AP Racing sells multi disk clutches down to 4.5 inches. I've never really cared about launching my car and would love to make the motor more responsive. The 20b obviously has more torque than a 2 rotor, but even so I'm not sure a multiplate clutch in that small of a diameter would be manageable on the street.

http://www.apracing.com/car/race/dat...CP6073-DE90-SF

 

i use an os gilken twinplate on my cosmo re, the plates are slightly larger than 6", it also has a light flywheel (11lbs)

makes the car very responsive, revs much quicker, and almost forces you to shift much quicker because the revs drop off just as fast

i daily drove my car all last summer to work (65mi round trip) no issues, but a tired left foot on holidays from stop and go

 

I have a Tilton 7.25" single disc for my racecar, a friend has the same in a dual disc version. They are good for about 300ftlbs per disc. When you get to the smaller clutches they don't even recommend trying to drive the car into the trailer with them. I would think that street driving would be similar on the clutch so smaller than the 7.25" might be a problem, an expensive one at that. The dual disc or triple disc Tilton would be pretty streetable and not cost multiple thousands to run.

 

If you use the rally type disc it's much more streetable and they last longer. The rally disc are the thicker version of the two types of metal clutches that Tilton offers.
The ultimate street or race would be the carbon clutch setup.

 

I installed a helix 7.25inch clutch on my old car, custom turbo conversion and I couldn't get a clutch that was OEM design to handle the power.

Used a cerametalic plate and was rated to around 380ft/lb before it went.

The clutch was hard to use as it wasn't hydraulic, very fine bite point so basically was either in or out.

 

Chris,

you forgot to mention that you want to use the car as a commuter/daily driver. year round. in the northeast.