Jim Smart
April 27, 2010

Tech | Engine Building
We Wrap Up Our Edelbrock/MCE Engines 427w Raptor

We began our Edelbrock/MCE Engines 427W Raptor stroker project with elements important to making power in the March 2010 issue. This month, we're going to wrap up our project with important points to releasing power wasted inside your engine. They don't always involve cam specifications, carburetor sizing, and cylinder head flow numbers. Marvin McAfee of MCE Engines in Los Angeles, California, stresses you must go looking for trapped power inside an engine.

Marvin's strategy for power includes internal friction reduction, reducing windage, improving oil return flow (scavenging), playing with valve timing, making finite adjustments to valve lash, and making modifications to induction and exhaust. He likes to get clearances to where they aren't too small yet they're not too large either. He wants liberal oil flow across bearing journals, yet he seeks a healthy oil wedge to keep moving parts happy. He likes his engines to have loose tolerances to free up trapped power, yet he likes things snug for durability.

Put your hands on the crankshaft in one of Marvin's blocks and give it a twist while it's on the stand. Rotary motion in Marvin's engines is buttery smooth-easy to turn, yet comfortably snug. Slide a timing gear onto the crank and feel unequalled smoothness because everything with Marvin is zero fit void of resistance. Put your mallet away because you won't need it.

Marvin's engine blueprinting regiment is a strict discipline he follows with every engine he builds-extreme attention to detail that begins with the teardown and close forensics analysis. This comes of Marvin's extensive racing background coupled with a career in aviation. Failure analysis is his specialty. If an engine failed, Marvin wants to know why. Engine failure can lead to engine failure again if you miss something important to its foundation, Marvin will tell you. A crank or rod that isn't true; a block with misaligned main saddles; a warped deck, cracked castings; fasteners that should be replaced; and a host of other things we haven't thought of. Marvin will tell you it isn't always the obvious, but the unobvious, that leads to engine failure.

Marvin blueprints every oil pump, checking rotor clearances in every way imaginable. He likes a nice, smooth slide fit along with proper spring pressure when he checks the pressure relief valve. Marvin wants at least 10 pounds of oil pressure for every 1,000 rpm along with volume with the engine hot. Raising pressure to increase volume will cost you power.

When Marvin gets parts back from his machinist, he goes over everything with a fine-tooth comb, measuring all dimensions and inspecting machine work in great detail. Screw-in oil galley plugs are installed where press-in plugs existed. All oil galleys and water jackets are chased thoroughly to rid debris. Brass core plugs (also known as Welsh plugs) are installed with an industrial adhesive. Internal surfaces are coated with GE Glyptal to improve oil return flow. Ragged edges, known as stress risers, or radiuses are chamfered to prevent cracking. Components are checked for proper fit again and again during pre-assembly (mock-up) and assembly.

The Edelbrock Glidden/Victor Pro-Port Cylinder Head
The Edelbrock Glidden/Victor CNC Small-Block Ford cylinder head is a replication of the head Billy Glidden designed and used for record drag racing numbers in NMRA competition. The Glidden/Victor casting was born to make the most of the 289/302/351W Ford V-8s. Because these castings come from Edelbrock's own foundry and machining processes, you know you're getting the best American quality possible. MCE Engines has prepared these head castings, massaging in significant improvements to improve durability. No additional port work has been performed though. Marvin opted for Manley hollow-stem stainless steel valves for his Edelbrock Glidden/Victor heads because they power the winners. And as we all know, everyone loves a winner.

"One sales/technical representative at a prominent cylinder head manufacturer said we'd be lucky to reach 500 horsepower with the cam we had chosen," Marvin tells us. "Achieving 600 horsepower is a no brainer. A more aggressive camshaft will get you there with this engine package. But 600 horsepower isn't what we're seeking here. Our goal is 550/550 on torque and horsepower-a nice compromise in our quest for both road racing and durability." Marvin went on to say, "I can't say enough about both Manley Performance and Edelbrock. These guys give you from mild street performance all the way to extreme duty, and they do it so well."

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In Marvin's quest for power, he wanted clean airflow beginning at the plenum, transitioning smoothly to ports, bowls, and valves. And this is what he achieved with Edelbrock Glidden/Victor heads and Super Victor induction. Valves and seats must have a clean transition to keep air turbulence minimal. This means a valve seat insert where there's no overhang or ragged edges-pesky zones that disrupt airflow. Valve guides need to be out of the way where there's no turbulence around the stem. This is where good port and bowl work is crucial. Intake manifold gaskets and ports must be right sized where there's no turbulence generated as the air/fuel mixture passes from manifold to cylinder head. By the same token, you want clean exhaust passages where turbulence is kept to a minimum and scavenging is thorough.

Specifics Description
Part Number 61099 (bare)
Combustion Chamber Volume 61cc
Intake Runner Volume 280cc
Exhaust Runner Volume 94cc
Intake Valve Diameter 2.15-inches
Exhaust Valve Diameter 1.56-inches
Valve Stem Diameter 11/32-inch
Valve Type Used Manley hollow stem stainless steel
Valve Guides Manganese bronze
Deck Thickness 5/8-inch
Valve Angle 15-degrees
Exhaust Port Location 2 1/2-inch spread, raised 0.520-inch
Spark Plug Fitment 14mm x 3/4-inch reach with gasket seat

Dyno Pull 1
Holley 4150 (0-80513-1), 1000cfm
0.84/0.84 Jetting
12.54:1 Compression
2-inch x 30-inch x 3 1/2-inch Hooker Headers
36 Degrees BTDC Total Ignition Timing

RPM HP Torque
4,000 399.3 524.3
4,500 467.0 545.1
5,000 513.6 539.5
5,500 541.5 517.1
6,000 551.1 482.5
6,500 541.2 437.3
7,000 522.5 392.0

We learn from this first pull Marvin's expectations were in line with what this engine made in Edelbrock's dyno lab. He predicted 550/550 and got it. Because this is a road race engine, torque is just as important as horsepower. What you don't see on this first pull, which begins at 4,000 rpm, is this engine's broad torque curve. Torque begins to come on strong around 2,500 rpm, peaking at 545.1 lb-ft at 4,500 rpm. Torque hands off to horsepower at 5,500 rpm, which tops out at 551.1 at 6,000 rpm. Most surprising is 551 horsepower at six grand, which means durability. With this engine, you get it all. In road racing and canyon cutting, you want torque to get you out of the corners and horsepower to blast you through the straights.

You may find these numbers disappointing, especially if you're a drag racer, but consider this. Performance is rooted in what we want the engine to do, and we're going to talk about that shortly. If you're building a road race or street engine, you want a nice balance of torque and horsepower. You want a seamless transition from a mid-range torque peak to horsepower as your engine heads into the highlands. Team MCE concluded from this first pull the Holley 4150 needed larger 0.85 jets for the next pull to optimize air/fuel ratio.

"Every engine has its sweet spot," Marvin comments. "We've worked with ignition timing and centered our limit at 36 degrees BTDC." He adds, "We could take it to 38 or 40 degrees BTDC and make more power, but be risking durability." Marvin stresses the difference between a dyno cell and real world conditions. Real world on a racetrack at speed put stresses on an engine we don't see under dyno cell conditions. Keeping timing conservative reduces the possibility of engine damage.

"And here's another tip," Marvin adds, "maximum cylinder pressure occurs within five degrees of top-dead-center (TDC), which means you want the light off to begin at approximately 36 degrees BTDC." "The single greatest power builder is compression ratio," Marvin tells us. "Add compression and you add power." This is the cheapest, fastest way to increase power while keeping octane requirements in mind.

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Dyno Pull 2
Holley 4150 (0-80513-1), 1000cfm
0.85/0.85 Jet Change
12.54:1 Compression
2-inch x 30-inch x 3 1/2-inch Hooker Headers
36 Degrees

RPM HP Torque
4,000 399.8 524.9
4,500 466.1 544.0
5,000 514.4 540.3
5,500 543.2 518.7
6,000 552.3 483.5
6,500 543.0 438.7
7,000 524.6 393.6

This jet change didn't accomplish much with only a slight gain in horsepower and loss of torque.

Dyno Pull 3
We're going to try out the 1,000cfm Holley 4150 (PN 0-80514-1) PC Series carburetor from Performance Carburetors. Although the Holley 0-80514-1 has annular boosters from Holley, Performance Carburetors fits it with down-leg boosters, screw-in air bleeds, high-flow needles and seats, custom billet metering blocks, non-stick gaskets, polished and flowed venturis, float bowl sight plugs, drag float extensions; longer bowl vent tubes, and a special CNC machining technique to perfect the surfaces. Pricing is just under $800 out of the box. For custom tuning to your application, add another $50. Here's what happened on the dyno with our PC Series carburetor.

Performance Carburetors PC Series 4150, 1,000cfm
0.93/0.93 Jetting
12.54:1 Compression
2-inch x 30-inch x 3 1/2-inch Hooker Headers
36 Degrees BTDC Total

RPM HP Torque
4,000 400.2 525.4
4,500 467.3 545.4
5,000 518.7 544.9
5,500 548.9 524.2
6,000 554.5 485.4
6,500 552.8 446.6
7,000 531.6 398.8

What's it cost?
We're not going to kid around, this is an all-out road race engine build. The total cost of parts, machining, and assembly put this bad boy just north of $15,000. A street engine would be easier on the wallet.

Dyno Pull 4
We've gone back to the Holley 4150 (0-81513-1) carburetor with 0.85/0.85 jetting, which yielded a near-perfect fuel mixture and consistent numbers. Team MCE has chosen to check valve lash in the wake of three pulls to see what it does for performance. Ignition timing remains the same.

Holley 4150 (0-80513-1), 1,000cfm
0.85/0.85 Jetting
12.54:1 Compression
2-inch x 30-inch x 31/2-inch Hooker Headers
36 Degrees BTDC Total Ignition Timing

RPM HP Torque
4,000 389.7 511.7
4,500 460.6 537.6
5,000 515.0 540.9
5,500 546.9 522.3
6,000 561.8 491.8
6,500 560.1 452.6
7,000 546.2 410.2

Sometimes, it isn't the big things you do, but the little things that gain power. When Team MCE performed a valve adjustment, it gained 9.5 horsepower and moved torque higher in the power band-losing torque in the process. Marvin will tell you engine planning and building are a series of trade-offs. If you want more horsepower, you're going to sacrifice some torque. And if you want torque, you're going to give up horsepower at a given rpm.

The message here is simple. There are no free lunches in the world of engine building. The 427W Raptor is a racing engine, although you could install it in your Main Street Saturday night cruiser for weekend fun. The catch, of course, is this engine's compression ratio of 12.54:1 along with a 1,000cfm carburetor. Forget pump gas unless you have a buddy who works at the airport or local dragstrip. And if you pump it into a street ride, you're illegal thanks to tough environmental laws.

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