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44 Posts
Hi all,
Sorry that this is not a 100% EV question, but I already drive an EV (Bolt/Ampera-e) as a daily. And my classic petrol car (Toyota MR2 1985) is now slower than my daily driver
I already have knowledge about motors and battery systems, however, I am doubting how you could add a small system to an existing petrol car.
Converting to full EV is somehow easier because you bolt on the electric motor with a plate.
Making a hybrid of a rear wheel drive or 4x4 gives you some options on the axles.
However, with an FF or MR layout (and a 4 cilinder in a small car), there are very little options to add a motor to add power to the drivetrain.
You cannot do anything with the axles, and there is usually very little space to do anything on the timing belt side of the engine (in my car there is no space)
I can think of some ways at this point and I am hoping to see some examples. Or something I hadn't thought off.
1: Remove alternator and place a (small) electric motor there. Maybe some nice small motor at 48 or 96v, that goes on the belt drive.
This would make an easy conversion, but the downsides are that size and power is very limited. How much could you do over a belt drive? probably 10kW is already to much and break belts really easily?
It would already allow you to start the motor via the added electric motor and do some nice regen, but it is only a small boost in power.
Ditching the alternator and the starter and possibly the 12v battery, it wouldn't really increase the weight, so that is nice. (we are talking about a very small battery pack of maybe 5 kWh or so)
Would make things more efficient with only small boost in performance.
2: Remove starter motor and add an electric motor there.
Would allow for more power, but it is probably very limited what you can do with such a tiny gear?
Motor cannot be to big as it will stick out to much from the ICE engine.
3: Try to get a gearbox for a 4wd version of the same car, and connect the output to the electric motor.
(in my case a corolla 4wd gearbox?)
This is already getting complicated and needs quite some work.
Also, because of the ratios, it is probably hard to match it on RPMs for an electric motor.
And you have to weld the 4wd center diff, which is usually some kind of viscosity coupler, when talking about older cars (without electronic guided 4wd)
4: Try to drive the front wheels with electric motors. This would make it 4wd and has some grip advantages.
However, even though it might grip better, I want it to remain a (mainly) rear wheel drive car because that is why it drives so nice.
5: Similar to point 1, find some space to fit an electric motor parallel to the petrol engine and use chain or other drive to connect electric motor to crankshaft pully.
In the MR2 that is possible, sacrificing trunk space. This would allow for some beefy electric motor putting down some power.
As engine can move in the rubber engine mounts, will the crankshaft location not move to much so that chain drive to fixed electric motor will work?
Downside is cutting the body, and it would be nice to be possible to revert all these changes to original.
Would allow for a 100kW motor if chain drive can do that, doubling the power of the car.
6: Go the Prius route. This would probably work out in term of drive axles since Toyota reuses a lot. Lots of work, but quite a power boost.
But it would ruin the driving experience if it would be the CVT operation. Even if CVT is faster.
I am afraid that only option 1 is not too intrusive for the car, and it somewhat of a small project that wouldn't take too long.
Of course at the same time it allows for the least amount of power.
Options 3, 4 and 6 I am probably never going to do.
Option 5 is an option if I feel confident about driving the crankshaft with a chain or other system. However, I know very little about chain and belt systems, so I am not very confident. Probably should talk with some motorcycle guys for that.
Thanks in advance.
Sorry that this is not a 100% EV question, but I already drive an EV (Bolt/Ampera-e) as a daily. And my classic petrol car (Toyota MR2 1985) is now slower than my daily driver
I already have knowledge about motors and battery systems, however, I am doubting how you could add a small system to an existing petrol car.
Converting to full EV is somehow easier because you bolt on the electric motor with a plate.
Making a hybrid of a rear wheel drive or 4x4 gives you some options on the axles.
However, with an FF or MR layout (and a 4 cilinder in a small car), there are very little options to add a motor to add power to the drivetrain.
You cannot do anything with the axles, and there is usually very little space to do anything on the timing belt side of the engine (in my car there is no space)
I can think of some ways at this point and I am hoping to see some examples. Or something I hadn't thought off.
1: Remove alternator and place a (small) electric motor there. Maybe some nice small motor at 48 or 96v, that goes on the belt drive.
This would make an easy conversion, but the downsides are that size and power is very limited. How much could you do over a belt drive? probably 10kW is already to much and break belts really easily?
It would already allow you to start the motor via the added electric motor and do some nice regen, but it is only a small boost in power.
Ditching the alternator and the starter and possibly the 12v battery, it wouldn't really increase the weight, so that is nice. (we are talking about a very small battery pack of maybe 5 kWh or so)
Would make things more efficient with only small boost in performance.
2: Remove starter motor and add an electric motor there.
Would allow for more power, but it is probably very limited what you can do with such a tiny gear?
Motor cannot be to big as it will stick out to much from the ICE engine.
3: Try to get a gearbox for a 4wd version of the same car, and connect the output to the electric motor.
(in my case a corolla 4wd gearbox?)
This is already getting complicated and needs quite some work.
Also, because of the ratios, it is probably hard to match it on RPMs for an electric motor.
And you have to weld the 4wd center diff, which is usually some kind of viscosity coupler, when talking about older cars (without electronic guided 4wd)
4: Try to drive the front wheels with electric motors. This would make it 4wd and has some grip advantages.
However, even though it might grip better, I want it to remain a (mainly) rear wheel drive car because that is why it drives so nice.
5: Similar to point 1, find some space to fit an electric motor parallel to the petrol engine and use chain or other drive to connect electric motor to crankshaft pully.
In the MR2 that is possible, sacrificing trunk space. This would allow for some beefy electric motor putting down some power.
As engine can move in the rubber engine mounts, will the crankshaft location not move to much so that chain drive to fixed electric motor will work?
Downside is cutting the body, and it would be nice to be possible to revert all these changes to original.
Would allow for a 100kW motor if chain drive can do that, doubling the power of the car.
6: Go the Prius route. This would probably work out in term of drive axles since Toyota reuses a lot. Lots of work, but quite a power boost.
But it would ruin the driving experience if it would be the CVT operation. Even if CVT is faster.
I am afraid that only option 1 is not too intrusive for the car, and it somewhat of a small project that wouldn't take too long.
Of course at the same time it allows for the least amount of power.
Options 3, 4 and 6 I am probably never going to do.
Option 5 is an option if I feel confident about driving the crankshaft with a chain or other system. However, I know very little about chain and belt systems, so I am not very confident. Probably should talk with some motorcycle guys for that.
Thanks in advance.