Short Answer
Overview
A cammed car is a vehicle whose engine has been fitted with a performance aftermarket camshaft (or a reground factory camshaft) that changes the valve timing, lift, and duration compared to the original equipment. The camshaft controls the opening and closing of the intake and exhaust valves. By altering these parameters, a cammed engine can produce more power at higher engine speeds, though it may sacrifice low-end torque and smooth idle characteristics. The term is widely used in car enthusiast communities, particularly in the context of hot rodding, drag racing, and street performance builds.
History / Background
The practice of modifying camshafts dates back to the early days of internal combustion engines. In the 1950s and 1960s, the hot rodding movement popularized cam swaps as a relatively inexpensive way to increase horsepower. Early hot rodders would grind down factory cam lobes to alter timing, or install aftermarket cams from specialty manufacturers. The advent of overhead cam (OHC) and variable valve timing (VVT) systems in later decades changed the landscape, but the fundamental principle remains. Today, cammed cars are still common in the aftermarket, with modern electronic engine control units (ECUs) often requiring recalibration (tuning) to work optimally with a modified camshaft.
Importance and Impact
The camshaft modification has a significant impact on an engine’s power curve, sound, and drivability. In motorsports, carefully selected cam profiles can yield substantial gains in peak horsepower, which is critical for competitive racing. In the enthusiast market, a cammed car is often associated with a distinctive ālopeā at idleāan uneven, choppy sound caused by increased valve overlap. This auditory cue has become a cultural marker of performance. However, the trade-offs include reduced fuel economy, increased emissions, and sometimes a need for higher idle speeds or upgraded valvetrain components. The modification also affects engine vacuum, which can interfere with power brakes and other accessories.
Why It Matters
For anyone considering engine modifications, understanding what a cammed car entails is essential for making informed decisions. A cam swap is not a simple bolt-on; it requires careful matching of the cam profile to the engineās intended use (street, strip, or track), as well as supporting modifications such as stronger valve springs, adjustable timing gears, and ECU tuning. Knowledge of camshaft terminologyālift, duration, lobe separation angleāhelps enthusiasts communicate effectively with builders and tuners. Additionally, recognizing the symptoms of a cammed engine (rough idle, lumpy exhaust note) can aid in diagnosing whether a used car has been modified.
Common Misconceptions
A cammed car always has a rough, loping idle.
While many performance cams produce a loping idle, milder aftermarket cams can maintain a near-stock idle quality. The degree of idle roughness depends on the camās lobe separation angle and overlap.
Bigger cam always means more power everywhere.
A cam with very high lift and long duration typically shifts the power band to higher RPMs, often reducing low-end torque. For street driving, a cam that is too aggressive can make the car unpleasant or even undriveable in traffic.
You can install a cam without any other engine modifications.
A cam swap usually requires upgraded valve springs to prevent valve float, and often new pushrods, timing chain, and lifters. Modern engines with VVT may need additional hardware or tuning to disable or adapt the variable system.
FAQ
What does a cammed car sound like?
A cammed car typically has a loping or choppy idle sound due to increased valve overlap. At higher RPMs, the exhaust note often becomes more aggressive. The exact sound depends on the cam profile and exhaust system.
Is a cammed car street legal?
It depends on local emissions regulations. Many aggressive camshafts increase emissions and may fail smog tests. Some jurisdictions have restrictions on aftermarket camshafts, especially in vehicles required to meet OBD-II standards. Checking local laws is recommended.
Can I install a camshaft myself?
It is possible for experienced DIY mechanics, but it requires specialized tools (e.g., degree wheel, dial indicator) and knowledge of engine timing. Mistakes can cause serious engine damage. Many enthusiasts opt for professional installation and tuning.
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