Choosing the Right T8 for your Buggy/Truggy

[jasonwipf]

Based on real life testing, racers opinions & testimony on this forum and many other forums I have put together a chart to help new people decide which T8 Motor (or any brand with similar KV ratings) might suit their needs. As well as avg. mah/min to help some determine what size packs for what situation might be needed. This is only a "general guide" so please feel free to chime in comments to assist in its tweeking.

[Marvin]

I think I'd agree with that overall.

Only thing though; I wouldn't use a truggy motor in a buggy, they are just too big and heavy in my opinion for buggy use.

[gnr racer]

Im sorry i dont undrstand that chart. im looking to convert my 8 2.0 buggy to electric, im pondering over a 2100kv or 2400kv, im guessing the 2100 would be ample as the 8e comes fitted with that as standard. im yet to research this forum yet for advice

[DCM]

you go for a lower KV and a higher cell count, you get better duration, and temps.

You getting the Rx8?

[gnr racer]

Sorry buddy im not sure what an 'rx8' is in the rc world?? i know its a Mazda sports car if thats any help.
seems from what i've read so far i need to be looking at rc monster in the us & castle creations for a better deal in converting my Losi, then i read about slipperrentials & i thought Oh God theres a fair bit to this conversion lark!!
thanks 'DCM' so the castle creations 2200 kv motor would do me fine?

[DCM]

when it comes to motors, make sure it is sensored.

[jasonwipf]

Originally Posted by gnr racer

Im sorry i dont undrstand that chart. im looking to convert my 8 2.0 buggy to electric, im pondering over a 2100kv or 2400kv, im guessing the 2100 would be ample as the 8e comes fitted with that as standard. im yet to research this forum yet for advice

yes do the 2100. That chart isnt just for the Tekin really, but any brand with similar KVs.

I agree marvin truggy motors are heavier in buggies and while i did it once i wouldn't do it again. Some people just really want torque or they get it then tone it down for their buggy and/or use it in their truggies when they convert them so they dont have to go buy another motor or system. So thats the only reason I put it there.

[AmiSMB]

I am currently using a T8 2250 in my buggy as I had got the 1550 and 2250 for my Truggy conversion but then the club where I race stated max 4 cell only and they were doing buggies only so did not want to spend even more so just transfered everything over. Am very happy with the 2250 in the buggy even if it is a Truggy motor.

[Marvin]

Originally Posted by AmiSMB

I am currently using a T8 2250 in my buggy as I had got the 1550 and 2250 for my Truggy conversion but then the club where I race stated max 4 cell only and they were doing buggies only so did not want to spend even more so just transfered everything over. Am very happy with the 2250 in the buggy even if it is a Truggy motor.

You should tell them that the 'official BRCA rules' for 1/8 electric allow 6S.

[jasonwipf]

/bump

[ianjoyner]

Okay so in helping me understands the trade offs between different setups:

Take the truggy 4 cell starting point. Why not just get the 2000kv and gear up if you want to go faster or gear down if you want more torque. What is the advantages of going up to the 2250kv or down to the 1700kv? Assuming you want more or less speed respectively. Thanks.

[chris_dono]

brushless motors have a "range" of gearing that will work.. too far outside either of these and you'll just get the motor too hot (and eventually smoke it)

[BRS]

Originally Posted by ianjoyner

Okay so in helping me understands the trade offs between different setups:

Take the truggy 4 cell starting point. Why not just get the 2000kv and gear up if you want to go faster or gear down if you want more torque. What is the advantages of going up to the 2250kv or down to the 1700kv? Assuming you want more or less speed respectively. Thanks.

It took me a bit to get my head round this, it really is a battery/motor combo with a sweet spot of around 30,000rpm

With my limited understanding of it all now this is how I see it.

Higher the voltage (ie cell count of the battery) the more efficient the system will be giving longer run times and cooler temps.
So if you go for a 6S (6 cells = 22.2volts) battery you need to match that to the right kv motor.
Motor kv x voltage = RPM's so to get 30,000 from 6S you need a 1400kv motor.. Simply going up and down motor kv's with the same batterys will put you above and below the efficeint range of the motor

Truggys also require a larger sized motor (longer usualy).

Another thing I didnt really twig for a bit was a larger battery cell count does not equal more weight its down to the mah rating. A 6S 2500mah lipo is approx half (dont pick me up) the weight of a 3S 5000mah lipo


Hope that helps

[Marvin]

Sam, a 6S 2500mAh pack would be the same weight as a 3S 5000mAh pack - look at the power of the battery - 22.2x2.5 = 55.5Wh, 11.1x5 = 55.5Wh. What affects the weight of the battery (essentially) is this power rating.

Basically, it is as Chris_Dono and Sam (BRS) have said, it's to do with efficiency. 2000KV geared up will do all the things that 2200KV will do, but will take a little more power to do so. Therefore, the overall efficiency is lower.

Gearing up/down is of course the cheapest way of doing things, and with the big motors, they're not particularly fussy, unlike 1/10th motors, so the differences aren't that much.

The ultimate efficiency run is to go as high voltage as possible, retaining the same total power. This is why the national grid is at such high voltage - the current is met with resistance, causing heat build up. That heat build up is where electrical energy is transferred into heat energy - thus less efficiency, as energy is lost from the intended purpose. The higher voltage you have, the less current you have for the same power output, and therefore, the higher efficiency you have.

Gearing a motor up draws more current, whilst when using a higher KV to do the same thing, the amount of additional current required is lower.

[ianjoyner]

Thanks all that's pretty well what I was thinking.

[BRS]

Originally Posted by Marvin

Sam, a 6S 2500mAh pack would be the same weight as a 3S 5000mAh pack - look at the power of the battery - 22.2x2.5 = 55.5Wh, 11.1x5 = 55.5Wh. What affects the weight of the battery (essentially) is this power rating.

Ah now I really get to the bottom of it cheers marv