Sorry if this is a stupid question, but I always assumed for some reason that people turn the bottle heater off before they spray. Is this correct? If so why?

 

It is that way on my system because that is how the switches work, one side is heater the other side is armed.

 

I would leave the heater off while spraying to keep the cars voltage up. The heater uses a lot of juice and will lower the voltage a bit. Higher voltage will give a little better spark. By killing the running lights on the dyno I have seen 1-2 gain in hp with no other changes.

 

It should be automatic in my opinion. Just leave it on, if for some reason when your ready to make your run and it is still bringing the temp up, and you want voltage up, just turn it off. I always watch temp in staging lanes and if needed I turn ign on so my runs will be more consistant, by way of same bottle press each run.
Robert

 

It really isnt going to make a noticable difference either way....

 

I aggree with catdrv65. For the short amount of time you are spraying the heater will make no difference, If you are worried about temp drop use a bottle blanket.
Dave