To see video of JMS' dyno run click here.
One of our favorite subjects here at Mopar Muscle magazine is engines, so it's no wonder we enjoy our annual Engine Challenge held each year at Comp Cams so much. Not only do we get to hang out at Comp's state of the art dyno cell and research facility, we also get to discuss Mopar engines with some of the top engine builders in the country during the competition. We vary the rules slightly each year, featuring a different Mopar engine in each of our Engine Challenges. This year, we chose the largest factory displacement Chrysler engine, the 440, and each builder had to use the same Indy SR cylinder heads, building what is commonly referred to as a "spec" engine because the major specifications of each engine are the same. As you can imagine, this was a close competition since all of the engines were limited to the factory stroke, a .060 inch overbore, and the same Rockett Brand 93 octane pump gas. JMS Racing Engines brought a strong contender to this year's contest, placing fifth with his 678 horsepower 440.
JMS Racing Engines was a newcomer to our Engine Challenge this year, but they made a lasting impression as their stout 440 screamed to more than 678 horsepower on Comp's engine dyno. Having made multiple pulls on his in-house dyno, Engine builder Mike Johnson came prepared to run his engine, and did very little tuning to optimize his combination while at Comp. His engine was tuned with 34 degrees of total ignition timing, and his carb was jetted with size 90 jets all the way around which Mike says made the most power on his dyno. Mike was so confident in his tune-up that he made all three of his qualifying pulls back to back in the first three minutes of his 45 minute qualifying session. Then after a brief cool-down he made his three judged pulls back to back as well. Having plenty of time left, Mike then jetted his carb with 92s, and bumped the timing to 36 degrees to make three additional pulls netting a best of 678.1 horsepower and 563.5 lb/ft of torque for a combined score of 1241.6.
Starting with a seasoned factory 440 block and a factory forged steel crankshaft, JMS Racing Engines utilized Ross PN 99764 forged pistons and RPM connecting rods as the foundation for their short-block. ACL main and rod bearings kept the rotating assembly spinning freely and JE piston rings ensured a tight combustion chamber seal. A Melling oil pump was used in conjunction with a Milodon PN30931 oil pan and windage tray to ensure this big-block received proper lubrication. All the machine work was performed in-house, and the rotating assembly was precisely balanced. A Professional Products PN 80013 SFI balancer was used to dampen any harmonics. To actuate the valves, a JMS custom roller camshaft was employed with Isky PN 1612RH "Red Zone" solid roller lifters. A JP Performance double roller chain and gears kept the bumpstick loping in time with the crankshaft.