I helped Ryan Maifield with the RC8e he ran at the J-Concepts Clash.
This is what he ran, Castle Combo with 2200 Kv motor geared 15/46.
He used 2- Reedy 35C 5000mah wired in series, 4S voltage.
In the main which was 12 minutes he used 3800 mah.
He said he drove a little conservative as we weren't 100% sure how long the car would run. Now keep in mind this is RM and I'm not sure he knows what conservative is.
Just figured I'd pass along what we've seen.