kingston mouldings mtb523

[torpedo1Participant @torpedo1]

Hi folks,quick bit of advice needed please!the setup I’m currently using is twin rs550 motors direct drive to 38mm props with turnigy 30amp esc on each motor and am using 4700mah 2s lipos one for each esc.what I’m planning to upgrade to is 2 hpi saturn 20t 540 motors giving 140watts each.going by what I’ve researched it will work with the esc’s I’ve already got with a good increase in power to enable it to get on the plane a lot better.have checked what amps they draw on rc car forum and they’ve been dynoed at 19 amps so within 30amps or 40 amp blow on esc! Is it a case of suck it and see ? Any advice is greatly needed from experts .

[torpedo1Participant @torpedo1]

dual motor upgrade for improved performance

[Dave MilbournParticipant @davemilbourn48782]

I'd not go down that road myself. Those HPI motors are intended to be run through gearboxes and would be too highly loaded with props on direct drive. My suggestion would be to upgrade to Graupner Speed 700BB Turbo motors (Part #G3308 or 6317) and 3S LiPo packs, and use slightly bigger props (say 40-45mm 3-blade). The alternative is to go brushless but that would entail a whole new ESC set-up.
Dave M

[Paul TParticipant @pault84577]

Hi Torpedo 1

Why mess with weedy electric motors when you could fit IC

Paul

Ever the petrol head

[torpedo1Participant @torpedo1]

Thanks for info dave but could struggle to put them 700’s in as I’ve put long propshafts in and really don’t fancy cutting them down to get them to fit!could put that down to first time ever building a boat and trying to get the perfect weight distribution without adding ballast

[torpedo1Participant @torpedo1]

Hi paul,would agree with you on the ic if I was building a bigger mtb and I’d like to see one in action with ic engines in .

[ashley needhamParticipant @ashleyneedham69188]

Tinfish. Paul is of course suggesting the easy option, as having fitted an i/c engine, you could rest on your laurels and put the boat on the shelf..as you would have no where to run it..

Ashley

[torpedo1Participant @torpedo1]

Hi ashley,would’ve considered ic but like a lot of people on other forums they can struggle to use them due to noise and pollution risk on their local pond.wonder if that’s why some convert to electric. Would like to say a I’m impressed with other peoples rc boats in the magazines and what skill they’ve got!

[Paul TParticipant @pault84577]

Ashley

There are still places where decent sized I.C model boats can be sailed without the health and safety police or the starched shirt club brigade jumping up and down.

When are you going to build a petrol powered monster?

Paul

[Dave MilbournParticipant @davemilbourn48782]

My measurements show that a 700 is only about 22mm longer overall than a stock 540, if that's any help. The extra weight would be partly offset by the addition of the extra LiPo cells (presumably these are fitted behind the motors?). Clearly you don't fancy stripping out the twin shafts and installing a noisy, smelly, oily thing which won't go backwards…………… (Welcome back, Paul!)
Dave M

[Paul TParticipant @pault84577]

Hi Dave

Its nice to be back.

Noisy, smelly and oily? I always thought you were a clean living chap.

To make I.C go backwards just use a decent rudder.

Paul

[ashley needhamParticipant @ashleyneedham69188]

Paul. No petrol powered monsters I am afraid just yet. The next..project..may have a hi-power brushless in it, although having floated it on Mums fishpond (its too big for the bath) i appear to have sufficient bouyancy for something conventional. Am undecided about using LiPo as well…

Ashley

[ashley needhamParticipant @ashleyneedham69188]

Paul. No petrol powered monsters I am afraid just yet. The next..project..may have a hi-power brushless in it, although having floated it on Mums fishpond (its too big for the bath) i appear to have sufficient bouyancy for something conventional. Am undecided about using LiPo as well…

Ashley

[torpedo1Participant @torpedo1]

No wonder the graupners are popular in boats they’ve got some torque compared to the hrs550s-8819f motors but it puzzles me as to why it has 7.2v stamped on to the case of the hrs550s or are hobby stores ordering their own build of motors from the manufacturers. Thought the 550’s were capable of more volts?

[torpedo1Participant @torpedo1]

Think I’ve got it sorted and I’ve changed the motors to hpi gt550(rebadged johnson st550)also changed props to raboesch 3 bladed 40mm.have tested it in bath and under load each motor pulls 10amps on my ammeter.the same ammeter I use to check output of alternators.forgot I had this tool until rummaging through toolbox lol.

[Paul TParticipant @pault84577]

You can't go wrong with Johnson 550s and pulling 10amps they will run all day long just watch out for a heat build up in the motor can after high speed sailing.

I use the same motors in my Trent and have a pair of computer cooling fans mounted over them to keep the heat down.

Paul

[torpedo1Participant @torpedo1]

Do your motors have the inbuilt fans like mine have? Just puzzled as to why you’d need to add extra fans.

[torpedo1Participant @torpedo1]

Have had MTb out and not a problem with heat buildup as cans just mildly warm. was a huge improvement over what I’d originally put in. Only problem encountered was propshaft had nipped up and had forgot the oil to lubricate it oops.never mind unplug battery to that motor and carry on with one motor &prop still no problem with heat buildup.

[torpedo1Participant @torpedo1]

hi folks,just a quick update on my mtb! have changed back to my old motors speed 660 and have noticed they're also johnson motors as well .have checked amp draw and they're pulling just over 5amps each and should give a lot longer run times. the only time i get off work and decide to test the new setup and the council decide to empty the boating pond for cleaning grrrr.

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