615-horsepower Mopar Six Pak Test is Video Diary of Day on Dyno

[usmusclecars]

With a generous 21-minute length, this dyno video of a Dodge 440 Six Pak goes well beyond the typical power run and numbers rundown. It’s almost like a diary of a half-day session, showing the hookup, break-in and tuning of a new engine.

The Mopar big-block, which is poked and stroked out to 493ci, posted a strong pull of 615 horsepower with 606 lb-ft peak torque. It’s built around a freshened ’66 block fitted with a steel Molnar crankshaft, Ross pistons, Cam Motion cam, Milodon oil pan, Holley carbs and Edelbrock heads and manifold. Compression ratio is a spirited 10.25:1 but still very streetable.

Testing was conducted at R&R Performance, a shop familiar to EngineLabs readers as it has seen some very unusual engines, including a 702ci V12 and an updated Ford SOHC cammer. Owner Ron Quarnstrom is one of busiest dyno operators in the country, usually running two engines a day on his SuperFlow dyno. EngineLabs asked him to enrich the video diary by summarizing what happens during a typical 1/2-day session.

He says mounting the engine and hooking up all the connections takes about an hour, with an occasional supercharged or E85-fueled engine taking longer. During cold weather (the shop is in Minnesota), a heater warms up the engine oil. If the block is really cold, it will be filled with hot tap water. Quarnstrom spins the motor briefly without fuel on to set the timing, then turns on the fuel pumps to check for fuel leaks around the engine and fill the carb bowls.

Engine break-in and gradual pulls

“I then pump the throttle three times and crank it over,” says Quarnstrom. “If the engine doesn’t start within one second, something’s wrong.”

With a new engine, Quarnstrom immediately goes to 2,000 rpm for about 20 minutes to break in the cam. The engine then comes down to work on idle quality and reset the timing. Since it takes about 30 horsepower for engine to keep a car at a 60-mph cruising speed, Quarnstrom has devised a unique step test to prepare the engine for a full WOT pull.

“I run it at 30, 60, 90 and 120 horsepower loads,” says Quarnstrom. “I get to look at the carb at three different throttle positions, just on the primaries. I can tell if it’s rich down and then goes lean up higher. That way I’ve already checked it at 90 and 120 horsepower to make sure it’s not lean before a 500-horsepower pull.”
R&R makes four WOT pulls, checking to make sure the engine gets stronger on each pull. Engines usually pick up two to four horsepower with each pull; but on the fourth pull, there won’t be an increase.

“The power increase is from the rings coming in,” explains Quarnstrom. “The reason I know this is that I have a blow-by meter hooked up. On the first pull it’s 5 or 6 cfm, then 4 or 5 cfm and then settles down to around 3 cfm.”

Quarnstrom won’t pursue any tuning changes during these initial runs because there’s no way to know if the improvement is a result of tuning or the rings. From the fifth pull on, then tuning changes can be addressed. R&R also has a variety of carb spacers and carbs to test.

“If I question the carb, I can put one of mine on just to show the customer what he could have,” says Quarnstrom.

The half-day session takes care break-in and tuning. A full day can test cams, heads or conduct precise EFI calibrations. But as you can see in the video, the Mopar Six Pak test discovered problems with valve-cover gaskets, made an ignition swap and also changed headers. For more information on dyno testing, check out the story on “Taking Your Engine to a Dyno Facility the First Time.”