recall the era when Detroit dominated the world of muscle cars
with earth shaking large displacement engines?
The Chevy 427 V-8 burst upon the automotive world powering
Junior Johnson's Nascar racer to an amazing 166 mph lap at Daytona
in 1963. Soon afterwards it went into production and became the legendary
mark IV or as known to most of us the Rat Motor.
Chevrolet has brought out a new ground shaking monster motor
for 2006 to power the 2006 ZO6 Corvette. The engine displaces
427.6 cubic inches (7008cc). The new ZO6 shares nothing with the
big block 427 of old. It is instead a new punched out version of
the LS2 small block and now pumps out over 500 HP. That's right!
500 HP! More then previous 427 or 454 big block engines. The power is
rated as SAE net instead of gross HP as in the 60's when the
prehistoric monster rat motors roamed the streets.
The LS7 is the newest small block dubbed the Gen IV by GM. The Gen
IV has been completely reworked to handle the larger displacement
and power output. The new block has a 4.13 bore and stroke of 4.00
with a bore spacing of 4.4 inches. The Gen IV block uses thinner
pressed in liners instead of cast iron liners of the older base
The LS7 uses a forged steel crankshaft, forged steel main
bearing caps and titanium rods along with forged pistons. But
wait! it gets even better! There is an 8 quart dry sump oiling
system and the LS7 427 redlines at 7000 RPM. Hmmm, smells like a
race engine to me!!
Oh to get one of these under my right foot and go Porsche
hunting in the foothills. I always did like the big bore weapons!
But.. enough daydreaming, back to business for now.
The monster LS7 makes the big power using only 2 valves per cylinder
so everything is optimized for max flow. There is a new low
restriction air cleaner feeding a 3.5 inch throttle body.
intake manifold is composite and feeds massive CNC machined intake
and exhaust ports leading to 2.20 intake and 1.61 exhaust valves.
The latter having sodium filled stems for superior high temp
The new heads utilize a 12 degree angle to the cylinder bores for
better breathing via a more compact combustion chamber design. The
old LS2 used a 15 degree angle. Valve lift for the new LS7 is a
whopping 0.591 via 1.8:1 ratio rockers.
A compression ration
that reminds us of the old rat motor days is used: 11.0:1. This
helps extract maximum power and breathing and helps increase
combustion efficiency. Exhaust is handled via hydro formed headers
that feed two variable baffle mufflers via huge 3.0 inch exhaust
Variable baffle mufflers? That right, at low revs (below 3500 rpm)
gases pass through a single well muffled system. Punch it and a
high vacuum bypass opens up allowing for an almost straight
through shot right through to the back of the exhaust system. I
can't wait to hear the music this system is sure to produce.
Maximum of 500 HP is
reached at only 6200 rpm. Peak torque of 475 pound-feet is reached
at 4800 revs. To give an idea of how good this motor really is,
385 pound-feet of torque is reached at only 1600 revs. This is the
maximum pound-feet of torque the new BMW M5 musters at 6100 rpm.
season is now open. Bag em quick while there is still good
Power is transferred through a high capacity clutch and gear
changes are made through an upgraded HD version of the corvette's
rear mounted 6 speed transaxle. Included this year is a trans
cooler incorporated into the radiator. The trans oil flows through
a second heat exchanger to control the temperature of the
differential lubricant before returning it to the