If you’ve spent time around car enthusiasts or at a racetrack, you’ve probably heard the term. So, what is a cammed car? In simple terms, a cammed car has an aftermarket camshaft installed, altering valve timing to increase engine power, often at the expense of a smooth idle.
This modification is a cornerstone of high-performance engine building. It changes the very character of an engine’s operation.
Understanding this upgrade is key if you’re considering more power. Let’s look at how it works and what it really means for a vehicle.
What Is A Cammed Car
To fully grasp the concept, you need to start with the core component: the camshaft. Inside your engine’s cylinder head, the camshaft is a precisely machined rod with egg-shaped lobes. As it rotates, these lobes push against the engine’s valves, opening them to let air and fuel in and exhaust gases out.
The stock camshaft in your car is designed by the manufacturer for a broad compromise. It must provide decent power, good fuel economy, low emissions, and a quiet, smooth idle. A performance camshaft, or “cam,” throws some of those priorities out the window.
Installing an aftermarket cam shifts the engine’s power band, usually higher in the RPM range. This trade-off is the essence of a cammed car.
The Core Function Of A Camshaft
The camshaft is the brain of your engine’s valve train. Its profile dictates four critical factors, often called the “cam specs”:
- Duration: How long the valve stays open.
- Lift: How far the valve opens.
- Timing: When the valve opens and closes relative to the piston position.
- Lobe Separation Angle (LSA): The camshaft grind’s “tightness,” affecting overlap.
Altering any of these specs changes the engine’s personality. A performance cam typically increases duration and lift. This allows more air and fuel into the cylinder, which means a bigger explosion and more power.
Valve Overlap And Its Effects
This is the most important concept to understand. When you increase cam duration, you often create a period where both the intake and exhaust valves are open at the same time. This is called valve overlap.
Overlap is beneficial at high RPM. It lets the exiting exhaust gases help pull in the fresh air/fuel charge through a process called scavenging. However, at low RPM, this overlap causes problems. Some of the fresh charge can go straight out the exhaust, and exhaust gas can dilute the incoming mixture.
This leads to the famous “lumpy” idle and poor low-speed manners of a cammed car. The engine is essentially optimized for a specific, higher-revving range.
How Overlap Changes Engine Sound
The uneven idle isn’t just a byproduct; it’s an audio signature. The loping sound happens because cylinder pressures are low at idle due to the overlap. Some cylinders fire weakly or inconsistently, creating that choppy, aggressive exhaust note that enthusiasts love.
Different Types Of Performance Camshafts
Not all cams are created equal. Different grinds offer different compromises between drivability and power. Choosing the right one depends entirely on your goals for the vehicle.
Street Cams
These are mild performance upgrades designed to work with mostly stock components. They offer a noticeable power increase, especially in the mid-to-high RPM range, while maintaining decent idle quality and low-end torque. Vacuum for power brakes is usually retained, and they often don’t require upgraded valve springs.
Street/Strip Cams
This is a common middle-ground choice. These cams provide a significant power boost for spirited street driving and weekend drag racing. The idle will be noticeably lumpy, and you might experience a slight drop in vacuum. They frequently require supporting mods like upgraded valve springs, a higher-stall torque converter (for automatics), and tuning.
Race Cams
These are extreme profiles meant for dedicated competition vehicles. They maximize power at very high RPM and have massive duration and overlap. Idle is extremely rough, low-end power is almost nonexistent, and street drivability is poor. They demand extensive supporting modifications and are not suitable for daily driving.
Roller Vs. Flat Tappet Cams
This refers to the type of lifter that rides on the cam lobe. Flat tappet cams are traditional and require a specific break-in procedure with special lubricant. Roller cams use a roller bearing lifter, which reduces friction, allows more aggressive lobe profiles, and requires no special break-in. Roller cams are more expensive but are the modern performance standard.
Why Cam A Car? The Benefits And Drawbacks
Swapping a camshaft is a serious decision. It’s crucial to weigh the dramatic benefits against the very real compromises.
Advantages Of A Cammed Engine
- Increased Horsepower and Torque: This is the primary goal. A well-chosen cam can add substantial power, often 30-50+ horsepower on a typical V8 with supporting mods.
- Higher RPM Power Band: The engine will make its peak power higher in the rev range, which is ideal for racing or high-performance driving.
- Aggressive Sound: The choppy idle and muscular exhaust note are a major draw for many enthusiasts.
- Improved Throttle Response: With more air flowing, the engine can react more quickly to throttle inputs.
Disadvantages And Challenges
- Poor Low-End Torque and Drivability: The car may feel sluggish or “boggy” at low RPMs, making stop-and-go traffic a chore.
- Rough, Unstable Idle: The engine may shake at stoplights and can sometimes stall if not tuned properly.
- Reduced Engine Vacuum: This can affect power brake assist, causing a hard brake pedal. It may also impact emissions controls and HVAC systems.
- Decreased Fuel Economy: Especially during normal driving, the engine is less efficient.
- Required Supporting Modifications: A cam swap is rarely a standalone job. It often necessitates new valve springs, pushrods, timing set, and always requires a professional tune.
- Higher Cost: Between parts, supporting mods, labor, and tuning, a proper cam installation is a significant investment.
The Cam Installation Process And Supporting Mods
Installing a camshaft is a major mechanical undertaking. It’s not a simple bolt-on mod. Here’s a general overview of what the process and related upgrades entail.
Step-By-Step Installation Overview
- Engine Preparation: The cooling system is drained, and accessories like the radiator, fan, and harmonic balancer are removed to gain access.
- Front Cover and Timing Set: The timing cover is taken off, revealing the timing chain or belt. The old sprockets and chain are removed.
- Camshaft Removal: The intake manifold, valve covers, and rocker arms are typically removed. On many engines, the lifters must also be taken out before the old cam can be slid forward out of the block.
- New Cam Installation: The new cam is lubricated and carefully installed. Correct alignment of the timing marks on the new cam and crank sprockets is critical.
- Reassembly: New lifters, pushrods, and valve springs (if upgraded) are installed. The engine is reassembled with new gaskets throughout.
- Break-In and Tuning: For flat tappet cams, a specific high-ZDDP break-in oil is used, and the engine is immediately started and held at 2000-2500 RPM for 20-30 minutes. Finally, a professional dyno or street tune is essential to adjust fuel and timing maps for the new cam profile.
Essential Supporting Modifications
A camshaft doesn’t work in isolation. To realize its potential and ensure reliability, these upgrades are often needed:
- Valve Springs and Retainers: Stock springs may not handle the increased lift and RPM, leading to “float” and engine damage.
- Pushrods: May need to be changed for proper length and strength.
- Timing Set: A double-roller timing chain is stronger and more precise than a stock set.
- Fuel System: More power requires more fuel. Upgraded fuel injectors and a higher-flow pump may be necessary.
- Exhaust System: A cam needs to breathe. Performance headers and a less restrictive cat-back system are almost mandatory.
- Intake System: A cold air intake and performance intake manifold help feed the hungry engine.
- Torque Converter (Automatics): A higher-stall speed converter allows the engine to reach the cam’s power band off the line.
Tuning: The Most Critical Step
You can install the best camshaft in the world, but without a proper tune, the car will run poorly or even be undriveable. The engine control unit (ECU) is programmed for the stock cam’s airflow characteristics.
A performance tuner uses software to adjust air/fuel ratios, ignition timing, and idle control parameters. They smooth out the idle, eliminate hesitation, and ensure the engine makes safe, maximum power. Never skip this step.
Is A Cammed Car Right For You?
Ask yourself these questions before committing:
- Is this a daily driver or a weekend toy?
- What is your realistic horsepower goal?
- What is your total budget, including parts, labor, and tuning?
- Are you prepared for the compromises in drivability and fuel economy?
- Do you have a trusted, experienced mechanic or shop to do the work?
For a dedicated race car or a weekend cruiser, a cam can be an excellent upgrade. For a primary vehicle used in traffic, a milder street cam or other bolt-on modifications might be a better starting point.
Common Myths About Cammed Cars
There’s a lot of misinformation in the car community. Let’s clarify a few things.
Myth 1: A Bigger Cam Always Means More Power
Not true. A cam that’s too large for your engine’s displacement, compression, and other components will kill low-end power and may not even make more peak power. The cam must be matched to the entire engine package.
Myth 2: You Can Just Drop In A Cam And Go
This is a recipe for disaster. As outlined, supporting mods and a professional tune are not optional; they are required for the engine to run correctly and survive.
Myth 3: Cammed Cars Are Unreliable
A properly selected, installed, and tuned camshaft in a well-maintained engine is very reliable. The problems arise from poor installation, incorrect supporting parts, or lack of tuning.
FAQ About Cammed Cars
What Does It Mean When A Car Is Cammed?
It means the vehicle’s engine has been equipped with an aftermarket performance camshaft. This changes how the engine breathes, increasing high-RPM power but typically creating a rougher idle and less low-speed torque.
Is Camshaft Good For Your Car?
It can be excellent for performance if your goals align with the trade-offs. It increases power and changes the engine’s character. However, it is not “good” for daily drivability, fuel economy, or emissions in a conventional sense. It’s a specialized modification.
How Much HP Does A Cam Add?
On a typical naturally aspirated V8 with basic supporting mods (exhaust, intake, tune), a street cam can add 30-50+ horsepower. The exact gain depends wildly on the engine, the cam spec, and the quality of the other modifications and tuning.
What Are The Cons Of A Cammed Car?
The main drawbacks are reduced low-end torque, a rough and sometimes unstable idle, decreased fuel economy, potential brake booster issues from low vacuum, and the significant cost of the cam kit, supporting parts, labor, and tuning.
Can You Daily Drive A Cammed Car?
You can daily drive a car with a very mild street cam, but it will still have compromises. A car with a aggressive street/strip or race cam is generally not a pleasant or practical daily driver due to poor low-speed manners, stalling tendencies, and reduced comfort.