sundogz

We're both confused here - For some reason I thought you were running 2s - my bad.[] Did you mean you've moved the batteries as far aft as possible? (you said impeller) That would mean you have the battery alongside or above the jet drive, at the transom? Again, pictures would help a lot here.

MaximuM*AltitudE

Finally REALLY finished up the boat, added cooling to my R1 ESC. Took an old 432M heat sink, chopped it to desired width, removed R1 lower case half, drilled corresponding holes in the heat sink, thermal pasted and screw the ESC to the sink and voila! CA'd the hoses in place and ran them through my e-box, no leaks and had two successful runs last night! ESC didn't even break a sweat and the motor got up to a whopping 98*F after almost 6 minutes of constant full throttle on 3S.





You can see the hose going into the E-box in the last pic. Thru the ESC, thru the motor and out the side! Works amazingly well. Will get a video when I have someone to take it! Lead weight is to balance the boat when I stack two 3S packs on that one side. Should keep it primed pretty well, although it already seemed to re-prime quickly last night.

Talk about snap, this thing would break your neck in real life lol.

wparsons

Here's the only shot Ican get at right now. The battery is now mounted sideways across the hull, abotu 1/4"in front of the motor. The ESC is to the left of the battery, servo and RXare at the back on the right. There's also two 370 brushed motors (dead weight)right at the transom, one on each side of the jet drive. I plan to gut the insides over the winter and put the battery along the right side of the drive, ESC and RX on the left, but Idon't think that'll change the balance point at all, just the overall weight will be lower.

sundogz

Have you tried it since you mounted the battery crossways? If so, did it improve things (priming). I'm thinking it would (as would a heavier battery. And since that motor is so torquey, it might be necessary to mount the battery(s) behind or alongside the motor to keep the intake submerged more (wetter) so it can prime faster.

wparsons

I only ran it once with the battery in front like that, any video of it (except in the pool) was with the battery across the hull.  It's better with the extra dead weight, but I think there's something else happening too.

In other videos it looks like you don't have to totally stop the motor to re-gain prime.  Mine has to stop spinning, and sometimes sit for a second before it picks up water again.

My only conclusions are something is funky with the impeller, or I need more weight to get the whole pump submerged more.  At rest the water line doesn't totally cover the flange on the jet drive at the transom, so maybe it's just too high on the water?

DRAGONFIRE81M

I have had that problem befor but i had some grass raped around the impeller . also like sundogs was saying about putting the battrys on the sides of the pump well drop your water line in the back . could you get a pic of the bottom of the intake ? also just to make sure the impeller is all the way back up agenst the stater . if its pulled just a little bit from it your only getting half of the impeller in contact with the what would be a wear ring for a jet ski this will give a primeing problem .

wparsons

I'll double check the impeller, but I'm pretty sure its as far back as it can get.

I had it out again today, haven't grabbed the video off the camera yet but it wasn't any better.  I took a better look at it when its resting, the water line barely covers the top of the steerable portion of the nozzle, and it definitely floats a bit transom down.  I also watched closer, and it doesn't seem to pick up any speed between 3/4 and WOT, just makes more noise.

I'm going to pull it apart to grease it tomorrow, and make sure the impeller really is as far back as it can possibly go.  Maybe it's just spinning too fast and cavitating, 35k rpm is definitely above where the little impeller is happy.  Might pick up a 2600-2800kv motor for it instead, that would keep temps down with a lot of WOT running too.

BUBBABOY333

here is my motor

http://www.hobbycity.com/hobbycity/s...WaterCooled%29

heres my esc

http://www.hobbycity.com/hobbycity/s...hless_Boat_ESC


so theres my plan for the sprint boat, now will this work? and im fairly new to lipos so which ones would go good with this setup? thanks
and also can i just swap them in or do i have to change some things?

sundogz

This is a powerful motor. I run these with 60A esc's (35A is borderline) in the larger ABC Hobby Jet Ski's and need to use an [link=http://cgi.ebay.com/3-Racing-28mm-Brushless-Motor-Plate-Axial-AX10-Scorpion-/160375925167?pt=Radio_Control_Parts_Accessories&hash=item25572669af]adapter plate[/link] to bolt it to the jet drive. A 2S 2500ma 30-40C lipo will do nicely, but 5000ma will give crazy long runtimes (20+ minutes) and the added weight may help priming. You will also need a 2.3mm to 3.17mm (1/8) coupler. Sounds like an interesting build - please post pics!

BUBBABOY333

alright well can you post a link with the adapter plate and coupler, also which esc do you recommend? also does it matter between a 2s and 3s?
is this esc good and how well will it stay cool?
http://www.hobbycity.com/hobbycity/s...hless_Boat_ESC

sundogz

Click on the words "adapter plate" in my last post. Yes, it does matter on batteries - 3s is too much for this 3900kv motor in this boat. That 60A Turnigy esc is fine. It may take some searching to find a suitable coupler. Maybe drill out one end of the stock coupler to 1/8" (I've never had good luck with this). Or get one custom made by [link=http://www.rcraceboat.com/]Jeff Wohlt[/link].

gunza355

dose anyone know where i can get an impeller in australia. my onetook on asticks and lost

jetnovice2

Personally, I think you are trying to add too much power, which is costing you unnecessary $$$'s.

These jetdrives don't need that much power, and IF you can get them to spin at about 20,000 rpm, then that is about as good as you are going to get, anything more is a waste, as the drives lose efficiency after that.

Imodded a much bigger boat than the Tear Into, added TWINjetdrives, and use these motors and ESC's, on ebay US$20.98 inc delivery for the motor and esc :

http://cgi.ebay.co.uk/ws/eBayISAPI.d...=STRK:MEWAX:IT

Does the boat I modded work OK ?- it sure does, see the YouTubevideo below:

http://www.youtube.com/watch?v=Az_dhF3sJzE

sundogz

Bubbaboy, you probably won't need the adapter plate. I had mentioned it because it was necessary in the slightly larger ABC jet as it had wider mounting screw spacing. And I also share Jetnovices concern that this is overpowered for the Tear Into, but to each his own! The RPM's should be about right on a 2S. It would be the equivalent of a 2600kv motor on 3S (3900x7.4=28860 divided by 11.1=2600) and will have plenty of torque.

BUBBABOY333

thanks, nice project. i was actually looking for balancing speed with run time. but i am also want someone to help me choose a good setup/motor because im stuck on i only want a watercooled motor(unles other wise convinced) because of the heat. Now i also need to be either told or directed to a detailed place to learn how to run the waterpickup from the jet. i was wondering if it would be efficient enough to run 2 water pickups going in each direction one for esc and and one for motor? Thanks
also another question, whats a better setup something like 2040 size 4800kv with 2s 2600mah or a 2040 3700kv with like 3000mah? also if you didnt know i kinda just want a put in and run instead of finding couplers and all that un necceessary extra.

sundogz

[link=http://cgi.ebay.com/FEIGAO-LONG-BRUSHLESS-MOTOR-15-TURN-2-3mm-SHAFT-/270487019482?pt=Radio_Control_Parts_Accessories&hash=item3efa485fda]This[/link] motor will bolt right in; [link=http://cgi.ebay.com/RC-Boat-Aluminium-20-3mm-Motor-Water-Cooling-Jacket-/110549309568?pt=AU_Toys_Hobbies_Radio_Controlled_V ehicles&hash=item19bd409880]here[/link] is a decent water jacket. Run it on 2S 3000ma lipo with a 35A esc and I think you'll have what you're looking for (good speed/long runtime and bolt-in). You could run 2 cooling nipples, but it's unnecessary. Sdg

BUBBABOY333

Thanks, also the dimmension as wilson stated before for another motor, motor is 20mm and the jacket is 20.3, will it still fit? and also the motor specifies max current 16A? so 35a be harmful? Thanks

jetnovice2

Think of it this way, you can plug a table lamp into the same socket as you can plug an electric fire into - because the circuit can handle the draw of the fire, so can easily handle the much lower draw of the lamp.

The motor requires max 16A and the ESC can handle easily 35A, and yes the motor at 20mm will be fine in a jacket at20.3mm - you need some clearance to squeeze it in

BUBBABOY333

Thanks guys so much for your help i will start ordering the parts and will post pics/vids of it. if anyone has any recommendations for vids or pics before i tear out everything let me know!

also as for charging the batteries which would you get or suggest one maybe?
http://cgi.ebay.com/6s-Digital-RC-Li...item19b6481b95
or
http://www.hobbycity.com/hobbycity/s...idProduct=7028

also this is what i beleive i should get, let me know what you think
Motor
Motor Jacket
Esc
Battery([2]-not used at same time)
Charger
Tubing

jetnovice2

59 pages in this topic with lots of ideas, failures,success's , pictures and videos

BUBBABOY333

just edited my post #1468, i didnt make new post but can you guys over read my edit for assurance, thanks guys for all the help!

BUBBABOY333

hey as you said above with amps and lamps and stuff, if i have 35a esc and 16a motor its ok, but what if i upgrade higher later on to like a 60a motor, will the 35a esc burn up?

sundogz

Yep. [sm=drowning.gif]

BUBBABOY333

ok, well im ordering the stuff and now i need some more help lol. I read before that someone on this forum used the traxxas blue waterproof mini servo. I was wondering what the part number for it was? Also can someone lead me in the right direction for water pickups in the jet drive? Im confused on to to properly mount it. Thanks

-Layne

similar

You need to mount the pick up in the stator, but keep it far enough forward to keep clear of the nozzle when it swings. I used pop rivets. For the pick up itself I pushed out the pin, and then filed the top off leaving a small tube, then drilled the hole in the stator and glued it in place. For the outlet I simply pushed the pin out of the rivet, drilled a hole the right size in the transom, and glued the rivet in place. You end up with a nice tidy rounded outlet on the outside, and a 10mm long tube ready to connect the water line on the inside. Easy, and cheap.

Hope that helps.