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427W Raptor Engine Buildup - E=MCE2
Part 1 In A Two-Part Series
Never before have we learned more about engine building and power production than we have with Marvin McAfee and MCE Engines. That said, we're about to learn something refreshing about how to look at how power is made. When we're planning our engine projects, we don't give enough thought to how power is made. In fact, as bench racers, all we can think about is high-rpm, foot-to-the-floor horsepower. However, there's a whole lot more to performance than just horsepower. There's also torque and durability. Torque is your daddy on the street. And without durability, all the horsepower in the world won't help if you scatter engine parts all over the asphalt.
When you're planning an engine build, the first question to ask yourself is what do you want the engine to do? When MCE Engines was planning the 427 Raptor, Marvin knew exactly what he wanted the engine to do-and, when we went to the dyno at Edelbrock, it did exactly what he expected it to do. Being magazine guys with bold cover headlines in mind, we were thinking 600-650 hp and 600 lb-ft of torque because these are numbers that sell magazines. And, these are very typical numbers for street-going, weekend-racing 427ci small-blocks that go together in car magazines. However, this isn't what Marvin had in mind.
MCE Engines had torque, durability, and horsepower in mind and exactly in that order of priority. Marvin will pointedly tell you power isn't worth a damn without durability. And if given a choice between power and durability, Marvin will go for durability any day because you can build more power into durability.
We will tell you the road to the dyno wasn't an easy one. We got into intense conversation with Marvin about power because we were seeking at least 600/600 and Marvin was thinking more like 550/550. Marvin was thinking of road racing and we were thinking of awe-inspiring circulation numbers from hot cover blurbs. Bench racing logic was, if 550 was enough, then why wouldn't 600 be even better? Marvin smiled, then, invited us to patiently wait for the dyno room.
Build For The Job
Our argument with Marvin about desired horsepower numbers really wasn't our fault. Madison Avenue has been brainwashing us for a century about horsepower. Horsepower always has the spotlight whenever a new car or truck comes out or when car magazines build engines. We all promote horsepower. However, horsepower isn't always the most important dynamic, especially on the street and certainly in road racing. Horsepower is a key element in drag and stock car racing at high rpm. On the street and in road racing, we need abundant low- and mid-range torque, because that's where our engines operate most of the time. Torque is what gets us started at the traffic light and onto a freeway. Torque is also what spanks the other guy when we're flexing muscles from traffic light to traffic light. Torque is what launches. Torque is also what gets the road racer out of a turn and back up to speed in short order. Torque is fundamentally nothing more than shear grunt, the kind of power you make with your upper leg muscles. And once torque gets us going, it hands off to horsepower at high rpm where an engine takes off like a bat out of hell. In a road-racing engine, we need liberal amounts of both torque and horsepower. We need an engine that can do both without faltering or breaking.
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.
Marvin calls these tall claims of 600-650 horsepower on pump gas as laughable because they are not true. To make brute horsepower and torque numbers, you must have compression and abundant airflow, which translates into whopping cylinder pressure and power. You must also have octane that will stand up to high cylinder pressures without detonation. There are no free lunches, Marvin stresses, when it comes to power. You're going to have to give up one thing to have more of another and there are no exceptions. He adds if you decide to cheat and go with nitrous or supercharging, you will sacrifice durability. When you can touch a button and get 150-200 horsepower, you will hammer the daylights out of an engine, Marvin offers with a snapper.
Marvin canvassed cam manufacturers for just the right combination of lift, duration, valve overlap, and lobe centers. He wanted something off the shelf anyone could buy. He found exactly what he was looking for at Erson Cams, a drag racing cam profile that offered him the smooth combination of torque and horsepower. And had Marvin been willing to go with a custom grind, he could have improved horsepower and torque numbers significantly. However, Marvin's madness is rooted in building something anyone else could build using off-the-shelf parts readily available to anyone. In his opinion, that makes things fair.
Erson Cam Snapshot
Part Number: E212991 with 1.050-inch (small) base circle.
Grind Number: R-278-2 (Intake/Exhaust)
Lobe Separation:112-Degrees +4
Lift: 0.592-inch (Intake/Exhaust)
Advertised Duration: 278/286 ‚degrees (Intake/Exhaust)
Duration at 0.050-inch: 238/246 degrees