Pete Epple Technical Editor
February 15, 2012

Back in the day, you could add a set of aftermarket heads, a bigger cam, and an intake manifold on a pushrod 5.0L and effectively double the power output. Although that sounds impressive, the base motor made a whopping 225 hp. (It’s amazing what was considered powerful in the ’80s and ’90s.) So what effect do heads and cams have on the latest 5.0L?

In 2010, MM&FF got its hands on an ’11 GT to customize for the SEMA show; this also gave us the ability to test parts. Our AMSOIL GT has been a great research and development tool, testing out many “first” products for the Coyote in the past 15 months.

Recently, the idea of adding a set of ported heads and larger aftermarket camshafts came up as a potential story, and the debate started on how the DOHC 5.0-liter would react. One side argues that improved airflow equals increased power. The other side states that Ford did such a great job maximizing the platform’s efficiency, there isn’t much to gain—at least, not when the cost is taken into account. After all, the engine operates above 100-percent volumetric efficiency through most of the rpm band.

We were left with a few questions. How would improved airflow through the already stout heads affect power and torque? What potential was there with the combination of larger cams and the variable cam timing? And how would it all be affected by boost? Well, there’s only one way to find out!

Our trip into the unknown started with a call to Total Engine Airflow (TEA). We have used TEA for some custom porting and cylinder head repair work in the past, and the Tallmadge, Ohio-based company is second to none. With a fresh set of stock castings, TEA went to work designing a CNC program for the Coyote heads.

When it came to camshafts, we had options. With Coyote camshaft technology still developing, we could have used a set of regrind cams, which are just that—stock camshafts reground with smaller base circles on each lobe allowing you to gain increases in lift and duration. The reduction of camshaft base circle usually means the lash adjusters need to be shimmed to make up for the material lost during machining on the camshafts. Our other option was to wait for a set of new billet shafts, and after talking with Comp Cams, we decided to do that.

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Comp Cams offers six different off-the-shelf grinds for the Coyote—three for naturally aspirated combinations and three for boost. After multiple anonymous calls to the Comp Cams tech line for advice, we opted for the mid-level boost cams. The new shafts measure in at 0.493-inch lift on the intake cam, 0.452-inch lift on the exhaust cam, and duration is 228/235 degrees at 0.050-inch lift respectively. The Copperhead ECU controls the advance and retard of the cams to optimize power and efficiency.

In stock trim, the cams have a 50-degree swing (from 81 to 131 degrees of crankshaft rotation). The purpose of this is to advance the cams for low-end torque, but retard the cams for high-rpm power.

While this works well with the stock camshaft, higher lift and longer duration, coupled with the independent adjustability of the cams can cause piston-to-valve clearance issues. To remedy this, Comp Cams sells its Cam Phaser Limiters, precisely machined blocks that are inserted in the adjustable cam gears, limiting the amount of adjustability in each camshaft. Comp’s Phaser Limiters still allow for the ECU to advance and retard the cams independently, but the range is reduced so piston-to-valve clearance isn’t an issue. The limiters reduce the amount of advance and retard from 50 degrees of total rotation to 25 degrees of rotation (12.5 cam degrees).

When it came to the cylinder heads, TEA used its CNC machine to open the intake and exhaust ports. The stock intake ports measure 193 cc; TEA opens then to 198 cc. "The CNC program is designed to improve airflow," explains Mike Downs, manufacturing manager for Total Engine Airflow. "The ports are opened about 5 cc, which isn’t huge. The design comes from everything we’ve learned in the Two-, Three-, and Four-Valve mod motors."

Swapping heads on a Coyote is not an afternoon project. The easiest way to handle the job is by removing the engine. For this, we headed to Blow-By Racing in Boca Raton, Florida, where Chris Jones and his team know the ins and outs of the Coyote. They started by removing the driveshaft, disconnecting the transmission shifter cable and electrical connections, removing the exhaust, and unbolting the BMR K-member. The body of our AMSOIL GT was then lifted off of the engine and trans, giving us all the room we could ever need to perform the swap.

Follow along as we swap the stock heads and camshafts for ported castings from TEA and larger camshafts from Comp Cams, and check back next month when we strap the AMSOIL GT to the rollers our Dynojet and hit the track.

Flow Numbers

Stock Coyote HeadsTotal Engine Airflow Ported Heads
Lift (Inches)Intake (CFM)Exhaust (CFM)Intake (CFM)Exhaust (CFM)
0.10049.432.189.680.4
0.200180.2147.8170.3165.2
0.300243.5180.0241.1211.2
0.400280.0189.7291.5233.8
0.500289.4201.4321.1244.2
0.600294.4207.7331.6250.8

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