Why uneven length of headers Subarus – make sound so unique – Jalopnik

Your car sounds like it does because of a stunning number of factors, but some cars have a certain striking feature that so much contributes to the sound, it is indispensable. In this case we are talking about the headers used by Subaru, which are more uneven than the bank account of Jeff Bezos and yours.

The patron saint of Automotive Awesomeness, Jason Cammisa, has shown how big an impact buyer length has in the direction of Subaru -Voon in episode 2 of his know it all series On Haagerty‘s YouTube channel. In one clip you can hear the Warble or A WRX Sti’s Turbo Flat-4 and the stock of uneven length headers. In the second clip, a modified WRX with runners of equal length-as accurately described by Cammisa as a Honda Civic.

So what is science here? Well, Subaru uses boxing engines that keep the center of gravity low and his cars with uneven length heads probably because it keeps the packaging tight. The flanges that are attached to the heads gather in a single pipe, but instead of going to a central turbo lens with equal length runners, the pipes of one cylinder bench run under the engine. There, together with the pipe from the other cylinder bank, which is only a few centimeters from the exhaust inlet of the turbocharger.

Vertis a recording of a WRX with OEM headers to look at the wave form and you will see a strong wrist followed by a weak pulse. In the meantime, a WRX with equal length headers would produce a wave shape that looks immediately. You can see this clearly in JC Media’s YouTube video on the subject, which refers to the next image of Come and drive with it.

In stock Subaru WRX/STI distribution pieces, the exhaust gases travel from the exhaust ports of each cylinder, go through the primary runners, meet each other in the first set of Merge collectors and are then sent to a final Merge collector. During this process, one bank must pass a secondary runner with a flex joint in the middle. To finish it all, everything is made through the turbo compressor and out through the exhaust pipe.

Because the travel distance for the pulses of the engine varies from cylinder to cylinder, the severity of each pulse is different from the time it reaches your ears. The sound is rough because one pulse bears more volume than the other, and what you hear are usually those at a distance from harder pulses.

Although this all explains why the exhaust sounds like it does, nothing explains why Subaru chose this design. It is unlikely that the stocking is the product of careful audio engineering, such as what Yamaha did for the intoxicating vocalizations of the Lexus LFA. On the contrary, the use of uneven length heads is probably a choice based on packaging problems, weight and limiting the amount of material used. Plus, in theory, by placing two of the cylinder banks within centimeters of the turbo compressor, more exhaust energy can get into the turbine wheel faster. Remember that you cannot eliminate the turbo delay, but you can at least reduce it.

Of course there are many aftermarket equal headers for Subarus, and it is not only because there is a contingent of enthusiasts who hate the WRX Warble. Equal length runners have other advantages that can influence the performance and lifespan of the engine.

For example, if the runners reduce the equal length the variations in the cylinder temperature, which can more often cause ring and piston disturbances on one side of the engine. Reducing heat also makes knock less likely, and because turbo cars are constantly working to combat beats, they need all the help they can get. Making the exhaust pressure also seems to deliver a smoother power, because the turbocharger gets a stable stream of exhaust gases, instead of a strong, immediate current from one cylinder bank and a weaker, delayed current from the other.

If you want to keep the sound of your Subie or your Saab 9-2X Aero, aka de Saabaru, a weird and nice car that I actually owned, there is good news. It appears that improved unique headers of third parties can offer performance close to or the same as headers of equal length without eliminating the tone. However, if you want slightly more certifiable insane, ensure that a Wrumer connects to your OBD2 port and play the engine noise that you want through the speakers, including a V12, a rotating or even a lawn mower. With the second thought, just get different headers.