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acoustic valve
- Thread starter en035
- Start date
172 coming soon
As Andy said, What is it and what does it do? :S
Excuse the ignorance, but engines arent my stong point, yet.. we all have to start somewhere
Excuse the ignorance, but engines arent my stong point, yet.. we all have to start somewhere
Clio 172 mk2
This valve opens and closes at certain rpm (operated by pressure in the inlet plenum) and changes the length of the intakes to the airbox in the process to improve torque.
If you've fitted a Viper looks like you'll have to remove it but make sure you block the vacumn pipe to the valve....you'll see this coming of the inlet next to the throttle body.
If you've fitted a Viper looks like you'll have to remove it but make sure you block the vacumn pipe to the valve....you'll see this coming of the inlet next to the throttle body.
Don't know whether you've got the same in the Mk1, but here's what it does in the Mk2.
There are two pipes feeding air into the air cleaner. One of them has the valve in it which attaches to the intake system and only opens when there's enough revs and enough throttle opening to need lots of air. When its closed it keeps intake noise down by closing that intake pipe, and also improves torque by a ram-air type effect by keeping up intake air speed in the other pipe.
If you fit something like a Viper, or even just disable the acoustic valve so it stays open on a standard intake system you make get more peak horsepower because of less restriction in the intake airflow, but you may also get less torque at lower revs because the ram-air effect from keeping up intake air flow speed isn't there. If you don't have a certain speed in that intake pipe the pressure pulses as intakes valves open and close can result in flow reversals - the air speeding up and slowing down to the point that it sometimes is flowing in the wrong direction - that decrease the amount of air that gets into the engine.
There are two pipes feeding air into the air cleaner. One of them has the valve in it which attaches to the intake system and only opens when there's enough revs and enough throttle opening to need lots of air. When its closed it keeps intake noise down by closing that intake pipe, and also improves torque by a ram-air type effect by keeping up intake air speed in the other pipe.
If you fit something like a Viper, or even just disable the acoustic valve so it stays open on a standard intake system you make get more peak horsepower because of less restriction in the intake airflow, but you may also get less torque at lower revs because the ram-air effect from keeping up intake air flow speed isn't there. If you don't have a certain speed in that intake pipe the pressure pulses as intakes valves open and close can result in flow reversals - the air speeding up and slowing down to the point that it sometimes is flowing in the wrong direction - that decrease the amount of air that gets into the engine.
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