The Engine Masters Challenge was designed to bring the best efforts of veteran engine builders to the forefront with street-based limitations. While some builders cry out for high-octane racing gas and no rpm limitations, others embrace the concept and bring their street-level talents up a few notches. This has been especially true for the builders of non-Chevy/Ford/Chrysler engines, who find the limits of the Challenge rules an opportunity to run with the more common engine makes on a more real-world playing field. Our subject engine builder, Michael Semchee of Austintown, Ohio, is just such a builder. He calls his engine building operation Semco, and he's a self-professed Pontiac guy.
Mike was a record-holding competitor when the NMCA ran its stock classes. His '67 GTO was easily capable of running 12.40s when outfitted to the stock class rules, and was a threat to win whenever he brought it to race. The class was eliminated, but Mike's desire to win with a traditional Pontiac V-8 has not faded away in the least. After reviewing the 2007 Jegs Engine Masters Challenge rules, he pulled the engine from the GTO and redesigned it for the competition.
The engine is based on a stock Pontiac 400ci block and crankshaft combination that Mike has owned and raced in various forms for more than a decade. We're happy to bring you a buildup based on these factory parts because they represent what most PHR readers are capable of getting if they don't have them already. After much research, Mike's Challenge-built Poncho cranked out over 560 horses and 534 lb-ft from only 409 cubes, which is truly respectable for a pump-gas engine. It made more than 435 lb-ft at the Challenge-minimum 2,500 rpm! But there's more to this story. The engine was wounded, and even greater power potential exists. It's not hard to see this engine being capable of 600 or more horses when the big picture is seen. Follow along, and we'll show you what we mean.
The block and crank for Mike Semchee's 400 Pontiac are both factory Pontiac parts, although both have been massaged for improved strength and durability. The crank was machined by Lunati to Mike's specifications, while the block was treated to a full machine job by Crank and Sleeve Shop's Jerry Dietz. ARP hardware is used throughout. The final bore size is 4.155, and with a 3.763-inch stroke, totals 409ci.
The crank wears Eagle H-beam forged connecting rods in a factory Pontiac length of 6.625 inches. For a Pontiac veteran like Semchee, using a stock rod length is common when building a solid street engine, but he admitted this might have been one area to reconsider. "If I had to do it all over again, I would probably go with a longer rod and a different piston," Mike says. He and the team will have the chance to look this over again soon enough.