Can the Exhaust Valve Be Closed for a Long Time?

[JasmineRose]

It is best not to keep the exhaust valve closed for a long time. Here is some relevant information about the exhaust valve: Introduction: The exhaust valve is a component in a turbocharged engine system that separates exhaust gases from the turbine. The separation of exhaust gases reduces the speed of the turbine, which in turn lowers the speed of the compressor. Working Principle: During the exhaust state, the float, due to gravity, pulls one end of the lever downward, causing the lever to tilt. At this point, a gap appears between the lever and the exhaust port, allowing air to escape through this gap. As the air is expelled, the water level rises, and the float, buoyed by the water's buoyancy, begins to rise. The sealing end of the lever gradually presses against the exhaust port until it is completely blocked. At this stage, the exhaust valve is fully closed.

[StIris]

Every time I'm asked about modifying car exhaust valves, I always have a few extra words to say: never keep the valve closed for long just for the sake of quietness! Last time I helped a friend check his car, he had kept the valve closed for so long that the exhaust backpressure skyrocketed, and the catalytic converter was completely clogged. The repair cost him several thousand. Poor exhaust flow can also cause the turbo to overheat, and worst of all, it might suddenly stall during aggressive driving—how dangerous is that on the highway! Nowadays, some aftermarket valves come with smart modes that stay quiet at low speeds and open automatically at high speeds. This way, you don’t disturb the neighbors or harm your car.

[DiHarley]

After repairing cars for twenty years, I've seen too many cases of improperly closed valves. There was a young guy who welded his exhaust valve shut for the sound effect, and within half a month, the engine malfunction light came on. A computer scan showed an exhaust temperature sensor alarm. Upon disassembly, we found the oxygen sensor clogged with carbon deposits, and the exhaust manifold was burnt and deformed. Keeping the valve open for smooth exhaust flow is the right way. If you really want quietness, opt for a variable valve exhaust system. Manually welding the valve shut is a sure way to ruin your car.

[SamuelLynn]

It's really annoying to hear the exhaust noise when picking up kids, but keeping the valve closed for a long time is not a good idea. I tried commuting with my MPV's exhaust valve closed before, and within two weeks, I felt the acceleration became sluggish. During maintenance, the mechanic said that closing the valve caused excessive exhaust temperatures, which burned out the sound-absorbing cotton in the rear section. Now I use a remote-controlled valve and just press a button before entering the neighborhood. If you keep it closed all the time, the emissions will definitely exceed the limit during the annual inspection, and you might even get ripped off by scalpers.

[VanMia]

Modding requires baseline experience. At last week's track day, I saw a heavily modified Civic that conked out after just three laps with valves fully closed - the exhaust backpressure bent the turbo blades. Proper valve modification should have rhythmic breathing: closed in city, open on highways; shut by day, open at night. Welding valves shut is like forcing someone to run while holding their breath - even the strongest lungs can't handle it. True car enthusiasts install a dashboard knob for real-time adjustment.

[RobertRose]

From an automotive engineering perspective, the exhaust system functions like a precision respiratory system. Prolonged valve closure is akin to covering one's mouth and nose, leading to a sharp increase in exhaust gas recirculation rates. Through actual testing, I've observed that driving with closed valves for just thirty minutes can raise cylinder temperatures by 70°C compared to normal operation, rapidly accelerating the aging of piston ring seals. This is particularly critical for turbocharged vehicles, where trapped high-temperature exhaust gases create vortex backflow impacting the turbocharger, causing metal fatigue in the blades that can lead to immediate failure. Allowing your vehicle to breathe properly is essential for long-term performance.