 R07 engine valley plate to route coolant to the cylinder heads and keep the intake manifold “dry” and therefore cooler for a denser fuel charge. |
The raised cam also provides clearance for inboard piston squirters that spray the underside of the pistons with oil for cooling their tops. I had an turbocharged import engine that had these oil squirters stock from the factory in the ‘80s, and the late Randy Dorton of Hendrick Engines showed me how they were hand-installed in the SB2s years ago. Lots of work, but effective in prolonging piston life.
The camshaft tunnel is isolated from the crankcase (basically an enclosed tunnel now) to minimize windage losses caused by oil falling onto the rotating crankshaft assembly from the cam, and to contain the valvetrain parts if there is a catastrophic failure.
Contrasting completely from the SB2's unique "mirror port" cylinder heads, the R07's aluminum cylinder heads resemble production LS-series cylinder heads – they have alternating intake and exhaust valves. The R07's shallow valve angle makes for a compact, efficient combustion chamber design that produces the required compression ratio with a lightweight flat-top or slightly domed piston.
Of course, GM Racing engineers and the teams optimized the R07's intake port layout for the single, centrally mounted four-barrel carburetor mandated by NASCAR. No EFI in Cup racing.
The aluminum intake manifold has an extended plenum to equalize fuel distribution among the cylinders. The manifold is dry; a separate valley cover carries coolant from the cylinder heads. The R07's distributor – yes, a distributor is still used in this engine for Cup racing -- is located at the front of the engine (finally!) to ease manual adjustments in ignition timing. No electronic ignition management allowed in Cup.
The Chevrolet R07 rocker covers are rigid cast aluminum with O-ring seals. The covers incorporate integral valve spring oilers that are pressure fed from passages in the cylinder heads, eliminating the need for external oil lines – a task the teams used to have to spend precious time to do. GM Racing also designed a high-efficiency water pump and a carbon fiber front cover that shields the aftermarket camshaft belt drives used by NASCAR teams.
The R07 has provisions for driving a conventional diaphragm fuel pump off of the camshaft – but it’s left unused by Cup teams. A remote-mounted mechanical fuel pump can also be driven via a cable from the rear of the camshaft. When using the cable drive, the fuel pump can be relocated to the rear of the car near the fuel cell. This enhances safety in an accident by mounting the fuel pump in a less vulnerable location – particularly during a right-front hit into a track wall, which can shear off a standard-mount mechanical fuel pump.