Have some LMT questions...
 

hi everyone, me again... :no: :lol:

i have a few questions about LMT motors for anyone who would like to chime in :whistle:

1) what would be the recommended motor to run on 30C 6s, (i know the 1940/7 is quite popular, but would it take the voltage/current?)
2) what is the main difference between the normal and the Hi-amp versions
3) anyone seen the new 'cooling' system, does it look like it would work, looks kinda like the fans the titans had...
4) pros and cons against Neus and Plettys?

heres a link to the website: http://www.lehner-motoren.com/index.php?la=en, you can see the cooling fans if you scroll down.

thanks in advance
jordan

I find with the Lehners, geared properly, they are very happy running around 40K rpm. Pick a kv that will get you around there on the voltage you want to run.

The Hi-Amp versions have 3 wires coming out the back of the motor instead of the 3.5mm sockets that the standard motors have on the back. If you you have a choice get the Hi-Amp IMO. Much more robust setup.

The plus side of a standard (non Hi-Amp) Lehenr is that the can be switched back and forth between Delta and Wye configuration by changing some solder paths on the back of the motor to run 2 different KVs. Kinda cool, but I still think the Hi-Amp is a more robust design. I actually solder wires into the 3.5mm sockets on the back of the standard motor so I can get rid of the 3.5mm sockets and run 5mm connectors on the ends of the short wires. 3.5mm connectors have no place in a high power set up.

I would pass on the new cooling versions. Its designed for airplanes and helis. It would probably just suck a bunch of dirt into the motor in truck use. Besides... If you run a reasonable rpm and gear it properly they run plenty cool.

hmm... good point on those cooling fans sucking all sorts of whatever into the motor jhautz. Also, what would be a good operating current to enter for the motor, i'm planning on running 30C lipos btw

Has anyone back to back tested a Neu and a Lehner before, any opinions on each of these?

I have both and I think that both are excellent. you wont be disapointed with either one. If you are in the US go with the Neu just for service reasons in case you ever need it. Not to mention they are much easier to get here as well. Price is similar, but I think Neu is a few bucks cheaper too.

Only reason I would recomend the Lehner is if you want a slightly smaller diameter motor (lehner is 36mm and Neu is 40mm) or if you want to run it with a controller that doesnt like 4+ pole motors.

Well im in Australia so i don't think location makes a huge difference

If the LMT motors are 36mm that means that they can be used with the RCM heatsink right? Is anyone using a LMT with a RCM heatsink? If so, what length sink do you use? (eg. XL, L etc.)

lastly, i entered:

22.2 volts, 60 amperes and 40,000 rpm, into the motor chooser and got a 1950/7

22.2 volts, 60 amperes and 50,000 rpm, into the motor chooser and got a 1940/7

22.2 volts, 60 amperes and 60,000 rpm, into the motor chooser and got a 1930/8

i'm not too sure what seems to be the best option :neutral: Do the rpm's make a big difference in performance, both acceleration and speed, and also efficiancy

thanks
jordan

You can use the rc monster heatsink with lehners. The guy at racing with the 1940 7t hi-amp, uses an L size rcm heatsink. The motor sticks out I think about 5 or 6mm past the heastsink end of the heatsink. He doesn't use the clamp part on the end, because it would hit the motor wires, plus I don't think it's needed for lehners.

Not really sure what car you want the motor for, and what sort of performance your after, but his 1940 7t on 4s (33k rpm max) has plenty of power for the track in a gorillamaxx and now his Kyosho ST-RR, so you don't need huge amounts of rpm to make good power.

Can't remember if you've said before, but what side of Australia are you on?

Patrick: I'm from Perth as well :party:

so would the 1940/7 be able to handle 6s pretty easily?

The 19 series are highend motors and I'm running my 1930/5 motor with 4s lipos with no problems at all( at such voltage you've exceeded the recommended rpm range by leaps and pounds). It's only warm or mid hot( you can hold it in your hand with no problems).
The only thing that is suffering of this crazy setup is the Mamba Max esc, but with a few tweaks here and there, you can make it happy.

Definitely I'm in love with the LMT, but I've no clue where to get them......hydro&marines do not charge credit cards, ductedfans.com is very lazy to help and FDM is no longer stocking them( just pictorially). Mike has already cut his relationship with them as far as I know( or is it the other way round?).

I want a 1940/5 for my MRX-4X conversion, the Neu is too big to fit in( I'll get a Neu for the MBX-5R, instead).

I don't see the need for a HS on a LMT. It runs cool enough, esp if you are going for a 6s setup.

don't know what you are running this in, but its 1/8 then I would figure ~1800W, lots of power but not too much over the top. Prolly get away with less for racing only. That means around 85A or so (likely under 100A) This mean you prolly do want the Hiamp as 3.5mm plugs are really only recc'd up to about 50-60A.

I run the 1940/7 on 5s and it is very happy. This is in a big Savage as well. I think that motor on 6s would be a bit much. If I had the choice from the list you made below I would go for the 1950/7 on the 6s in a monster truk or truggy. It sounds like you will be running this in a truck of some sort. The slightly bigger 1950 will be happier in the heavier vehicle. For a buggy the 1940 would be a perfect choice but on 6s I would go for something more like a 1940/9. You really dont need to push these motors that hard to get them to make power. Another thing to keep in mind is that the Lehners give loaded kv values while almost all other manufactureres are giving unloaded kv values. so I tend to add +15 or 20% to the kv that Lehner lists when comparing the kv to other brand motors. And I also use the kv rating from http://www.lehner-motoren.com/ms19.php?la=en rather than from the speed calulator. I know there used to be some discrepancy in the kv on the calculator, I'm not sure if thats fixed or not.

Like Patrick says, you can use the rcm heatsink, but you cant put the bar across the back so it doesnt act as a clamp, and in reality it doesnt neeed the heatsink. The lehners run cool enough without it.

sorry, i never mentioned i will be running it in my UE-Gmaxx (build thread in the Gmaxx section). I'm not going to be racing it, so i'm definately wanting it to be a bit overpowered :yipi:

Looks like the 1950/7 is the go as my truck is full Alu/Carbon. So, am i right in saying that in a larger vehicle, the 1950 will run cooler and not be pushed to the limit, but be a tiny bit slower than the 1940 would be on 6s?

i really appreciate all the help, thanks guys
jordan

Yes it should run cooler than the 1940. No it shouldnt be slower. With the bigger motor you can pull taller gearing to make up for the lower RPM.

ok, so i've been crunching numbers in the calculator. I've been using 51/20 as a benchmark gearing (have no idea what pinions to consider with this one):

Enter Front/Rear Differential Gear Ratio (?): UE 1/8 scale
Enter Transmission Gear Ratio: E-maxx 2nd gear
Enter Spur Gear tooth count (?): 51
Enter Pinion Gear tooth count: 20
Enter total battery voltage: 22.2v
Enter kv rating of brushless motor 1867 (Lehner 1950/7)
Enter tire diameter in inches: 5.8

Total Motor Speed (?):41447.4 RPM
Theoretical Vehicle Speed (?): 49.23 mph (79.09 km/h)

not too shabby!! but then i tried with 51/25 gearing:

Enter Front/Rear Differential Gear Ratio (?): UE 1/8 scale
Enter Transmission Gear Ratio: E-maxx 2nd gear
Enter Spur Gear tooth count (?): 51
Enter Pinion Gear tooth count: 25
Enter total battery voltage: 22.2v
Enter kv rating of brushless motor 1867 (Lehner 1950/7)
Enter tire diameter in inches: 5.8

Total Motor Speed (?):41447.4 RPM
Theoretical Vehicle Speed (?): 61.54 mph (98.86 km/h)

thats more like it :lol: with tyre ballooning it pushes the 'theoretical' speed way over 60

Is it weird that the motor rpm did not change with the change of the gearing? Would it be alright to run that gearing, no warnings came up on the calculator, but would it be harmful to the motor or ESC? (probably going to run a MMM). I'm guessing some cooling issues might be experienced, and maybe a total lack of bottom end :whistle:

thanks alot
jordan

As far I know hydro&marine accepts Paypal :intello:

VWT4: how do you compare the performance of the Bigmaxx to the LMT 1950? Have you run either on 6s?