Technical High ratio gearbox

[ivantate]

I am thinking about upgrading our MPI Sei Sporting to a 1242 engine. If I do this I would like to fit the gearbox out of a SX.
I hope the larger engine will pull the higher gears without affecting performance.

Does anyone know if it is just the final drive that is higher or all the gears are different? or if anyone has one for sale?

 

[chaos]

I am thinking about upgrading our MPI Sei Sporting to a 1242 engine. If I do this I would like to fit the gearbox out of a SX.
I hope the larger engine will pull the higher gears without affecting performance.

Does anyone know if it is just the final drive that is higher or all the gears are different? or if anyone has one for sale?

Do you mean a Sei SX? If you do, then the ratios are a little bit longer over the sporting which would mean you may lose a little acceleration but the engine will run at a lower rpm for a given speed, which should turn out to be more economical
As to whether the not the longer ratios are a result of a different FD or totally different gear ratios (or both), I have no idea TBH

 

[Asteris]

Differential gears are as follows:

58/15 for Sporting
57/14 for Sporting Abarth and Schumacher edition
57/16 for Suite, S, SX, Young and the rest

 

[Advanced Driver]

Do you mean a Sei SX? If you do, then the ratios are a little bit longer over the sporting which would mean you may lose a little acceleration but the engine will run at a lower rpm for a given speed, which should turn out to be more economical
As to whether the not the longer ratios are a result of a different FD or totally different gear ratios (or both), I have no idea TBH

You should be able to hold lower gears for longer though. I've only driven my 899cc Sei, so I don't know how torquey the other engines are, but if the 1.2 has a lot more torque then it may even be a little faster with taller gearing.

There is also a difference between racetrack performance, and performance on public roads. Being able to reach 60mph in 2nd (I don't know whether that would be possible with the SX 'box) can make a significant difference on a 60mph road.

 

[HP]

1242 on Sei S gearing was slower than 1242 Sportings at the drag strip last year.

 

[garethgje]

I am thinking about upgrading our MPI Sei Sporting to a 1242 engine. If I do this I would like to fit the gearbox out of a SX.
I hope the larger engine will pull the higher gears without affecting performance.

Does anyone know if it is just the final drive that is higher or all the gears are different? or if anyone has one for sale?

HI similar thread here
https://www.fiatforum.com/showthread.php?t=39784
hope it helps.

 

[ivantate]

Cheers.
Its a Sei Abarth so its 57/14 at the moment. Economy, wear and tear and comfort would be the reasons for changing.
I guess finding a Punto 75 engine (sounds like it fits an MPI) would readdress the performance balance.