Intake runner volume is a popular way to compare cylinder heads. It tells you the size of the passage leading to the intake valve. It is expressed in cubic centimeters (cc).
How is it measured?
For aftermarket heads, the easiest way to find the intake runner size is to look it up online. Most of the Cylinder Heads on SummitRacing.com will list the runner volume.
For OEM heads or ones that have been machined, you will need to Measure the Intake Runner.
How does it affect performance?
The intake runner volume influences how the combustion chamber is filled during the intake stroke. In this case, bigger is not always better. It depends on what you use the engine for.
Small runners increase the velocity of the air going into the chamber. This builds more torque at low rpm. Small runners are best for street cars. They will accelerate better from a stop and perform well below 6,000 rpm. However, at high rpm (racing), the small runners may restrict the airflow, limiting the output.
Large runners will feed the engine at high rpm. This can help increase peak horsepower. However, they won’t start making power until higher in the rpm range. This results in poor drivability on the street.
The table below gives some basic rpm guidelines based on intake runner volume:
| Engine Size | Intake Runner Volume | Approximate RPM Range |
| Small Bore / Short Stroke | ||
| 350 c.i.d. and less | 170-180cc | Idle-6,000 |
| 302-350 c.i.d. | 200-210cc | 2,500-6,500 |
| 347-400+ c.i.d. | 215-220cc | 3,500-7,000+ |
| 383-421+ c.i.d. | 235cc or more | 4,000-7,500+ |
| Large Bore / Long Stroke | ||
| 350 c.i.d. and less | 180cc | Idle-5,500 |
| 302-350 c.i.d. | 200-210cc | 2,000-6,000 |
| 347-400+ c.i.d. | 215-220cc | 3,000-6,800+ |
| 383-421+ c.i.d. | 235cc or more | 3,800-7,200+ |
| Big Block | ||
| 468-500+ c.i.d. | 320cc | 3,500-7,300+ |
| 500-565+ c.i.d. | 360cc | 4,000-7,500+ |
Notes
- Many factors go into determining the power range of an engine. The values listed here are for reference purposes only. Your actual results may vary.