Exhaust engineering

[Aches n Pains]

Thought you guys might be interested in this video. It speaks to a number of things that have been said around this forum regarding alternative exhausts.

http://www.youtube.com/watch?feature=player_embedded&v=KjKUKhHQLHg

Loved the recommended treatment for drag pipes.

[jwhughes3]

Very good demonstration of wave mechanics.

I am still chucking over "Constabulary"

John

[skids]

Yeah. Me too. A term that I will remember.

[ViperRon]

I finally got what I feel is my happy medium with my Mac exaust system. It has the tapered tip mufflers but has always been loud and to me loud means lack of restriction loss of back presure etc etc. I made a set of baffles using washers and some pipe. In the picture it appears that basically the baffel in the mack pipes is a bent pipe with baffel cuts sealled on both ends. The baffel in mine ended about 5 inches from the enf of the pipe leaving a large open area that I believed was magnifying the sound. The baffel had an opening that I could slip a 6 inch piece if pipe in and it ended at the end of muffler. I welded 2 strong washers one in the middle and one on the end of the pipe. I put a smaller washer into the one inch pipe to restrict flow comming out. I then drilled a bunch of holes threw the one inch pipe on both ends of the smaller washer for exaust flow. So now basically I have flow comming out being restricted by small washers thew little holes on one side over the large washer and back thew small holes into the one inch pipe and out. I built both sides with exactly the same amount of little holes and tacked the outer washer to the outer edge of bevel of muffler so that inside of one inch is supported by the inner baffel and the outer washer holds the pipe tight inside. I cut a heat resistant gasket and got stainless washer as a trim plate to cover so it looks clean and completely seal leak. Two small screws attach the stainless trim washer to baffel.



The advantage of doing it this way is the ability to change the level of baffeling without pulling the baffel. I started out with a 1/4 hole in the small washer and ran the bike and could tell it quieted it greatly but maybe lost some power so i drilled the center hole of the little washer a little by little driving till i felt I hit a good spot with the inside at a little over 5/8ths. Its alot closer to the sound of the factory pipes there is more back presure and feels like its running better and I do not attract the eyes of every cop now.

[James England]

Excellent. Thanks for posting that!

[Aches n Pains]

Viper Ron,

We need pictures of your pipes on your bike. Very good write-up.

[skids]

That video is quite good. I would say (and I repeat myself a lot) that if you are after an exhaust system that gets some "benefit" from exhaust scavenging, there will be advantages at some rpms and disadvantages at other rpms. I suppose that scavenging might be important to drag racers who hold the rpms high for the launch and keep them high throughout the race.

[ViperRon]

Pictures

Here are some pictures.





[/IMG]



I may have comented before the center small washer final hole was 5/8 actually it was 7/16. I used a 1/8 bit for the internal holes drilled arround the baffel and it was 6 rows of 7 in a line on both sides of the baffel.