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Old Nov 17, 2012, 12:11 AM
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minimono with wildcat ep outrunner motor?

So it looks like the wildcat ep outrunner motor will bolt right in minimono along with a jetti 70amp esc I added cooling too. Will it be too much motor? Just want more power without worring about heat or trying too squeeze everything out of stock eletronics. Doing flex cable upgrade also with octura x432 or x435 prop
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Old Nov 17, 2012, 05:59 PM
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Unless you put on a lot more prop, it'll actually be slower than stock. The minimono motor is 2200kv and the wildcat is 1800kv, so on a 3s pack you're down ~4500rpm.

Going too big on the prop will make handling suck, since it's a small and light boat I would aim for something with a bit more RPM than stock and stay with smaller props.
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Old Nov 17, 2012, 08:41 PM
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Ok thnx I thought since it was a bigger motor in size it would go faster but forgot about rpm. I have a 28-45-2700 ammo inrunner I guess I can try. Is a x435 too big of prop?
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Old Nov 17, 2012, 08:48 PM
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minimono

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Old Nov 17, 2012, 09:17 PM
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I have new 3s packs I just bought. I guess i will keep stock motor for now & upgrade esc as I just tried another esc on stock motor & it seamed to rev up more on the stand. I have those plastic props from offshrore & a x430 I just got from them too.
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Old Nov 17, 2012, 09:26 PM
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Old Nov 18, 2012, 07:41 AM
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I wouldn't add 500kv and more prop at the same time, only change one thing at a time so you know what caused an issue if you have to troubleshoot.

Stock prop is 30mm, I would go with an x632 on the stock motor with an upgraded flex shaft and see how that works for you. If you still need more speed them I'd go to either a 35mm prop, or a motor with more kv.

The 70a ESC is overkill, but as long as it isn't killing the balance you should be fine.
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Old Nov 30, 2012, 07:09 AM
How high will it go?
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KV and rpm's is an unloaded number. Just because he picked a motor with less kv, does not mean the boat will go slower. It comes down to the ability (torque) of a motor to over come the prop it's trying to turn. A prime example is my KOS P1 running on 5s with a 2200kv motor. That's 40,000 rpms, but under load it only turns 25,000rpms according to my eagle tree rpm sensor(depending prop also). There are also other factors like internal resistance of the batteries and how much amps they can put out. Sometimes a lower kv motor can be more efficient, and wind up giving you more speed.
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Old Nov 30, 2012, 07:47 AM
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If the first motor isn't over propped, then dropping kv on the same prop will most definitely lose speed. Since this boat is definitely not over propped stock, it'll run slower with a lower kv motor.

If you're losing 15000 rpm under load, something isn't right. That means you're only turning 63% of the unloaded RPM under load. Are you sure the RPM sensor is setup right? Are you sure it's actually a 2200kv motor? How many amps are you pulling? Have you tried a smaller prop with radar to see what is actually faster? Dropping that much means it's running way out of it's efficiency happy range.
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Old Nov 30, 2012, 08:25 AM
How high will it go?
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He is not keeping the same prop. That is why I mentioned torque. It's all relative.

I've done extensive testing with props and motors. Everything is accurate. The way eagle tree sense rpm's is my wiring directly into two of the leads going to the motor. I may have the numbers off a bit though. It may have been 31,000 rpm under load, I did so many tests I would have to go back and look at the data again. My point was just that advertised rpm's and kv's are not always the best way to pick a motor, or prop. It's about the combo, batt/motor/prop. I always search for the most efficient and fastest combo I can find for the batteries I am using.

It's why I hold track records in slot car racing. While everyone was "cheating" using 28,000 rpm motors, I set the track records using 20,000 rpm motors. That's because we were using 500ma wall transformers, and the 20,000 rpm motor had a lower"kv" and was more efficient.

His limiting factor will be the batteries he can fit in there really. So a lower kv motor, with a bigger prop might work out better for him.

You could just put a nice x430 sharpened and balanced prop on the stock setup and go like this, don't know why you would want to go much faster with that little boat.
minimono with x430 prop sharpened and balanced (7 min 19 sec)
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Old Nov 30, 2012, 10:32 AM
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His first post didn't mention a prop change, he brought that up with asking about a higher kv motor.

Too big of a prop on such a small boat will ruin the handling as well, too much torque and not enough hull.
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Old Nov 30, 2012, 10:33 AM
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Old Nov 30, 2012, 10:56 AM
How high will it go?
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Retoabcr, resistance is resistance, doesn't matter if it's water or land or even air. The relationship between resistance, and power output is the same.

Wparsons, he did mention it in his first post
I agree on putting to big of a prop.
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Old Nov 30, 2012, 01:59 PM
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Ooops! Missed that..

In regards to amp draw, etc. You're basing the whole thing on the boat being over propped stock, which it isn't. Lower kv doesn't mean more efficient, and unlike a slot car that has fixed size wheels, the prop can change load on the motor.

2200kv on 3s is already a very low and safe kv, no need to drop any lower.
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Old Nov 30, 2012, 08:46 PM
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