Another simple 2 stroke expansion chamber design program scroll down to. This small java applet uses design rules according to, and, to size a tuned pipe for a 2 stroke piston engine. Unlocking the secrets of 2 stroke expansion chamber exhausts e1. The exhaust would not go all the way through the pipe in 1 cycle. This program calculates the dimensions for both double and triple stage diffuser expansion chambers from a few basic engine dimensions. Once again before i start thanks to the author of the website. New version of 2t exhaust calculator it is a freeware 2 stroke expansion chamber exhaust calculator program download at. Freeware 2 stroke expansion chamber exhaust calculator program. How to design a two stroke expansion chamber performance.
Two stroke design software the following are spreadsheets for different aspects of 2 stroke designmodification. Forum main motorelated two stroke exhaust question. Repost next we calculate the bmep brake mean effective pressure being the average cylinder pressure. The way to calculate the return timing and length of the negative wave in a 2 stroke expansion chamber is by this formula. Small values of kh are best suited to grand prix engines with narrow power bands, larger. I would go with the carbon guard and could build any of the first 3. As soon as you add 1 or 2 more cylinders to the mix, the soundwaves for lack of a better explaination begin to collide in a way that disrupts the whole purpose of an expansion chamber. As motorcycle engineers gained more knowledge of the 2 stroke and its working principles,it became obvious that to increase power they needed to have a method of varying the exhaust port timing. Free expansion chamber design utility download expansion. The books ive read seem to indicate a tradeoff between enhanced pipe action and power output reducing diameter and motor overheating with a toosmall pipe. Do it right by doing it yourself this screenshot is sheet 1 of 4 sheets. Performance fabrications is dedicated to manufacturing the finest bespoke hand crafted exhaust systems available. Twostroke waveaction engine simulation motion software. The official home page of our 2 stroke wizard tuned pipe.
Racingsm software has features for many different areas 2 stroke exhausts development, drag racing features, simulators, carburetor tuning, connectingrod analysis etc with all this knowhow along with lufo racing heritage, we believe this is a very fair price. While moving downwards after ignition, the piston exposes the exhaust opening, and the burned gas streams into the exhaust pipe like a high pressure shock wave. Using the plot cone dimensions from the two stroke freeware expansion chamber calculator i show how to draw a cone plot on to flat papers to be traced on to sheet metal. Freedownload here this program is not a part of mota, but it has been put together by the same engineers as a. But im curious as to how an expansion chamber would affect a four stroke engine. Two stroke tuning by alexander graham bell excellent book. It is the twostroke equivalent of the tuned pipes or headers used on. Im looking for advice on pipe guard protection for the shiny new fmf gnarly bolted onto my first ever 2 stroke sherco300. You can also save and load the data by using the provided functions. The invention of the 2 stroke expansion chamber was the result. How to plot two stroke expansion chamber cones on paper. There is this nice animation of a 2 stroke engine with an expansion chamber. The worlds leading 2stroke engine simulation software for 3. This is the first video in a series looking at the science and mysteries of 2 stroke expansion chamber exhausts.
He reportedly said youll know when you have the design right, because the chamber will then be impossible to fit on the motorcycle. Two stroke engines operate in two strokes, instead of four, and this animation illustrates the two stroke engine operation in conjunction with its expansion chamber showing the reflected pressure wave on the fuel charge. Direct comparison between different types of exhausts for the two stroke engine, on the left you can see the engine and its exhaust, in the. I bought an expansion chamber design program, and it produced numbers more in line with what i though i should have from what ive been reading. Wrt1d1x2sw where wrt1 is the wave return time for the first part of the wave, d1 is the distance from cylinder port to beginning of diffuser, and sw is the speed of the wave which is determined by the temperature and. A simple 3 stage two stroke exhaust calculator based on formulas of g.
What will a two stroke run like without an expansion chamber. This pipe consists of an expansion chamber which serves to create both the returning rarefaction and pressure waves. But because of the limited worldwide activity in two stroke engine development, program sales were limited and further development was curtailed. Ok, i had a question up a week or two ago about why two strokes have their expansion chambers in the pipes. This animation will explain the inner workings and basic principle of two. On a two stroke engine, an expansion chamber or tuned pipe is a tuned exhaust system used to enhance its power output by improving its volumetric efficiency. An expansion chamber is an exhaust system used on a twostroke cycle engine to.
This will get you started by providing, for your engine, the dimensions of an expansion chamber with a 2 stage or 3stage diffuser. You know that changing the exhaust pipes on your two stroke motorcycle can have a marked effect on the engines power characteristics, but do you know why. Simply put, its because the two stroke exhaust system, commonly referred to as an expansion chamber uses pressure. This coefficient kh is called the horn coefficient, with typical values between one and two. Im a metal fabricator by trade have made custom expansion chambers since 1974.
We also have a simple 2 stroke expansion chamber design program. Without a pair of really good chambers you will never get much power from you rd 350 ypvs. Why do twostroke engine exhaust pipes look so strange. Two strokes can function with significantly better. How an expansion chamber works a nice animation another good. Engineering acousticssonic supercharging of 2 stroke. Near the end you will be presented with the latest and best software for design and analysis of 2 stroke pipes.
The expansion chamber an improperly named device utilizes sonic energy contained in the initial sharp pulse of exhaust gas exiting the cylinder to supercharge the cylinder with fresh mixture. Freedownload here this program is not a part of mota, but it has been put together by the same engineers as a starting point for those wishing to begin from scratch. Engineering acousticssonic supercharging of 2 stroke engines. The calculations are assuming a speed of sound in the exhaust gas, which is not known exactly. The program i used for most of the distances and diameters was the 2 stroke wizard pro version 3. This expansion chamber is not the product of simple correlations as for other products that abound on the web, but an automatic design created by motawhich is a full wave action 2stroke engine simulator. Without a pair of really good chambers you will never get much power from.
The stock pipe is basically a straight pipe anyway but i want to pit a straight pipe on it with a new school silencer on it. The chambers is the single most important thing when it comes to tuning the 2 stroke engine. On a twostroke engine, an expansion chamber or tuned pipe is a tuned exhaust system used. Tecumseh 2 stroke mods motorized bicycle forum motored.
This stroke occurs immediately after the detonation of the charge. Has anyone experimented with varying the diameter of the tailpipe section including silencer to dial in a 2 stroke pipe. First we look at how the initial sonic compression wave is. Howto how two stroke expansion chambers work, and why you should care. Building your own racing expansion chambers rdrz 350 ypvs why should i even bother making them. Im building a little street legal 30s style hillclimber out of a 73 dt1250. A 2 stroke can be made to be quieter than a 4 stroke because there is no valve clatter to deal with. The businesses and individuals that purchased the original dynomation 2 stroke program were pleased with the capability and accuracy of the software. The expansion chamber that sick bike parts and pirate cycles sells seems to be proportioned well, although i suspect the lead in pipe will be. The bmep value will provide an indication of the average exhaust gas temperature we need to calculate tuned length of the epxnasion chamber exhaust, as well as. From reference 1, we know that wave speed in the pipe is effectively.
File type pdf two stroke engine expansion chamber design software two stroke engine expansion chamber design software unlocking the secrets of 2 stroke expansion chamber exhausts e1 this is the first video in a series looking at the science and mysteries of 2 stroke. I bought a new two stroke piston engine on special for the purpose of showing how to measure up exhaust port area and timing to plug in to the 2 stroke expansion chamber exhaust software. Unlocking the secrets of 2 stroke expansion chamber. I got sick of the silly free programs and the expensive for sale programs and that wasteoftime 2 stroke wizard and so made my own expansion chamber calculator spreadsheet. The program takes your info and spits out a sheet with lengths and diameters. You silence the exhaust with oem style mufflers one or better yet 2 from a small motorcycle with sound pack material inside. The bmep value will provide an indication of the average exhaust gas temperature we need to. How twostroke expansion chambers work, and why you should. Read my expansion chamber theory page to get a full understanding of how expansion chambers work and click here to read more of.
The first cone is longer in this design but that is to eliminate the need to make a long b section that gently gets. Two stroke engine expansion chamber design software. Dans motorcycle two stroke motorcycle exhaust pipes. We now have a simple 2 stroke expansion chamber design program. The 2 stroke engine animation demonstration has an added device commonly known as an expansion chamber attached to the exhaust port.
The expansion chamber an improperly named device utilizes sonic energy contained in the initial sharp pulse of exhaust gas exiting the cylinder to supercharge. My professional 2 stroke expansion chamber design software is more sophisticated than other programs that only use a few basic formulas. Expansion chamber for 2 stroke what do u recommend. The official home page of the 2 stroke wizard tuned pipe 4t exhaust header wizard software.