Runtime.....question using 4s?

[Rampokker]

I don't think you'll make 20 mins on that setup. I'm running the same setup with turnigy 4s 5000mah batts and get around 16 mins. I also don't think the extra 800mah from the 5800 batts are going to make enough of an improvement. You may have to look at a lower kv motor. Have a look at how much mah the batt takes after a 10 min race, and then you'll be able to work out how much more mah you need to get 20min.