Motor KV?

[M.M.]

If i purchased a hacker b50 8l for this boat:
http://cgi.ebay.com/25-deep-vee-ARTR-with-motor-and-ESC-racing-spec-white_W0QQitemZ290323053764QQcmdZViewItemQQptZRadi o_Control_Vehicles?hash=item43989a3cc4&_trksid=p4634.c0.m14.l1262&_trkparms=%7C301%3A0%7C293%3A1%7C294%3A30

Can i run it on 2s and 3s? With a turnigy 120A ESC

[Diegoboy]

Yes. :thumbup1:

[M.M.]

Thanks. :rockon2:

What about one of these motors?
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=6678

[Diegoboy]

That motor kV is too low for 2S or 3S

[M.M.]

What would be better for KV? because i have two 3s 2200 25c lipos that i run in parellel, and i have 2 2s 5000 20c lipos that i can run in series or parrellel. So what is better high or low KV? I would prefer to run the 2s in parellel to get 10000mah. Then ill have the 3s in parellel for just messing around.

So around what is a good KV for 2 and 3s?

[TRUCKPULL]

The 2880 kv motor it comes with would be OK (about max RPM for a mono) on 3S.
I would not run it on 4S.

It would also be OK as a Sport boat on 2S

Larry

[ozzie-crawl]

with your 2s 5000 in series run either a ammo 2300 x440 prop see you around 45mph. if more speed is wanted try a 8xl x640 prop

[M.M.]

So it would be better to run a lower Kv motor with higher voltage, rather than lowering the voltage with a higher Kv motor?

[domwilson]

This thread has a lot of good info. http://forums.offshoreelectrics.com/showthread.php?t=271

[ozzie-crawl]

generally yes. i have seen a lot off people try and run these on high kv 380 or cheap 540s motors and usally all they do is pull high amps
i look at it this way the bigger xl motors can pull more amps but they have more power so they can spin the same size prop a lot easier so they dont pull more amps. my 25" mono runs a ammo 2300 on 4s with a x440 and i only run a 45amp esc. the esc and batteries you have should be enough for a 8xl
i would start with a x440 and go from there

[domwilson]

Agreed. Someone once told me, a "S" motor should be considered like a 4 cyl. An "L" like a 6 cyl. and a "XL" like a 8 cyl. At least as far as the chinese 2 pole motors go. Take a look at post #19 in my previous post for general guidelines.

[ozzie-crawl]

i like that analogy now with the 580l we also have the supercharged v8

[M.M.]

[quote]with your 2s 5000 in series run either a ammo 2300 x440 prop see you around 45mph. if more speed is wanted try a 8xl x640 prop [quote]


Well i got an 8xl coming my way, now what can i do for the prop situation? Because i beleive it is an 1/8 shaft. Can i just use a little shim? That way i can run the 3/16 x640

[domwilson]

[quote]with your 2s 5000 in series run either a ammo 2300 x440 prop see you around 45mph. if more speed is wanted try a 8xl x640 prop [quote]


Well i got an 8xl coming my way, now what can i do for the prop situation? Because i beleive it is an 1/8 shaft. Can i just use a little shim? That way i can run the 3/16 x640

Yes. You can put a small piece of k&s tubing in the prop to shim it up http://www.offshoreelectrics.com/info-pages/fit-propellers.php

[M.M.]

Ok, thanks:w00t:

Now i need ozzie crawl to check out this thread and make sure an x640 is the right prop?

[M.M.]

Just ordered an octura x640. :banana:

How fast do you think she will go?

[785boats]

Hi M.M.
I've had the 8Xl in that hull on 4s & ran an X642 & X645 on it with no heat problems. The X645 made it a bit skippy in the corners at full noise though.
The X642 was more stable. So you've got some room to experiment with that motor. I think an X640/3 blade would be a good option too. I'll have to get one to try it.
Hope this helps a bit.
Paul.

[M.M.]

Sweet, so i shouldn't have any problems with heat for the 8xl and x640. :thumbup: Hoping to try this set-up out this weekend.

[785boats]

No problems as far as I can see, as long as the hull is not running wet.
An X640 is a light load on an 8XL in that small hull.
To continue that analogy (by domwilson) of the motors a bit further. If the 8XL is like a V8 engine then the props are the gears in the 5 speed gearbox bolted to that engine.
I would say that the X640 is third gear, the X642 is fourth gear & the X645 is fith gear. They all load the motor accordingly.
Cheers.
Paul.

[domwilson]

In a 25" boat, that setup will scream. Might be a little overpowered. But go for it.

[M.M.]

Just got the motor mounted up:bounce: Its huge compared to the 380 that was in it. Now just waiting for the prop, which should be here in the next hours. :banana:

[785boats]

Here's one by one of our club members with an 8XL in it. Not sure of the prop or the actual speed though. Mine looked similar in speed with an X642 on it. So here's what you're looking at.
Paul.
http://www.youtube.com/watch?v=IDjcgq6zFzs

[M.M.]

:w00t:

Took it out this weekend and man i can fly. I was running in super rough water so i couldnt really get on it. But when i did it was like a rocket. Now i just need to solder the square flex to the prop shaft. How do i do this?

[sailr]

1/8" shaft! You'll spin that puppy in two immediately! You need a .150 cable with that motor!


[QUOTE=M.M.;102968][quote]with your 2s 5000 in series run either a ammo 2300 x440 prop see you around 45mph. if more speed is wanted try a 8xl x640 prop

Yes. You can put a small piece of k&s tubing in the prop to shim it up http://www.offshoreelectrics.com/info-pages/fit-propellers.php

[ozzie-crawl]

if its the sqaure ended flex setup it maybe .150 flex with a 4mm prop shaft.
these can work okay if there isnt a lot of power,i havent had any problems with mine running a ammo 2300, but i did originally run that setup in a 7xl powered cat and as 785boats will tell you they split in the sqaure part of the prop shaft

[M.M.]

Yes i beleive that it is a .150 cable, with either a 4mm ot 1/8 propshaft. I forget who it was but somone said that they soldered the flex to the prop shaft. This way it was more like a traditional flex drive, and does not use the squared end. I wan to know the best way to join these two pieces.

[ozzie-crawl]

you maybe able to solder them togethor but i havent tried. if you do try this there is a bit of slop in the sqaured ends so just have to be carful that the flex is central other wise it will vibrate.another possability is take your strut to a machine shop and have it drilled out to 1/4 then you can put in a piece of 1/4 brass tube and a standard speed master bushing and run a .150 flex with a 3/16 prop shaft. i think 785boats may have done this

[M.M.]

I think i will try to connect what i have for now, then when that fails i might go to a wire drive and 3/16 propshaft. :thumbup1:

[Brushless55]

Here's one by one of our club members with an 8XL in it. Not sure of the prop or the actual speed though. Mine looked similar in speed with an X642 on it. So here's what you're looking at.
Paul.
http://www.youtube.com/watch?v=IDjcgq6zFzs

I love it... Like a built V8 in a small car! :banana:

[785boats]

Hi there M.M.
Soldering the two pieces together is pretty easy. Just make sure you clean all the lube out of the socket & off the flex first.
I just drilled a hole in a piece of scrap wood so the shaft was a tight fit in it to hold it steady & vertical, tinned the flex & the socket, heated the socket until the solder melted & pushed the flex in. Removed the heat when I was sure the solder on the flex had melted (just a couple of seconds) & hold steady until the solder 'sets'.
You will need a big soldering iron for this.
But as Ozzie said make sure the flex is centered & true to avoid vibration.
I did this by keeping a slight amount of twisting pressure on the flex & it sort of self centers. Maybe I was just lucky but there are no vibration problems with mine.
This was on a 32" cat with the same setup as these 25" hulls.
I ended up putting a complete new 3/16" stinger on my 25" hull after splitting two of those sockets.
Just remember, you will need to leave a 1/8" to 3/16" gap between the strut & drive dog once you solder that shaft.
Also, as the shaft is 4mm you will need a short piece of 3/16 brass tube to sleeve the 3/16 bore props you will most probably be using.
All the best.
Paul.

[M.M.]

I have already got the brass tube to convert from 4mm to 3/16:thumbup1: So do i need any special flux paste or anything to tin both of these?

[785boats]

I just used odinary electronics solder with the flux already in it but a bit of solder flux would probably help if you have any.

[M.M.]

Okay ill give it a shot:tiphat: