Removed LS-3 silencer - looks great!
Popular Reply
12-26-2014, 11:09 AM
Pro
Hello folks. While I am certainly not an expert on very much, the physics behind the operation of a Helmholtz resonator is one of the few subjects I do know quite a bit about. I am a physics major, and I have degrees in electrical and acoustical engineering. It's how I make my living, and I have done work for automotive manufacturers, so I have some insight into what is important to them.
Helmholtz resonators are nothing new, and they are found in our daily lives in all sorts of applications. The devices operate on the principle of harmonics caused by the compliance of a compressible medium. Virtually any object that holds a volume of air that has a connection to the outside atmosphere via a small opening can be classified as a Helmholtz resonator. Examples of the principle are found in almost all acoustical musical instruments, whistles, pipe organs, and vented (sometimes called ported) speaker enclosures.
When used in the intake system of our Corvettes, the chamber does two things. First, it can improve the fuel economy of the vehicle by being tuned to a specific frequency that aids in airflow in a narrow bandwidth of RPM. The benefits provided at the "sweet spot" in the RPM band fall off rather sharply on each side of the tuned frequency... so most manufacturers will tune the resonance chamber for the RPM where the vehicle will see the most use. In our cars, that's probably going to be between 1500 and 2000 RPM. Above or below that, there will be less to no fuel economy benefit.
The second thing the resonance chamber does, is act as a muffler for the incoming intake air. If you can remember flipping your old cars air cleaner lid over because it sounded cooler when you tromped on it, you already have experienced removing the muffling effect. Yup, those long snouts on most OEM air cleaners were designed to reduce the amount of intake noise, and when the lid was fully sealing the air cleaner, the part was indeed a Helmholtz resonator.
The bottom line is this... GM spends a lot of time and effort to maximize not only the fuel economy of the Corvette, but to improve the overall fuel economy of the corporate average. Every little bit helps, and it may surprise you to know the lengths that are taken to raise the corporate average even a fraction of a percent.
They also want to reduce overall NVH, so a resonator is a much better solution than heavy sound deadening that would actually hurt fuel economy.
So, yes, the part is there for very valid engineering reasons. But, removing it will not cause any damage. The result may be a small decrease in fuel economy at cruising speeds, and a bit more noise at large throttle openings. Kinda like when we flipped our air cleaner lids over... :-)
Garry
Gilbert AZ
Helmholtz resonators are nothing new, and they are found in our daily lives in all sorts of applications. The devices operate on the principle of harmonics caused by the compliance of a compressible medium. Virtually any object that holds a volume of air that has a connection to the outside atmosphere via a small opening can be classified as a Helmholtz resonator. Examples of the principle are found in almost all acoustical musical instruments, whistles, pipe organs, and vented (sometimes called ported) speaker enclosures.
When used in the intake system of our Corvettes, the chamber does two things. First, it can improve the fuel economy of the vehicle by being tuned to a specific frequency that aids in airflow in a narrow bandwidth of RPM. The benefits provided at the "sweet spot" in the RPM band fall off rather sharply on each side of the tuned frequency... so most manufacturers will tune the resonance chamber for the RPM where the vehicle will see the most use. In our cars, that's probably going to be between 1500 and 2000 RPM. Above or below that, there will be less to no fuel economy benefit.
The second thing the resonance chamber does, is act as a muffler for the incoming intake air. If you can remember flipping your old cars air cleaner lid over because it sounded cooler when you tromped on it, you already have experienced removing the muffling effect. Yup, those long snouts on most OEM air cleaners were designed to reduce the amount of intake noise, and when the lid was fully sealing the air cleaner, the part was indeed a Helmholtz resonator.
The bottom line is this... GM spends a lot of time and effort to maximize not only the fuel economy of the Corvette, but to improve the overall fuel economy of the corporate average. Every little bit helps, and it may surprise you to know the lengths that are taken to raise the corporate average even a fraction of a percent.
They also want to reduce overall NVH, so a resonator is a much better solution than heavy sound deadening that would actually hurt fuel economy.
So, yes, the part is there for very valid engineering reasons. But, removing it will not cause any damage. The result may be a small decrease in fuel economy at cruising speeds, and a bit more noise at large throttle openings. Kinda like when we flipped our air cleaner lids over... :-)
Garry
Gilbert AZ
12-24-2014, 02:38 PM
#4
Le Mans Master
What difference did removing the silencer make ? Just for looks?
12-24-2014, 02:43 PM
#6
Safety Car
nice job, definitely cleaned up the 'neighborhood' !
12-24-2014, 02:54 PM
#9
12-24-2014, 04:14 PM
#10
Pretty sure they don't put that box on for looks, what does it do???
12-24-2014, 04:24 PM
#11
12-24-2014, 04:27 PM
#12
Originally Posted by Rwasdin5@yahoo.com;1588560709[B
]Exactly what does it do besides look ugly[/B] , on a nice looking motor. No performance gain & no difference in noise level. Just cleaned up the looks in my opinion .
12-24-2014, 05:51 PM
#15
Burning Brakes
12-24-2014, 06:08 PM
#16
Team Owner
Originally Posted by mikeCsix View Post
It's called a Heimholtz Resonator and helps smooth airflow into the plenum.
It's called a Heimholtz Resonator and helps smooth airflow into the plenum.
Smooths airflow... why??Who knows!! I have swapped the LS7 air filter setup into my last 2 LS3's and there was no issue at all,but it did "feel" a little better.
12-24-2014, 06:31 PM
#18
Safety Car
It smooth's out the airflow to prevent air impulses from interfering with the MAF sensor readings that are reported to the ECM. The LS3/LS7 MAF sensor is very sensitive to turbulent air and GM engineers felt is was necessary on the LS3. The Heimholtz Resonator also reduces intake noise.It would be interesting to data log before and after the removal and see the effect, if any, on the fuel trims.
Last edited by Mike's LS3; 12-24-2014 at 06:35 PM.
The following 2 users liked this post by Mike's LS3:
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h8snow (10-09-2020)
12-24-2014, 07:03 PM
#20
??? I don't drive with my hood open for people to comment on whether necessary engine parts look good or not. Honestly, all the times I had the engine exposed I've never noticed it. I guess I should remove my dry sump tank, the coolant reservior, the alternator, and some other odds and ends that look pretty stupid next to the block.