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  1. #1
    RC Racer
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    Very Technical Weight Question Regarding 3800kv/Sidewinder SCT Combo

    So I'm thinking about getting the 3800 SCT combo. I'm using my Slash 4x4 as an MT though with 4.87" Trencher tires. Is the combo ESC up to the task? I've estimated the weight of my truck at about 6.3 pounds using Traxxas' site and SPC site using their weight listing. The only thing I'm not 100% sure of is the additional weight the Trenchers and possible castle system impose.

    Here are my estimations:

    Slash 4x4 = 5.025lb http://traxxas.com/products/models/e...platinum-specs

    SPC Battery = .69lb http://spcracing.com/index.php?productID=59

    Trenchers = .5lb over stock (adding 2oz per tire so .5lb total)

    Est. Total = 6.215lb

    The only unknown is how much more the Castle 3800kv system weighs Vs the VXL stocker.

    Castle lists the SCT combo good up to 6.5 pounds. I'm thinking it'll work. Here's my logic:

    Castle engineers and marketing reps said that it's on par with the MMP just not as many tuning options.

    Most importantly, the MMP SCT system is also listed as a 6.5lb max so what gives?
    http://www.castlecreations.com/produ...x_pro_sct.html
    Last edited by hailjack; 07-07-2011 at 11:29 AM. Reason: spelling

  2. #2
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    I would say the ESC will overheat, unless you do the mod where you put the included fan for the motor on top of the ESC to cool that down. Or just get the superior MMP 'cos it can handle more amps (about 50% more (80A v 120A (approx.)))

  3. #3
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    I've never seen the amps capable of the Sidewinder published but it's got to be more than 80A. The 3800kv motor is good for 800 watts and with just an 8.4v battery, it would yield 95A.

  4. #4
    RC Turnbuckle Jr.
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    I have the sct/3800 combo on my pede with mashers the most I've seen the esc es 150F, 120F on the motor geared 11/54.
    Last edited by RC-Fan; 07-07-2011 at 03:28 PM.

  5. #5
    RC Turnbuckle Jr. asheck's Avatar
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    Those ratings are supposed to be constant, I have seen bursts of 150 with my SV2 , or SCT, whichever you call it, as they are the same. I have done alot of testing of the 3800 system in my Pede 4x4, with Trenchers. If you stay geared conservatively it should do fine, if you are one of those guys who pushes it hard, then there are some things you can do to help it, like put the fan on the esc, and / or add an external BEC. BTW, be aware that with those tires 12/54 is as high as I would gear on 2s, that should be good for around 40mph, on 3s 10/54 will give around 50. If you really want to bash at higher speeds, I'd suggest just getting the 2400 combo and 3s.
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  6. #6
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    Thanks, asheck. My gut is leaning toward this Sidewinder SCT combo since I tend to run on the conservative side. Plus my truck is still under 6.5lbs. I just want to keep decent temps and run a little offroad with this monster. 2S is plenty speed for me, and it's my understanding that the CC 3800 will increase it even more. I have it geared at 11/54 currently as I went down 2 teeth upon installing the Trenchers. My temp gun arrives today so I'll begin some testing of temps with the stock system.

    I'd like to know how you're getting a theoritical speed of 40mph though? That seems rather high. My speed chart with the help of an android market app says with 4.87" tires (trenchers) and 11/54 gearing on 2s should yield around 31mph.

  7. #7
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    So I got my temp guage today. ran it on 11/54 gearing with 2s and vxl system. Motor topped out at 128, esc at 108, and battery at 85. This was a mixture of offroad including gravel, big rocks, loose dirt, packed dirt and a 6foot pile of packed dirt. The run also consisted of 3 speed runs onroad with wide open throttle. Ambient temp was about 80.

    With temps that low I may not even have to worry about another system.
    Last edited by hailjack; 07-07-2011 at 07:14 PM.

  8. #8
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    Quote Originally Posted by hailjack View Post
    So I'm thinking about getting the 3800 SCT combo. I'm using my Slash 4x4 as an MT though with 4.87" Trencher tires. Is the combo ESC up to the task? I've estimated the weight of my truck at about 6.3 pounds using Traxxas' site and SPC site using their weight listing. The only thing I'm not 100% sure of is the additional weight the Trenchers and possible castle system impose.

    Here are my estimations:

    Slash 4x4 = 5.025lb http://traxxas.com/products/models/e...platinum-specs

    SPC Battery = .69lb http://spcracing.com/index.php?productID=59

    Trenchers = .5lb over stock (adding 2oz per tire so .5lb total)

    Est. Total = 6.215lb

    The only unknown is how much more the Castle 3800kv system weighs Vs the VXL stocker.

    Castle lists the SCT combo good up to 6.5 pounds. I'm thinking it'll work. Here's my logic:

    Castle engineers and marketing reps said that it's on par with the MMP just not as many tuning options.

    Most importantly, the MMP SCT system is also listed as a 6.5lb max so what gives?
    http://www.castlecreations.com/produ...x_pro_sct.html
    I think you are overlooking the weight of the dirt, mud, grass, rocks, etc jammed and crammed in the wheels and tub.

  9. #9
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    I've run both the Velineon and Sidewinder SCT in my Slash 4x4 and they act totally different. The Velineon ran fairly cool, even geared high, and was fairly fast. The Sidewinder runs hot as the sun (motor is 130, ESC is 175-180) and is insanely fast with a ton of torque, even geared much lower (18t vs. 13t) and will pull the front wheels off the ground with a center diff and any amount of traction. With the extra weight of the bigger tires, expect the ESC to get even hotter. You might get away with it if you can drop a couple more teeth on the pinion or add a couple to the spur.
    Slash 4x4
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  10. #10
    RC Turnbuckle Jr. asheck's Avatar
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    I'd like to know how you're getting a theoritical speed of 40mph though? That seems rather high. My speed chart with the help of an android market app says with 4.87" tires (trenchers) and 11/54 gearing on 2s should yield around 31mph.
    Tire ballooning , and I was figuring 12/54. The Trenchers will expand quite a bit at those speeds , adding a few mph , easy. Also with tires so big, 1 tooth can make a big difference. I have confirmed speeds of up to 45mph on 13/54 . Sounds like your doing fine , though
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  11. #11
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    Gotcha. How much did you account for in ballooning just so I can check my gearing/speed model? When I put in 5.9" it yields a speed of 40.1. That would be a total increase of 1" in diameter.

  12. #12
    RC Turnbuckle Jr. asheck's Avatar
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    Balloning varies by alot of factors, Speed, road temp, vehicle weight, even how frequently you run the tires. So I kinda adjust it accordingly, but I think the 1" at 40 will get you pretty close. I would say at 55, it's more like 1.5 +. Of course there are also things like battery voltage drop, that make a guaranteed estimate impossible.
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  13. #13
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    can i run the 3800 sct combo with 3s in my merv if i put the included cooling fan on it?

  14. #14
    RC Turnbuckle Jr. rag6's Avatar
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    The new Sidewinder escs have a factory bolt on or built in fan. In the little merv, it should be fine unless you gear it to Saturn. May want to ask on the merv forum to be sure though...
    Ya can't polish fertilizer...

  15. #15
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    the new ecs in the sct kit is different then just an sv2 with a fan on it. and in my area im hearing alot of good things about it , also it looks to be the same ecs the use in the little savage xs

  16. #16
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    I now have 2 sidewinder SCT 3800 kits. One in my slash 4x4 and one in my exo terra.

    Today I ran 13/54 2s and I didnt see any temps over 85 degrees. body off, 55 degrees outside.

    115 I think is the hottest my exo has gotten on warmer days

    They both have copious amounts of torque - not geared too high for any amount of speed but man, you can hear the concrete ripping up when I roll on it

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