So I was having a discussion the other day while watching the local b-ball team miss free throws. .. good game even though they lost.
What about using a transverse mounted fwd trans in back and adapting the trans input shaft onto a bevel gear with a driving gear mounted to the driveshaft output? Sure, sure, you'd be modifying the bellhousing, would probably trim some of it off. It still puts a clutch/bellhousing assembly on the engine so you don't save on footwell space but it moves the 75+ lbs of transmission to the rear of the vehicle. .. I'm thinking (?!??
) you could maybe have a flat plate bearing carrier attach to the existing bellhousing mounting points and hold the end of the trans input shaft in place, a (driven) gear carrier flange splined onto the trans input and an attached housing to hold the driving gear in place, wouldn't even have to share the sump with the trans.
You wouldn't care where the driven gear sat on the spline as long as it had full engagement with the spline and the driving gear so the right angle drive could be assembled then bolted to the trans with an o ring seal on the inner side.
Gear size might be a problem since you don't want a reduction and would prefer a slight overdrive. .. makes for a big set of bevel cut gears to get the tooth contact desired and you'd actually want some sort of ratio just to keep face wear down.
Front engine/driveshaft/rear wheel drive requires a right angle gearset anyway, basically your just moving the power loss further up the supply chain. ..
The driveshaft should get a center support which could be mounted onto the interior of the tunnel easily enough.
Engine left or engine right orientation of the transmission would affect weight balance. .. seems like "engine right" orientation would make it easier to create the gear set in the smallest space in my opinion.
Engine choices become limited only by your ability to make a clutch housing with output shaft and transmission torque capacity.
I'm assuming that you would use the tunnel as a "torgue tube" of sorts but may need a guibo or similiar just to avoid vibrations from non parallel shaft alignment caused by engine or transmission rotation on their respective mounts.
The driveshaft would tend to wind up if you used a line-lock and slipped the clutch at the starting line so a full throttle launch might get interesting
Seems to me you could end up with a locost version of this
http://www.xtrac.com/pdfs/1007%20-%20SUPERCAR%20TRANSVERSE%20SYNCHROMESH%20GEARBOX.pdf with the gearset preceding the diff.