Engine Masters Challenge is sponsored by AMSOIL, Presented by HOT ROD, and Operated by the University of Northwestern Ohio.

John Kaase and Royce Brechler's 473ci MEL engine just rocked the dyno at the University of Northwestern Ohio with an amazing performance. Built to the 2017 Engine Masters Challenge Vintage class rules, the engine produced a plateau of torque that never dipped below 630lb-ft during the entire scored rpm range of 3,700-6,200rpm, carrying them into the lead with a peak of 769hp along the way.

See all 76 photos The see-though plenum and runner were both built to show off exactly what goes on inside a running engine.

Vintage class rules for this year require factory iron head castings and prohibit welding or filling ports with epoxy. That rule is thanks to Jon Kaase's Y-block entry from 2015 that had totally reshaped ports that essentially turned the top end of the engine into a high-flowing small-block Chevy. How could the MEL's unimpressive factory heads produce such numbers?

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A quick glance at the engine reveals thick adapter plates on the intake and exhaust that allow the engine to use speed parts made for the much better breathing Ford 385 engine family, but all of the airflow afforded by the intake and headers have to squeeze through the head ports, so what gives? Look a little more closely and you may notice what looks like a deck plate. Class rules forbid those as well, and it turns out they aren't deck plates at all, they're head gaskets!.

See all 76 photos These o-ringed slabs of aluminum are the engine head gaskets.

Removing the cylinder head reveals the true magic, as the combustion chambers appear to be sunken below what was formerly the deck surface. Indeed they would be if it weren't for the head gaskets. Jon referred to these as "valve seats" and true to the rules they aren't welded or epoxied in place.

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See all 76 photos The head studs are 7/16-inch diameter rather than the factory 9/16-inch. The bolt holes in the block were machined to move the head rearward to allow for a larger intake valve. Much larger.

See all 76 photos The huge 2.250-inch intake valve and 1.73-inch exhaust valves were custom made for this engine.

See all 76 photos The short side radius was terrible on both factory ports. Dropping the combustion chamber allowed for a much taller port with a gradual turn.

See all 76 photos During testing, the conical springs had trouble controlling the heavier intake valve at around 6,200rpm. Kaase said that the valve float would go away at around 6,500rpm, but the score would have suffered tremendously. His initial solution was heavier springs all around, but the added friction caused a 10hp loss across the powerband. The compromise solution with the beehive on the exhaust dropped the power loss in half and kept the valves under control. Because the ends of the custom valves aren't hardened, Kaase used lash caps on each stem.

See all 76 photos MEL engines traditionally have the combustion chamber in the block, just like a Chevy 409. Not this one. Kaase machined the deck perpendicular to the bore. Custom 4.25-inch Diamond pistons wear Total Seal rings.

See all 76 photos By comparison to the wild heads and valvetrain, the bottom end is simple, with a 4.160-inch Lunati crank and rods secured by ARP fasteners. Kaase ran 10w30 Amsoil Dominator racing oil with a Melling pump.