Racing go kart

Ive seen electric karts been built around the 20kw range and they look a blast but when the e85 125 come out they get left in the dust and it doesn't have to be this way.

Qs 138 90h is like a gift from the karting gods when it comes to this i can not believe someone has not spotted the potential of a dual motor setup with its standard 428 sprocket and a kart with a 50mm axle and dual 428 half sprockets the gearing can be low as 1-2 for an 80 mph top speed on the 6 inch wheel and 50kw peaks no sweat.

2 controllers 8kg, battery packs they can be combined 42 60ah lg cells total 38kg then enclosure 10kg so the go kart would be a heavy beast the layout is vital for it to not drive like a pig but it could smoke the tyres to pieces and if that could be lay out in a nice fashion could have a race machine that would really move off the mark and pull at any rev range to 7k.

Its shows that the 20kw karts dont have to be heavy just a 3kg controller 25kg battery pack and 10kg motor on a kart chassis gives about 75-80kg total weight for a novice machine many can make an enter a sport and hobby learn a wealth of experience while having fun.

Im going to try and get a sponsor and make this a reality there has to be someway of getting this past the post id say £3g complete would see 2g on the mod and 1g on the kart itself maybe i could allow people to book track time but i need to raise the funds for this.

Best idea ive got is to make a kart and sell it climb my way up the chain.

Ive got a votol 200 clone controller and a qs 138 70h so im going to make a 20 kw peak kart out of that and see if i can move it on at a fair price sell all my kuberg and dualtron goods and i should be in a position to then afford to make the kart so this is going to be a long term goal for myself unless someone stepped in and wanted one i would make 2 then and hit the karting scene in pairs so they best be able to drive becuase A 50kw small kart wont be no joke and B they will be lapping with me id like Hamilton to come step back on the scene show him he ain't shit without mclaren get to the back the pack son.

50mm axle 428 rear split sprockets come in 20-30t flavours
Qs 138 70h splined shaft sprockets come in 12-17t giving a theoretical top speed range of 50-106mph

Just about manage to gear a single 70h version with a 12t motor and 30t split sprocket then a dual motor of this version could be geared up the the future.

Qs 138 90h im not sure in the shaft size and key used so i don't know for sure what sprockets that uses but i see theres a 16t version available at least meaning 2 of them could have a 65-100mph speed range just with the rear split sprocket swap alone.

Qs138 70h 9.8kg
Qs138 90h 12.4kg

So theres around 5kg in it between them in a dual motor setup without the controller weight difference only 10kw in power down still peak at 40kw but gain handling with the 10kg back in weight.

At the moment im playing with the idea and setup but its clear that its relatively easy game with the gearing of the shelf parts will suit from 20kw single upto the 50kw dual.

Great idea!
The dual motor set up could be a serious advantage in tight corners if you're able to split the the rear axle in the middle. So it can act like a limited slip differential where the inner tire can have a lower speed than the outside tire. That will make cornering easier and faster and will preserve the tires from wear.
I hope you will be able to get your idea to track!

SlowCo said:

Great idea!
The dual motor set up could be a serious advantage in tight corners if you're able to split the the rear axle in the middle. So it can act like a limited slip differential where the inner tire can have a lower speed than the outside tire. That will make cornering easier and faster and will preserve the tires from wear.
I hope you will be able to get your idea to track!

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Thank you SlowCo ill let you know where my build thread will be when i set it up but it wont be on here this forum is falling apart turning into a bunch of keyboard warriors and admin is powerless just shuts threads down well im not wasting my time with that i don't get a thing from my contributions then get locked out enoughs enough for me.

Ill still comment on the forum but ill keep my builds and ideas in the background and just show a complete working kart link maybe thats about it no one will get to see my ideology on here due to the efforts of the over privileged wankers hell bent on having a slanging match rsther than a discussion so magnets locks the thread up this is the 3rd time past few weeks whats up with the world narrow minded fools and boneless foundation.

I don't mind if my tab cooling idea failed i wanted a group brainstorm not paragraphs of why 18650 is king and false information on prismstics but theres we are i even said a 4680 cell would be a perfect choice for this but no ill just make fire cuz i cave man very little knowledge communicate with grunts.

SlowCo said:

The dual motor set up could be a serious advantage in tight corners if you're able to split the the rear axle in the middle. So it can act like a limited slip differential where the inner tire can have a lower speed than the outside tire. That will make cornering easier and faster and will preserve the tires from wear.

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You do not seem to understand how a Kart chassis works.
The entire chassis design and geometry is based on “flex” due to the absence of any form of suspension.
When set up correctly and weigh balanced, the inside rear tire is NOT in contact with the track on tight corners.
The front steering geometry forces a weight transfer from that inner wheel such that no “tire scrub” happens.
This is not an accidental feature, it has taken many clever chassis designers , years to optimise this “suspensionless” handling set up which is now universal on race karts.
If you used a split axle with twin motors, you would need to completely revise the front end to try to keep the weight evenly spread on all4 wheels, otherwise you will lose traction and accelleration due to the inner wheel lifting.

Hillhater said:

SlowCo said:

The dual motor set up could be a serious advantage in tight corners if you're able to split the the rear axle in the middle. So it can act like a limited slip differential where the inner tire can have a lower speed than the outside tire. That will make cornering easier and faster and will preserve the tires from wear.

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You do not seem to understand how a Kart chassis works.
The entire chassis design and geometry is based on “flex” due to the absence of any form of suspension.
When set up correctly and weigh balanced, the inside rear tire is NOT in contact with the track on tight corners.
The front steering geometry forces a weight transfer from that inner wheel such that no “tire scrub” happens.
This is not an accidental feature, it has taken many clever chassis designers , years to optimise this “suspensionless” handling set up which is now universal on race karts.
If you used a split axle with twin motors, you would need to completely revise the front end to try to keep the weight evenly spread on all4 wheels, otherwise you will lose traction and accelleration due to the inner wheel lifting.

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Couldnt have said it better myself the axle will remain solid to keep the fundamental handling characteristics
and pkay to this by keeping to a simular weight layout and not exceed a stock 125cc karts weight by too much been a light driver i can go 15kg over and still have a puker setup.

F1 test drivers go round in a 125 kart and lose 0.2 seconds over a 55 second lap with 20kg added and the kart only struggled in climbing the chassis managed to carry the weight on downhill sections and improve the sector.

Ive got a motor controller and bms yo get me 20kw theres a bjt if debate in a tab cooling thread thats got it shut down by a 18650 loving elon wanna be so magnets has shut it down and i can not share my design drawings to brainstorm and have the community pull them apart so i can have many minds help improvement.

Sad really they let flippy get his way by starving me of input but like i said to magnets i wont be stopped in my ideas and I'm prepared for it too fail but for it to not be in an open conversation without condescending talk is beyond me why i get locked out too.

Tab cooling is not easy or it be done but i think lg cells 60ah tab either side is perfect candidate 20 cells on 20 connections and i clever pcb could link a heat path out of the cell with 20 small ram water block on a thermal pad thats one idea but without illustration and a brainstorming round to see and solve potential issues to at least see a prototype pack that is not a fireball mess but very even temp grade across all cells and cycle life the cell much better it doesn't have to be complex if the path is direct but guess im the only one that realized 18650 has poor heat path to tabs and can but prismatic has a good connection to tab not its surface.

Theres many layers of foil each one has a thermal path along it to jump to the foil across theres a resistive path as such and crossing 100 foils takes time and is poor thermal connection but all those foils are within a few cm direct connection to tab, i guess ipl either get it wrong or right but i wint be stooped be nice to have some help like i see others threads never get shut down this is ridiculous now.

Ianhill said:

Hillhater said:

SlowCo said:

Me not understanding karting chassis...

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You do not seem to understand how a Kart chassis works.

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Couldnt have said it better myself

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Sorry and thanks for clearing that up. I was under the impression that the inner rear tire was alway scrubbing in corners and that the dual motor set up could provide an ideal "electric differential" for the tire speed difference. But I stand corrected.
I will be following this idea as I do find it very interesting!

SlowCo said:

Ianhill said:

Hillhater said:

SlowCo said:

Me not understanding karting chassis...

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You do not seem to understand how a Kart chassis works.

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Couldnt have said it better myself

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Sorry and thanks for clearing that up. I was under the impression that the inner rear tire was alway scrubbing in corners and that the dual motor set up could provide an ideal "electric differential" for the tire speed difference. But I stand corrected.
I will be following this idea as I do find it very interesting!

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You wouldn't be the first to try treat it as a car seen one build go mysteriously quiet same fate i believe.
It can be done but changes the chassis to much and the steering never feel like its razor sharp its lighter to turn in make a good granny machine.

There's differing cart spec classes not sure if its smae global but uk have bambino, cadet then youth/adult they then number the cart series and its the 401 karts ill aim to match with first ince thats proven and nailed down ill be ready to try the dual motor and take on the e85 shifter carts but they really are beasts light, agile capable, fighting one them with ease is the ultimate goal of like version 2.5 say.

Version 1 rear brake only version 2 would need front brakes and that adds as much money as the second motor plus weight so version one simple and proberly be the best for most to drive and follow along without putting to much cash into it, plus feeling warp speed and having extra weight pulling it wide becomes a handful for the best of us only big tracks suit that.

Don't the rules prohibit anything but a straight axle? If diffs could be used I'd have thought they'd be commonplace. 50kw is probably a very lowball figure, iirc folks have pushed the 138 70 up to 30kw so far and there's still more to go so god only knows what the 138 90 can go up to when pushed to its limits, wouldn't be surprised if bursts over 100kw would be possible with 2 of them. Would lipo's be suitable or would they fall down on range/power density?

stan.distortion said:

Don't the rules prohibit anything but a straight axle? If diffs could be used I'd have thought they'd be commonplace. 50kw is probably a very lowball figure, iirc folks have pushed the 138 70 up to 30kw so far and there's still more to go so god only knows what the 138 90 can go up to when pushed to its limits, wouldn't be surprised if bursts over 100kw would be possible with 2 of them. Would lipo's be suitable or would they fall down on range/power density?

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Ive heard of 20kw on the 70h but 30 my god that be enough to give a shifter kart trouble on its own.
Lipos have enough choch for a few laps but im looking for 20-30mins of flat out so about 25 laps say of a small sub minute track be about the aim thats good enough to call a race, the pack in mind stores 4.4kwh with 3.5kwh usable.

Yeah, that looks way outside the band where lipo's make sense. Iirc the 30kw 138 70 was at 120v but I've only heard about it in other discussions, not sure where the thread is. I've got a 138 70 and the 150 amp controller here, still meaning to get around to putting it in a bike frame and would love to know just what it's capable of, would be a shame to spend big bucks on a controller only to find it could go higher still.

You've got a kart chassis? And where are you planning to run it, in competitions? E karts are something I can see taking off in a big way, we're around the tipping point where it's cheaper to build electric than IC for the same kind of performance.

stan.distortion said:

You've got a kart chassis? And where are you planning to run it, in competitions? E karts are something I can see taking off in a big way, we're around the tipping point where it's cheaper to build electric than IC for the same kind of performance.

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Ekarts are not new.
There was a “European Electric kart championship” way back in the early 2000s, with some pretty professional teams competing...and there have been many kart constructors offering ekarts “off the shelf”,...quite apart from all the electric “rental” karts that seem common these days.
The issue with ekarts is finding a competition to race in. Existing kart classes are well defined and regulated down to fine detail such as tyre type/ size, safety equipment, and specific engine model.
So there is little chance of just “joining in” with an existing organised race, it will be practice sessions and possibly casual clubby “Open” races or random “Run wot ya brung” ..if you can find them.
I hope you have a friendly local club/ kart track, because many of them are very choosy as to what they allow onto the track.
My local track had to restrict even casual practice to separate sessions for Cadet, 2 stroke, 4 stroke, TaG , and sub divide into Junior and Adult for some of those. “Non Regulation” karts were serriously scrutinised and given very limited options for track access....sometimes solo !
That means no mixed classes on the track, which severely limits track time for everyone.
The downfall of most previous ekart efforts has been the batteries...too heavy, too expensive, not enough capacity, and too slow to recharge (dual packs for hot swapping ?)
Technically it is all possible ( at a cost) but if you have followed Nuxland’s thread.....it is not as easy as you may think !

Casual racing for myself at the local track, theres a few about but 1 i like 20 miles away from me and charges £30 for the day ro run what u brung.

I wont be competing the rules are tight so this us lioe a track car more than a race car maybe i should change the name to track kart becuse in theory only racing it will be doing is in a group track day.

Mind don't mean this wont be no fun because this will have a target in its head and i will have to be cafeful of that some will drive extremely attacking to punt you out the bend.

I've done karting on off since i was 7 broke my arm and kept going till race end so im aware of the games played even on a practice day your never really safe from idiots even when im out there on my own lol.

Theres also an abandined multistory that will get some attention in the winter months keep my hand in the game.

stan.distortion said:

Yeah, that looks way outside the band where lipo's make sense. Iirc the 30kw 138 70 was at 120v but I've only heard about it in other discussions, not sure where the thread is. I've got a 138 70 and the 150 amp controller here, still meaning to get around to putting it in a bike frame and would love to know just what it's capable of, would be a shame to spend big bucks on a controller only to find it could go higher still.

You've got a kart chassis? And where are you planning to run it, in competitions? E karts are something I can see taking off in a big way, we're around the tipping point where it's cheaper to build electric than IC for the same kind of performance.

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Not got the kart yet ill be quiet next week i got a week away then when im back ill be after picking up the model im after then its a kodi sigma rs3 im not going to say my methods till i got it but i can get rolling chassis used but very good nick.

120v on in innruner the motors rated at 7000rpm ive not even recieved mine to say what hard facts are but 120v would spin at 11666 rpm without limiting it been an ipm motor it could be done but it needs help first, the rotor is balanced with putty so theres one limit it can come off the rotor and then hell will play out.

One method to making a major improvement to the motor would be to take the rotor out take the putty off and send it off to get lazer abliteration balancing that way the rpm limit can be pushed a bit the design wont go to high mind i heard a vesc spin one up to 8k and the harmonics were audible that was suspect of rotor vibration but if that was sorted the stator assembly would become an issue soon after the windings would need a thermal epoxy pulled through in a vacuum to help stabalize the whole area.

Then you enter the realm of machine tolerance errors so the size and evenness of the airgap and magnet shape and densitys deviance no 2 motors are really alike if the machine viewing it has enough resolution then its a bit like the cpu lottery as to what max peak your chip hits.

But 30kw through one these motors would be exactly like a liquid nitrogen pc good for high figures useless in real life for repeatability usability etc.

Higher the voltage used further from the efficency zone of the motoryou can get, this motor is reaching peak efficency at 5krpm but the overvolted one will want to spin on to 12k meaning at that point about half your energy in is coming back out as heat noise and vibration.

Be better to run 2 motors at 6krpm gear them to use the torque to get you the speed you need and you will have an efficient ride this is where i shine because ive done the overvolting crap out of my scooters melted my cheap motors so now when big boy time comes i can extract what it has to offer.

Ive read so much about motors its hard to keep it all fresh at the front of the mind but for me i done 3 years collage got a nvq 3 and a 17th edition and had experience working in aluminuim mill and a steel works then i got a job on the railway servicing the power car bogies but learning the basics at college gives the ability to approach differing tasks and apply some level of whats going on theres always finer detail and someone better but ill give this my best apply many hours of thought process to finesse it make it stand out to those that come before.

Interesting about the motors, is it 30kw input or output?
I have ran my 138 70h with something like 32kw input at something like 7600rpm if I remember correctly.
And ran 8000rpm no load, or almost no load I guess. It was with the chain and rear wheel.
But that was all with fw, and something like 85V.

j bjork said:

Interesting about the motors, is it 30kw input or output?
I have ran my 138 70h with something like 32kw input at something like 7600rpm if I remember correctly.
And ran 8000rpm no load, or almost no load I guess. It was with the chain and rear wheel.
But that was all with fw, and something like 85V.

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Your spot on by there by the sounds of it rpm wise over revving the motor is pointless the iron is the limiting factor in that case so to really get an efficent rev range of say 12k + rpm the iron would have to be draticlly reduces or removed as a result torque will suffer can counter it with a tighter airgap but thats a completely different motor then.

Be nice to see at what point the stator saturates feom current and starts becoming wildly inefficient 32kw seems hell of alot thats like 380 battery amps maybe 800 phase peaks surely thats a melted winding in few seconds if that whats the controller and setting you used for that ???

It was a maxed out votol em150.
540phase A and set to 400 battery A
I have never reacted 400battery A as far as I know, but during FW I have reacted maybe 370 or something like that.
I dont remember exactly, but it is all in the ktm thread.

j bjork said:

It was a maxed out votol em150.
540phase A and set to 400 battery A
I have never reacted 400battery A as far as I know, but during FW I have reacted maybe 370 or something like that.
I dont remember exactly, but it is all in the ktm thread.

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Damn! I've been dismissing the em150 as a base level brick, you've got many hours out of it at those amps? Off road is damn hard on a controller too, constantly changing traction so load and rpms are up and down like crazy.

Been looking for the kv of the 138 70h motor but couldn't find nothing but i see on bjork thread larsb said its about 60kv so from a 20s setup ill set it up with 140% field weakening to get the 5000rpm upto 7000rpm, ill gear it 10t, 23t for a 54mph top speed.

By using a 23t split sprocket if i decided to go dual motor down the line i can get another 23t and use 17t motor sprocket and have a 93mph top speed so the rear end is quite flexible in that regard but i think its best i start simple get results

Make the murray inspired Fan kart in time lol if only ah, bags of it but be nice if someone did push karting that far its all obtainable off the shelf parts edf electric jet and a custom floor pan, the nikki lauda edition spools the fan to max constant above 50 mph karting could use the skirts of the early Brabham cars to solve the sealing issue karts would have with lots of corner jacking and the advancments of the t50 lauda in its fan design to create a virtual long tail kart and imporve aero massively as karts have some of the worst aero due to the human but that could be smoothed out raising top speed and the aero gains means the fan almost pays for itself energy wise.

[youtube]nT6ImqfHLog[/youtube]

They aint no joke fp smoked his rig out

stan.distortion said:

j bjork said:

It was a maxed out votol em150.
540phase A and set to 400 battery A
I have never reacted 400battery A as far as I know, but during FW I have reacted maybe 370 or something like that.
I dont remember exactly, but it is all in the ktm thread.

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Damn! I've been dismissing the em150 as a base level brick, you've got many hours out of it at those amps? Off road is damn hard on a controller too, constantly changing traction so load and rpms are up and down like crazy.

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I'm not sure when I went up the last little bit, but before that I ran 500pA and 300bA.
Then I learned that it was limited to 540pA, so I turned up the last little bit :wink:
I think I have ran it for 40-50 hours on the bike. All the time I have ran 90V fresh of the charger.

However, I dont normally run these high rpm. That was just a short test on the street.
I am a little worried to burn out the controller from high back emf.
I think I usually see top rpm:s in the 5500-6000 range, and top currents around 300bA.
It has been a while since I logged anything, so I dont remember exactly.
And this is just short peaks, the average power I use is not very high.

It also has some sort of compensation to get more bottom to mid range out of the ipm, and very snappy throttle response in sport mode.

However, the program has changed on the newer ones. So I dont know if they has the same possibilities.

I got a blood 72701 it looks like a Votol 200 clone max350ba 750pa 90v overvoltage and 50v under voltage.

Funny thing is that voltage range fits a 32s lto pack perfectly just a damn shame its 25kg for about 1.1kwh usable, 33kw pack power and get many many thousands of cycles and charge it in 45mins with the chargery still slow as hell really for these cells.

Makes sense on a small hybrid machine just getting all that in a kart its a bit too small and it be a bit too heavy something like a small offroad buggie would go well with the assistance and a bit more packaging room.