Exhaust Tuning?

[shadowhunter04]

Hey guys, it's been a while. Over the winter though, I thought it'd be fun to do some work on the bike. Anyways, I thought I'd try making up my own exhaust. I've got a buddy who owns a climate-control company and said he could help me put together some seamless welds for a new exhaust system. What I'm interested in doing is making a tuned exhaust. I realize that there are many aftermarket kits you can get, but I thought for my own learning experience, that I'd give it a try.

What I was looking for is if anyone has done this so far (results/findings) and if anyone knows what the stock intake cam duration for a GSX-600F. Also, if anyone's got a power band chart for a stock pre-98 bike that'd be great too! Thanks guys for your help!

If anyone else is interested, here's a link to a pretty handy resource (among many). I know it's for a HD, but the concepts are the same and so can be applied here.

How to Build a Harley Davidson Torque Monster

[Tmod]

Here is another resource for ya to try.

http://dairally.net/daihard/chas/MiscCalculators/DaiPipes.htm

http://headerdesign.com/extras/design.asp Register on this site and you get free access to a online program that will help in your header design.

A few tips on selecting the right pipe size and the affect the wrong selection will have.

1) Primary Pipe Size:
The size of the primary pipe is the number #1 mistake we see in self designed as well as aftermarket headers. The size of the primary pipe should be the same diameter as the cylinder head valve throat, not the valve but the throat. Exhaust system effectiveness depends largely on maintaining gas velocities from the time the exhaust valve opens to the time it is deposited to the atmosphere. If for example your primary pipe size is to large (often the case because many believe bigger is better) and your exhaust valve throat diameter is one tubing size smaller than your primary tube size you have changed your gas velocity by roughly 20%. This change is gas velocity will affect the scavenging properties of your header because the pressure pulses (negative pressure) used to scavenge the cylinders will now come later in the exhaust stroke or even after the exhaust valve is closed.

2) Primary Pipe Length:
Determining the proper primary tubing length is extremely important to the timing of the pressure pulses used in scavenging the cylinders and ensuring fresh charge. If your primary pipe length is to short the pressure pulses may reverse so quickly that you may actually be forcing exhaust residue back into the cylinders. If your primary pipe length is to long then the pressure pulses will have no effect on scavenging because that negative pressure that we desire at TDC will happen well after TDC.

3) Collector Diameter:
Many believe and commit the same error here as they do with primary tube size. That is that bigger is better. The fact is that the collector has a bigger job that just merging the 4 or 3 pipes into 1 although this is one of its functions it also provides secondary scavenging characteristics for our headers. When the exhaust valve opens and sends spent exhaust gas down our primary tube and merges into our collector the pipe size difference between the primary and the collector causes a pressure wave reflection sending a negative pressure back up our primary pipe and assisting scavenging the pressure wave continues on past the primary pipe and into the collector when it emerges from the collector again it sends another wave reflection back up the primary pipe behind the first reflection and thus prolonging the scavenging effects and ensuring clean fresh charge is digested into our cylinders. Improper diameter will slow down exhaust gas velocities and thus delay the start of this secondary scavenging wave.

4) Collector Length:
Proper collector length is important in timing the secondary scavenging characteristics of our header. If the first 3 factors are correct the incorrect collector length (short) will cause our secondary reflection to be timed to close to the primary reflection and may allow for pressure to rise above atmospheric over TDC. If the length is to long then our secondary reflection may be too late in the stroke to be effective in assisting scavenging.

Tmod

[GregS]

Good write up TMod. One thing that also needs mention is the use of cross over pipes, like Suzuki uses in the stock setup. Their size and location can strengthen or weaken power band width dramatically. Also since generally we run some kind of muffler we need to consider its design / size / length. And finally we need to consider the material we make the system from, the heat of the exhaust affects the flow and reversion characteristics.

[Tmod]

And finally we need to consider the material we make the system from, the heat of the exhaust affects the flow and reversion characteristics.

Or any thermal barrier coating that might be applied.

Tmod

[shadowhunter04]

Those links and posts are great guys! Have you ever made your own exhaust design? If so, how did it work?

[Tmod]

Nope never did fabricate my own exhaust but rather used the info to make a smart decision in what to buy for my vehicles. I don't have a tubing bender and especially one to make mandrel bends.

Tmod