What is the Best Camshaft for the 1999-2004 Mustang GT?
Mustang PI Camshaft Specifications
In 1999, ford decided to release and put the Power Improved (PI) cylinder heads into production. Needless to say, they have not looked back in this department. With the PI cylinder heads came the PI-specific camshafts. The new, improved camshaft profile boasted .535 inches of intake lift and .505 inches of lift on the exhaust lobe. The duration on the intake was dropped from 204 degrees, in 1992-1998, to 192 degrees on the PI cams. The exhaust dropped from 208 degrees to 184 degrees. Most would agree that’s a pretty impressive cam profile for a stock engine. Lets explain what some of these camshaft terms mean, as they will appear in most aftermarket cam descriptions.
What is Camshaft Duration and how is it Measured?
Camshaft duration is measured on both the intake and exhaust lobes. The standard of .050 inches is used to measure duration on the lobes to help simplify things a bit, since there are many cam manufacturers. So, duration is measured .050 inches after the intake or exhaust valve opens, and .050 inches before it closes. Therefore, out of 360 degrees of total cam rotation, the PI intake valve is open for 192 of those degrees, at .050 inches lift.
What is Valve Lift?
The valve lift is advertised as the maximum lift of the cam on both intake and exhaust lobes. Camshaft lobes are egg shaped, at the top and pointy part of the egg would be maximum lift. This would be .535 inches on the PI intake lobe, and .505 on the exhaust lobe.
Overlap and Lobe Separation Angle
Overlap is the amount of camshaft degrees; the intake and exhaust valves are simultaneously open. This is usually what gives an aggressive cam its “lopey” sound. The lobe separation angle, or LSA, is the degrees between the intake and exhaust max lift points of the camshaft.
Should I upgrade my stock 99-04 camshafts?
The stock GT cams from ford are unlike traditional solid billet cams. They are hollow steel tubes with keyways ground on the outsides. Then, powdered metal cam lobes with matching keyways are locked in place on the shaft. This produces a strong, durable, and most important, lite-weight camshaft. Although impressive in stock form, performance can be gained in the aftermarket for all engine applications. After all, the more air moving through the cylinder heads, the more horsepower is gained.
Upgrading Cams on a Naturally Aspirated Mustang
Naturally aspirated mustangs (1999-2004) with bolt-on parts will gain horsepower with a cam profile with more duration and lift, thus the benefit to upgrading from stock. For example, 205-210 degrees intake lift, and 200-205 degrees on the exhaust. Also, increasing the valve lift to .550 would be beneficial. However, anything above that would require aftermarket valve springs. An aftermarket sheet metal intake manifold would increase airflow, allowing for duration to be further increased, as more airflow through the intake is possible.
Upgrading Cams on a Forced Induction Mustang
Whether supercharged or turbocharged, a cam profile with longer duration is going to be highly beneficial. With the intake valve open longer, the combustion chamber will have a longer time to be force-fed the air/fuel mixture. The larger intake charge results in a significant increase in horsepower. A good number is between 214-218 degrees of duration and .550 lift with the stock valve springs.
Is Changing Your Mustang’s Camshafts Difficult?
We all know working in a confined engine bay can be daunting. Installing cams on the 99-04 Mustang GT is no easy task. Special tools are required that most DIY’s don’t have. Unless you have experience, or a great knack for all things mechanical, this is a job best left to your local shop. Sometimes the cost of install greatly outweighs the aggravation of the install. Not to mention the engine could be ruined completely if installed wrong.
How do new Camshafts Affect Drivability?
With an aggressive cam comes the infamous “lope” associated with an aftermarket cam. So, if your looking to keep your mustang as a “sleeper”, you may want to steer clear of cams with high valve lifts and overlap. Also, on automatic mustangs with aggressive cams, it is sometimes necessary to upgrade the stall converter. Aggressive cams often require an increase in the engine idle. Without a higher stall rating, you will find it hard to keep the car from surging forward at idle.
So, what are the Best Cams for a 1999-2004 Mustang GT?
All in all, it all depends on the goals and plans for your mustang. If it is a daily driver, some owners find the “lopey” idle obnoxious and would opt for a smooth idle. If the main goal is maximum horsepower, obviously a more aggressive cam is more desirable. Of course, the cam alone will not result in a large horsepower increase. As with any engine, it’s all in the combination of parts used. But, with better intake and exhaust flow, the right came will make that mustang power plant come alive.