Advisor
Tips & Tricks
Exhaust Flaps
Get Mega Sound with an Exhaust Flap
Power sound with the exhaust flap
Exhaust flaps are extremely popular on the tuning scene. Why? Because a sporty sound is generally a top priority.
Not everyone wants to upgrade the whole exhaust system in one go, so many people opt for an exhaust flap. However, these days it comes with stringent volume regulations. Today we’re going to show you what it is, what it can do, and what its upsides are.
What is an exhaust flap?
An exhaust flap is located in the rear muffler section, and gives you the option to change your engine sound at the touch of a button – even while you’re driving. Whether you want to enjoy the deep, throaty sound of motorsport, or you prefer a quiet ride, an exhaust flap gives you complete control, usually via a remote or a permanently installed button in the interior. You can also control the flap automatically. So an exhaust flap lets you adjust your engine’s sound profile quickly and easily.
Here’s how an exhaust flap works with naturally aspirated engines
There are three ways to control an exhaust flap: overpressure, vacuum pressure, or an electric motor. Pneumatic systems that operate with overpressure or vacuum pressure run in conjunction with a pressure box that closes and opens the flap. This is driven by the pressure in the intake manifold of naturally aspirated engines. By using a solenoid valve, you can also operate the flap with a button.
Electrically controlled exhaust flaps
There are also electrically controlled exhaust flaps. These are usually installed by the manufacturer and open the flap between 50 and 70 km/h (32 and 43 mph). Instead of the pressure box and valve combo, all you need for this is an electric motor. Pressing the button powers the flap to open or close it. The advantage of electrically controlled exhaust flaps is that they can’t cause dead air problems in your engine.
Advantages: What can an exhaust flap do for you?
Sound! The overwhelming advantage of an exhaust flap is the outstanding sound it produces: a deep, loud, full-bodied growl that gives your engine a completely different feel. So for motorsport fanatics and tuning fans, it’s quite simply a must-have. Add the right look and performance, and you’re sure to get noticed. Another plus is that you can change the sound easily on long trips. Press the button and the growl becomes a purr, which might be nice for your passengers if they prefer a quieter ride. The best exhaust flap is one with all the options available whenever you want them. You can simply change the sound again and again, however the mood takes you.
Does an exhaust flap have any downsides?
That’s really a matter of opinion. If you’re going to use an exhaust flap, there are some stringent regulations you need to know about. Especially if you plan to drive in urban areas. We always recommend using professional tuning practice and avoiding poorly manufactured exhaust systems, which are illegal, and therefore a downside.
Exhaust flaps and vehicle inspections – what is and isn’t legal?
As we mentioned earlier, there are poorly manufactured and/or illegal systems out there. However, they are few and far between, because high-quality systems meet the requirements, or their labelling tells you at a glance what’s legal. Unfortunately, all exhaust flaps tend to get tarred with the same brush just because they make the engine loud. Consequently, cars are often taken out of service by mistake. Don’t let that happen to yours: pay attention to product quality and specifications. (This article refers to German regulations; be sure to check the regulations in your own country.)
Here’s what’s legal:
- If your car already has a button to open the exhaust flaps, that’s fine. Manufacturers are subject to stringent regulations on this too. In Germany, noise measurement regulations were reformed in 2016. Driving noise must now be between 74 and 75 decibels.
- If you had your exhaust system separately approved before 2016, your driving license is still valid.
- If in addition to the exhaust flap you’ve also changed other parts on the exhaust, you need a full approval, where readings are taken for the entire system as well as the volume. NB: Play it safe and get your system from professionals. If it fails the test, you’ve thrown a lot of money down the pan.
Here’s what’s illegal or not OK:
- The 2016 reforms brought in a blanket ban on integrated exhaust flap systems. Manufacturers now need EC approval for them. This requires the system to have an integrated controller that keeps driving noise volume within legal limits at all times.
- If you’re thinking you’ll get an ABE (general type approval) from the German Motor Vehicle and Transport Authority (KBA), you’re out of luck. You need an EC type approval, which means a massive amount of red tape. That’s why high-quality systems are so expensive.
Likewise, you can also forget an increase in stationary noise with an exhaust flap. That changed in 2016 as well. The legal maximum volume is documented on your vehicle registration and it’s a hard limit.
Conclusion
The bottom line is this: do the sensible thing and get yourself a high-quality exhaust. That way you’ll get a brilliant sound profile, and you won’t start quaking every time you see a police car. Check out our online store for the relevant approval.
Ask the pros
If you have any doubts, just get in touch. We’ll help you find the right exhaust for you, and of course we can install it as well. Send us a chat message or visit our help center.
His first car was a Polo Mk1 with a 40 Weber twin carburetor and 129 PS (95 kW). His second was an Audi 50. Today Bartek tunes Lamborghinis to 1000 PS (735 kW). Even as a young boy, Bartek disassembled vehicles and put everything back together better. He wrote his high school diploma with oil on his fingers. The trained automotive mechanic with a focus on engines and gearboxes was determined to go into motorsports. In his 10 years in Formal 1, he supervised 73 races, including as engine mechanic for Ralf Schumacher at Toyota. Since 2010, he has dedicated himself fully to his company BAR-TEK® and helps his customers to bring VW and Audi engines to peak performance.
Expert in
Engine
Gearbox
Create comment
Please leave us a comment.