Pete Epple Technical Editor
February 15, 2012

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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