spektrumFlux

My 1st run is not ideal too as placed the water inlet in wrong place and no water flow into the system which resulted in the Motor malfunction after about 5 mins of run.
For the 2nd run, I have changed the water inlet location, borrowed an identical Motor from friend to test it out.
The water flow is fine through the system (In-Motor-ESC-Out) then smoke after 1~2 mins run.....

SkR8Pn

whats the dimensions of the bearing your using for the mod?

Thanks

damfurst

I'm using a 10mmX3mmX4mm all stainless steel. Boca Bearing is where I got it from part # MR103-zz. You can buy a package of 10 of them for $9.95. I take a piece of 1/8" brass tubing and sand down the outside of it to make a bushing that will fit the 3mm hole. The bearing will fit right in where the rubber seal is. I figure it's better to have the front of the shaft supported than to have the seal there. And keep the shaft greased of course.

sundogz

Did the first motor also melt the motor wires? On your second run, could you see a stream of water coming from the outlet while you were running? BTW, the plumbing should go: IN-ESC-MOTOR-OUT. But that didn't cause your problem.

SkR8Pn

Thanks again, now its the waiting game till they get here......

spektrumFlux

On the 1st run, the motor wires did not burnt while the system is running withoutany water cooling for about 5 mins until the motor dies down eventually probably due to motor overheated.
On the 2nd run, I have replaced a new motor and the water cooling is running well with continuous stream flowing out of the outlet tube. But then the smoke and saw burned motor wires after only 1~2 mins run time.

Thanks.

sundogz

My best guess is that it was a defective motor. Maybe someone else will chime in here.

seehuusen

I've had wires burn up in my boat before, remember to use heavy gauge wires for boats, they need to accommodate  A LOT of amps!!

seehuusen

LOL, must've answered at the same time Sundogz

I agree, it's a dud in my opinion as well

spektrumFlux

my very first RC boat and already wasted 2 motors and hours of frustration. :-(

btw, what's the difference if using those lower kv Motor like 2600kv type as compared to 4450kv?


Thanks.

sundogz

Yes, I can see your frustration, and on a motor that I suggested to use! But I don't believe it happened because of the kv range. People have been using the 4800kv motors but notice a dead spot in the upper 1/4 throttle segment, so this 4450kv should have eliminated that problem. But to answer your question, a lower kv motor will use less amps to get the job done - and yes, high amps are what killed your motor(s), but we don't know why they drew so many amps. If you decide to go with a 3S system, you want to stay around 3000kv unless you go with a larger motor like a 28mm. With a larger motor the kv range is not so critical, as it will push through the 'envelope' with the extra power available. But it is still advisable to stay in those kv ranges for best balance of throttle response (2s-4500kv, 3s-3000kv.)

spektrumFlux

thanks for the explanation. :-)

I will stick with 2S Lipo battery.
Just wondering ..... if using a 2600kv vs 4450kv motor (both 20mm Leopard motor) on the same boat, will there be any difference in the speed?

swervyn

ive got 2 of the leopard 2040 4450kv and used it for my first motor, had no problems but felt it was lacking "torque"? so changed to a 3500kv outrunner

swervyn

really like that bearing mod damfurst, surely will keep more water out than a loose rubber seal? curious to know how you hold the bearing in place? CA adhesive or just it just jam in there tight?

cheers

damfurst

I think the most difference it makes is to keep the shaft from wobbling and wearing the hole through the pump. I had this happen on a Graupner mini jet that already has a bushing in it and was sucking a ton of air through the hole. So I drilled the pump out and rebushed it and then added the bearing mod which actually came from Dragonfire in the other Jet thread a few years ago. Has made all the difference in the world on the graupner drive so I've always done it on the Nqd drive as well. It fits tighter on the Graupner drive than it does in the Nqd so it probably wouldn't hurt to use a little CA or Shoe goo to stick it in place. I haven't done either on any of mine however.

sundogz

Yes, if you are using a 2S lipo, there will be quite a difference. 4500x7.4=33000rpm's target speed. 2600x7.4=19240rpm's and would be quite a bit slower. You might consider going to an outrunner or a 24 or 28mm motor (since you probably have no faith in the Leopard by now). I would try to get a free replacement for the bad motor first, since you already have a 20mm water jacket and 2S lipo. Surely you won't get another lemon!

Siftyish

Hi there, this is my jet sprint and this is how Kiwis do it - its 1.2mm thick aluminium- all tig weldedthen polished- i am a fabricator by trade and have built a few miniture boats but this is the smallest- its 400mm long - it runs a nqd jet unit (copy of graupners mini jet) with a 2040 watercooled brushless motor, 40A watercooled esc and a 3 cell 2200 lipo battery-, it goes very well !! i have since added planing strakes to the hull, they add alot of grip and provide sum hull lift at speed in the water, the boat has not delta in it (flat area in hull for jet unit) and that helps with traction- the hull is about 500g and performs very well with a good holeshot and top end speedthe was rather fiddley to fabricate but its fricken awesome!! now im building the real deal with a Nissan SR20DET 2L turbo engine as a eco hybrid type performance boat

spektrumFlux

will check with the seller, hopefully can have a replacement.

btw will using a high C battery like 40~80C 2S has any adverse effect on Turnigy 60A ESC + Leopard 4450kv Motor?

saw on YouTube those modi boat are really fast while my run seem very slow.

Ratrunner

the higher C rate for the battery the better (especially so with boats). no harm can come from running even a high 100C + battery.

Wheelnut

My Feedback: (81)

siftyish,
That is AWESOME!!!!!!!!!!!!!! VERY NICE JOB
Hope to see a video of it. What are you using for a hatch?

sundogz

Siftyish: She is a beauty! I can see that it must have taken a long time to build. Wow, if you ever decide to sell it.....

Spectrumflux: Those boats that go real fast have larger motors in them. The 2040 gets the job done, but is a minimal motor and has to have water cooling to keep it from cooking. My larger [link=http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=11179]outrunner[/link] isn't really pushed very hard and I don't use water cooling on it.

spektrumFlux

I'm getting bit of confused..

assuming using 2S Lipo for below setup,
will the [Turnigy 450/500 H2223 Brushless Outrunner 2900kv] be faster compared to [Leopard 4450kv]?

beside the bigger shaft diamter on the Outrunner motor, can it be mounted onto the existing mounting?


Thanks. :-)

Ratrunner

with both motors on 2S, the following applies

the 2900 kv motor would be way slower than the 4450kv motor on 2S

KV is a reference to the motor RPM per volt.

so on 2S the 2900KV would max out at 24360 RPM, vs the 4450KV at 37380 RPM.
the above examples are for a fully charged 2S (8.4V)

the 2900 KV would be better on 3S and it would then have 36540 RPM and at a much greater torque.
for a fully charged 3S (12.6v)

if you wanted the 2900Kv motor, it should be run on 3S, not 2S.

Jason.

sundogz

I had to edit my incorrect first response - Thank you Ratrunner for the reminder that we were talking 2S here. The outrunner is 600w which makes it almost 3 times as powerful as the 220w Leopard. [link=http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=11177]This motor[/link] would be more suitable for use with 2S. It has the same mounting hole spacing, so only needs a 2.3 to 3.17 coupler to install. Be sure to use a high 'C' rating lipo, as it will draw a lot of amps and will puff cheaper batteries. It would be better to use the 2900kv on 3S IMO, it won't draw nearly as many amps - and since you've already burned up one motor....

Edit: Many people are using [link=http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8594]this inrunner[/link] on 2S and 3S with success. I run it in my Jet Skis on 2s and it does very well.

seehuusen

WOW, great work siftyish!!! I love these little boats, seen several from NZ, on the back of 4WDs being put into remote creeks and what not... MAN THEY ARE AWESOME... Pretty much the reason I got the Tear Into