TandemJeremy – Member

You will have many issues tho – with it being a front wheel drive car mating up the drivetrain will be hard. The motorcycle engine is unit construction – gears in the same unit as the crank – so its hard to use a car gearbox as you have to modify the crankcases in a major fashion ( the exception would be a K1100 bmw motor I think and some shaft drive twins)

You don't modify the crankcases at all. You run a conversion gearbox like this one and chaindrive from the engine to the gearbox. The drive shafts slot into this gearbox

Then you have the gearing issue – motorcycle engines rev to 10 000 rpm plus and will be geared for 200 mph at the red line in top for something like that kwak – so you need to drop the gearing hugely.

The ability to rev much higher is part of fun of it and the gearing is a minor issue and can be sort with the chain drive

Peak torque while similar will be at much higher revs than the car – 7000 rpm needed to get rolling – think of the poor clutch!

Heavy duty plates and springs will be fine for this

Then there is the physical size and shape – motorcycle engines such as you mention are DOHC with vertical intake manifolds – a bit hard to fit under the bonnet.

A large bike engine is significantly smaller than a car engine and gearbox of a comparable capacity

GTDave……the Kwak engine has as much torque as a standard 1.7 puma engine and 75 more bhp……should work

Ken – Hmmm – don't like that gearbox thing at all. Chain drive? No reverse? Motorcycle high and close ratio gears? I was thinking about mating a car gearbox to the motorcycle engine using a geared primary drive. I have heard of this being done. Basically cut the gearbox off the motorbike engine and bolt on a car gearbox. Motorcycle gear ratios are all wrong for car use.

I think you will find that including the intake trumpets the engine is considerably taller.

It has as much torque yes – but that torque is at much higher revs. Even dropping the overall gearing peak torque will be a twice the road speed in first gear making for a lot of clutch slip.

Having a love of the Puma still, I was thinking of what I'd do if I had the money to play with. Someone suggested an Audi FSI engine, but what I'd thought of was getting hold of a VAG TSi engine with a 7-speed DSG box. SEAT are using it in a new hot hatch, putting out around 180ps. Small, light engine, good fuel consumption, low CO2, would make a really nice, quick Puma that's fairly cheap to run.

Here we go, copied from Autocar, would be nice in a Puma:

A Swiss tuning company has created a 200bhp version of Volkswagen’s 1.4-litre Golf GT.
Sportec has tweaked the fuel, ignition timing and boost pressure settings of the turbocharged and supercharged unit, increasing power from the standard car's 158bhp.
The 1.4-litre unit now has 211lb ft of torque, whereas the new 2.0-litre Golf GTI produces 206lb ft.
The modifications have cut the 0-62mph time from 8.2sec to 6.8, while 111mph (180km/h) arrives 3.2sec earlier.
Fuel economy is only mildly affected, dropping from 44.8mpg to 42mpg. The conversion costs £550, including installation.

Not sure I'd use that kwak motor, it's good but I don't think it has the low end of the current Busa (certainly doesn't feel like it does in use, though that could be gearing). Better tuning options for the Busa as well, given its heritage. But then Busa engines are very expensive, for all these reasons.