after 25+years tinkering with all things Porsche,i considered myself a porschephile.but while watching an episode of chasing classic cars,wayne purchased,as he says ,the holy grail of 356's,a speedster GSGT with a four cam.i was not aware that the crankshaft was constructed one throw at a time with one piece connecting rods,apparently a wartime Germany machining process.man what a piece of mechanical artistry!
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All the roller bearing (most 4cam?) engines were built like that; more power than their plain bearing counterparts. The cons- detonation destroys the bearing cages right now! and these engines weren't expected to do more than about 30,000 miles between rebuilds.
I have heard of VW roller bearing cranks in 69 and 82mm. A mechanic friend (owned his own VW performance shop) built a 1750 or 1776 with dual port heads, stock cam, kadrons and a roller crank for his brother and the thing went and revved like it had a W110 or C35 cam in it. It was a really cool little engine! They can be rebuilt but (I believe) it's all custom work so it's worth a fortune.
The heat treating alone is a fortune....
Plus, the overall cam-driven, dual distributor ignition system was famously "bouncy" and those engines didn't start to settle down and run even half-way right below 5K rpm (and a lot of people say 6 grand). Those twin-cam engines were definitely NOT for the street.
Rainer Cooney at Meister Engineering in New Hampshire is reproducing 356 twin-cam engines, only HIS are crank-fired ignition (to overcome the terribly innacurate original dual disti system) and his engines are remarkably smooth, although a bit expensive.
A bit? I'm scared to ask.
Peter Venuti and I will be up there in a few weeks - I'll ask.
They were called Hirth cranks after the company that made them.
The Hirth cranks really didn't like low rpm lugging. And Porsche solved the distributor drive issue by moving the distributors from the cams to a geared drive off the crank pulley.
Absolutely beautiful art/machinery though.
