Daily Slideshow: Picking a Camshaft for Your Corvette
Good idle? Check. Top end power? Check. Bottom end power? Not so fast. Camshafts are all about compromise. Here’s what you need to know.
NA or Boost?
The type of application you are set on building changes the entire process of selecting a camshaft. Naturally aspirated motors typically require different camshafts due to the nature of how air moves into the cylinder compared to a turbo motor. More on this later, but for now we will start with one of the basics…
Lobe Separation Angle (LSA)
This is the distance between the centerlines of your intake and exhaust lobes. If nothing else changes in your camshaft increasing lobe separation angle will not affect peak horsepower too much, but it will greatly affect an engine for a bulk of the mid-range. The lower the number the more power and torque you get earlier on at the expense of a decrease in idle quality and other tuning complications. Consider a low LSA around 102 and a high LSA of about 114. Something around 108 degrees is a good middle ground.
Valve Lift
The most important thing you need to be familiar with if you don’t build motors is that there is a limit on the piston to valve clearance. Skipping over this or ignoring it can lead to catastrophic results. Any time you have piston to valve contact you are going to have a massive headache and an even bigger check to write. Even head gaskets can affect this so know this number and do not exceed it!
Duration
Turbo and NA cars require very different camshafts to maximize performance. Generally speaking, you won’t see as much duration on a turbocharged engine because the turbo is slamming air into the cylinder as opposed to relying on the suction of the piston to pull in a fresh intake charge. Understanding this concept will help you eliminate static and focus on what you need.
Valve Over Lap
Duration has a direct correlation to valve overlap. What is valve overlap? Simply put it is the time between the exhaust stroke and intake stroke where both valves are slightly open. This narrow window is crucial to a naturally aspirated engine’s performance. Not necessarily the case with a turbo since again air is being rammed into the motor by force!
Exact Numbers
Exact numbers of what lift, duration and lobe separation angle you need will vary greatly from one LS to the next with consideration needing to be made for individual modifications. Your driving style, intended use, and ability behind the wheel will determine what is best for you. Do lots of homework as engine modifications can get expensive quick. The goal shouldn’t be to just make more power but to do so in an efficient way that coincides with the way you drive your car and the environment in which it is driven. Thanks for reading.
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