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Suzuki kei truck at 50kph flat ground

Posted: Apr 11 2019 12:36am
by Overclocker
Image

660cc engine (to be removed)

700kg (ish) curb weight

i just need it to cruise at 50kph on flat roads. what's the smallest motor that could do this? a golden motor 5000w watercooled would do it?

Re: Suzuki kei truck at 50kph flat ground

Posted: Apr 11 2019 12:40am
by Chalo
Why the smallest motor? Why not the most dependable, most efficient, or most cost effective?

You're already opting for 700kg of relatively useless pig iron, after all.

If you want to use the smallest motor, figure out the power requirement at 50kph and use an RC airplane motor that delivers that much. (Or don't, because that would be regrettable.)

Re: Suzuki kei truck at 50kph flat ground

Posted: Apr 11 2019 12:46am
by Overclocker
Chalo wrote:
Apr 11 2019 12:40am
Why the smallest motor? Why not the most dependable, most efficient, or most cost effective?

You're already opting for 700kg of relatively useless pig iron, after all.

If you want to use the smallest motor, figure out the power requirement at 50kph and use an RC airplane motor that delivers that much. (Or don't, because that would be regrettable.)

LOL

a local guy's selling a Golden Motor 5k, that's why. i could either use it for an off-road go kart, or to convert a kei truck. take out another carbureted 660cc from the streets can't be bad right. why so much hate

Re: Suzuki kei truck at 50kph flat ground

Posted: Apr 11 2019 1:50am
by Chalo
"Will this motor work?" is a different question than the one you asked.

If 5kW is all that motor will deliver, my guess is that it would be weak, but might sustain 50kph in favorable conditions. If 5kW is nominal, that's a little more feasible.

A lifetime of being forced to coexist with cars is why so much hate. It's not OK.

Re: Suzuki kei truck at 50kph flat ground

Posted: Apr 11 2019 6:07am
by Overclocker
thanks chalo very helpful :roll:

https://www.diyelectriccar.com/forums/s ... hp?t=15508

i found this formula:

The POWER requirements of your car at a particular speed is:
Power in Watts = ((Mass in kg) (9.8m/s²) (Velocity in m/s) (Rolling Resistance)) + ((0.6465) (Coefficient of Drag) (Area in m²) (Velocity^3))

lemme see...

Mass in kg = 700 (assuming small battery pack)
Velocity in m/s = 13.8 (which is 50kph)
Rolling Resistance = 0.02 (street tires on asphalt)
Coefficient of Drag = 0.4 (this truck is a box)
Area in m² = 2 (it's a tiny truck so maybe even less?)
Velocity^3 = 13.8^3 = 2628

Power in Watts = 3253


the watercooled Golden Motor HPM5000B is rated 5KW continuous? my BHT motor is rated 1000w and i do 4000w bursts all the time. the HPM5000B is starting to look like a viable motor...

Re: Suzuki kei truck at 50kph flat ground

Posted: Apr 11 2019 12:31pm
by grindz145
Subscribed, photos or it didn't happen ;)

Re: Suzuki kei truck at 50kph flat ground

Posted: Apr 11 2019 12:47pm
by SlowCo
I would love to see how you'll convert it so I'm going to follow your build. Good luck and success!

Re: Suzuki kei truck at 50kph flat ground

Posted: Apr 11 2019 12:52pm
by fechter
That's not much bigger than most golf cars.

You might consider some kind of transmission in case you hit a hill. 2 speeds would likely be enough.

Re: Suzuki kei truck at 50kph flat ground

Posted: Apr 11 2019 2:01pm
by SlowCo
fechter wrote:
Apr 11 2019 12:52pm
You might consider some kind of transmission in case you hit a hill. 2 speeds would likely be enough.
Maybe only remove the ICE engine and mount the electric motor to the gearbox? That way you can choose the gear ratio as needed and are even able to carry/move more serious weight.

Re: Suzuki kei truck at 50kph flat ground

Posted: Apr 11 2019 2:47pm
by Chalo
Overclocker wrote:
Apr 11 2019 6:07am
Coefficient of Drag = 0.4 (this truck is a box)
Yes, this truck is a box. Most trucks have Cd of greater than 0.6. (0.4 was the Cd of the Jaguar XJS.)

If you use faulty assumptions, your calculated guess winds up being less worthwhile than an uncalculated rough estimate based on real world experience.

Re: Suzuki kei truck at 50kph flat ground

Posted: Apr 15 2019 12:25am
by Ribfeast
My kart is pretty much a golf kart, I think it has a 5kW motor and I've peaked it at around 15kW in spikes. For something with that weight I'd recommend more like 20kW nominal, or more. Unless it is just for use around a private property?

Or look into one of these and convert it to lithium?
http://pickman.com.au/listings/pickman-kw4wh1/