Which is quicker?

[Gfwilliams]

Hi,

I have currently got a 7x1 brushed motor in my Tamiya Dark Impact...

How much quicker(if at all) will a castle creations 5700Kv brushless motor be?

In other words, is it worth upgrading?

Thanks a lot

[GSMnow]

Your 7 turn brush motor may have a peak of torque higher than the 5700, but the 5700 brushless motor makes great torque at any rpm from stopped to about 40,000 rpm depending on your battery. Top rpm miht be a bit less on 6 cell NiMh maybe a bit more on a solid 2S LiPo. If you geared both motors for the same top speed, the brushless might not have the hammer hit from a dead stop, but it will keep pulling hard as the speed climbs where the brush motor is falling off. And the greater efficiency of the brushless 5700 will make for much longer run times at a similar level of performance. Geared within reason, the 5700 will still be able to pull a wheelie or even back flip the car at over 30 mph. The cost of a Sidewinder 5700 package is probably cheaper than if you had to buy any decent ESC and a brush motor, but the brushless has basically no wear. I have been running my 5700 Mamba Max for a full year and all I had to do is oil the bearings once in a while. A hot brush motor like your 7 turn is going to need brushes every few runs and the comm will need to be trued in fairly short order as well. And of course after a few comm cuts the armature is garbage. As long as you don't overheat a brushless motor to an insane point it will last virtually forever. My motor has topped 200F a few times with no loss of performance, but that is pushing it. After running my Mamba Max 5700 system, I can't bring myself to ever run a brushed system again.

[Gfwilliams]

wow!!

thanks a lot that helps a lot!!

only thing is, would it be better to get a 7700Kv motor (for top speed)?

Thanks for the advice

[maddog2099]

I don't think you can run 3s lipo on the 7700. If that's the case I'd stay with a 5700 if it were me.

[Gfwilliams]

yes, but I don't think that I could fit a 3s lipo in the car (but I am not really sure)

That is worth considering thought

[chilledoutuk]

The problem with the 7700 is you need a extremely good battery to handle the current demands or performance will suffer.

I recomend that if you want to go the high kv root you look into getting the speedpassion granturismo gt with either a novak or lrp brushless motor with a sintered rotor as i suspect they should be more efficient than the castle and speedpassion motors.

[GSMnow]

How fast do you really want to go? And where are you going to attempt it? My Mamba Max 5700 can push my XXX-T faster than I need to go under any normal circumstances. Geared for anyhitng less than 45 mph, it has anout power to back flip it at almost any speed on a good 2S LiPo. If you can only run 6 Cells NiMh or a 2S then the 6900 or 7700 could put out a little more power due to lower internal resistance allowing more current. But that is only if you have cells that can pump out that insane current. You really do need to figure out what motor rpm range you can actually use. In most cases, 40-45 mph is scary fast. If you truly have a hug area to run and want to run over 45 mph, than you should go to a 3S LiPo setup[ on either a 4600 or 5700 motor. The 5700 on 3S is more rpm than the 7700 on 2S and even the lowly 4600 on 3S is the same rpm as the 6900 on 2S. Either of these setups can easilly be geared to push a 4 pound car/truck over 60 mph while pulling less current than a 2S 7700 setup trying to hit 50 mph. It all comes down to power. 2S at 100 amps is 740 watts, almost 1 hp. But at 3S 1000 watts is only 90 amps.

If you are concerned about fit, check out Max Amps. They have a 3S 5000HV LiPo pack that is the same size as a 6 Cell NiMh pack.
http://www.maxamps.com/Lipo-5000-111-Pack.htm
And it is lighter. Not exactly a cheap pack, but that is serious power.

[Gfwilliams]

Thanks for all your help, it does help a lot!

I have decided to buy a 5700 motor then buy the 3s lipo at a later stage... when I have the money

I run the car in my back garden and in my road, which both have plenty of space so higher speeds are possible

George

[JEAM]

Thanks for all your help, it does help a lot!

I have decided to buy a 5700 motor then buy the 3s lipo at a later stage... when I have the money

I run the car in my back garden and in my road, which both have plenty of space so higher speeds are possible

George
Hi george,
Since a few weeks I,m running my E-Firestorm on a MM5700 + LRP3300 NiMH 6pack and its already great fun !

I,m (not yet, haha) a great driver so instead of buying a Maxamp 3S Lipo and go crazy I decided to buy the new Maxamp 4700 NiMH/7 cell pack.

Also I don,t think my charger is Ok for Lipo, so I do some more practice on NiMH and in the meantime save money for Lipo,s + charger haha.
Oh yeah, almost forgot,
I also followed the advice from "GSMNOW" to get DEAN-plugs for the batteries and ESC.

Jean

[Gfwilliams]

Jean,
Sounds pretty much what I am intending to do...

I have already got deans connectors (a LOT better than the tamiya ones)

I have currently got a fair few NiMH 6 cell packs so will stick with them untill funds and skill allows!!

George