High Performance Electric Sandrail

Hello EV enthusiasts, I am very new to the EV world and have many questions at the inception of my latest project - an electric sandrail or dune buggy.

I just finished building my first sandrail from scratch last year and am dissapointed at the performance vs cost. $13,000 and 500 manhours produced a very nice but mild manner 1750 lb family sandrail with 110 hp and 13 inches of travel but now I want more and I think a hybrid rail may be the answer.

The two most important attributes of a high performance sandrail are suspension travel and power to weight ratios. There are lots of problems attaining both of these with reliability required in offroad environments. You already know the benefits of electric power and it’s related torque curves but it will also allow us to eliminate the two of the weekest links on any sandrail, the transaxle and the CV Joints/axles. Transaxles alone usually cost any where from $6K to $12K and the axle angularity is your limiting factor for rear suspenion travel so lets get rid of both of them!

Overall Concept goals:

  1. Retro Fit my full size sandrail by pulling out the Toyota 22R motor, VW Transaxle, CV joints/axles, large radiator and fuel tank and replace them with one electric motor at each rear wheel, a battery pack and a gasoline powered onboard generator.

Constraints and Assumptions:

  • GVW not to exceed 2000 lbs
  • Batteries+ 2 motors+ one generator must weigh equal to or less than 700lbs
  • two electric motors, one for each rear wheel allowing for max suspension travel
  • combined torque and power performance similar to Tesla EV sports car (248hp peak (185kW)
  • Small onboard gasoline engine to keep the batteries charged.
  • Fuel consumption of the generator should be assumed as unconstrained. In other words, I will put what ever size generator and fuel tank as required to meet the electric motor power consuption.
    -Typical power consumption on a sandrail will be 5 to 20 second busts at full throttle (hill climbs and jumps), 30 to 400 seconds at 70% power (getting somewhere) and lots of 30% to 40% throttle just cruising around and enjoying the sights.

Here is where I need your expertise and experience:

  1. What electric motors should I plan on using and how much will they cost and weigh?

  2. Will the motors survive repetative 5G shocks if mounted properly? If not, I could remote mount them at the trailing arm pivoit and run a belt to the rear wheel stub axle.

  3. What battery type should I use if they have to withstand sever poundings and vibration?

  4. How many batteries will I have to have assuming I have a generator capable of continuously recharging them? I want as little as possible for weight reasons.

  5. How do I calculate the size of generator needed once we make some assumptions about the motors and batteries?

  6. What kind of torque controls should I use? I need some sophisticated engough so that I can add a steering sensor that will shut down one motor or the other at full lh or rh turn (this will take the place of conventional turning brakes used to steer the sandrail like a tank in tight situations)

I know this is a lot to ask so if anyone with answers is in portland Oregon, maybe I could just take you to lunch and we could go over it all.

John Rokus

Yer asking a lot here. I’ve been investigating something along the same lines, but have not come up with a viable solution yet. Everything I’ve seen to get decent power and performance requires about a 30KW generator to run a motor large enough to give good performance and unlimited range.

Check out this link, American Armature offers some high powered electrical systems. As you can see, the AAI-EVP-500 Alternator can provide 14,000 watts of power, you’d need at least 2 of these to provide enough power to run the motor. You’d also need an inverter that could provide the correct voltage to the motor. Their AAI-OBVP-500 Inverter can give you 120 or 240 out, which should be able to directly power any motor you want to run. It’s also likely that you could find an inverter that could take both inputs and combine them internally (requiring just one inverter instead of two) and is able to put out any voltage, which means optimizing power output to the optimal input for the motor chosen.

A pair of these would increase weigh by 200lbs, add another 100lbs if you go for extra capacity. But, this is as far as I’ve gotten along this particular track. I don’t even know where you’d find these, at this time. And, this doesn’t include the ICE needed to run the alternators.

I was considering a small diesel ICE sized and optimized to run the alternators at whatever the alternator’s optimal RPM is, BUT it would also need to be able to maintain that speed constantly, even when the alternator was putting out full power. The more power an alternator is providing, the more of a load it’ll put on the ICE. The nice thing is, if the ICE is optimized to run a specific speed, then it only needs to be as large as is required for that speed and power level. Knowing that power and speed required, you can size the ICE even smaller, and turbocharge it to make up the subsequent loss of power from undersizing the motor.

Hope this helps, and I hope you get somewhere with it. I won’t be in a position to start playing with this for a couple more years.

Cool idea. :slight_smile:

I’m not a very experienced EV guy, but here’s what occurred to me:

*Motors with as much power as you want will be at least 60+ lbs., I don’t know anything about sandrails, but isn’t that a lot of unsprung weight? It might be better to remote mount them just for the sake of traction.

*Lithium batteries should take the vibration fine.

*The size of you generator, ideally, should be greater than your average power consumption at the motor. With the motors you outlined above, your generator would be around 92kW (@50%, leaving room to charge the batteries while cruising). (theoretically)

Telco and Sir Joab, thanks for a quick response. I am starting to understand why this hasn’t been done yet.

Perhaps full electric with remote recharge at the tow vehicle is a more realistic choice.

hey, where in oregon are you? I’m in Portland area… there’s a ton of OEVA guys… go to oeva.org and join the list and ask some of the locals.

I live in St.Helens but work on Swan Island for Freightliner or Daimler Trucks North America.

Ever hear of Synkromotive? we’re by the St Helens exit off 405… near jack in the box…

Should come visit, my Electric motorcycle conversion is finishing up.

OK, good to know, that right on my way home. Does the building say Ducati on it?

no thats the motorcycle store…

this is an EV company, it says Synkromotive on the door.