Four-Valve Cylinder Head
A four-valve head has two intake and two exhaust valves per cylinder, improving breathing and allowing a central spark plug.
What is Four-Valve Cylinder Head?
It is standard on most modern engines. It usually works with two camshafts (DOHC). Smaller valves are lighter and allow higher revs. Some engines use three or five valves per cylinder, but four is the most common.
How it works
Larger total valve area lets more air in and out of the cylinder each cycle.
Why it matters for your car
More valves mean more parts to adjust if the engine uses shims. Valve timing must be correct to avoid valve damage.
Other terms
- Aftermarket Parts
- Brake Bedding-in
- Brake Pad
- Charcoal Canister (EVAP Canister)
- Charge-sustaining Mode (Hybrid Mode)
- Dual Action Polisher
- Heated Windscreen
- Keyless Entry And Start
- Lane Change Assist
- Leak-down Test (Cylinder Leakage Test)
- OAT Coolant (Organic Acid Technology)
- Paint Runs (Sags)
- Planetary Gear Set
- Range Extender
- READY Indicator (EV And Hybrid)
- Rear Spoiler (Rear Wing)
- Side Impact Beam (Door Beam)
- Trade-in (Part Exchange)
- Transmission Cooler
- Wing Mirror (Door Mirror)