An in-depth look at how to use the factory VVT (Variable Valve Timing) system found on the Ford 4.6L 3 Valve engine to generate more performance.
What are cam phasers?
Ford’s cam phasers are specially designed, computer-controlled cam gears for all 2005 and newer Ford Modular 3 Valve engines that have the ability to adjust camshaft position while the engine is running. Since the modular engine uses two camshafts, two cam phasers are used.
How do they work?
Engine oil is pressure fed to the cam phasers through a series of passageways in the cylinder heads and camshafts. The engine computer controls a pair of solenoids that adjusts this oil flow into and out of the cam phaser’s control chambers, giving the ability to retard the cams up to 60 crank degrees.
Why did Ford put them in the engine?
When the cams are retarded 20-40 degrees during part throttle engine operation, it takes less power to turn the engine over. This helps to increase the engine’s fuel efficiency. Another power benefit is that the cam phasers allow the camshafts to always be in the best position for maximum power, regardless of what the engine’s rpm is. The engine makes more torque and horsepower and extends the high rpm powerband by an extra 800-1000 rpm.
Why should I modify the cam phasers with a COMP Cams® Limiter Kit?
If there is a downside to the stock cam phasers designed by Ford, it is that they have such a wide range of movement. Since the cams can theoretically be retarded by up to 60 degrees, there is very little piston to valve clearance in the engine. This minimal piston to valve clearance limits us to fairly small cam profiles with very little overlap.
What does the COMP Cams® Phaser Limiter Kit do?
These limiter plates replace the factory back-plate on the cam phaser. They have posts which extend into the cam gear’s control chambers, limiting their movement to no more than 20 degrees. This gives more piston to valve clearance and lets you install bigger, more powerful camshafts with safe piston to valve clearances. While keeping up to 20 degrees of movement available, all the wide-open throttle benefits of the cam phasing are retained, since the normal retard the cams see at wide-open throttle is only around 9 degrees.
Do I have to reprogram my engine’s computer after installing the Cam Phaser Limiter Kit?
Yes, you MUST reprogram your engine’s computer for the engine to operate properly after installing the cam phaser limiters. The guidelines for reprogramming are simple – just make sure that the maximum retard amount entered for any of the cam phaser tables and DTC strategies in your tuning software does not exceed 20 degrees.
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