My Z-Car buggy is running a Neu(Tekno) 1512 2.5DF 2050 KV motor running on a Mamba Max Classic with a Common Sense RC BEC. Powered by 2 x 2S 5000 mah 35C hard cased ROAR style LiPo packs in series to make it 4S 5000 total. I'm still workig on the final gearing, I currently have it geared at 16 to 50 with 3.4545 (11:38) ring and pinion gears inthe front and rear diffs. With normal 4.3 inch tall buggy tires, it should theoretically top out around 36 mph. I use 14.8 volts and no tire ballooning, and the results have been quite close on a rader gun. I may gear it one tooth slower 15:50 to get 33.7 mph. I have been using an Eagle Tree data logger and it seems I am only hitting about 32 mph on the longest straight. There is a ridge in the middle of the straight, when I go over that, the tires unload and they are hitting about the predicted 36 mph. With the 36 mph gearing, I am hitting about 1700 watts for the peaks out of slow corners. That is 118 amps at 14.4 volts. On a good solid lap, I am pulling an average of 250 to 330 watts depending on grip. Driving more careful to avoid too much wheel spin actually produced the higher power rating as it was putting more power to the ground. Traction pulls current.
I agree the two hard cased packs weigh more than a 4S soft case, but I have 5 of them now and use them in all my 1/10 stuff also. I have 2 pairs I am treating as 4S packs now, and if I use them n the 1/0, I try to do the same number of cycles and balance charge them together.
I see a lot of people stuffing the "truggy" motors into buggies. I really don't see the point. I was very happy with the performance of my little Medusa 36x50, but I went with the larger Neu 1512 to lower the temps a bit and gain durability. A 1512 in a slightly higher KV on 4S would give you more power than you will ever need. The 2050 has a bit higher internal resistance than the 2650 so I like the softer torque hit. It makes it easier to drive, making so you are not spinning the tires so much. I like how it runs on 3S even, but if I geared it up to be competitive on the straight, I think the current may get a bit too high, the 2650 on 3S is probably a better setup for the higher current.
I won't name names, but I have now had 4 other 1/8 drivers take it for some laps, and owners of a Castor and a HotBodies Ve8 liked my power band and balance at least as good as their own cars. The extra bulk I am dragging around actually helps in many cases. Right now it is up to 8.5 pounds. I will be trimming down my aluminum battery tray and shaving a few ouces on other parts to try and get it to 8 pounds flat.