with 64dp over 48dp, is there any truth to this?

No truth other than the less resistance thing. it's all about effective diameters that is why there is conversions from 48 to 64dp, the overall diameters can be the same with an entirely different tooth count, I had all the conversions in an old phone for working out rollout on foams just look at the Xray gear charts they show FDR's for 48 and 64 working on the same effective diameters
Calculation is the same (Spur \ pinion)*internal(1.9)=FDR