# Fiat Punto - Potential Project



## mmw109 (May 28, 2010)

Based on the low response rate, I guess not many people have experience with this generation of Fiats.

Perhaps people could still help me with my basic questions.

1. CVT gearboxes : Has anyone used these in EV conversions before and with what success ?
2. ECU : Can the original car's ECU be kept on (to keep running all remaining systems such as auto, ABS/ABD, mileage ...).

(This "Continuously Variable Gearbox" gearbox is essentially two conical pulleys with a belt between them I think. The belt just gets slid along to change the ratio in a 'continuous' - manner. These boxes are not able to handle very high torque due to potanetial slippage, but on small cars like the punto, I've found it to work very well).


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## Woodsmith (Jun 5, 2008)

In terms of the ECU, keep everything. You wouldn't want to find some systems stop working because a sensor or a bit of loom is missing.

The CVT may or may not be a problem.
They are usually designed to adjust ratios to suit the torque/power curve of the original ICE and may not take to the output of the motor as well. It might not be able to cope with full torque at zero, or very low rpm.

Also, to keep a series motor efficent it would prefer to run at its maximum rpm but there is no torque there. Again the CVT might not cope with that either.

There is a thread in Tech about using automatic transmissions. Reading that may give you some insight that might help your decisions on using the CVT.

Where are you based? Any photos of the car? Some members may recognise it by a different, local, model name.


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## mmw109 (May 28, 2010)

Thanks for your reply.

Here are some punto details.
http://www.moderncars.co.uk/fiat_punto.html
The engine bay shown here is off the 8v engine, mine is a 16V engine, that already uses a potbox for the throttle control. The ECU also controls the engine timing (no distributor).

I suppose once installed, it might take some experimentation to get the gearbox to behave like we want. It does have various options. "economical", "Drive" and "Low" which aim to keep the engine at three different rpm's. Or if no luck, then it can pretent to be a manual sequential box, so could just be left in 2nd or 3rd.

Unfortunately, this project looks like it may never happen or at least not for some time. Or I may opt for a simpler car as my 'first' conversion instead (e.g. 2CV).


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## Woodsmith (Jun 5, 2008)

If you have the facilities to work on more then one project then it mau be worth keeping the Punto to one side as you learn on a simpler project. That is how I ended up with an MR2 as a slow moving project and a compact tractor as a s fast moving project. The tractor is the learning curve and test bed for ideas and the pack and controller will be used to test run the MR2 before I get higher voltage parts.

A 2CV should be a nice little project.
A later one with disc brakes should be good. You may be able to get reasonable urban performance from it being so light weight.


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## mmw109 (May 28, 2010)

I have no facilities, the punto is still in use. but I might be able to take over my dad's garage with a 2cv project, as he is pretty keen on that sort of thing. I remember him spending ages in his land rover with a water bottle attached to the air intake to try and increase efficiency. Have to find the right car first, they don't seem to be as common as they one were .


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## Duxuk (Jul 11, 2009)

CVT transmissions use rollers, that is cylindrical weights which are flung out by centrifugal force to push against curved ramps. The shape of these ramps determines how far the conical pullies on the "variator" are pushed together. The other pully is spring loaded to keep the tension. You can change the weight of the rollers to change the characteristics for differing use. Lighter weight rollers will effectively "gear it down". You can even just remove an equal number of rollers in a symetrical manner to get the same effect. In other words CVTs are easy to adjust to different motors. You may be able to get heavier rollers from a more powerful version of the car or another car using the same transmission. A lot of this goes on in the world of modern scooters which almost universally use CVT. My "dream EV" would have 2 throttles. One to vary the voltage at speeds of up to 40mph. Then at maximum voltage a second pedal would vary the ratio of a CVT hydraulically to give 40-80mph, all at max. voltage. Well I can dream can't I?

Andrew.


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## mmw109 (May 28, 2010)

Kind of like a helicopter where the pilot adjusts the rotor pitch ? We can but wish ...

The existing CVT must have some adjustment, as it can select 'gears' (pre-adjsuted rations in 1-6) or operate at any of three target points. So using an automotive CVT, you would only need, to get a way to access the control electronics ('only'...)


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