Mar 192017

Some say car modifications can often cause headaches. Symposer delete is literally the cure for headaches.

The chassis structure of a modern vehicle has gotten stronger and stiffer to meet the current safety regulations. This stiff structure also isolates to the cabin to outside world, muting the passenger compartment from exterior noises. Enhancement to interior quietness is never as critical as the recent years, any rattle in the modern interior is now more noticeable. As the result, the passenger compartment is now a very quiet place.

This quietness also cause a disconnect between the car and the driver. The audible notes from the road, engine, and exhaust are now too subdue for performance perspective. These natural mechanical notes are the unique characters that car enthusiasts look for as they provide the sensation cues to help the driver to become one with the vehicle.

Manufacturers add the engine/exhaust notes back into the cabin by either electronic sound enhancement, or sound symposer.

The former uses the audio speakers to play a pre-recorded sound track to artificially simulate the notes where brand specific designations range from BMW Active Sound, Lexus Active Sound Control, to Soundaktor for VW. The latter, sound symposer is employed in the FiST.

Regardless which sound enhancement is in your car, there is no replacement for the authentic unaltered mechanical notes. The sound symposer in the FiST works well, and bring some much-needed engine roar from the little hamster engine. The symposer can also be easily eliminated to better fit your preference. In our case, it is interfering with the Mountune MP215 Performance Upgrade, and the Mountune High Flow Exhaust. On a long drive, it literally gives us headaches.

Function of Sound Symposer

Sound symposer is a rather new technology. It was first developed for the Europe-only 2005 Focus RS, and Focus RS500. The symposer consists of a sound box that capture specific engine-generated oscillations in the induction system downstream of the turbocharger and convert these oscillations into sound frequencies. These sounds are plumbed into the outlet box behind the dash in the passenger compartment for the sporty growl.

The goal of the symposer is to achieve refined sound at low-to-medium throttle load yet sporty and powerful at higher load while the sound should never become intrusive.

Ford went the extra mile with the sound symposer to further defining the unique characters of the ST from other Fiesta models. Sound symposer perhaps is the best approach in this application since the FiST’s small engine displacement doesn’t push sufficient airflow to the exhaust system for a good sounding deep rumble at low revs while the turbocharger muffles out the high revs sound.

The characteristics of the symposer sound is tuned by the shape, size, and internal chambers of the symposer unit that cause the paddles inside the unit near the throttle body to vibrate and generate the low frequency noise. The sound waves are then plumbed via the sound pipe into the cabin. The unit is tuned in such a way that more sound feedback is generated between 1,500 – 3,500rpm, and enhancing the sound waves between 250 to 450 HZ with a larger sound window decibel under acceleration.

This audible feedback provides more responsiveness to the driver under throttle input. The system gets louder with the car’s acceleration which makes the car more fun and connected of which offers the driver the sense of oneness and dynamic harmony between man and machine.

Why remove a plastic piece that worth a million bucks?

Bear in mind though, car manufacturers spent hours and hours in research and development to get the sound right. Symposer delete is how you ruin a million-dollar part in your car in a matter of 60 minutes.

Like anything that we do here in Lamzgarage, everything has a functioning reason behind it to justify. The sporty growl from the stock symposer combined our upgraded intake and exhaust is simply a bit too intrusive. This is not the fault of the symposer. The intake and exhaust upgrades are pushing more air in and out of the engine. The increased air flow in the induction system changes the sound waves generating parameter of the stock symposer tune that causes undesirable drone when engine rpm is near 3,000 to 3,500 rpm in 6th gear with medium throttle input.

This RPM range also happen to be the cruising speed on the freeway. During a passing maneuver or when climbing a prolonged incline, the drone can be unwelcoming. It can aggravate a headache, or become an annoyance when trying to carry a conversation with the rear seat passengers.

While the purpose of the upgraded intake and exhaust are to enhance performance, the symposer contributes only sound. It is the most logical to eliminate the symposer to fix the drone.

A secondary benefit, and probably makes minimal difference in performance is the benefit of reducing turbo lag. The idea is that with the symposer elimination the turbo has less plumbing to charge which result in more instantaneous throttle response and quicker turbo spool.

Mountune Sound Symposer Delete

We went with Mountune once again on this as we are intended to stay with Mountune as much as possible, and Mountune simply is one of the best aftermarket supplier for FiST.

This kit allows the elimination of the sound symposer box in the engine bay. It acts as a blockoff plug at the location where the sound box is eliminated.

What comes in the box?

  • CNC Machined Aluminum (HE30) black anodized finish primary delete bung
  • 2 x AN4 threaded plugs
  • 2 x 90 degree AN4 fittings; accessible source for boost pressure, if additional engine monitoring is need
  • Installation instructions

Passenger compartment engine note comparison video is a click away at the bottom of the second page.

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