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GTP-2e Speed Car project
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fastbaja5b
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GTP-2e Speed Car project - 11.13.2011, 07:28 PM

Working on a Speed Run car at the moment (comp with a few mates) only limit we have set is 4s Lipo max and on road 1/8 chassis

At the moment have put in a HK120A esc and HPI Alphastar 2350kv 4 pole motor (cheapy 1515 1y clone they throw in the Flux 2350)

Reading some of the Ofna forums on rctech most people advise to gear for 55mph on 4s lipo, at present I have geared for around 40-41mph (general rule with 1/8 offroad anyway) and am finding that the motor is very inefficient at this level.

After 5-6 minutes it's coming off at 160-170f, esc and battery is cool (Turnigy 4500mah 30/40c)

Attached is an eagletree log.

So any options? Is the motor just too weak for this application (a lot of the Flux 2350 guys say it runs hot on the Savage Forums, and my experience with the Flux XS Motor is it is also one that runs hot as it has cheaper components)

Should I get a more appropriate motor like a Tekin or 1515 1Y? If so what application are these Alphastars suitable for without heating up like a Feigao!
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SV6000
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11.13.2011, 08:50 PM

Mate if your motor is hot and your esc and batteries are cool i would gear up, i know it sounds weird but give it a try.

If you have no joy i would pick a bigger motor. There is always a 1527 1D that has a KV of 2300. Really long motor and high KV

As far as speed cars go, the lower the KV and the higher the voltage the better.


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fastbaja5b
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11.13.2011, 09:06 PM

Quote:
Originally Posted by SV6000 View Post
Mate if your motor is hot and your esc and batteries are cool i would gear up, i know it sounds weird but give it a try.

If you have no joy i would pick a bigger motor. There is always a 1527 1D that has a KV of 2300. Really long motor and high KV

As far as speed cars go, the lower the KV and the higher the voltage the better.
Yeah I may try that, but also concerned on the Amp draw that'd bring. I know in my SC8e the Neu 1515 1Y is geared a lot lower than this and doesn't get warm, which is what made me query the motor over the gearing.


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brian015
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11.13.2011, 09:38 PM

Since you have a 4s limit - you want a higher kv motor to get maximum speed - If I were you I'd start with the CC 2650 and see how high I could gear it for speed runs.
   
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11.15.2011, 06:48 PM

you are not putting enough load on the motor. Gear up and temps will come down.

The castle 1512 2650kv would be a killer motor, but as said since 4s is your limit a higher kv will make higher speeds more easily attainable.


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snellemin
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11.15.2011, 08:03 PM

Go bonkers and do 1515 2700kv on a good 4s pack. Slap the 47T spur and make sure you have the hardend ring gears. You can also use RCM 46T delrin spur kit.

Get the Novak Ballistic 8 2650kv motor if you want to go sensored with a Tekin RX8 esc and added caps. Sensors will help if you want to start to overgear a bit.

Read here what my 4s GTP setup does--http://www.rc-monster.com/forum/showthread.php?t=30604


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Last edited by snellemin; 11.15.2011 at 08:06 PM.
   
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fastbaja5b
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11.15.2011, 11:11 PM

Thanks for the feedback, I have put a 21t pinion on (from the 18t) and put on a heatsink and reset my ESC timing from lowest to normal, so will see what effect this has. Also need to settle down the back end as it tends to kick out on power.


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x-y
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11.16.2011, 12:44 PM

leopard 4082 or 4092 + xerun 150a + 6s ......... and you will pass 100mph easy :D


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steveo
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11.25.2011, 05:17 PM

your limit is 4s you could go with a leopard 4082 2200kv ( offshoreelectrics sells this wind) and take advantage of the torque and keep feeding it gears, i had a rc8 buggy that went 50 with ease with a medusa 3680 2000kv motor- but first gear up as stated earlier
   
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