The basic operating rpm range for a camshaft is its “sweet spot.” This range is where the engine will produce the most Torque and Horsepower.
How is it measured?
The rpm range is determined by the camshaft manufacturer. The listed range is a result of testing the camshaft on a dyno with different combinations of engine parts.
Many factors affect this range, including:
- Carburetor CFM Rating,
- Intake Runner Volume,
- Combustion Chamber Volume,
- Valve diameter,
- Header Primary Size,
- Compression Ratio,
- Engine Displacement,
There is no formula to find the rpm range for a camshaft. If you have questions, the best course of action is to contact the manufacturer.
How does it affect performance?
The rpm range has a lot to do with Duration. Generally, cams with smaller duration numbers make peak horsepower at lower rpm. These cams are often used for stock replacement, daily driver, and towing applications.
As you increase the duration, you increase the peak power the engine can make. However, you also move the power curve higher in the rpm range. This results in less low-end power.
For example, let’s look at the duration for two different camshafts:
||Truck, street, 4WD, and towing applications
|1,500 – 4,000
|3,400 – 7,000
- Camshaft #1 will have plenty of low and mid-range torque. It will also work well with the stock converter and compression.
- Camshaft #2 has excellent top-end horsepower. However, it requires at least 10.5:1 compression, a 3,500+ stall converter, and rear-end gears to get the best performance.
To get the best performance from your engine, match the intended rpm ranges of the following parts as closely as possible:
- Intake manifold
- Cylinder heads
I hope you enjoyed this post. I’m sharing this from Summit Racing. Here is the link to all kinds of things camshaft related. We also have an article on the camshaft lift.