Stock Can Modification

[aerodyne]

Have recently purchesed a 2005 Le Mans, love it to bits. Have read about modifying stock cans to produce a little more volume, but these threads seem to be a few years old.

Has anybody done this modification? if so how? does it affect the performance at all?

Thanks in advance for any help.

[rocketeer]

Have recently purchesed a 2005 Le Mans, love it to bits. Have read about modifying stock cans to produce a little more volume, but these threads seem to be a few years old.

Has anybody done this modification? if so how? does it affect the performance at all?

Thanks in advance for any help.

I removed the end caps and cut the inner snorkel off and drilled three 1/2 " holes in the end plate surrounding the snorkel as per a previous post. Reattached the end cap using blue loctite on the screws (highly recommended) and ended up with little more rumble and it "feels" a bit more responsive. Spark plugs look good but idle speed dropped a 100 rpm which I readjusted with the left side throttle body idle screw. Planning on changing the crossover in the future but for now I`m quite happy with the results. How loud your mufflers are is a personal choice. I had FBFs and found them too loud.

Good luck.

[motoguzznix]

Here is the link where I posted my mods on the standard cans:

 

Unpacking the cans

 

There are power graphs added that show the gains of my mods. To make things clearer a scetch with my mods:

 

The upper drawing on the scetch is straightforward to realise. The dotted areas of the internals of the cans should be removed.

If you are experienced in sawing and welding the job can be done within two hours. After pulling the cover saw completely through behind the front welding seam. The rest of the mods in the 1st chamber can be done by sawing partially through from the up- and downside. For the mods in the 3rd chamber I cut' a square window on the upper side. The window is cut on three sides and the sheet metal bent away. Although the inner can is in stainless steel, it can be welded easily with a non stainless wire as the welding seams are invisible and there was no rust inside my cans after two years.

[aerodyne]

I removed the end caps and cut the inner snorkel off and drilled three 1/2 " holes in the end plate surrounding the snorkel as per a previous post. Reattached the end cap using blue loctite on the screws (highly recommended) and ended up with little more rumble and it "feels" a bit more responsive. Spark plugs look good but idle speed dropped a 100 rpm which I readjusted with the left side throttle body idle screw. Planning on changing the crossover in the future but for now I`m quite happy with the results. How loud your mufflers are is a personal choice. I had FBFs and found them too loud.

Good luck.

 

 

I removed the end caps and cut the inner snorkel off and drilled three 1/2 " holes in the end plate surrounding the snorkel as per a previous post. Reattached the end cap using blue loctite on the screws (highly recommended) and ended up with little more rumble and it "feels" a bit more responsive. Spark plugs look good but idle speed dropped a 100 rpm which I readjusted with the left side throttle body idle screw. Planning on changing the crossover in the future but for now I`m quite happy with the results. How loud your mufflers are is a personal choice. I had FBFs and found them too loud.

Good luck.

Thanks for the advice, plenty to think about, will give it a go when I get chance next week, Thanks again.

[Skeeve]

Here is the link where I posted my mods on the standard cans:

[relevant portion of link quoted below to aid in understanding the pic]

 

To make things clearer a sketch with my mods:

 

WRT upper diagram:

"I want to describe my modifications on the original exhaust cans of my V11. The result of my modifications was 3 HP more on the dyno in the higher rpms with an exhaust note almost stock.

My mods: The idea was to let the gassses pass the muffler without changing the direction. Originally, the gas enters through to to chamber 3, turns back to 2, 1 and back out via the very long end tube.

In the first chamber I cut' out 50 mm from the tube which enters from the collector. (On the mufflers I modified, there was the catalytic converter in that place).

The 2nd chamber remained untouched.

In the 3rd chamber I cut' out 50 mm from the upper tube which goes out.

The 4th chamber with the steel wool remained untouched too.

So the exhaust gas flow finds an open end in chamber 1, passes to chamber 2, 3 and can leave from there via the much shorter end tube. No change in direction."

 

Lower diagram:

"My next step would be to eliminate the wall between 1st and 2nd chamber (drilling out the welding spots). The wall between chamber 2 and 3 has no spot welding. I leave approx. 50 mm of the tubes on both sides of that chamber wall. This will be welded into the can to divide the volume in now only two chambers of similar volumes. Chamber 4 remains untouched again.

So the gasses enter chamber 1, pass via 4 tubes into chamber 2 and leave from there through the end tube. The gas flow passes now 2 chambers of a bigger volume and have more room to move. The backpressure will further decrease, the power will (hopefully) make another step upwards and the noise level will slightly increase. I intend to perform this during this winter.

I hope my descriptions are clear, the pictures on the previous posts should help that.

Attached is the power graph: completely stock, slight modifications on engine with CR +0,5, like above with my modified mufflers."

[dlaing]

Be sure you look at the photos in this thread

Skeeve's images are particularly revealing

http://www.v11lemans.com/forums/index.php?...20can&st=15

How hard would it be to remove all the innards except for the steel wool end cap, and then put in a perforated tube aiming at the in pipe and out pipe, and surround it with steel wool? Kind of a shortened version of a conventional race muffler inside a DOT approved carcass.

I think this could be powerful yet not too loud.

There would be a bottle neck at the stock end of course, but maybe a good option for those that need to fear Law Enforcement.

But perhaps it is too much trouble. I know I won't try it unless I take welding classes.

One of Skeeve's photos

[motoguzznix]

In the meantime I performed the mods following the lower drawing on the scetch.

 

The effort in welding and sawing was much greater than the first mod and a really sweaty job.

 

The exhaust note is now wonderful. Smoother than straight through pipes, not so hard, but noise level increases with throttle opening and higher rpms and gives a very nice sound. Not relly quiet but far from noisy. Acceptable for long trips on the bike.

 

Removing the steel wool makes the can neither noisier nor flow better because the end tube is not open to the steel wool packing. The cause for the steel wool is the entering gasses pass through the big tube until they are reflected and dampened by the steel wool. When they arrive there they are still very fast and hot, so this is the area where most of the energy of the exhaust is dissipated in the original design.

 

David

I was also thinking about a change like you described above, but I think the next step must be to increase the diameter of the end tube.

But every change in the can design that exceeds my first simple mods is not worth the effort. You would be better by building a silencer from new than modifying the stock one.

[Skeeve]

But every change in the can design that exceeds my first simple mods is not worth the effort. You would be better by building a silencer from new than modifying the stock one.

 

[emphasis added]

 

Yeah, I think that was my final thought over on the original thread for modifying the stock cans: there's just so little you can do to them that's worth the effort involved!

 

I think about the limit as far as "reasonably easy" is just to pull off the end cap and drill a bunch of tiny little holes in the end of the can to vent the area stuffed w/ steel wool [chamber 4]: the flow won't be signficantly increased, but it should help a tiny bit (esp. at full chat), & of course you'll get a slightly deeper "boom" out of the stock cans w/o increasing the noise level to the point that the neighbors will notice or care.

 

To increase flow, pulling up a tab on the bottom of chamber one, drilling a couple of 1cm or 3/8" holes in the bottom of the main exhaust line & resealing the tab, and then pulling a tab on the top of chamber 2 and drilling a couple of 1.5cm or 1/2" holes in the top of the outlet tube [or even cutting out an entire section of it] & resealing the tab will be about the limit as far as time & effort worth the results. And even then, only for someone who's perrenially short of funds & has the skills & tools necessary to do it himself [or a willing friend w/ the tools/skills who is up for the experiment just for the fun of it.]

 

Next stage: designing a muffler that will fit w/in the stock envelope & provide all the stock mounting points, but will provide superior performance w/ acceptably quiet noise levels! This task is so trivial, it will be left as an exercise for the reader...