Speed Calculations?

I punched in a few numbers for these.

HV-6.5
HV-4.5
9xl
8xl

All these numbers are on 14 cells and the stock tires. Going off gearing from other fourms.


4.5 72/12 50.8
6.5 72/12 43.4
9xl 66/18 32.1
8xl 66/18 36.1

Thats weird? The hv are faster. And y is the 6.5 and 4.5 so close?

[SpEEdyBL]

What kv values did you use for the HV motors? They have very different kvs. Anyhow, I am going to test the HV4.5 against either a 7xl or an 8xl to see which is better/faster in a 1/8 buggy.

[jnev]

You can gear up on the 9xl because it is a lower KV as well.

um 4800kv for the 4.5 and 4100kv for the 6.5. oops 3100 for the the 6.5 i messed up ill fix it.


4.5 72/12 50.8
6.5 72/12 32.8
9xl 66/18 32.1
8xl 66/18 36.1



So a 9xl on 16 cells would be faster then an 8xl on 14 cells? Y is the 4.5 faster? I know the XL have more torque.

[BrianG]

Total motor rpm is simply motor kv times voltage. If you do the math, you can easily see why.

[Finnster]

The gearing is a bit low on your XLs. For a 8XL, a 16.3:1 FDR is about perfect on my Revo. I can tell you from radar testing that an 8Xl in a MT will do ~41 mph properly geared w/ good cells. The 6.5 is quite a bit slower, but eh 4.5 may be a bit faster, but is tempermental to gearing and will fry otherwise. I would think a 9XL should be 38-40mph realistically.

What gearing for an e-maxx?

Same gearing
--------------
9xl geared to 39mph 66/20 with stock tires/// 44mph on 40 mashers

9xl geared to 42mph 66/22 with stock tires/// 48mph on 40 mashers

9xl geared to 43mph 64/22 with stock tires/// 50mph on 40 mashers

8xl geared to 47mph 66/22 (or was it 64?) But said overheating may result and it also said too much votage on 14 cells?


So will the 9xl get to hot? Theres some hot days in texas! Im tired of taking brakes every 5 mins.

Cause if it dosent get to hot it looks like Im going with the 9xl!

[wallot]

I use 18.15785 : 1

with 2000kv motor at 19.2V

with big joes 40mph
with race tires 36mph

works very well

actually thinking of 1700kv motor with about same setup as 40mph is just too crazy .... but so much fun when nitro guys see it

I think the 9xl has 1800kv? So bitire will give you speed but You lose torque? I watched the Losi 8ight that had a 9xl on 4s and it was crazy! It was just spinning the whole time! When Every I go with the brushless I going to be making some more videos. So new comers can watch the crazy power of brushless!

Will FLM diffs, Integy diff case, Integy diff collor, and traxxas bulks be enough to handle the power?