The Power Phase - COMP Cams Ford 3v Cam Phasers

The new COMP Cams® Phaser Limiters for Ford’s 3 Valve Modular Engines Limit camshaft movement to maximize power

Ford’s Modular engine family of V8 engines replaced the venerable Windsor design a few years ago, and it looks like it’s going to stick around for quite some time. That’s a good thing, because the Modular design has quite a few innovations that make it a great candidate for making power. But it also has its weaknesses.

Ford 3-Valve Cam Phaser

Ford 3-Valve engine

One is that in order to keep the overall dimensions smaller so that the engine will fit into as many cars as possible, Ford kept the bore at a small 3.552 inches and made up for it with a longer stroke (3.543 inches for the 4.6 liter block). The tight packaging also limits the overbore size; most engine builders only feel comfortable opening up the cylinders in the Modular engines an extra 0.030 of an inch.

“Obviously, the problem with the Modular block design is it has a very small bore and long stroke,” Matt Patrick from COMP Cams® explains. “While that’s great for emissions and it’s not bad for torque, with a two-valve cylinder head configuration you just can’t put a big enough intake valve in there to make it breath like you want. That ends up really hurting the performance. So with the original two-valve cylinder head configuration you were really hurting there when you were trying to get performance out of that engine.”

“So when they came out with the three-valve head, they finally got a good cylinder head on that thing. The exhaust is a little bit less critical than the intake side, and getting two intake valves in each cylinder means it has a lot more area to work with. Now when you combine that with the new intake and exhaust ports you’ve got in the three-valve head design, you’ve got an engine that really breathes a lot better. They are just excellently designed ports. The intake manifold is also really nice. When you add it all up, the overall induction package with the three-valve heads is very nice on this motor.”

An innovative part of the three-valve cylinder head is the phaser technology that Ford employed to maximize engine efficiency. Camshaft phasers are computer-controlled cam gears that either advance or retard the camshafts while the engine is running. The effect is optimized when the valves open to match engine speed. In a conventional engine where the timing chain locks the valve train so that the timing cannot be changed, the camshaft can only be optimized for a very small rpm range. Cams ground for daily commuting generally work best in the low rpm range. They may idle well and make good low-end torque, but they will start wheezing as the rpms increase. Race cams are usually the opposite. They run like mad when the rpms are screaming, but stumble at idle and can be misery to drive in stop-and-go traffic. The purpose of a cam phaser is to adjust the cam timing (when the valves are opened and closed in relationship to the position of the pistons) so that the intake valve closes sooner at lower rpm levels and later as the rpms increase. When done correctly, it can help improve engine performance all across the operating rpm range.

This dyno chart demonstrates the flexibility of the cam phaser technology and what the changes will produce in your engine. Note in the
dyno chart the different horsepower levels that are possible through the reprogramming of cam centerline. Once the computer is reprogrammed
to fit these curves together, the cam phaser actively adjusts the camshaft to always be in the area of maximum power production.

When it comes to creating power, Patrick says the COMP Cams® dyno tests have shown that Ford uses the cam phasers to retard the camshaft timing approximately 10 degrees (measured in degrees of crankshaft rotation) through the rpm range when operating at full throttle. But the phasers are also used for a much different purpose during part throttle operation. At part throttle the phasers can swing the cam timing by as much as 60 degrees, to help the engine improve fuel consumption and exhaust emissions. But the problem with such radical swings in cam timing means a cam with very small duration and lift must be used to guarantee there won’t be contact between the pistons and valves.

“Any time you advance the cam, the intake valves get closer to the pistons, and any time you retard the cam the exhaust valves get closer,” explains Billy Godbold from COMP Cams®. “With the stock phasers changing the cam timing by as much as 60 degrees, that really limits how much cam you can put into the engine if your goal is performance. Say you took a three-valve Ford and put a big old cam into it and didn’t do anything else, you’d crash all the exhaust valves into the pistons. It really puts you into a box in terms of what cams you can put into a three-valve engine because you have to follow the original exhaust lobe profile to keep from banging valves into the pistons.”

The solution that COMP Cams® engineers came up with was to design a limiter for the phaser unit that still allows it to do its job, but keeps the phaser from either advancing or retarding the camshaft more than 10 degrees. If you remember, it is 10 degrees of retard that allows the Modular motor to work best at wide-open-throttle, the other 50 degrees of movement is only used to increase fuel efficiency at part-throttle operation.

“The Cam Phaser Limiter provides us with a tremendous amount of freedom when it comes to designing performance cams for the three-valve motor,” Godbold explains. With the Cam Phaser Limiter, now we can make a cam change and add 25 to 30 horsepower at the rear wheels. That’s awesome, and it’s easy to do. If you are willing to change the valve springs, we can provide you with a kit for your three-valve motor that includes the Cam Phaser Limiters, camshafts and valve springs that will add 48 horsepower at the rear wheels. It’s these new Cam Phaser Limiters that really allow us to unlock the power in Ford’s three-valve motors.”

Patrick adds that the Cam Phaser Limiters and the COMP Cams® performance camshafts for the three-valve motor can also help unlock more horsepower from upgraded engines. Since Ford’s phasers are controlled by computer, a little time on a chassis dyno will allow you to map camshaft advance/retard curves that are precisely matched to your engine combination. “We had an outside company do some independent testing on our Stage Three cams,” he explains, “and they just dropped them into an engine with a CNC-ported three-valve head with a stroker five liter short block. So it was a bigger motor that flowed more air. Initially, when they just bolted in the new cams and the Cam Phaser Limiters, it picked up right at 50 horsepower. Then, when they went back and started playing with the cam curves, they picked up an additional 22 horsepower. So there is a lot of power to be had by dialing in the cam curves to your specific engine package if you have bigger cylinder heads, more displacement or an otherwise more radical engine.”

Thumpr™ Gives Modern Engines a Muscle Car Vibe

The benefits of the COMP Cams® Cam Phaser Limiters in Ford’s three-valve engines just keep growing. Now COMP Cams® has used the Cam Phaser Limiter to expand the hugely popular lineup of Thumpr™ camshafts to the three-valve engine. The result is the efficiency and power that comes from modern engine technology combined with the raw and powerful sounds more commonly associated with ’60s era muscle cars.

Because the Cam Phaser Limiters allow much greater exhaust duration than the stock cams, COMP Cams® is able to use a Thumpr™ grind on a cam for the Ford three-valve heads. It is one of the first fuel-injected applications for the Thumpr™ Cams, and hearing that distinctive rumble coming from a modern muscle car will definitely turn heads. And the sound isn’t just all show - Thumpr™ cams improve the power to the tune of about 25 horses at the rear wheels as well.

“What is great about the Thumpr™ Cams for the three-valve heads is they make the same amount of power as our NSR (No Springs Required) Series of camshafts,” Patrick says. “But because of the Cam Phaser Limiters, we can crank in a bunch of overlap and it really gives that engine the most incredible exhaust note you’ve ever heard. It’s hard to believe. I would recommend anybody go to the COMP Cams® website (www.compcams.com) and find the page dedicated to improving three-valve engine performance. It should have that video on there where you can listen to the sound it makes yourself. You just won’t believe how good those cams sound. It really sounds like a ’60s era muscle car. And since you are also gaining around 25 horsepower, you are not only getting that great sound that sets your car apart, you are also getting the improved performance to back it up.”