by Mike Buckel, Ramcharger • courtesy of the North Georgia Mopar Club
The Engine Lab Race Group continued to focus on Hemi circle-track and drag-race engine performance improvement. The single four-barrel ram manifold for the circle-track engines was a huge challenge, due to uneven cylinder-to-cylinder fuel distribution.
Drag racing had taken a full turn away from gasoline, and we needed data on nitro-fueled engines. I successfully ran methanol fuel, but there was no way a nitro-fueled engine would last through a 10-minute, full-power dyno run.
I consulted with John Platner, a graduate of the first Chrysler Institute class, who had worked on the inverted V16 airplane engine and the A-311 Indy car engines. He had run up to 15% nitro and concluded that it could quickly destroy an engine. He was currently running single-cylinder engines to characterize emissions.
A solution appeared to be in dyno room 7B, a high-capacity dyno with a flywheel on the output shaft. The flywheel was equivalent in inertia to a loaded Imperial. This room was built to test automatic transmissions for high-performance engines, and had bulletproof walls and windows.
The engine and transmission were installed at the input to the dyno. From idle, an automatic system would fully open the engine’s throttle, allowing it to accelerate up through the gears, loaded only by the flywheel. After shifting into high gear, the throttle would close, and a load switched on the dyno to slow everything back to idle where it would start over again. Testing in this room is one reason that the Torqueflite Super Stock cars did so well from 1962 on. We never failed a transmission throughout the Super Stock years.
The Transmission Lab had a room full of these engine/transmission/flywheel dynamometers that tested every engine/transmission combination in production. There was no shielding in this room, and there were a dozen or more engines running side-by-side at any given time. It was always a thrill to go by that room and hear what sounded like a lot of drag racing. I don’t remember how many cycles were in each test, but it was sufficient to make the Torqueflite the most durable transmission on the market. Back then most automatic transmissions would barely go 50,000 miles between overhauls.
The Rock Cycle test was another spectacular Transmission Lab test. The test consisted of rapidly shifting from forward to reverse with the throttle well open in a cloud of tire smoke. The test ran until the tires blew or until the programmed number of cycles was achieved. Because of carsickness only a few people could ride as observers during these tests.
Joe Nunez (“Dr. Zorba” because of his hair style) was a recent addition to the Engine Lab with a background in instrumentation, such as it was in those days. The idea of dynamically testing fuel engines was hatched after Nunez pointed me in the direction of the X-Y plotter that would plot two electronic inputs.
So we began by installing a standard 413 in Room 7B with soft rubber mounts under the front and rear center of the engine with the throttle outside the room at the dynomometer console. The engine would freely rock from side to side. An arm was affixed to the side of the engine and attached to the floor through a load cell. The load cell constrained the engine rocking while generating an electronic signal proportional to the engine torque. Engine speed was fed to the X-axis of the plotter and the load cell signal to the Y-axis. Calibration of the load cell was achieved by running the engine at steady state against the dynamometer and with test runs accelerating the 413 against the flywheel.
A 482-cubic-inch, 8.5:1 engine was built for the nitro test, and a small fuel tank installed in the room. The testing required getting the engine started, turning on the X-Y plotter, opening the throttle and watching the whole thing spin up. At 7,000 rpm the throttle was closed. On 90% nitro a power reading of 1,350 horsepower was attained, probably still a Chrysler record.
Rotary load cells were just being introduced to the market with the biggest rated at 350 lb.-ft. We tried one anyway. On the first run, the load cell failed and the prop shaft made at least one lap of the room. We found out that the windows had been installed backwards, with the clear glass on the inside and the bulletproof glass on the outside. We were racing this engine combination at 11.5:1 compression at 172 mph, while the 8.5:1 engine ran 163 mph. We estimated that the high-compression engine was developing about 1,000 horsepower more, 2,000+, than the low-compression engine.
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