Jim Smart
February 18, 2010

What Works . . .
When Marvin sat down to pencil out his 427W Raptor project, he knew exactly what he needed this road-racing engine to do. Architecturally, he needed a brute block that would stay together, which meant a stock 351W block would never do for an engine expected to make 550-600 horsepower and turn 6,500-7,500 rpm. We contacted Ford Racing and ordered an M-6010-N351 wet-sump block, which is perfect for road or drag racing thanks to a four-bolt main design, higher nickel content for strength, 2.749-inch main journals, non-siamese bores, thick nodular iron main caps, heavy-duty webbing for incredible strength, semi-finished cylinder and lifter bores, thick decks, 9.500-inch deck height, and a 4.000-4.030-inch bore range.

Marvin's plan for power was common sense-raw street smarts of how power is made. No matter what the hot shots will tell you, power, durability, and cash flow are all about compromise. To have a whole lot of one thing, you must sacrifice from another. Marvin subscribes to the air pump theory of how an engine makes power. How much air and fuel can you huff into each bore and light off as the piston reaches top dead center? If you want boatloads of horsepower at 7,500 rpm, you will sacrifice torque. And if you want low-rpm grunt out of a traffic light, you're going to give up horsepower. It is the age-old rule of physics and how horsepower and torque dance with each other.

No matter what kind of Otto four-cycle internal combustion engine you're thinking of, horsepower and torque pass each other at 5,250 rpm. This formula is "horsepower equals torque times rpm over 5,250 rpm. But, what really matters is how horsepower and torque respond before and after 5,250 rpm that counts. The ideal situation is to have a broad torque curve where an engine pulls like stink as early as possible and remains strong as close to peak horsepower as possible. What's more, you want an engine to make the most power possible at the lowest rpm range possible, which is where durability comes in and keeps you in the race. If your engine is making 650 horsepower at 7,500 rpm, but comes unglued all over the track before reaching the finish line, where's the benefit? No one remembers the poor slob who finishes twelfth who was leading the race early on.

When Marvin was planning the Raptor, there were skeptics, including one cylinder head manufacturer who said we'd never clear 500 horsepower with the Erson mechanical roller cam Marvin had chosen. In fact, we were also among the skeptics who said it probably couldn't be done. This is when Marvin became very determined to prove his point. He chose the Edelbrock/Glidden/Victor Pro-Port CNC Raw cylinder head (No. 61099) in combination with the port-matched Super Victor intake (No. 2924) for the Raptor project because, in his opinion, it was ultimately the best cylinder head for the job. Marvin saw room for growth in the Edelbrock/Glidden/Victor CNC Pro-Port head where anywhere from 500 to 750 horsepower could be made depending upon cam selection, compression, and carburetion.

Valve selection is as crucial as cylinder head type, port and chamber design. "Don't cut corners on valves," Marvin stresses, "Manley Performance has got you covered from dead stock to high-end racing." Manley can make a custom dimension valve for your engine project, which is something not all manufacturers do. Start with Manley's catalog and fill out the spec sheet with your requirements. Marvin decided to go with hollow-stem stainless steel valves for the Raptor project. Lightweight titanium valves would have been cost prohibitive.

The E=MCE2 formula is about growth-building one heck of a foundation on which you can grow, and that's what we're doing here. If your objective is 500-550 horsepower, you have a solid foundation that will live to see a lot of action. If your plan is an all out drag racing engine with 650-750 horsepower, expect shorter engine life and yet tremendous power.

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