It may surprise you that your car or truck exhaust contains not only a muffler but also a resonator, and possibly two.
I remember resonators on cars from the fifties. Being a car guy as a kid, I noticed them on my dad’s cars. I’d ask what they were, and my dad would reply, “The resonator softens and changes the engine sound out of the exhaust.” He was correct.
But then, what if you did not want to soften the engine sound? Going without a resonator may uncork that raspy roar of certain vehicles and give it a more aggressive sound. But, do the pros balance out the cons of a resonator delete?
What Is a Resonator?
A resonator is a type of muffler that can vary anywhere from about a foot to about 3 ft. long. A resonator’s job is not to muffle sonically loud engine exhaust sound. The muffler does that. The job of the resonator is to shape that sound.
In the past, resonators were placed between the muffler and the tailpipe exhaust tip. Resonators are now fitted to the exhaust system between the catalytic converter and the muffler.
How Does a Resonator Work?
As the name resonator implies, it is utilized for resonance (harmonic reinforcing reflections of sound pulses) inside and outside of the exhaust system, in order to cancel certain frequency emissions of engine sound, while slightly enhancing other frequency emissions.
Exhaust system engineers will ask… What sound do we want out of the exhaust tip for this automobile? We want a smooth performance sound, or a sharp biting sound, or a soothing quiet sound, or a deep rumble type sound.
The resonator is then designed and tuned for the sound that the engineers (or more probably, the sales engineers set to the task) feel would fit the character of an Americana car or truck.
My favorite example of these resonator performance settings is the Alfa Romeo Spiders of every vintage, 1962 through 1993. These cars featured simple 4-cylinder engines that produced a classic ROWERROOOMMM sound. Cleverly constructed with the use of resonance technology, the pleasant sound was a signature of sorts and contributed to the character of these cars for their life.
The performance-enhancing use of a resonator in today’s automotive exhaust technology still serves an important purpose, either to enhance a performance exhaust sound or to help muffle an annoying high-frequency howl or low-frequency drone. Or, to help silence an engine almost completely.
Types of Resonators
There are three main types of resonators, all with slightly different functions.
#1. Helmholtz or Chambered Resonator.
This type of resonator is intended to cancel out certain specific sound frequencies that the muffler of the vehicle cannot cancel. These are often not flow-through designs, but rather are dead-ended and are welded into the side of the exhaust pipe.
The end of the device pipe connects to a multi-chambered housing which does the sound deadening work.
#2. Dissipative Resonator.
Similar to small cylindrical mufflers, this design allows exhaust flow through a louvered housing attachment internal to the device itself.
The internal housing is surrounded by sound-deadening chambers of different sizes, filled with either glass fibers or empty, depending on the frequencies to be dissipated.
#3. Expansion Chamber Resonator.
This design uses internal tubes of varying diameters to make one or more specific size chambers. The diameter transitions are set up to force sound pulses to reflect back into the exhaust flow.
This design can be effective for cancelling higher frequency sounds as the sound at the tail pipe will show a much lower frequency exhaust note.
What Is a Resonator Delete?
A resonator delete means to remove the resonators from your vehicle’s exhaust system. From our standpoint, there are benefits and drawbacks to taking a resonator delete on your car or truck, We’ll discuss the possible benefits and drawbacks.
We say “possible” because changing any exhaust component on most modern vehicles may cause unintended effects.
We find the engine systems on today’s vehicles to be very complicated, and exhaust system performance is factored into this information mix. Some benefits could be countered with unexpected performance losses.
Furthermore, it is unlikely that you will be able to forecast accurately what your results will be before starting this project. So, if you make this change, do not destroy or throw away the parts you removed. You may soon wish to put that resonator back in.
Pros of Deleting Your Car’s Resonator
The benefits of removing your car’s resonator may include:
#1. More Sporty Exhaust Sound.
Your car may sound sportier to you, but it may just sound louder to your next-door neighbor.
#2. Less Weight.
Your car will weigh less. How much less? Since a car weighing 3,200 lbs. is fairly typical, any amount would probably be impossible to tell.
If you were truly building a race car, a small weight benefit would be a good thing to chase. In this case, there would be no need for a resonator.
#3. More Power.
Your engine may experience a little performance increase. Experts say that removing a resonator could gain you an additional 3 to 5 horsepower. Once again, as with the weight benefit, this power increase will be virtually impossible to tell.
#4. Better Gas Mileage.
You may have better fuel economy, and, once again, change will likely be negligible.
Cons of Deleting Your Car’s Resonator
The following negative effects may result from removing your car’s resonator. Some of the negative effects may be extremely unlikely, but we will mention them anyway.
#1. Louder Exhaust.
Increased exhaust sound. In the form of low-frequency droning or high-frequency howling. A very buzzy-sounding exhaust.
#2. Rattling.
Other exhaust piping adjustments may create rattles of the exhaust piping knocking against other structures.
#3. Less Power.
In some rare cases, removing a resonator may cause a small loss of power. The car manufacturer may have found that the resonator supported maximum exhaust flow and thereby increased engine power in the car.
You would have removed the resonator. Power loss would be small and likely undetectable.
#4. Poorer Gas Mileage.
If you lose power, you may experience a small negative change in gas mileage. You would experience a negligible gas mileage loss, if any.
#5. Check Engine Light.
This is highly unlikely since you only deleted the resonator. A check engine light and an OBD II code may be produced after the stated resonator delete. The Onboard Diagnostic System monitors the car and may detect issues with the emissions systems.
The exhaust system is part of the car’s emissions system. Deleting or modifying the exhaust system may detect non-conformity in one or multiple emissions sensors, and may generate one or multiple OBD II fault codes.
#6. Premature Failure of Replacement Parts.
You have taken the resonator delete parts and placed them where the factory original resonator once existed. The new parts you have placed may not be of the same quality as the original factory resonator.
This could potentially create a failure to replace parts in your exhaust system, leading to a leak and/or complete break of the exhaust pipe. That kind of failure is likely not covered by your vehicle warranty.
Is a Resonator Delete Legal?
Your state may have laws in effect against modifying your vehicle’s exhaust system. Before making this change to the exhaust piping, you would be wise to check with your local motor vehicle office to determine if deleting the resonator is a compliance violation.
Will a Resonator Delete Pass Emissions?
For emissions testing, which writes the actual exhaust stuff out the tailpipe, resonator deletion will not have any adverse impact.
However, your state may not pass your emissions inspection based on the modification to your exhaust system, assuming this is something they want to regulate. If this is an issue, you will need to determine this with your local motor vehicle office.
And, lastly, removing a resonator may have caused your OBD II system to have set a code, and your Check Engine Light is illuminated. If that is the case, your car will not pass the emissions inspection until the fault is cleared.
Muffler Delete vs Resonator Delete
Lots of people promote removing the muffler instead of the resonator to modify the sound of their car’s exhaust because the muffler is the primary exhaust system’s sound-mitigating device in your car.
Other options
Sure, take out the entire exhaust and put back in a straight pipe system. And if your only goal is to make your exhaust louder, there are alternatives.
How Much Does a Resonator Delete Cost?
Your car’s resonator removal isn’t expensive. Single exhaust systems can cost as little as $100 for a kit, which contains a pipe and the parts you need to complete the job. If you have a muffler shop, do the whole job it could be costed out at more than $300, parts included.
A dual exhaust resonator removal could come close to double this estimate.
If my car does not have a resonator, should I install one?
Late model:
Your car manufacturer has evaluated the benefits associated with resonators. They concluded a resonator was not necessary.
Your car manufacturer likely conducted extensive analysis and testing before coming to that conclusion. For these reasons, it is reasonable to presume that you can add a resonator to your car’s exhaust system and experience little or no change.
Easy note: If your car is still in warranty, adding a resonator could be a violation of the warranty of your car manufacturer. You could check with your dealer on this inquiry.
Older than 5 years:
If your car is more than five years old and out of its warranty period, you might be able to see some benefit from a resonator (or two if you have a dual exhaust).
You will need to consider your individual need (droning or howling exhaust, medium-speed was excessive noise, etc.) then you would need to select a resonator from various options from a good aftermarket supplier.
Consider your options cautiously as the proposed improvement may not be possible. There is no way to predict if pulling your old resonator will give you any benefit to your car’s exhaust note.
And at least one of the worries and disadvantages with removing a resonator discussed above, is to be applies to adding a resonator.