How much motor can the Sphere handle without a heatsink for 3-4 minutes (on carpet)? I know it can handle a 10.5, and doesn't even get noticeably warm. So how low can I go? 8.5? 6.5?

3.5 4 minutes oval

Depends on witch Sphere.

Sphere-- 5.5
Sphere competition-- 3.5

If you don't plan to run the heatsink on a Sphere (#80500) or Sphere Competition (#80700) my rough advise is to go 2 turns higher then our recommended motorlimit (which is with a heatsink). Obviously this depends a lot on the car, number of cells, etc but 2 turns higher should be safe.

So, as following (with/without heatsink):
- Sphere #80500: >5.5t / >7.5t
- SphereCompetition #80700: >3.5t / >5.5t

On Sphere Competition TC-Spec (#80750) you can obviously not run without a heatsink because it's an integral part of the design...

Thanks for the help guys. I'm really surprised to hear that some of you go as low as 3.5 with the Sphere Competition. That is a true testament to the design of the Sphere. I've always been impressed with it's temperature (or lack thereof).

And, thanks Burito for the official recommendation.

James, have you run any li-po 21.5 at Bandit yet?

Nope, not yet. The meeting is coming up real shortly, and it's looking like we will probably stick with the usual classes at least for the first points series anyways. (Might be a bit premature for lipo classes.)

why not run them together with 13.5/4 cell? I know for fact, Baker, Dan Ball, and I aren't going to buy any 4 cell packs again..... so we'd be out.

That's definitely a possibility. Let's continue this conversation here (http://www.hobbytalk.com/bbs1/showthread.php?t=198892), since it's not related to this thread.