Car Tech: What makes a Subaru a Subaru.

First, we'd like to offer a disclaimer: this is not a sales pitch. We here at Empty Road love cars of all shapes and sizes, but Subarus have always been a little...different. There's a reason for that.




This (assumingly) is what car people think of when they think "Subaru." The sound of a modified WRX/STI is something truely unique. These are four cylinders that do not really sound the way a four cylinder should. Instead of a high pitched scream, all that comes out of the tail pipe is a low, deep, unmistakable rumble. The reason for this is a combination of a few things: engine design, exhaust header design, and whether or not the engine chews on a turbocharger.

The boxer style engine (used in Subarus, Porsches, old VWs, and other odd-balls) is unique in the way it's cylinders are layed out at a 180 degree angle: they're flat. This design means that the use of harmonic balancers and balance shafts is un-needed. It also gives the vehicle a low center of gravity: there's a reason helicopters use this design.




The flat design helps give Subarus their sound. The firing order of the pistons also plays a part. A Subaru has a firing order of 1-3-2-4; which means that while one cylinder bank is releasing exhaust, the other is waiting its turn. It all adds up to a pulsing sound. That pulsing is amplified by how the exhaust headers are designed.













These are aftermarket Borla, UN-EQUAL LENGTH (UEL) exhaust headers for a naturally aspirated Subaru(the bold is just for emphasis).







This is what they sound like with an aftermarket exhaust (axleback). Because of the firing order and the odd length of the headers, exhaust pulses are collected and exited at odd times.

But, without the UEL headers, the same car would sound like this:



This is a naturally aspirated car with stock, EQUAL LENGTH (EL) headers and a modified exhaust. Yes, it does sound different.



And these are why. These are the stock headers on a naturally aspirated Subaru. As you can tell, they are equal in length. It allows the exhasut pulses to be collected and exited at an equal length.


Now, on to turbocharging. Some of you out there who have inherited your grandmother's old Outback are porbably curious as to how to make your Subaru sound like your rich friend's WRX. The first thing you should do (after taking off the Coexist bumper sticker) is realize that you'll never truely get that sound unless you go turbo.

A stock WRX/STI not only has UEL headers from the factory, but they also have a devise that acts as second muffler: a turbocharger. This turbine that forces air into the engine to make more power is also in the way of exhaust gases. It causes a turbocharged Subaru to sound "smoother" than a naturally aspirated one. The sound may be very similar if you add UEL headers to your grandmother's old Outback, but it will not be the same.