Wrapping-up this series, we’ll examine a few other interesting features of the GM LS7 V8.
The airbox might be the bane of cold-air induction vendors everywhere, utilizing a Donaldson air filter and
providing 20% more flow than the system used on the standard LS2. Building on the cross-ram design of other GenIII/IV
engines, the LS7 gets its own intake that’s proportionally larger and matches the head’s raised intake runners. The
exhaust manifolds are actually tubular headers, manufactured using GM’s hydroforming technology and welded into a
complete assembly. The rest of the exhaust is a full three inches in diameter, meaning that aftermarket exhaust vendors
likely won’t find much room for improvement.
The cam specifications are said to be in the
neighborhood of 211 degrees of intake duration and 230 degrees of exhaust duration at 0.050? of valve lift, which is
larger than other GenIII camshafts but significantly smaller than would be used by most aftermarket builders for an
engine of this performance level. That speaks highly of the cylinder head?s performance, while greatly easing the task
of achieving emissions compliance and acceptable drivability. The lift at the valve nears 0.600?, which is necessary to
make the most of the larger diameter valves. Generally speaking, a lift of a bit more than 25% of the valve diameter is
favorable, as this creates a valve curtain area (the area formed by the circumference of the valve and the lift off the
seat) that?s slightly larger than the throat area (the area just prior to the valve seat, typically 85-90% of the valve
diameter), and allows the port/seat junction to limit peak airflow.
Without a huge bumpstick, the 11:1 static compression ratio must produce a rather high
dynamic compression ratio (which
unfortunately is rather difficult to accurately calculate without knowing the intake valve closing point). That, of
course, will necessitate premium fuel. Speaking of fuel, EPA estimates put the fuel economy at 16 MPG city, 22 MPG
highway; shocking for a vehicle with this much performance.
There?s more – much more – to the new Z06 than just its engine specs (the same of which couldn?t be said for the
ZR1). But so long as internal combustion engines dominate the automotive world, they will form the heart and soul of
performance cars. Rest assured that the Z06 will be hearty and soulful.