What is the Best Camshaft for a 1999-2004 Mustang GT?
Written By: Josh Honeycutt

Choosing the right camshaft for your 1999-2004 Mustang can be a daunting task. Superchargers, nitrous and other performance modifications all affect what type of camshaft is right for your Mustang.

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 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. Let's explain what some of these camshaft terms mean, as they will appear in most aftermarket cam descriptions.

~ Camshaft duration - total amount of time the valve is open
~ Valve lift - how far the valve gets pushed into the cylinder
~ Overlap - amount of time both the intake and exhaust valves are opened
~ Lobe separation angle - the amount, in degrees, that the intake max lift and exhaust max lift are separated by

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 simplify things 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, and the top, 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, light 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 an install greatly outweighs the aggravation of the install. Not to mention the engine could be ruined completely if the cams are installed wrong.

How do new Camshafts Affect Drivability?

With an aggressive cam comes the infamous “lope” associated with an aftermarket cam. 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.