If you think these engines look powerful bolted to the dyno stands, you should hear them m
With the seven participating Hemi Challenge engines at the Competition Cams research and development center, and the new Superflow 902 dyno installed in the test cell, the fun part of our competition was about to begin. Exactly how much power would these engines make? Would they all last at least six pulls on the dyno? Keep in mind, this was not just a single-pull, top-horsepower competition. Each engine had to make three qualifying pulls from 3,000 to 7,000 rpm before making the three judged pulls required by the rules of the competition, so builders had to build their engines to last. The flat-tappet cam requirement and the 93-octane Rockett Brand fuel also forced the builders to be creative in coming up with a powerful combination. Each builder had their own ideas about how to make power-we had heads from Indy, Stage V, Mopar Performance, and even one engine with '68 casting factory Mopar heads. Induction ranged from single Dominator or Demon carburetion to dual Edelbrock carburetors, and even a tunnel-ram sporting dual 750 dominators.
Did the engines make power? You bet. Did we come up with a winner? Not yet.
Remember, the whole purpose of this competition was to show the readers what is available when it comes to the Hemi engine and to highlight each builder's techniques for making power. the retail cost of the parts in each engine will be divided into the horsepower/torque readings from the dyno, so the leader will not necessarily be the builder who made the most peak power, but the one who delivered the most bang for the buck. As of this issue's deadline, we haven't factored the cost portion of the contest, but we do have the dyno results and feel you'll be impressed. All of the engines survived the contest and made very respectable power, and while all were streetable engines, some were a little more exotic than others.
We'll highlight each engine in this article and give you the results of the dyno portion of our competition, but you'll have to stay tuned for the final results, which will be coming in a future issue. Also coming in future issues will be the details of each engine builder, their shop, and an in-depth analysis of each engine in our competition. Follow along, and we're certain you'll gain an in-depth knowledge of the potent engine called the Hemi.
Since this was the first year of the Royal Purple/Mopar Muscle engine challenge, we can't say it didn't go off without a hitch. Some of the parts that were required to set the Hemi engines up on the dyno didn't arrive in time, so we were really scrambling to make the competition happen on schedule. If it weren't for Mike Bond at Competition Cams, as well as Arrow Racing, Karbelt Speed and Custom, TCI, MSD, and Lakewood, we would have certainly been delayed. These guys all came through on short notice to provide us with the hardware necessary to get the job done. The engine builders themselves were also very accommodating, offering whatever parts or help they had to make things happen on schedule. We at Mopar Muscle would like to thank everyone involved for making the competition run as smoothly as it did, and on time. Superflow not only set up Comp's new 902 dyno in record time so the competition could happen, they sent customer service engineer John Seaman to Memphis to ensure things went smoothly. Along with the three drums of 93-octane go-juice, Rockett Brand sent vice president of engineering Tim Wusz to help with the competition and to answer any questions about the fuel we used for the testing. Several of the competitors consulted with these guys, and the exchange of information between everyone involved was incredible. It's amazing what you can learn when some of the best engine builders in the country consult with engineers from the likes of Comp, Superflow, and Rockett Fuels.
Enough about the setup, let's get to the meat of the competition. To ensure fairness, the order in which the competitors ran their engines was chosen randomly out of a hat. The procedure for all competitors was the same. The engine would be qualified by making three pulls from 3,000 to 7,000 rpm. We used an acceleration test of 300-rpm-per-second for all of the pulls. This is fairly slow acceleration for a dyno pull, but remember, these are supposed to be street motors. We are not just measuring power, we're ensuring the engines are legitimate street engines and have the endurance to back up the power they make. We didn't want any engines designed to make one killer pull on the dyno, just to explode the next time they started. During the qualifying session, each competitor had five minutes between pulls to make tuning changes or adjustments. If a competitor aborted a qualifying pull because of a problem, it had to be made up with a full pull, and no tuning was allowed during make-up pulls. Once the engine was qualified, the competitor had ten minutes to inspect the engine and make final adjustments before the scored pulls. In the scored portion of the competition, each engine was required to make three full pulls in a 20-minute time period. Tuning was allowed during the 20 minutes as long as all three pulls were completed in the allotted time. The pull used for scoring was the one with the best combined peak torque and peak horsepower. We're happy to say that all seven of the engines in the competition made their pulls in the allotted time with no major problems.
Larry and his team do some last minute tuning before their first judged pull of the compet
Hemis Only - Larry Shepard
Our first competitor in the dyno challenge was Larry Shepard of Hemis only, based in Akron, Ohio. In addition to his Hemi engine building expertise, Larry is an accomplished Top Fuel mechanic and clutch man. Needless to say, Larry knows his way around the Hemi engine. Larry's motor was one of only two sporting dual quads and the only one with Edelbrock carburetion. Larry also chose to use Mopar Performance cast-iron cylinder heads, stating a thermal advantage over aluminum pieces. Larry also claimed that the use of cryogenics, in addition to special metal coatings inside the engine, would give him a technological advantage.
Do tunnel-rams make power? Absolutely, this combination by Jeff Dickey of J.D.'s Engine an
Larry definitely wins our award for having the most patience of anyone in the competition. Since his motor was the first big motor on Comp's new dyno, it was run several times and made several partial pulls while John from Superflow calibrated the machine. We figure he needed an oil change before he even qualified, no question about endurance here. Next, an electrical problem caused the dyno computer to shut down fuel and ignition during the first qualifying pull at about 5,000 rpm, causing Larry's engine to misfire and diesel backwards for several seconds. The problem was repaired quickly, but everyone in the room cringed when the engine refired, fearing damage had been done. Luckily, the motor survived and, after minor timing adjustments, made all of its required pulls to set the pace with some impressive numbers. On his best pull, Larry made 701.8 hp and 639.6 lb-ft of torque (1341.4 combined score). these numbers are even more impressive considering that on teardown we found one of Larry's piston domes had been caved in during the qualifying runs due to the dyno malfunction. Larry's numbers certainly would have been better if his engine hadn't been damaged.