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Sep 13, 2019, 04:45 PM
Just Plane Nutts
AirDOGGe's Avatar
Quote:
Originally Posted by Vmeed
I just ordered this kit,

I will update after I install. If itís not suitable for the boat, I have a 1/12 scale crawler!

https://www.amazon.com/gp/product/B0...NFG8OL60&psc=1


Start taking apart the crawler. 4500KV is not ideal here. See post #70.
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Sep 13, 2019, 05:15 PM
Registered User
tware's Avatar
Quote:
Originally Posted by AirDOGGe
Start taking apart the crawler. 4500KV is not ideal here. See post #70.
do you mean for 3S? I went with the 3000kv recommendation my JetJam, and it was as slow as stock on 2s. I've been using 3600-4200kv now and I'd rather have to set the throttle to a lower end point and/or have unusable throttle at the top end than not enough power.
Sep 13, 2019, 05:42 PM
Registered User
While not ideal, mine was absolutely nuts with a 4500k on 3s. No self righting anymore. But I did not notice anything alarming and I've since put sevral packs through it now with no issues. I went up to some 800mah 3s quad copter packs which just squeak into the thing once all the factory supports are gone. Now the stock 2s battery does not have the c rating to handle that motor. But I have no idea what I'm doing as far as boats just guessing and hoping it sticks. Well aside from general rc knowledge.
Last edited by Scalecrawler88; Sep 13, 2019 at 06:09 PM. Reason: Spelling
Sep 13, 2019, 08:48 PM
Just Plane Nutts
AirDOGGe's Avatar
With KV rating, the motor can only spin that fast with no load. When you put a load on it like a jet pump, the higher KV motor will suffer a greater RPM drop and higher heat production.

Roughly the same as taking a tall, thin man who can run very fast and making him carry heavy sacks of cement. Guaranteed he will be working harder, sweating harder and getting less work done than a stronger man who runs slower empty handed.

If you want more power, don't go up in KV. Instead go DOWN and then go up in voltage, which is where the power really is. For 3S try the 2800-3300KV range. With lower voltage 2S power you can only do so much.
Last edited by AirDOGGe; Sep 13, 2019 at 09:10 PM.
Sep 14, 2019, 12:53 PM
Registered User
tware's Avatar
I just tub tested my SJ with a Park 400 4200kv on 3S. Pure insanity. Not sure how much of that power is usable, but if its 1/2, I'll be happy. I will probably be using 2S and setting throttle to 75%. Hope to get it in a Lake tomorrow.
Sep 30, 2019, 11:46 PM
Registered User
I have had my sprintjet out 3 times in total now. After about 7-8 minutes it loses a significant amount of power and goes about half its normal speed. I don't think I have reached the LVC at all but After each run the motor is very hot. Could this be the cause of the power loss? Also has anyone tried watercooling one of these little boats yet I'm feeling like it may be needed for the boat to reach its potential.
Oct 01, 2019, 12:51 AM
Registered User
One of the culprits behind my last power drop has been found lol
Oct 01, 2019, 12:35 PM
Which stick makes it go up?
hobbyjumper's Avatar
I discovered that the pointy end of my sunglasses arm is just the right size for poking out the pebbles that get sucked up and lodged in the nozzle :-)
Oct 06, 2019, 01:00 PM
Registered User
We just got a couple of these last weekend. Seeing some pretty cool brushless mods in here and will need to upgrade soon. Here's a video we made of the of the first few runs up the creek. Sorry boats are still just stock.

ProBoat SprintJet 9 (6 min 7 sec)
Dec 25, 2019, 07:10 PM
Registered User
Quote:
Originally Posted by Scalecrawler88
I'm in process on doing a brushless conversion to my Sprint jet, so far it's stuff I had laying around and a 30$ gool rc combo off Amazon. The motor is a direct bolt up btw. The dean's plug will be switched out as well just haven't gotten there yet. I'm also guessing the little guy will need a ride plate to even have a prayer of hitting full chooch. I have a few options for batteries to try from my small helis and flite test foamies.

what gool combo is that? need some info.
Dec 25, 2019, 07:13 PM
Registered User
Has anyone discovered a quick combo that will bolt in and run 2s brushless? the park 370 motors are hard to find these days. need a motor ESC combo. sounds like 4500 kv on 2s will be pretty good compared to stock.
Feb 04, 2020, 11:05 PM
Registered User

3s


My boat works awesome stock on a 3s 500mAh battery. Good speed, and self rights great without the weights. I doubt the lipo cutoff works with 3s so be careful.
Feb 05, 2020, 09:46 AM
Registered User
Quote:
Originally Posted by jtthebiggafigga
My boat works awesome stock on a 3s 500mAh battery. Good speed, and self rights great without the weights. I doubt the lipo cutoff works with 3s so be careful.
Stock esc can handle 3s?
Feb 07, 2020, 10:03 AM
Registered User

So far so good


My stock esc has handled 1 test run in a pond for about 5 minutes straight full throttle almost the whole time. Motor was warm, not hot, esc/rx cool, battery warm. This is a 3S 500mAh Zippy 35C that is about 2 years old. I just swapped the power lead for xt-30 and if it blew the esc/rx, I already have all my brushless upgrades ready. Slow throttle sounds a little choppy like the esc is overworking, but full throttle is fine. I need to get out to a creek and give a full test and I want to include a battery buzzer to save the battery because the stock cutoff probably won't work on 3S.
Feb 08, 2020, 11:06 AM
Registered User
Quote:
Originally Posted by jtthebiggafigga
My stock esc has handled 1 test run in a pond for about 5 minutes straight full throttle almost the whole time. Motor was warm, not hot, esc/rx cool, battery warm. This is a 3S 500mAh Zippy 35C that is about 2 years old. I just swapped the power lead for xt-30 and if it blew the esc/rx, I already have all my brushless upgrades ready. Slow throttle sounds a little choppy like the esc is overworking, but full throttle is fine. I need to get out to a creek and give a full test and I want to include a battery buzzer to save the battery because the stock cutoff probably won't work on 3S.
I'm surprised it took the voltage at all, thanks for the input and look forward to more. I got brushless Jet Jam and will be getting on of these as well.


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