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Discussion Starter #1
Hi all I race a VW powered Formula car in autocross and am tired of problems with combustion motors. I did want to convert 2 yrs ago but went with new 180 hp air cooled motor instead. Still too much oil, carb tuning probs etc. I have been looking at EV West kits and now found this forum. My general question when looking at motors the specs say Continuous RPM 5000 Max RPM 10,000. What is going on as far as acceleration torque at 7000 to 8500 rpm?

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Hi
Autocross - so relatively short events and lower speeds??
You can spend big bucks with an AC motor from somewhere like EV West - and get OK power
Or spend a lot less for an old school DC motor from a forklift and get three times the power

This is my car

Its driver lets it down !
But the car is fast
On our annual 1/8th mile drags it does 7.8 seconds and 96 mph

I'm using a Hitachi forklift motor - they cost about $150 from the scrappers - and a Paul & Sabrina controller - $1000
With a Chevy Volt battery pack - $2000
Direct drive to a Subaru LSD
At max power I'm feeding it 1200 amps and 340 volts - 400 kw - 540 hp - the efficiency drops off but even so that is over 400 hp
 

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Discussion Starter #3
Wow thanks thats what i want to be able to do. Could you tell me a bit more about your rear, Direct drive to a Subaru LSD ?
 

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An AC motor has constant torque up to a certain point. Then it has constant power.
So you could get 500Nm up to 5000RPM, then after that point you'd be limited to 400Kw.
A Tesla drive unit would run constant torque up to about 7-8k RPM, then constant power past then.
You can buy a large Tesla unit for $3000, throw an open source control board in for $400, and push 300Kw through it.

I wouldn't recommend EV West - if you want a motor solution check out HSR Motors Base Large Drive Unit Package | Tesla Drive Units | Products | HSR Motors - $8000 for 335Kw (449Hp). Max RPM 15,000, 9.73:1 gear ratio.

DC motors are basically the same, except usually the RPMs don't go much above 6000, and the torque at higher RPMs falls off faster. They do have insane torque since often you can push 1000+ amps at low speeds.
 

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I also wouldn't recommend EV West. I used to, but I no longer do.

Another forum user bought everything from them, and literally every single component was faulty. They didn't refund, they made him troubleshoot it for week after week (still ongoing), up to and including ridiculous bullshit like spending a day swapping out for gold pins on a connector instead of just giving him a working unit. They charge top dollar and provide dollarstore quality control it seems, and then follow up with garage sale level of customer service.
 

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That could be an interesting project. I'm curious: the car isn't a Formula Vee - what is it?

EV West can be a useful source of information, but since they don't make anything, they're not really the best source of information on any product. They seem to mostly buy used stuff at auctions for resale.

Motor torque depends on the motor design and the current run through it. For any application of a motor there will a current limit, usually due to the battery, the controller, or how much heat can be handled in the motor. So from zero to some motor speed the available torque will be constant. Higher motor speed requires more voltage, so at some speed it won't be possible for the battery and controller to supply enough voltage to drive that peak current; past that point current will drop off and so will torque. How it drops off depends on the motor type, the battery and controller capabilities, and programming choices for the controller. In production EVs, the motor power is usually limited to a constant value over a wide range of speeds - even though the motor could use more - to protect the battery.

Perhaps a question in the Motor section of the forum would be a better place to get into motor details... and it would help to mention which motor you're considering (and why).
 

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Discussion Starter #8
It started as a Spec Formula Ford Road racing car. All the cars had a 1600 VW motors or a comparable motor with modern wishbone suspensions and coilover shocks. When I bought it the motor was worn out and too slow for me so I upgraded the motor to almost double its power. I also haven't run it much fully dressed bc I need access to problem when they happen. Yes it looks like a lot more reputable suppliers than EV West out there. Thanks for the heads up guys.
119983
119984
 

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It started as a Spec Formula Ford Road racing car. All the cars had a 1600 VW motors or a comparable motor with modern wishbone suspensions and coilover shocks... View attachment 119983 View attachment 119984
Interesting... I wondered if it might be an early Super Vee, or one back-dated to the air-cooled engine. Formula Ford have Ford engines, of course, and eventually Formula 1600 was created as Formula Ford with specific Honda engines allowed; it's interesting that a sanctioning body (it looks like FRCCA) created this variation (F/S is FRCCA's Formula 1600) with air-cooled VW engines, and that anyone would choose it. Of course in autocross there are different classes, and usually a place for almost anything.

I assume that's a Hewland, or a modified VW transaxle. If you put an electric motor on that transaxle the transaxle will be relevant, and fortunately adapter plates for VW transaxles (which should work with a Hewland) are readily available.
 

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Discussion Starter #10
Yes it is a Formula 1600, I bought it 2 yrs ago to make it a dedicated autocross car. The car was originally built in 2007 as an entry level formula car. Mine is #8 of eight, they rolled out the cars in 07/08. Needless to say 08/09 put them out of business. I got a great deal on the car because the guy i bought it from way underestimated how hard the seat was going to be on his back. I had a custom VW transaxle built and yes I have seen the adapter plates that is what inspired me to look into this. For now my gearing might be too tall for EV as I have two (2) 2nd gears. I race at an event at Pocono on the infield road race course and if you can get up to 75ish you are good. Usually an autocross is in 2nd gear top speed 55. It was always tough to go from 2nd to 3rd across the gate and then back again in an autocross course. I had it built with a 2nd gear ratio in 3rds position and a 3rd gear ratio in 4ths position. This way all you need to do is move shifter forward and backward for 2nd and 3rd gear shifts. My other challenge, besides space for batteries, is needing more rpms. Right now I get to 70 at 7000 rpm which is pushing my motor it can go to 6500 ok but driving it for a few seconds on red line is risky. I would love to set up a motor combination that could rev 7500 to 8000 briefly.
 

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Yes it is a Formula 1600, I bought it 2 yrs ago to make it a dedicated autocross car. The car was originally built in 2007 as an entry level formula car. Mine is #8 of eight, they rolled out the cars in 07/08. Needless to say 08/09 put them out of business. I got a great deal on the car because the guy i bought it from way underestimated how hard the seat was going to be on his back. I had a custom VW transaxle built and yes I have seen the adapter plates that is what inspired me to look into this. For now my gearing might be too tall for EV as I have two (2) 2nd gears. I race at an event at Pocono on the infield road race course and if you can get up to 75ish you are good. Usually an autocross is in 2nd gear top speed 55. It was always tough to go from 2nd to 3rd across the gate and then back again in an autocross course. I had it built with a 2nd gear ratio in 3rds position and a 3rd gear ratio in 4ths position. This way all you need to do is move shifter forward and backward for 2nd and 3rd gear shifts. My other challenge, besides space for batteries, is needing more rpms. Right now I get to 70 at 7000 rpm which is pushing my motor it can go to 6500 ok but driving it for a few seconds on red line is risky. I would love to set up a motor combination that could rev 7500 to 8000 briefly.
With my device I don't need to change gear - the single speed will spin the tyres and take me up to 96 mph at the end of the 1/8th - I was going to try a 1/4 mile at the end of last season but the virus got in the way

The lack of gearchanges is a real advantage - with your gearbox and a DC motor I would expect to be able to do the entire event in third or fourth gear
My motor is an 11 inch diameter unit and is 102 Kg
I would suggest a smaller 9 inch diameter motor which will weigh about 60 kg
A smaller motor will require less voltage and will withstand higher rpm's

I love my Chevy Volt cells - but fitting them may be fun
Can you make wide sills each side of the car and put them in there?
I have about 133 kg of batteries
How much does your car weigh at the moment??
 

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Discussion Starter #12
I could widen the sides but, I have an area about 12" wide x 28" thats 20" tall between front of motor and back of my seat hoping to use that space for Tesla batteries. For now If I could get low torque roll out to 8K rpm my current gearing will work. Right now my car is 900lbs with me 1100lbs.
 

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IMHO the important thing is to get the batteries LOW DOWN - mine are on the floor - my motor is also on the floor

My car is 805 kg - 900 with me in it - so not far from twice as heavy as yours

Why do you want such high revs?
With an electric motor the crude approximation is
Revs = Voltage and Torque = Current

The problem with high voltage is that it then needs more batteries
Tesla batteries are designed so that when you put them all together you get the voltage you need for a modern motor
But that then gives you a Tesla battery - about 600 kg - great for range - not so good on the track

Tesla battery is designed for a lot of power - but its also a LOT of battery
A 100 kwh battery producing 400 kw is running at 4C - so that is what it's designed to do

A 16 kwh Volt battery producing 128 kw is running at 8C - so that is what it is designed to do

The batteries are the most important expensive and difficult part of any electric car
 

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Use an Emrax 228 (100kW 12kg!) or 268 (200kW 20kg!), when you would be light. A small Tesla-Drive Unit (85kg and 200kW) is also good and cheap (Engine about 2500€ + 500€ for a EVBMW Controllerboard).
 

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I assume that the potential battery space between the driver and the engine which was mentioned in another thread is longer than in the original car design, because the original Ford inline-4 has been replaced with a shorter VW flat-four.

Use an Emrax 228 (100kW 12kg!) or 268 (200kW 20kg!), when you would be light. A small Tesla-Drive Unit (85kg and 200kW) is also good and cheap (Engine about 2500€ + 500€ for a EVBMW Controllerboard).
The advantage of an axially short "pancake" motor like these from Emrax or from YASA might be that it is much shorter than even the VW engine, so that battery space could be larger.

Unfortunately, pancake motors (which are typically but not always axial-flux designs) are generally not used in production EVs, so they are low-production aftermarket parts and accordingly expensive. At least Emrax appears to be the economy option, compared to YASA, but I don't know what actual prices delivered in a single quantity to an amateur builder might be for either.

I would be very suspicious of the quoted power values - they are likely only for very brief duration, if they're possible at all. Pipistrel has used Siemens but now uses Emrax motors in their battery-electric aircraft (both companies are Slovenian), but with extensive modification for adequate cooling; their E-811 is a version of an Emrax 268 used in a Velis Electro and it is - even with the upgrades - only rated at 57.6 kW peak and 49.2 kW continuous, not 200 kW under any conditions. The earlier PEM 60MVLC motor in the Alpha Electro (essentially the same aircraft, and the same motor, but less developed and not type-approved) is rated at "60 kW 1 min, Cruise 50 kW @ 2100 – 2400 rpm". In autocross competition, the "1 minute" or "peak" values could be applied.

Part of the challenge with power ratings is that they are very dependent on conditions, including especially speed. The Pipistrel application is directly powering a propeller (the prop is actually bolted to the motor shaft), and so it is limited to 2,500 RPM. But at 2,500 RPM the E-811 motor's power ratings of 57.6 kW peak and 49.2 kW continuous correspond to 220 Nm (peak) and 188 Nm (continuous), not the 500 Nm (peak) and 250 Nm (continuous) claimed by Emrax. If you could sustain 220 Nm all the way to 4500 RPM, you would have 104 kW available, but only up at that speed.

The YASA motors are not for high shaft speed, compared to typical modern EV motors (they are only rated to 8,000 RPM), but Emrax motors are positively slow... 4,500 RPM maximum. That means they must be geared with much reduction than a production EV motor, and so their torque output to the wheels is multiplied by a much lower ratio.

Emrax motors can be stacked to double the power, although the stacking is crude and bulky compared to stacking YASA motors, but if you're going to buy two motors and two controllers anyway to drive two wheels, I don't see the logic in combining them on one shaft and using a differential instead of using one motor to drive each wheel.
 

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Discussion Starter #17
Thanks will be posting a pic with spacial dimensions of battery area later in my How many Tesla batteries thread.
 

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@brain_ I dont think that money is the biggest problem here. A Emrax 228 cost about 4000€, a 268 about 7000€, Tesla about 3000-3500€. Yasa are MUCH more expensive.
The Emrax in the Airplanes are hardly limited, because of the very low rpm and the small and low "C" Battery (Energydensity is much more important then powerdensity).
I use the 228 on my Smart Roadster with the original 6gear sequential automated gearbox (with shift pedals). At 5500U/min the Motor could deliver about 110kW Peak. The lower RPM is not a Problem, you dont use the lower Gears.
 

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Discussion Starter #19
Money is not as important as space. My compartment is 32" from motor side of transaxle to fire wall behind seat. 19" wide and deep but it tapers down to 12" wide at lower frame
120022
 

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Stick a nice 9 or 12 inch diameter motor in where your engine was and fit Chevy Volt batteries in the new sidepods you are going to make
 
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