Lehner Hi-Amp vs LK

[nate]

Interested in the Pros and Cons on the Hi amp and the Fan cooled LK version on the Lehner line up. I have searched a few forums and discussions on this topic, but cant seem to find a good answer to this question. Would the LK be better for sport runs, or SAW setups? Whats the difference in amp draw between the two? I assume the LK with water cooled jacket would run much lower temps? Worth the extra price you pay? Also, I have seen some of the 19 series motors have a max 85,000RPM limit. Are these motors @50k rpms reliable for saw passes?

[nata2run]

Hi Nate, you're right it has been discussed a few times on forums. But it's not Hi-amp vs LK, because both models I believe has been designed with Hi-Amp. I'm assuming the "raw copper" leads coming out the back, weather 3 or 6 indicates the Hi-Amp capability. the non Hi-Amp version I believe has little solder strips or small terminals on the back. The fan supported will run cooler for any longer runs or sport runs. The non fan version has been used in many saw applications. I'm a big fan of the LK model and stick with those. The extra cash is worth it. Amp draw on the same non LK and LK will be very close if not identical. 85k rpm? You best not to try :-) 50k and slight over is ok, but you should build up experience to run equipment on that level, but motors are quite capable.

[RaceMechaniX]

Nate,

All the fan cooled motors are the Hi-Amp version. As Nata2run mentioned the Hi-Amp versions have the tinned stator wires coming directly out the back instead of being soldered to a PCB board at the end of the motor. I would only recommend the Hi-amp versions for boats and preferably the fanned version. Boats have high sustained currents and as such more cooling is always better.

The RPM will depend on the size motor you run. In general the smaller diameter and short length motors can run higher speeds. Larger motors and motors with long shafts (xx80's) should be run at lower speeds.
Although the guidelines suggest the 19 series motors are good to 85k RPM, this is not practical even for SAW's. Specifically a 1950 is very stable below 50k RPM and cautiously stable between 50k and 60k RPM. I would not run it higher than 60k.

I have a lot of experience with the 1950 in SAW boats and have not seen any problems when properly done. A big part of this is the driveline connected to the motor. i.e. the coupler and shaft need to be dead nuts concentric and preferably balanced. If you use a cheap coupler that has suspect concentricity it will quickly ruin the motor as will a poorly assembled cable or bent wire drive.

TG

[nate]

Thank you guys for the tips and help, as I do more and more research through the forums, it becomes very apparent that alot of the high RPM SAW setups become unreliable due to poor rigging in the driveline, even at 40k rpm and below with the wrong prop and adjustments. Lets be real for a moment, The setup that I want to use in the rigger I just purchased is a bit much for such a low quality hull (China Ebay) hull. No one has explained this to me, but the more I look at high rpm applications, it seems that the driveline is cut down as short as possible to keep down length in the drive shaft, lower vibration and flex in the drive line I suppose?

Im not trying to break a record, I dont have the experience or knowledge to do so yet, But, I think I can get a good reliable setup going to get me in the high 70's with ease. I wasnt going to attempt 80k rpm anyhow, and I don't believe thats even possible, but a lehner motor should do just fine along the line of 46-49k rpm level using a smaller prop and right pitch. Guess now the more important part, is learing how to setup the drive line properly. Any Ideas?

I have already pulled the trigger on a Lehner 1950/6 (Non-Fan cooled) 2090kv, and a swordfish 220amp Pro HV ESC, I plan to run this in the rigger on 6s, now doing the calculations, thats around 46,3xx rpm, but whats really being put out at the prop depending, I don't know, maybe 38,000. Is there going to be issues with that rpm level? I will be using a different motor mount, trust bearing, Octura coupler, flex shaft ect. Thanks guys.

[RaceMechaniX]

You should be OK with that set-up. Take your time and make sure the driveline is lined up very close and it is as free as possible.

TG