[Mr. Wyndham]

From: http://media.gm.com/content/media/us...eb/0214_camaro

This is pretty cool!

Precision Machining Process Makes for Perfect Bores

[DETROIT – Deck plate honing a cylinder block, a precision-machining process typically reserved for high-performance engines, will be used on the Camaro ZL1 6.2L supercharged V8, helping maximize engine life, reduce friction between engine parts and increase horsepower.

Deck plate honing refers to a machining process in which aluminum plates, sometimes called torque plates, are clamped to the block, simulating the cylinder heads, before the final bore and hone of the cylinders takes place. The clamp load of 10 bolts per head creates normal, minute distortions in the block and thus makes the bore slightly out-of-perfect shape or cylindricity.

While the simulated cylinder heads, or deck plates, are attached to the block, a boring machine does its work boring, and then honing each cylinder. Later, when the actual cylinder heads are assembled to the block under identical torque loads, the cylinder bores are near perfect for the engine’s lifetime of piston travel up and down in the bore up to 6,200 times a minute.

“It amazes me what GM does with some of their production engines,” said Andy Randolph, engine technical director at Earnhardt-Childress Racing. “Deck plating is a time-consuming process that fine tunes the bore to get every ounce of power, torque and durability possible. It’s standard practice when building high-end race engines. It tells me the Camaro ZL1 will have some serious performance.”

The deck plating process is used in applications where cylinder head pressures are greater than average, to ensure cylinder sealing and prevent scuffing of the piston against the bore wall. In the Camaro LSA engine, this means improved bore life and ring sealing. True bores and better sealing are keys to optimizing power. This is a common process also used with the Corvette ZR1 and Z06 blocks.

The deck plate bore-and-hone process uses billet aluminum plates with steel bolt sleeves for compression limitation. The plate’s bolt attachment points have the same height and clamp loads as the actual cylinder heads. The LSA cylinder block is made of 319T7 aluminum and has cast-in-place cast iron cylinder bore liners. The final honing process brings the final 103.25 mm (4.06 inches) bores to within a tolerance of eight microns or .00031 of an inch. The deck plates remain installed for the final honing of the crankshaft bores.