Is 4S+3S in serie possible?

[Over_revO]

It will be for a revo, but my speed target is not important, i just want to know if the Neu 1521 1900kv will produce more power on the same volt as the neu 1515 1.5d ?

Its not speed related, i can give you all the detail but it will still not answer my question, i dont want to sound like i dont care tough lol its for a revo for now.

We are still working on stability and tires setup, but so far we got 81.9mph on a run i lost control... it showed 84 mph on the radar and 81.9mph on GPS, then i lost control in side of the road and it did cartwheels lol Lonnnnnnng cartwheel!! :D

We already found a better setup, i just want to let my friend order the right stuff, it will be used for other vehicle, its more for informative purpose right now, im trying to see what would be the advantage of running a Neu 1521 on the same setup he have right now.

He also want a 12S esc...

:)

[suicideneil]

Target speed is incredibly important, since it takes a specific amount of power to move any given truck to that speed- if you dont have a goal/ target speed, how can you know which motor/kv/voltage/lipo combo would be required in order to produce the required power? Your only hope would be to hazard a guess and use a setup that was clearly overkill, but then you may find it costs too much or goes up in smoke (or the trucks driveline does)...

Anyway, look at the Neu website: http://www.neumotors.com/Site/1500_series_.html

You will see that the 1515 1.5d is rated at 22v (6s lipo) and 1250 watts continuous, 2500 watts peak.

The 1521 1.5d is rated for 31v, 1750 watts cont. and 3500 watts peak.

Assumming they used the maximum voltage to generate those wattage ratings, then with a little bit of my amazing mathes skills I get the larger motor producing about 1100watts on 6s and about 2300watts peak.

Then again my mathes is shite when it comes to the more tricky theoretical stuff like this, so dont take that as gospel.

What I will say though is that the 2700kv neu being ran on 6s is enough to kill the MMM if you arent careful- a noob ran his 2200kv castle motor on 6s and geared for 75mph in his Savage flux, and toasted the esc. Granted your revo will be lighter and only used for straightline stuff, but the motor is a real amp hog; I would personally chose the larger lower kv motor option and run that on 6s, until he/you get a HV esc, then current draw wont be half as bad with a nice low kv motor.

Will be needing vids of your speed runs though, its the law...

[Over_revO]

Heres the video,
http://www.youtube.com/watch?v=-i0ludmC4fA

We installed a heat sink on the neu and now it dont overheat for the few sped runs we do, we let it cool down after a couple of runs.

As far as speed , we want the fastest possible without over heating, if it have low kv i will regear. 90-100mph is what we are looking for in some truck we plan to use.

But my primary question was to know if the 1521 would perform as well or more with the MMM on the same setup, we will regear if it dont spin fast enought, i know how to use the speed calculator and the kv rating.

Thx for the help :)

[suicideneil]

Jesus, thats fast enough to make you a dude in my books!

Anyways, there is a guy by the handle of jzemaxx who put a neu 1521 1.5d in his 1:8 scale XTM MMT, though he used a custom ordered 1524 1700kv motor for his record attempt and made it to 80.4mph, though he was running a somewhat higher voltage @ 10s (several threads, this and this one are a good read).. I think the smaller neu you are using will produce more power on the same voltage compared to the larger neu (based on my fuzzy logic/mathes), but if you were to step up to a higher voltage MGM, use the larger and lower kv neu, it would easily produce much more power to get you to that ~100mph goal. My only concerns then would be tyres exploding, tranny and diffs exploding, and general aero dynamics- very long upside down skids as seen in that video.

However, you can belt the tyres or use MT foams, beef up the diffs with rc-monster hybrids or LST2 modified diffs to fit the erevo bulks, and a drag-bar or very big wheelie bar should help keep the nose down, along with maybe a front wing.

[jzemaxx]

Originally Posted by suicideneil

Jesus, thats fast enough to make you a dude in my books!

Anyways, there is a guy by the handle of jzemaxx who put a neu 1521 1.5d in his 1:8 scale XTM MMT, though he used a custom ordered 1524 1700kv motor for his record attempt and made it to 80.4mph, though he was running a somewhat higher voltage @ 10s (several threads, this and this one are a good read).. I think the smaller neu you are using will produce more power on the same voltage compared to the larger neu (based on my fuzzy logic/mathes), but if you were to step up to a higher voltage MGM, use the larger and lower kv neu, it would easily produce much more power to get you to that ~100mph goal. My only concerns then would be tyres exploding, tranny and diffs exploding, and general aero dynamics- very long upside down skids as seen in that video.

However, you can belt the tyres or use MT foams, beef up the diffs with rc-monster hybrids or LST2 modified diffs to fit the erevo bulks, and a drag-bar or very big wheelie bar should help keep the nose down, along with maybe a front wing.

Yup that was me......80.4mph on camera. Did end up going 85mph on the GPS off camera several weeks later, but got tired of replacing tires so I quit. The XTM dwarfs a E-revo which is much lighter so speeds should be easier to attain with it. I would think with my old setup on a E-revo it would have gone close to 90mph. I was running 12S. . I had another setup that was ready for testing that would have pushed the XTM over 90 with a 1527 and 20S. 20lbs with 12S, means with 20S that truck would have been close to 25lbs Tires would never have held....... Now I'm racing and the XTM is parked and hasn't been off of shelf for quite sometime.