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scr8p, your right....2.65, gear it the same as you would your B4

JK Racing wrote:2.25 internals on the stealth....

I'll have to dig up my gearing, but be aware that 3800 is a BEAST, being a 4 pole motor (monster torque, enough for 4X4SC trucks weight 6-8 pounds).

Beast in the sense of just too much power? Or beast in that it could cause some stress to the tranny and internal gearing? My initial thought was to give me the power that I wanted when I felt that I needed it. I don't plan on going full tilt with it all of the time as I like to modulate speed accordingly here and there.

JK Racing wrote:scr8p, your right....2.65, gear it the same as you would your B4

Ok, with that said, what would be a good starting point FDR to shoot for? And correct me if I am wrong, but is this how you calculate the FDR.... (Spur / Pinion)*Internal??

ex. (81 spur / 30 pinion)*2.65 = 7.155

mdutcher wrote:

JK Racing wrote:2.25 internals on the stealth....

I'll have to dig up my gearing, but be aware that 3800 is a BEAST, being a 4 pole motor (monster torque, enough for 4X4SC trucks weight 6-8 pounds).

Beast in the sense of just too much power? Or beast in that it could cause some stress to the tranny and internal gearing? My initial thought was to give me the power that I wanted when I felt that I needed it. I don't plan on going full tilt with it all of the time as I like to modulate speed accordingly here and there.

I also do have the option of swapping out the 3800Kv motor for a not as beastly 4600kv one. I just wanted to start somewhere.

the 4600 is a 4 pole also...more beastly.

as long as you can control your throttle finger, no issues.

your calculations are correct, I havent looked up my gearing yet, but like I said, match what you would use in the B4.

JK Racing wrote:the 4600 is a 4 pole also...more beastly.

as long as you can control your throttle finger, no issues.

your calculations are correct, I havent looked up my gearing yet, but like I said, match what you would use in the B4.

I thought the lower the KV, the more power. So, it is the higher the KV the more power than? I was a little confused.

I will start with what I have in my B4 than.

mdutcher wrote:

JK Racing wrote:the 4600 is a 4 pole also...more beastly.

as long as you can control your throttle finger, no issues.

your calculations are correct, I havent looked up my gearing yet, but like I said, match what you would use in the B4.

I thought the lower the KV, the more power. So, it is the higher the KV the more power than? I was a little confused.

I will start with what I have in my B4 than.

Yup, the KV (killavolt) number is how many RPM it will turn for every volt of input power. A lower "Turn" number ie a 6.5 makes more power than a 22.5 because of less resistance-

Keep in mind that we are talking about two different ways of measuring power:

kv - the HIGHER the KV, the faster it will turn, but you will have less torque than a lower kv motor (all else being equal)
Turns - the LOWER the turn number, (ie 6.5 vs 10.5), the faster it will turn but it will also have a lower torque number (all else being equal)

So in your initial example, the 4600 kv motor should make your vehicle move faster (more top speed) but it would have less torque than the 3800 kv.

Similarly, a 7.5T motor would be faster than a 13.5T motor but the 13.5T would have more low end torque.

I believe this is why crawlers and heavier vehicles typically use motors with higher Turn ratings or lower kv numbers.

Someone correct me if my above statements are incorrect but that's my understanding.

my understand is almost opposite...

lower KV - lower RPM - lower "watts" or power

maybe?

KV*V=~RPM under no load.

A low turn # (e.g. 3.5T) has a higher KV rating than a higher turn # (e.g. 21.5T).

So lower turn motors have faster top end speeds than higher turn motors but lower KV motors have slower top end speeds than higher KV motors. For acceleration it's the opposite.

finally found what I was looking for...KV/Watts chart...I understand these are Novak motors on the chart, but it should hold true for any motor, as KV goes up, so does watts (or horsepower as I understand it). It may not really be a direct link to torque, but it is as close as I can come to explain my understanding.

JK Racing wrote:finally found what I was looking for...KV/Watts chart...I understand these are Novak motors on the chart, but it should hold true for any motor, as KV goes up, so does watts (or horsepower as I understand it). It may not really be a direct link to torque, but it is as close as I can come to explain my understanding.

I think that you guys are all saying the same thing. Regardless, it would seem that the higher the Kv, the faster the motor is, when talking about top end speed - this is where I was slightly misguided prior to my post a few days ago. I do appreciate the clarification though.

back to the question at hand, power/gearing.

you want to run a 10.5(4200kv) motor (i wouldn't use castle, but thats your call).
using novaks final drive chart http://v2.teamnovak.com/kb/knowledgebase.php?act=art&article_id=29
you want to be at a final drive of 8. using a 81 tooth spur you'll need a 22 tooth pinion.

keep in mind that this is a starting point, you can go up or down as needed just monitot temps.
you don't want a 540 sized bl motor to hit the 170 range.

I've got a 4000kv 8.5T motor and I personally think it is way too much power. I'm probably going to go down to a 13.5.

fred is that a hobbywing motor? most 8.5's are around 5000kv.

i find 10.5 the perfect mod motor for 2wd. i tried a novak 8.5 (5000kv) and it was crazy, but the 10.5 seems just right.