Looking for some opinions on Custom exhaust pipes

[chronic]

I started to play around with the length of my savages stock exhaust. Moving the convergent cone a bit further back. Not sure of the results. Trucks finnaly running like a top anything I do seems like a miracle compared to the last few weeks.

But a friend and I were talking about machining our own pipes. Making them adjustable. And trying different sizes for different volumes.

I'm kind of looking for ideas. Has anyone been bored enough to venture off into custom exhaust tuning.

I think it would be a fun project. Wouldn't take long to replicate a simple pipe design out of aluminum. So, just looking for ideas.

Thanks.

 

[ShiftPoint]

Buku does this, their manual explains how they work and act at different length's.

read this and you will have an idea of how they work and how cone postion effects the pipe

http://www.rc411.com/pages/scopes.php?scope=47&page=1

go to this page there is an animation of how these pipes work and effect preformance
https://www.bukupower.com/HowItWorks.aspx

here is the anamation
https://www.bukupower.com/animatecorrect.aspx

 

[chronic]

Thanks for that! I've read buku's website, but that article had some more info buku didn't.

 

[twinengsav]

I wish I new the exact mesurments of the pipe this guy made, him and another guy are into aluminum michining, he made his own pipe and boy did it ever work good, the only thing I can tell you about it is it looked like an airplane pipe, long ones, about the same diameture but longer then stock, and it dosent drop out the bottom it just shoots straight forward and I would say it was about 2"-3" longer then stock and then it tapered in to O about 3/8" exhaust and instead of compleatly straight forward as it tapered to a smaller diameture it curved downwerdsin front of the front shocks, it worked really good and had a sound all its own,,
not sure if that helped but that is the one I seen and seen the difference in performence,, "WoW" ....

 

[ShiftPoint]

Thanks for that! I've read buku's website, but that article had some more info buku didn't.

that's actually a link }{op posted, the insturction manual that comes with the pipe it has a lot of detial in it, to get an idea, it is about 12 pages.

good luck with your project.

 

[chronic]

Thanks bud. I've been doing some research and found lots of good stuff. I've got some ideas similar to what you're describing twinengsav that I probably will try. But some specifics I have had a hard time finding.

Like for instance, the importance of the angles of your divergent and convergent cones. I would assume shallow angles could hinder projection of certain waves and more extreme angles could be too agressive hindering flow. Should the two tapers be parralell? I would guess so... but maybe you want a lighter angle off the divergent cone and more extreme off the convergent forcing more pressure...

Also expansion chamber volume. It sounds like with most bigger two stroke engines they can't argue with bigger being better. Perhaps it creates a stronger back purge boosting your charge more?

Just some ideas I have to figure out. Should be a fun project until I blow my engine lol

 

[ntenc1]

Longer pipe will give you better top end. It simply has more un burnt fuel in it to shot back into the combustion chamber. Short pipe will give you more bottom end. Long pipe is retarding the timing and short pipe is advancing the timing.

 

[ShiftPoint]

Longer pipe will give you better top end. It simply has more un burnt fuel in it to shot back into the combustion chamber. Short pipe will give you more bottom end. Long pipe is retarding the timing and short pipe is advancing the timing.

I thought this is how it was too, but actually it is the opposite of this, shorter tuned length ( cone close to the header/mill) is better for top end, longer tuned length is better for bottom end (torque)

 

[ntenc1]

Thanks for the info man. I've been wrong all along.

 

[ShiftPoint]

Thanks for the info man. I've been wrong all along.

No problem, I thought the same thing till I got the buku pipe, did you read (look at the links in my post above, there is a page with some info and a nice anamation of what happens in the pipe and motor. It's pretty cool.

 

[chronic]

Close to finishing the first half. Although my orgional idea went out the window when I scraped my threads. It will still work... I should probably just start over. I'll have pics of the pipe soon. Maybe next week when I actually get a couple hours to work on it and finish it. Rather than rushing on breaks and turfing my project.

Anxious to see if it works or fails.