Why did my lipo swell like a balloon?
 

I thought my gearing was safe, but maybe I was wrong. Here's the setup.

RC8T CE, 1800kv 1y motor, MMM, Turnigy 5S 25C 5000MAH lipo. Geared 18/46. 5.5" imex tires.

Top speed should be ~50mph with no tire ballooning, but I had ballooning.

Battery swelled up in ~8 mins. Esc went into protect mode. Of all days, I forgot my temp gun. Battery was hot as hell, motor was at the high end, esc on the low range of hot.

Geared to high and the Lipo needs/should be 40C+ for best performance and to be able to supply the amps needed.
Thicker CD fluid100k will help to prevent tire balloning

Your prob geared realistically for 55mph+

Differential Ratio: 4.3
Transmission Ratio: 1
Other Ratio: 1
Spur Tooth Count: 44
Pinion Tooth Count: 18
Total Voltage: 18.50
Motor KV: 1800
Tire Diameter (inches): 5.5
Tire Ballooning (inches): .25
Motor Current Draw: 0
Motor Coil Resistance: 0
Spur/Pinion Ratio: 2.44 : 1
Total Ratio: 10.51111 : 1
Tire Circumference (inches): 18.85 inches (478.78 mm)
Rollout: 1.79:1
Total Motor Speed: 33300 RPM
Vehicle Speed: 56.55 mph (90.84 km/h)
Effective KV Value: 1800
KT constant: 0.75 oz-in/A
Motor Torque: Amperage not specified...
Final Torque: Amperage not specified...
Final Power: Amperage not specified...

That sucks if I'm geared to high. On 4s this gearing would get me around 40mph which I thought was ideal for most racers.

So if I want to bash at 50-60mph, what setup would I need?

40c batteries? I'm assuming those are the turnigy nano techs'

Also, my CD is thick as heck right now. Pops wheelies at almost any speed.

Here's a picture of the setup on 4s.

http://i182.photobucket.com/albums/x...s/IMG_5941.jpg

The easiest way to go fast is drop in a 6s pack

Use BrianG's speed calc and play around with different voltage and gearing, the link is in his sig.

I've used the speedcalc, that's how I know I was doing 50mph.

Would a 25-30c 6s be enough for a safe 60mph? Should I put my 2200kv motor back in? I thought the 1800kv would be a safer choice.

Those tires are heavy and that puts a HUGE draw on everything. Also are you driving through grass, thats another huge load. Why the need for such high speeds? Realisticly, try putting the stock 54t spur back on and try it.

The 1800 will be more forgiving and have more power, the 2200 wil be easier to gear up for high speed runs but the 1800 can be geared up as well and prob run a little cooler.
Again, with the price of 40C batterys getting so cheap I see no reason not to spend another 10-15.00 for a better battery. You spent a lot a bread already, why penny pinch now ? My 2cents

I like going 50mph, its 10mph of more fun.

Bondo, you are referring to the Turnigy nano-techs right?

Brand isnt vital so long as the C rating can be trusted ( ergo, dont buy cheap ebay no-name lipos or maxamps crap )- The Turnigy Nanotech packs are fine, but you really need to use batts with a higher C rating in larger models; lots of overhead is better than 'just enough' in terms of what the battery can output vs what the motor can draw if you load it heavily enough.

The nanos have a good rep for sure though, look at the 35/70c or 45/90c packs..

Exactly as Neil said, no brand in particular just get some 40+C and you'll be much better off.

Turnigy also makes lipo's that are 40/80C and not nano-techs... Just an FYI :-)

Thanks. I'll pick up a 40C 6s.

Make sure you pay attention to the RPM's on the calc as well, important you dont merge past 40K to keep temps in check. The 1518 is better suited for that 6s pack and will make all the speed you'll want. Also, you can try a smaller spur gear ?