DragBikeMike
Serious Thumper
Offline
SuzukiSavage.com Rocks!
Posts: 4174
Honolulu
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This post will take awhile. I have lots of pictures to insert and it will take me multiple replies to complete. Please hold off on any comments until I finish the initial portion of the thread so it will make sense. I will state that I’m finished with the initial report when I finish up.
I wanted to evaluate and test the stock muffler to see if I could improve the flow without dramatically increasing audible noise. I also want to be able to return the thing to stock condition if possible, so I will be doing any modifications in stages, testing for flow and noise level after each stage is complete. Todays post covers stage I.
I was able to reduce the restriction from 35” H2O to 29” H2O. It’s still very quiet (pretty much like stock). It runs good. It was inexpensive to modify. It looks pretty much the same. It was quite a bit of work (but don’t forget I was doing lot’s of inspecting & measuring & testing along with the mods). It’s not as easy as installing a Dyna muffler.
What I did was similar to the “Hartman Modification” discussed in the tech section. You can find more details on that mod at jonline.org/savage/Tips. The difference between the Hartman Mod and the DBM mod is I stick to the stock flow path through the muffler. I don’t claim that this is any sort of “tuned” system, it’s simply less restrictive.
I know most of you have no interest in utilizing the stock muffler. Some think it is ugly. Others don’t care for the sound. Some are concerned with the weight. I personally find the animal a thing of beauty. Not necessarily because of how it looks (however I do think it looks pretty good), but because of the potential associated with it’s volume. It’s very large, much larger than say a Harley Dyna unit, or a SuperTrap. If you do a mathematical evaluation of just the cylindrical portion of the stock LS muffler (4.15” OD x 11” long) to just the cylindrical portion of the Dyna muffler (3.25” OD x 13” long) you will see that the LS muffler has 41 cubic inches more internal volume than the Dyna. Peek inside of the mufflers and you will see that the conical section of the LS muffler has way more volume than the Dyna. Also, keep in mind that Harleys (most models) use exhaust systems where each cylinder shares two mufflers. They use a crossover pipe so that each individual cylinder is actually connected to two mufflers. I think that the volume of the muffler makes a significant difference in how well the device can do it’s job (allow maximum flow while effectively attenuating noise). That extra volume allows the hot gasses to accumulate without building up excessive pressure. There’s nominally 500 degrees of crank rotation before the next slug of hot gas comes down the pike so that extra volume is a nice place to store the stuff while it meanders out the back door.
Next time you pull up behind one of those new racy Camaros, take a look at those two, beautiful, stainless steel works of art hanging under the car. They are huge. How about any of those late model sport bikes like say a Hayabusa, GSXR, ZX-10, R1 or RR1000. They all have very large-volume muffler systems. Totally stock, those machines all make big horsepower and are quiet. Buell designed the eighth wonder of the world when he came up with that magnificent (albeit not too pretty) 55 gallon drum hanging off the bottom of the engine. It received accolades from the motorcycling press for affording excellent performance and lowering the center of mass while meeting federal noise standards. It also had this innovative valve system that opened up additional portions of the muffler under WOT conditions. Majorly cool Erick. Now corvette just happens to have a valve system like that.
I’m not a muffler designer so I just sort of made up my own names for the various components. Please forgive me if the names I assigned turn out to be in disagreement with the actual name of a particular part of the muffler.
Let’s get started.
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