A camshaft for a turbo engine is pretty tricky and our old NA engine’s high revving cam had to go. Brian Crower custom ground us a cam for our special 50mm roller bearing journals. A radical roller profile, our BC cam has a pretty short duration and a spread lobe center compared to a typical racing cam. It does however have a very high lift. The short duration and high lift leads to very fast valve motion which means you have to have some trick stuff to contain it all. You want a wide lobe separation angle to keep from blowing boost out the exhaust port. The firing order from an LS engine, switching cylinders 4 and 7 was also used to improve cylinder filling of the rear cylinders. This firing order is also a little easier on the engine internals due to improved crankshaft harmonics and better cooling.
You can see the radical profile of the BC cam’s almost square lobes! The milky lustrous look is WPC treatment we applied to the cam to reduce friction,
The BC valve springs are vacuum degassed chrome vanadium steel. The springs are a dual spring with a flat wound damper inbetween the inner and outer springs. The damper helps attenuate harmonics induced spring surge. The springs have been WPC treated to improve their fatigue life. They also run much cooler after treatment.
Brian Crower provided roller lifters. Roller lifters can handle a much more radical cam profile to maximize area under the lift curve as well as have reduced friction. BC lifters have pressure fed rollers for a longer service life.
Instead of a roller chain we opted to use a Jesel belt drive. A belt drive helps protect the valve train from crank harmonics and whip and runs smoother with less friction. The belt drive is run dry so oil is not in the front cover area. In fact a front cover is no longer used. A big advantage is that cam timing can be quickly and easily tuned.
As you can see our current small block is a far cry from what you would find in production Chevys on the street. The design is old but not obsolete by any measure just yet. Stay tuned in our next edition we will get into the really trick and unusual stuff, the heads and turbo system!