Is my friend talking **** ?
 

A buddy of mine just told me he bought a 67` 912 with a roller crank motor that was built for racing. He says that its the original motor from the car and porsche built 201 of them to be legal to race in the scca events. Sounds like a sham to me. Is there such an animal ? Oh yea its one of those found it in a barn stories although he asked me to help him retrieve it this weekend.

kurt

912 roller crank
 

The 67' 912 has a Super 90. The same motor used in the later 356's. I know there were roller crank motors for those cars. I don't know whether or not if there was a racing 912 that was delivered with that motor though. But the parts were there so who knows it's very possible. The 912 aways seems to be a side note when people talk about 911's in books. It's hard to find any real info on them.

Bobby

Bobby,

The 356 Super 90 and 912 engines didn't use a roller crank ... that was the Hirth roller-bearing crank for earlier 1500 Super engines. There were also aftermarket SPG rollers sold by EMPI in the '60's for 36-horse pre-1960 VW 1200 engines, which were what the 356 engines were based on, that would also fit in a 356 engine.

There is plenty of information out there on the 356 and 912 engines in books by Clymer, Elfrink, and, of course the various Pellow writings which deal with that minutiae of the 4-cylinder variety!

www.hcpresearch.com

Thanks for clarifing Warren. My writing skills are lame. I didn't mean to suggest that the Super 90 was a roller crank only that it was used in both cars. So if some 356's had roller crank motors ie. (the 1500 you mentioned) then why not for the 912 as well.

Bobby

Bobby,

It was undoubtedly a matter of expense, and practicality ... the four-cam Carrera engine used one, but it was a pure racing engine, so higher maintenance and repair costs were to be expected. If the Hirth cranks were damaged by oil contamination or lugging the engine, they had to ne replaced as an entire unit with rods ... a VERY expensive proposition, because the individual joints were splined and pressed together with the rods and roller bearings at the factory, and had to be sent back to the factory to be refurbished ... time delays, and big $$$.

The conventional balanced and counterweighted crank design of the Super 90 engine proved so good and reliable that the Hirth roller cranks of the Carrera engine were not needed in street engines, and that the high cost couldn't be justifed. Even the pure racing engine designs stopped using them in the '60's.

You hit the nail on the head Warren. I had a 67' 912. It was my first Porsche. That car was a piece of crap. It had been so abused and worn out that when I backed out of the driveway, which was sloped down to the street which sloped back up, that I made sure my hand wasn't on the car door window frame where it met the roof. Other wise it could pinch the hell out of your hand. The car had only one good part left. The motor, which was still running strong although a bit leaky cause of the old seals.

Bobby