Are you wondering what the difference is between a turbo and a naturally aspirated (NA) cam? If so, you’re not alone.
The debate over which type of cam is better for a particular engine has been raging for years, with no clear consensus in sight.
In this article, we’ll take a closer look at the key differences between turbo and NA cams, including their design and how they impact performance.
Turbo Cam Vs Na Cam
A Quick Comparison Between Turbocharged Camshafts Versus Naturally Aspirated Camshafts:
|Parameter||Turbo Cam||NA Cam|
|Lobe Separation Angle||Wider||Narrower|
|Intake Centerline Angle||Advanced||Retarded|
|Power Band||Higher RPM||Lower RPM|
|Boost Compatibility||Compatible||Not ideal|
Design and Construction
Turbocharged engines and naturally aspirated engines have different airflow characteristics, which affect how their respective cams are designed and constructed.
A turbo camshaft is specifically engineered to work with the forced air induction system of a turbocharged engine.
They have a different profile, valve lift, and duration than a naturally aspirated camshaft.
Turbo camshafts are typically designed with a lower overlap to avoid wasteful reversion that can send boost out of the exhaust port instead of into the engine.
They also have a lobe profile that accommodates a larger lobe separation angle.
On the other hand, NA camshafts typically have more overlap to aid in scavenging the cylinders, as the engine relies solely on the vacuum created by the piston to draw air/fuel mixture into the cylinder.
Turbo camshafts and NA camshafts differ in terms of design and construction to suit the different engine airflows.
You cannot use a turbo camshaft in a naturally aspirated engine and vice versa.
Overlap is defined as the period of time when both the intake and exhaust valves are open during the engine’s combustion cycle.
A turbo camshaft is designed to have less overlap compared to a naturally aspirated camshaft.
The reduced overlap helps to prevent the exhaust gas from re-entering the combustion chamber, which can lead to dilution of the air/fuel mixture and reduce engine performance.
Lower overlap also helps to reduce the overlap of the exhaust and intake valve opening, which can help to increase the air/fuel mixture in the combustion chamber, resulting in more power.
In contrast, a naturally aspirated camshaft has more overlap to ensure that the combustion chamber is scavenged efficiently.
Turbo camshafts have less overlap than naturally aspirated camshafts to avoid wasteful reversion of exhaust gases and ensure efficient boost delivery.
Naturally aspirated camshafts have more overlap to scavenge the combustion chamber effectively.
Valve Lift and Duration
The valve lift and duration of a camshaft play a crucial role in determining the performance characteristics of an engine.
A turbo camshaft has a shorter duration and lower valve lift compared to a naturally aspirated camshaft.
The lower lift helps to reduce turbulence in the intake air, while the shorter duration improves the response of the turbocharger.
A turbo camshaft is also designed with a slower ramp rate on the camshaft, which helps to reduce valve train acceleration and deceleration, leading to less stress on the valve springs.
In contrast, a naturally aspirated camshaft typically has a higher valve lift and longer duration to optimize the air/fuel mixture and maximize the engine’s power output.
Turbo camshafts have a shorter duration, lower valve lift, and slower ramp rate to improve the response of the turbocharger and reduce valve train stress.
Naturally aspirated camshafts have higher valve lift and longer duration to optimize air/fuel mixture and maximize power output.
Valve timing differences
The main difference between a turbo cam and an NA (naturally aspirated) cam lies in the valve timing.
Turbo cams tend to have less valve overlap and a larger lobe separation angle, around 114 degrees on an aftermarket cam, as opposed to 108-110 degrees on an aftermarket NA street cam
The lower valve overlap ensures better scavenging of exhaust gases, while the larger lobe separation angle helps to reduce overlap and optimize turbo performance.
In contrast, NA cams typically have more valve overlap, which helps to increase intake and exhaust flow at lower RPMs, but can cause a loss of boost pressure in turbocharged engines
Valve timing is an essential factor that differentiates a turbo cam from an NA cam.
The former has less valve overlap and a larger lobe separation angle, whereas the latter has more valve overlap.
The valve timing directly affects the engine’s performance at various RPM ranges, making it crucial to select the right camshaft for your specific application.
Advantages of Turbo Cam over NA Cam
Turbo cams offer several benefits over NA cams in turbocharged engines.
They are designed to work with the specific airflow characteristics of a turbocharged engine,
Additionally, turbo cams have reduced valve overlap, which helps to prevent exhaust gas reversion, leading to improved scavenging and better turbo response
Advantages of NA Cam over Turbo Cam
While turbo cams have their benefits, NA cams also have advantages in certain applications.
NA cams tend to have more valve overlap, which helps to increase intake and exhaust flow at lower RPMs, making them better suited for street-driven vehicles.
NA cams can help to improve low-end torque and throttle response, making them ideal for stop-and-go driving conditions
Fuel economy comparison between Turbo Cam and NA Cam
When it comes to fuel economy, a turbo cam is generally more efficient than an NA cam.
This is because a turbo cam allows the engine to run more efficiently, which can result in better fuel economy.
However, the gains in fuel economy may not be significant enough to justify the cost of installing a turbo system
Power and torque output comparison between Turbo Cam and NA Cam
The main difference between a turbo cam and an NA cam is the duration and overlap of the camshaft.
A turbo cam typically has less duration and overlap than an NA cam, which allows the turbocharger to compress air more efficiently and create more boost.
This results in increased power and torque output from the engine.
On the other hand, an NA cam typically has more duration and overlap, which allows for better low-end power and throttle response
Exhaust note and sound quality
The exhaust note and sound quality of an engine are determined by several factors, including the camshaft profile.
With a turbo cam, there may be a deeper, throatier sound due to the different duration and overlap compared to an NA cam.
However, the sound can vary depending on the specific camshaft profile used and other factors such as the exhaust system.
Ultimately, the sound is a matter of personal preference.
When it comes to cost, there can be differences between turbo cams and NA cams.
Turbo cams may require additional modifications, such as valve springs and retainers, to handle the increased boost pressure and heat generated by the turbocharger.
Additionally, some turbo camshafts may be custom grinds, which can add to the cost.
On the other hand, NA cams may not require as many modifications and can be less expensive.
How Do Turbo Cams And NA Cams Differ In Terms Of Lobe Separation Angle And Overlap?
Turbo cams typically have a larger lobe separation angle and less overlap than NA cams.
Do Valve Internals Change When A Camshaft Is Installed?
No, valve internals do not change when a camshaft is installed. Camshafts only affect valve timing.
What Is The Difference Between A Turbo Cam And An NA Cam?
Turbo cams have a fuel pump lobe and a larger lobe separation angle for less overlap.
NA cams, on the other hand, are designed for naturally aspirated engines with different specifications.
What Should I Consider When Choosing Between A Turbo Cam And An NA Cam?
Turbo cams and NA cams are designed differently, so consider the engine type and specifications.
Additionally, turbo cams have a fuel pump lobe, and NA cams are designed for naturally aspirated engines with different specifications.
Can A Turbo Cam Change The Internals Of The Engine?
No, a camshaft only alters the timing events for each valve, and it doesn’t change the valve internals of the engine.
Turbo cams are designed for boosted applications, while NA cams are for naturally aspirated engines.
Turbo cams have a larger lobe separation angle for less overlap, while nitrous cams have very long exhaust duration.
Understanding rod ratio and piston dwell time is crucial for choosing the right camshaft for a boosted application In general, choosing the right camshaft comes down to understanding the unique needs of your engine and application