benjy6

i saw a nice homemade pipe on youtube that gave the fg monster a nice rich sound
what do i have to do to make my own tuned pipe?
http://www.youtube.com/watch?v=hrnJ10AiHtE- This is the video

troppo

I would be interested in this as well, i have all the info for a four stroke but not a two stroke. Looking forward to one of the GURU`s replying
Cheers
Troppo

SAVAGEJIM

Our pipes use an expanding chamber design, so knowing the speed of sound in the exhaust gases in the pipe, the temperature of those exhaust gases, and desingning a pipe volume and associated header lengths as well as baffle design (if you put thm into the pipe), the stinger diameter and even length are all considerations in designing a pipe. There are more parameters, I have to dig up one of my books again to explain the matter in detail. First and formost, the important thing about designing an exhaust system for our gassers is to know what the timing profiles of our engine ports are. Knowing the durations, specifically when the exhaust ports open and close, is important because you want to design the exhaust system such that the return pulse to come back precisely some time before the exhaust port closes so you casn return as much of the overscavenged fresh fuel air back into the cylinder. When a pipe does this, some have called this action coloquially as being "on pipe." And typically, there are three RPM bandwidths that the pipe does its thing, thus, the engine being "on pipe." These are"Low RPM pipes or "torque pipes." Torque pipes do their thing by offering their return pulses during low to mid RPM ranges. So, not to far from idle, a torque pipe puts the engine "on pipe" in many cases as soon as the engine leave idle RPM range and when the clutch engages (which typically must also be tuned to engage at low RPMs). Clutch tuning is important here, because if you set the clutch shoes to engae at too high of an RPM, you could waste a significant part of the valuble RPM range during which the engine is "on pipe" for those low RPMs. Additionally, low RPM pipes are usually referred to "torque pipes" because generally, an engine will have more torque area under its torque curve at lower RPMs. This is not alweays the case; I have seen engine dyno curves in which the engine can actually produce the best meat of its torque at mid RPMs. Because of this, the name "torque pipe" is not really a good description for low RPM pipes. I simple prefer to call them low RPM pipesMid-range RPM pipes do their thing at mid RPM ranges, and also in many cases include some of the higher ends of the low RPM bandwidth and some of the lower ends of the high RPM bandwidth. And lastly, high RPM pipes do their thing of course in the high RPM bandwidth.

SAVAGEJIM

I forgot to mention: When a pipe is offerring its return pulse, what I should have clarified is that the pulse should be coming back to return the overscavenged fresh fuel-air charge preferrably at the instant the intake ports close and up until the exhaust port closes. I cannot remember just what duration this window is, (I think it is about 15degrees), but if the pipe is giving its pulse back too early, i.e. the cylinder intakes are still open, the engine must work just a tad harder to pump against that, this eating away a little at your HP and torque output.

ophirw

Hi benjy6,

I think that 1st of all you need to know if you are able to construct complex designs in metal, if you are up to that task than you will need to read
about the "Kadenacy effect" which is the basic physics concept behind the theory of 2 stroke pipe design.
A good place to start reading & learning about how to design a 2 stroke pipe is wikipedia: http://en.wikipedia.org/wiki/Expansion_chamber
you will learn the basic terms & can continue from there.

check out this thread: http://www.rcuniverse.com/forum/m_83...tm.htm#8302339
they have posted some SW links & theory links.

Dirty_Vinylpusher

Hey guys I asked this question a while ago and someone sent me [link=http://www.modelpowerboat.com/forum/article/tunedpipe-designer.htm]this.[/link]

da mad maori

cool page
looks confusing tho lol

SAVAGEJIM

It's really not that bad at all. After playing with the calculations and sketching them out on a piece of paper, doing the calculations a few times actually gives you a very good understanding of designing the volume chamber and header length for a given engine's timing profile and the RPM you want it to do its thing at.

troppo

Thats a little more complicated than tuned length headers for my car and bike lol, but thats a great help in understanding the whole theory, thanks guys

Dirty_Vinylpusher

Yeah first time I looked at that page I was like... "ummmm yeah ok whatever..."

Then I got a mate who's really good with maths, formulas and equations etc to look at it and he got it straight away.
Once he had explained it to me it wasn't as confusing.
Am gonna have a go at making a pipe one day.

benjy6

well its a damn good thing i bought a pipe first
im bad with math so im gonna have to practice and practice
as they say practice makes perfect

and thanks EVERYONEfor the replys and help aids