[944project]

This is the first time I ever post to a forum. So, please excuse my ignorance on the workings of this place.
I have a Porsche 944 sitting in my garage and my first thought were to drop a Chevy small block in it, till I stumbled across this site. Now, I am wondering what kind of performance I would get from it if I turn it into a ev? Could it be a quick car with decent range?
Any thought on this would be greatly appreciated.

 

[Guest]

Could it be a quick car with decent range

Easy answer: YES
Realistic answer: YES but it will take money as will any project you want that will take you from here to there in an instant.

A good controller: Zilla, Soliton1 come to mind.
A good motor: Warp series and many others come to mind but Warp was designed for a vehicle not a forklift.
Good batteries: Lithium all the way. TS, CALB, GBS, Kokam, and others. Depends on your budget.

Budget is your largest constraint for what you want. Look over at EVDL for others who have converted vehicles like yours.

Welcome.

 

[Woodsmith]

If you are thinking performance then you should have a read of CroDriver's thread.

 

[Duncan]

Hi Gottdi

but Warp was designed for a vehicle not a forklift.

What are the differences?

I am interested in what different design compromises are in the Warp -

 

[Guest]

Hi Gottdi

but Warp was designed for a vehicle not a forklift.

What are the differences?

I am interested in what different design compromises are in the Warp -

85 mph vs 5 mph.

 

[Duncan]

Hi Gottdi

85 mph vs 5 mph.

OOOOOHHHHH.......

Give me something to work on!

- the Warp motors look just like a fork lift motor to me - what are the differences?

Bearings?, yoke design?, brushes?.........

Motors don't care about speed - I have seen a fork lift doing 500mph!
(In the hold of a cargo plane)

 

[Woodsmith]

85 mph vs 5 mph.

Ignoring many other factors, gearing could account for that difference.

I would hazard a guess that Warp motors are designed around a higher working voltage and balanced for a higher shaft speed with correspondingly high speed bearings.
The armature, not only being balanced, will be bound much tighter with stronger material to prevent expansion of the windings and explosion of the comm bars.

I could well be wrong, and they just get forklift motors and paint them red, but I doubt that will be the case.

I would like to know too so that I could see if I could improve my 11" Still forklift motor to get more then 3000rpm out of it safely.

 

[Duncan]

I would hazard a guess that Warp motors are designed around a higher working voltage and balanced for a higher shaft speed with correspondingly high speed bearings.

Balanced is balanced,
Roller/ball bearings are normally rated to a decent speed.
Not sure about the higher voltage - can't think of any changes that are required

The armature, not only being balanced, will be bound much tighter with stronger material to prevent expansion of the windings and explosion of the comm bars.

Yes - possibly

I could well be wrong, and they just get forklift motors and paint them red, but I doubt that will be the case

I am more cynical - I think the red paint theory is likely

I would like to know too so that I could see if I could improve my 11" Still forklift motor to get more then 3000rpm out of it safely.

I intend running my 11 inch Hitachi at up to 5000rpm - but I will have some steel to keep the bits in!

A lot of things are able to take a lot more than "design" loads because there is no real advantage in designing down to the operating loads

Apologies to 944project for de-railing his thread,
A 944 would make a superb EV project - much better than ruining a nice car by putting an agricultural V8 engine in it

 

[944project]

No, worries keep me thinking. I need to do a lot more research on the electrical aspect of this. Where would I find some formulas on weight to power ratio? I am mechanically inclined, I can build almost anything. It's the electronics that have my head spinning.
Thanks guys.

 

[Woodsmith]

I would hazard a guess that Warp motors are designed around a higher working voltage and balanced for a higher shaft speed with correspondingly high speed bearings.

Balanced is balanced,
Roller/ball bearings are normally rated to a decent speed.
Not sure about the higher voltage - can't think of any changes that are required

I intend running my 11 inch Hitachi at up to 5000rpm - but I will have some steel to keep the bits in!

When I enquired about balancing I was asked what speed it needed to be balanced to as they have to check the harmonics throughout the speed range.
I think with the higher voltage it might be more to do with higher temperature insulation and the ability to advance the brushes.

I will also have some ballistic sheilding around my 11" motor but I am hoping to never use it. Scary as it will be behind the small of my back if it lets go.

No, worries keep me thinking. I need to do a lot more research on the electrical aspect of this. Where would I find some formulas on weight to power ratio? I am mechanically inclined, I can build almost anything. It's the electronics that have my head spinning.
Thanks guys.

Yeah, sorry for the hijack too but it is all stuff you may have asked later anyway.

I am the same as you, mechanical I can understand because I can see how it works, electrical I went to college for but with electronics I am lost.

 

[Duncan]

Continuing to hijack

When I enquired about balancing I was asked what speed it needed to be balanced to as they have to check the harmonics throughout the speed range.

This activates my sniff factor! - balancing is about the input forces

Harmonics are related to stifness and mass

You balance a wheel or other rotating mass - to a tolerance

A Harmonic analysis is a completely different animal and requires things like the rotational inertia and stiffness of all related driveline parts, motor mounts,

I think you were being fobbed off

- End Hijack-

Where would I find some formulas on weight to power ratio?

I assume you are trying to work out what size motor you need,

IC engine - has a power curve - you can get max power at high levs - less available at lower revs.
Truck engine can run max power continously
Car engine is not designed to run max continously

What you actually feel is Torque - power = torque times speed
for any given speed a certain amount of power can give so much torque

Electric Motor
Most electric motors are rated at their continous power output at a given (low) speed
If you increase the speed you can increase the continous power (until the motor explodes)
The amount of intermittent power is normally limited by the battery pack or controller
but if you tried to run continously at a high power you will overheat the motor

So to your Porsche

IC engine - 150 - 200Hp, 112 - 150Kw

You will need ~ 12Kw to cruise at 60 mph and ~ 27 Kw at 90 mph,
So these should be your "continous" numbers,
My fork lift motor is rated as 10Kw at 48v - at 150v it should be OK at 30Kw

Acceleration
I will be limited by my controller - 150v and 500 amps = 75Kw
If I had a Soliton controller - 200v and 1000amps = 200Kw
I would then be limited by batteries
Say 180v and ThunderSky 200Ah = 180v x 200 x 4C = 144Kw

If you had this setup in your Porsche you could blow the doors off the IC ones - BUT they could beat you up a long hill or towing a boat

 

[Plamenator]

Woodsmith grasped very well the difference between a forklift motor and an electric car one.
In my opinion the difference is not that big. Forklift motors are meant for 48-80V and 1000-2000rpm. Take one of those, apply 144-288V and you get the current breed of WarP/Kostov/ADC motors.
Increasing the voltage increases power and rpm - both desirable as indeed you would not want 5mph max out of a car. However this has a cost to it - commutation/comm arcing becomes much worse and the new rpm put the commutator to a test (it can fly appart from the centrifugal force).
To address those problems you need to:
1) either advance the brushes or introduce interpoles to tackle arcing.
2) design a commutator that can survive 5000-6000rpm.
This is what makes an electric car motor out of a forklift one.