Since the dune buggy has been converted over to a 36 Volt battery pack and controller, if you switched from from a 24 Volt 500 Watt motor to a 36 Volt 1000 Watt motor, but do not change the gear ratio, then the dune buggy would have more torque and a slower top speed.
The reason for the lower top speed is that the 24V 500W motor runs at 3750 RPM on 36 Volts, and the 36V 1000W motor runs at 3000 RPM on 36 Volts.
A 24 Volt 500 Watt motor produces 1000 Watts of power when running on 36 Volts, so switching to a 36 Volt 1000 Watt motor would not provide any more power and would only result in a slower motor RPM which would increase torque for faster acceleration plus better hill climbing and lower the top speed.
If a 36 Volt 1000 Watt motor was installed and the battery pack was increased to 48 Volts then the dune buggy would have more torque and a faster top speed. A 36 Volt 3000 RPM motor running on 48 Volts would spin at 4000 RPM which is only 250 RPM more than the 24 Volt motor running on 36 Volts however with all that extra power the motor would have an easier time running at its highest speed so the dune buggy would go faster.
Dual 24 Volt 900 Watt Currie motors are an option. They would run at 2600 RPM at 24 Volts and 3900 RPM at 36 Volts. Currie motors have sprockets for #25 chain though and running 1800 Watt or more through #25 chain would wear it and the sprockets out fairly quickly.
1000 Watt motors are tough on #25 chains and sprockets though which is the reason that most 1000 Watt motors come with 8mm chain sprockets installed on them. A 1000 Watt motor will not break a #25 chain or sprocket, it will only wear them out faster than normal. #25 sprockets for 1000 Watt motors are readily available.
Switching the razor Dune Buggy over to 8mm chain may not be an easy task. The 1000 Watt motor would come with an 8mm chain sprocket on it so that not a problem, and 8mm chain is readily available, however plain bore axle sprockets for 8mm chain are virtually impossible to find and I do not know of a single supplier who carries them, and if one was available it would not have an 19.85mm bore to fit the axle.
A plate sprocket for 8mm chain could be bolted onto the existing axle sprocket. The Dune Buggy's original sprocket for #25 chain has 32 teeth, and we do not carry a 32 tooth sprocket for 8mm chain however we do make custom sprockets. We could custom make a 32 tooth sprocket for 8mm chain and one could be ordered on this page:
Hello. I would like to increase torque and top speed of my razor dune buggy. I currently have a 24 volt 500 watt motor with a 36 volt(1000 watt) controller battery pack and throttle. Its a nice ride but would like as much overall power as possible within about a 350$ budget. Would a 36 volt motor be better than a 24 volt? I have see others with a currie 24 volt 900 watt motor set up do very well. What is your view on that? What is the recommended controller to use in that case? Could I purchase the controller already set up for a razor dune buggy? Would a 36 volt 1000 watt motor produce more overall power? Im ok with running either 36 or 48 volt battery pack. Also I do not want to sacrifice any torque for increase in top speed. Thank you.