In this latest episode of “Faces of GM”, Jim Campbell, Vice President of Chevrolet Performance, heads to the GM Wixom Performance Build Center, in Wixom, Michigan to personally put together the heart that will power the unique number 69 COPO Convertible – the supercharged 327 LSX .
Chevrolet plans to auction off the convertible COPO at the upcoming Barrett Jackson Scottsdale event on January 19th. All the proceeds from the car will go directly to the American Heart Association, and some lucky guy or gal will get a piece of Chevrolet’s history.
In the video, Campbell bolts together the 327 LSX from bare block to a rotating long block with the help of all the Performance Build Center’s awesome tools and machines. One of the coolest machines is the head bolt Machine, which tightens all the head bolts down at once. Can you imagine being able to install your cylinder heads in a matter of seconds, with no worry about torque specs?
One of the most interesting parts of the video is when they have the long-block completed, Campbell bolts on an LS7 intake and exhaust manifolds, and wheels the engine to the cold test cell. We were curious about what goes on during the cold test, and why they use the LS7 parts specifically. So we called up our buddies at Chevrolet Performance, and got in touch with Engineering Supervisor, Robert Nichols. “Basically the LS7 parts act as adapters to hook up to the test machinery,” he tells us. “We regularly hook up to LS7s during our normal production process, and we use those parts on the COPO engines to be able to hook up to our cold test fixtures. We don’t need the supercharger in place for the test.”
During the cold test, an electric motor spins over the LSX and air flow is simulated through the entire engine. The engineers then read the pressure of the air coming in through the throttle body and out the exhaust with transducers, and compare the sensor readings from known-good engines.
“We’re making sure that the long block assembly of the engine is functioning and sealing,” says Nichols. “We have a torque transducer between the engine and the electric motor that can tell exactly how much compression each cylinder is making, and shows us how well the valves and rings are sealing. We test the oil pressure to make sure the oil pump is functioning correctly and to see if the bearing clearances are good. We also use accelerometers on each side of the block to detect the vibrations and make sure there is no excessive valvetrain noise.”
The engineers also check the ignition and timing during a cold test. They even have sensors that we drop over the coil packs that can detect the electromagnetic field over them, and even tell if the spark plug gap is correct. Very, very cool stuff.
Finally, after the LSX checks out in the cold test they move it to GM Racing side of the shop, where the big 4-liter Whipple supercharger is bolted on, along with all the finishing touches. Campbell is sure to mention that the engine is “rated” at 550 horsepower. However, based on the build specs alone, we think that might be a bit on the conservative side – don’t you?