JBrady

Well, decided to pull of the silencers from my LS 400. These are usually refered to as resonators but I feel the term SILENCER is much more appropriate.

For future reference on the LS models the center straight through canister is a resonator, the twin side entry muffler looking parts are the silencers and the mufflers are last.

I have been driving my LS without mufflers for some time. The sound is amazingly subdued. I removed the silencer section ( 60mm section, Y pipe to twin 50mm, twin silencers, 50mm exits. This left only the cats, Y pipe and resonator.

On start-up the engine sounded GOOD!!! like a hot Corvette. I decided to take it for a spin. WHOAH.... VERY, loud. I had hoped to leave it off through Sunday's meet at the track but NO way.

Did learn something very interesting. Initial throttle response was off as was low end power. On the first full throttle run the car did not seem as fast and it broke up slightly at high rpm. After driving it several miles the midrange came back. I decided to try a few more full throttle runs. The second pass also broke up at high rpm. After a couple more passes the break up stopped and the car got noticably quicker. Now, this is not enough information to make scientific judgements but my theory is the reduced backpressure caused the engine to flow more air and lean out the mixture. At high rpm is where restrictions really come up and therefore would be leanest at high rpm/power. The OBDII system started adjusting for this and the power increased.

Also, after first removing the silencers I shined a light inside the 60mm pipe that connected to them. It is about an 18" straight section that flows into the silencer Y pipe. Inside there was an angled pattern with carbon deposited along all sides except for a narrrow "V" shaped pattern running along the top. This indicates the high flow vs. reversion area of the pipe. After running without the silencers the entire inside of the pipe had carbon deposit! More data for the reversion vs. low end torque argument.

I took some pics, will post tonight or tomorrow.

Lvangundy

Wait...

Isn't this like mine?

Or wait..you have your rear muffelrs removed don't you?

I think mine is the same, except you have the rear mufflers removed. At least your OBDC2 can adjust the engine to changes in the airflow..

SilverFlare

can't wait for the pix ..

JBrady

No, it was only a test, I put the silencers back on :eek:

Yours is a full system. When you have exhaust exiting between the car and the road it resonates between the 2 and creates more sound inside the car than if you extended the pipes to the rear or even sides. Also, longer pipes do surpress so noise and tune the exhaust note differently.

I was also hoping to place a spacer between the o2 sensor and the bung to reduce the amount of restriction the sensor creates... unfortunately there wasn't enough room as the threaded part of the sensor is less than 1/2" total depth.

JBrady

Hey SF... you really should try removing the mufflers. Not loud, simple to do and easily replaced if you desire. Takes less than 30 minutes including jacking up the car. I could do it in 15min on a lift.

healerhand

John,

I removed everthing. My system was loud, but i have 4 resonators and calm things down. Initially, i just had two Magnaflow 3" in and out. It was loud, similar to a Mustang 5.0. With two 18" resonators, it helps little and with two more, it helps a lot.

Do you know where i can get the silencer 3" in and out? What is the different between silencer and resonator?