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[JIM WORNER]

OK all you wizards out there, a hopefully simple question.
What should I buy as a direct replacement for a 540 size motor?
Hopefully an inrunner to use the same mounting plate.
I have already got 2 Mtronics 30 amp reversing speed controllers
so not too hot and not too expensive (OK Cheap )
I look forward to being educated!
Thanks  Jim W

[inertia]

Jim
I've recently made two identical models into which I would previously have fitted 540s, but the main purpose of building them was to go brushless. The motors I use are the Turnigy 2822/17 1100kv and the Leopard 2826/17 1050kv, both running on 3S LiPo packs. They are easily as powerful as any stock 540 and I find that low-speed and reverse control is surprisingly good. Neither runs anything more than lukewarm. The speed controllers are respectively the Fusion Hawk 18A and the Leopard (Hobbywing) 30A Marine V3. The Leopard motor and ESC are available from Component Shop.
Inrunners tend to be too fast for anything but out-and-out fast electrics. The two motors I use both fit a standard 380/400 GRP mount https://www.howesmodels.co.uk/product/Standard%20Motor%20Mount%20for%20385-400%20Motors
Hope this helps.
Dave M

[SteveB66]

I see a lot of stuff about brushless motors but has anyone looked at the rc car market. They all come in various winds and most are 540 size. Ok some are limited to 2s lipos, but would it matter?

[Tugtower]

In runners are for direct RPM .. and also require you to cool the motor and the esc..


A near direct replacement for a 540 motor would be a 1000KV-1500kv Outrunner.. which only require the esc to be cooled.


Outrunners generally require a much smaller ESC then inrunners (which is also far cheaper) outrunners also give you the torque u need to throw larger props, inrunners in boats generally only can drive subsurface props fast and can struggle with overheating with submerged props, although not impossible to use effectively.


The best way to work out what size motor you need is to know roughly what sort of speed you want. to go, reasonable fast, you would want around 8-9,000 rpm on a x40-45 prop.


The maths bit is... the Motor KV x Voltage (battery u want to use) = the RPM


Some outrunners also DO not Require the use of lipos... some of them the motor draw is so small that you are able to use a NHMI 7.2 or 8.2 pack!
Ive other projects that use a 1100KV 28mm outrunners running off a 25 amp esc in a 7.2V Nhmi on a x35 prop and i get great performance in a boat that's 500mm long.


One of my current projects i'm using a 1500KV Overlander Thumper outrunner on a 30amp esc. (which can use front mounting  brackets) which will give me around 11,100RPM on 7.4v 2S lipo
 
The boat is 800mm long. so a fair size ( i've used this motor before in another boat of similar size an it goes like a bat outta hell!)


First 2 photos are my current project. the last photo is a previous one.

[Tugtower]

Oh and before i forget... Brushless motors require a Brushless ESC.. Brushless motors are AC current.. brushed motors are DC..


You stated you had 2 mtronic esc's I will assume they are brushed ones. (only 2 motor cables positive and negative)..


You cannot use  brushed esc's with a brushless motor.


Brushless motors have 3 power input cables, your ESC must have the same


You must make sure when swapping to brushless you have the correct ESC to power the motor you pick other wise a fire will happen! that means you need an ESC that can support the AMP draw of the motor)


Most bushless motors will tell you the size of ESC you require as a minimum.
Mtronics do a range of brushless ESC's, although i find them to be overpriced, ''Seaking'' (made by hobby wing), I've found to be the more reasonable priced and suited for model boat applications, they also come with a water cooling jackets ( if you pick a marine use one), and have program-ability VIA the transmitter ( no program card required) to do forward and reverse.

[JIM WORNER]

Thank you to all who have replied, from the replies and from club members advice I have ordered a pair of Turnigy  D2826-10 1400kv motors complete with mounting brackets.  These will mount on reversed 540 mounting brackets and will be fitted in a Weddico Tiger C42 speedboat.  The ESCs I have are the Mtronics 30 amp brushless reversing ones.  I will post a picture when I have all the bits to hand.  Once again thank you for the replies, they make for interesting reading.
Cheers  Jim 

[Tugtower]