High Revv, Light Weight, What am I missing?/Different type of Conversion Options

[Gunn1]

With all of the talk about light weight, high horsepower replacement engines for our favorite Porsche, have we forgotten all of the lightweight, high revving 4 strokes out there? There are dozens of possible alternatives currently being housed in various motorcycle brands. Are there any working examples of this type conversion out there? Thinking besides the lightweight, they tend to be compact and have smaller cooling, electrical and mechanical systems. Would seem using one for a conversion would be a no brainer. What am I missing?
Thanks

[ClayPerrine]

Back when I was fixing cars for a living, I had one of these come into the shop:

(IMG:http://www.914world.com/bbs2/uploads_offsite/www.discountcabrio.com-1143-1457287848.1.jpg)

It's a Honda 600 convertible, built in 1965. It has a 600cc motorcycle engine, connected to the rear axle by a long motorcycle chain. To get reverse, Honda put a gear in the center of the sprocket that spun the wheels backwards. That gave you 6 sequential gears, both forward and reverse.

Well, the owner had just bought the car, and he said it didn't pull very strong. When I examined the car, the original engine had been replaced with a 1100 Honda Hurricane motor, complete with Kerker header and a bunch of high performance mods. It had 10 inch X 10 inch wheels and tires, full harness assemblies on both sides, and the Hurricane instruments had been beautifully grafted into the dash.

I said it sounded fine, and asked him to take me for a ride. Well, he was shifting at about 2500 RPM. Needless to say, shifting that early killed all the performance. So I asked if I could drive, and he let me. About the time I hit 6K on the tach, I hear a loud "OOOOOHHHHHH SHHHHIIIIIITTTTT!!!!!!" come from the passenger seat. I then proceeded to smoke a brand new Corvette up until the next light. After that the vette got me for about 50 yards... until I got he Hurricane spooled up.

I explained to the delighted owner that he would have to tach the engine up to get the car to move in any reasonable fashion. I didn't charge him anything and thanked him for the drive. I also told him that if he wanted to sell it, I wanted to buy it.

He left with a roar and a shit eating grin on his face.


The thing about that car was that it only weighed 1200 LBS, about what the motorcycle weighed. So the engine was fine with pulling that load. If you tried that in a 914, you would be adding another 900 lbs of weight, and you would have to rev it even more to get it to move decently.

In all truth, a motorcycle engine is fine in a very, very light car, but by the time you get safety and confort stuff on the car, you are just outside the envelope for that type of engine.