Based upon exactly one ride in a Caterham Hayabusa-powered Seven, I went with a car engine:
KB is right on these points, but as with most things, you can find get-arounds (or you must just learn to live with it)1. Bike drivetrains don't have a flywheel, and the consequences are noticable when driving at a constant speed. The car gets into an odd oscillation where drivetrain backlash causes a slight but noticable back-and-forth jerking. The car speeds up a tiny bit, causing the driver's foot to lift very slightly off the gas, causing the car to slow down, which causes the driver's foot to very lightly press more on the gas, and it repeats. If the driver barely accelerates or decelerates, the problem vanishes, so to avoid it, the driver has to always be speeding up or slowing down.
This is a very real, and very annoying result of the bike transmission's straight cut gears.. I had to retrofit a giubo (rubber donut) into the driveline and the oscillation effect is virtually gone- a true night and day difference in the BEC driving experience.. Just my opinion, but all BECs would benefit from using a TRT or Giubo in the driveline2. Gearing. 60 mph is about 6000 rpm - I kept looking for another gear.
This is 100% true and it is tiresome.. do not plan to drive your BEC cross-country.. despite the high rpms on the freeway, I still take mine out of town all the time (recently went 8 hours one way), and it was livable with noise-cancelling earbuds and music -hell, I drove it to work this morning 3. Hair-trigger clutch. Even though the owner had the car for several years, he regularly stalled it.
Something's wrong with the pedal ratio (needs to be about 7/1, maybe more). If the owner is stalling it, it needs a rework.. Mine took some fiddling for setup, but it now acts no different than a 'normal car'.. easy-peasy to daily drive..4. No low end. Yes, it may have 180-200 hp, but it's all up at the high end and takes time to get there.
In general this is true as most bike engines are peaky, but not all of them (mine only has 110HP).. BECs need to be wrung out a bit more than a 'regular' car (mine likes for me to shift above 8k, but don't mistake this for total lack of torque).. I can lug it around if I want to- pretty good grunt even down low-- part of it is my chosen engine, and part of it is the 1.9 bike tranny gear reduction --on paper I get to nearly double my bike's 55 ft lb rating as my 'geared torque' is closer to 100 ft lbs at the crank; FAR more than my car's OEM torque); but in general, you do in fact need the revs to get the 'big' power/torque5. No reverse. Even though there are solutions, it gets annoying.
True is true 6. Unless the intake and exhaust perfectly copy the bike installation, power won't be as claimed.
Those engineers area a clever bunch.. as stated, be as true as possible to their design to get the power/torqueFor a trackday car, absolutely. For the street, not so much. Believers can claim that the above doesn't bother them, which is fair enough, but the issues do exist.