2005 Hemi Engine Challenge - Domesticated Elephants

Those who have been following our Hemi engine challenge know that the big horsepower and torque numbers put up by our contestants were certainly impressive, but there was more to our contest than raw power. Cost was factored into the power and torque the engines made, so the competitors had to budget wisely, spending money where it made the most economical sense. These engines also had to demonstrate the ability to make power on 93-octane fuel and were subjected to multiple dyno pulls at a relatively slow acceleration rate to test their longevity and streetability. What is streetability? To us, it is defined by many factors, such as being able to idle in traffic without overheating, running strong on gas that's available at the local station, and longevity that will allow many years of reliable cruising.

This month, we'll go inside the Indy Cylinder Head and Mid America Racing entrants to see what combination of parts makes these engines true street performers.

Indy Cylinder Head Indianapolis, IN
Indianapolis, Indiana, home of the Indy 500 and the NHRA U.S. Nationals, has long held the title as the racing capitol of the world, so it comes as no surprise that one of the leaders in aftermarket support for Mopar engines grew from a shop in Indianapolis. Indy Cylinder Head began supporting Chrysler enthusiasts with quality aftermarket products more than thirty years ago and hasn't looked back since. Realizing that big-block Chrysler heads would always be limited by their relatively short valves and subsequent lack of port volume, Indy manufactured quality heads using valves 1/2-inch longer than stock, and dramatic horsepower gains were achieved. Since their early days, Indy has branched out and is now manufacturing quality products for nearly anything Mopar, including their Legend line of Hemi cylinder heads, intake manifolds, and blocks. nearly all of the competitors in this year's challenge utilized some type of part manufactured by Indy Cylinder Head in their engines.

With years of research and development and countless hours at the track and on the dyno, the crew from Indy Cylinder Head was expected to perform very well at our challenge, so their fifth place finish had us scratching our heads. The engine made good power and torque, but based on our experience with Indy it was definitely down on power. Upon the tear-down of their motor, the cause of their problem was evident. Rather than bring one of their established combinations to our competition, Indy chose to use our contest for some research and development. Experimenting with a new billet, flat-tappet camshaft in their motor caused several of the cam's lobes to wear excessively, almost to the point of being round, which severely limited the output of this engine. Had they not been using their entry for research, their numbers certainly would have been better, but trying new technology is the way to stay ahead of the competition, and for that we compliment Indy Cylinder Head.

Indy Cylinder Head is well known for making reliable power so we were particularly interested in what goodies were stuffed into their Mopar Performance Hemi block. What we found inside was a different approach than was used by the other competitors. Indy had chosen to build cubic inches by the utilization of a relatively long-stroke, small-bore combination, which theoretically should make killer torque. After performing all the block machining in-house, Indy installed a Callies 4340 411/42-inch stroke crankshaft combined with the block's bore of 4.2 inches to net their 499 ci. Manley 6.86-inch, center-to-center-length, H-beam steel connecting rods were chosen because of their reputation for strength, and the use of Aries small dome pistons achieved a pump gas friendly compression ratio of eleven-to-one. No special internal coatings were utilized in this combination as Indy claims a limited benefit at the rpm range of the competition. To keep everything well oiled, Indy utilized Milodon's 7-quart pan along with their 11/42-inch internal pickup and high-volume pump. A Milodon windage tray was also installed to keep power robbing oil off the crankshaft. To keep costs down, a stock 440 balancer, timing cover, and pulleys were used to finish off this stout short-block.

We were interested in which of their many available cylinder heads Indy would use to top off this motor. Knowing that cost as well as power would be factored for the competition, the guys at Indy chose their CNC 285 aluminum units (PN 426-1) for this engine. These heads come fully CNC ported and flow an impressive 440 cubic feet per minute out of the box. Filled with stainless steel 2.25-inch intake and 1.94-inch exhaust valves held in place by Comp cam's 927-16 valvesprings with 10-degree titanium retainers, these heads certainly had the potential to post big power numbers. To actuate the valves Indy used their own rocker kit (PN 426-27) with 1.6-ratio intake and 1.55-ratio exhaust rocker arms. A fully ported and polished 426-2 intake manifold utilizing a 4150-size flange was matched with a 4500-flanged Barry Grant 1090 King Demon carburetor by the use of an adapter that was ported with the intake. We have experimented with this setup ourselves and have seen gains of 12 to 15 hp over 4500-flanged intake manifolds. When the time came to select a camshaft for this engine, the Indy crew had a choice of installing one of their proven custom grinds or to experiment with new technology. Always attempting to stay on the cutting edge and ahead of the competition, Indy chose to experiment with a flat-tappet camshaft that was custom ground from a billet core commonly used for roller camshafts. Specifications on the custom grind were .624-intake and .617-exhaust lift and 255- and 259-degrees duration at .050 inch lift. In theory this cam would give much more precise valve timing, but, unfortunately for Indy, it wasn't compatible with the steel lifters and caused several lobes to be damaged during the dyno pulls, severely limiting the power of this engine. Even so, the more than 649 hp and over 600 lb-ft of torque are a clear indication of this combination's potential had it not been for the damaged camshaft.

While we're sure the guys at Indy expected more from their entry, we have to congratulate them for their willingness to experiment with new technology. It is no wonder that Indy Cylinder Head is the leader in the Mopar aftermarket. This is a solid combination of parts that offers not only power but longevity. We encourage you to call Indy about your project as they have combinations catering to any budget or power level.