We also have a simple 2 stroke expansion chamber design program. There are many ways to boost the power, one of which is by installing a tuned pipe. Small values of kh are best suited to grand prix engines with narrow power bands, larger. Do it right by doing it yourself this screenshot is sheet 1 of 4 sheets. Free download 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.
Two 2 stroke exhaust expansion chamber calculator using 3 methods. 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. 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. The way a two stroke motor works causes them to be f. Method 1 and method 2 two and three stage diffuser. This program calculates the dimensions for both double and triple stage diffuser expansion. A submenu offers the two selections constructing the development pattern of a cone and printing the development pattern of a cone. But thats just how we start your brief then we recognise the balance between drive and top end power because a pipe is a compromise. Freeware 2 stroke expansion chamber exhaust calculator program download at. The strong low pressure pulse of a racing two stroke expansion chamber can drop the pressure to 7 psi when the piston is at bottom dead center, and. Developed by pedro, with more than 20 000 lines of code, all the knowhow applied to software comes from us and also a lot from the legendary portuguese 2 stroke tuner lufo racing, this software is directed for all 2 stroke. Why dont 4stroke motorcycles have expansion chambers. Jan 23, 2019 2 stroke exhaust expansion chamber calculator using 3 methods. Here is the official description for 2 stroke wizard tuned pipe.
You can also save and load the data by using the provided functions. Twostroke waveaction engine simulation motion software. Could it give a four stroke the two stroke famous bighit. Two 2 stroke exhaust expansion chamber calculator for. As the forces in a two stroke pipe design have become more wellunderstood, designers have been able to create engines that take more advantage of them and in fact require an expansion chamber to run at all. Two 2 stroke exhaust expansion chamber calculator apps. However, the wave may also suck fresh mixture out the exhaust port into the header of the expansion chamber. The official home page of the 2 stroke wizard tuned pipe 4t exhaust header wizard software. He also proved that the return waves are generated all along the length of the diffuser and baffle cones. Small values of kh are best suited to grand prix engines with narrow. The first cone is longer in this design but that is to eliminate the need to make a long b. The bad designed chamber have a weak pressure wave that dont suck the charge out of the cylinder, and then dont push much fresh charge back into the cylinder, producing less horsepower, wasteing fuel and polluting more. I have plans this winter to put my yz 125 motor in it but i would like to see how this little motor runs with a good pipe vs the stock one that i think is holding it back. I have been around bikes for a long time, 59 years old and started at 15 and have not, until now had such a performance gain form just putting a set of pipes on.
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. The calculations are assuming a speed of sound in the exhaust gas, which is not known exactly. It is also very good for expansion chamber designs. The way to calculate the return timing and length of the negative wave in a 2 stroke expansion chamber is by this formula. Blair, professor at queens university belfast, and published by the society of automotive engineers. Any donations greatly appreciated, please use paypal link.
The expansion chamber is the most tunable component on the modern two cycle engine and dramatic gains in power can be achieved with the correct design. Two 2 stroke exhaust expansion chamber calculator, fast, free and save your internet data. Expansion chamber design according to blair introduction all the information presented was taken from the book design and simulation of two stroke engines written by dr. Download my free calculators spreadsheet to check your computers ability. Using apkpure app to upgrade two 2 stroke exhaust expansion chamber calculator, fast, free and save your internet data. Thank you for your interest in dynomationtwostroke designed for windows98xp. Transfer port time is set at a minimum of 26 degrees. Two stroke tuners handbook 2 another mistake commonly made, sometimes even by those who have enjoyed some success in modifying twostroke engines, is to believe in a kind of mechanistic magic. We now have a simple 2 stroke expansion chamber design program. Npp neils power pipes handcrafted custom pipes and. We have possibly the biggest collection of expansion chamber templates in the world. Jan 28, 2011 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. Bigger carburetors, higher compression ratios, altered port timings and expansion chambers often do bring an improvement in power output, but more and. How to plot two stroke expansion chamber cones on paper.
We only deliver legal and safe mod apk for android. After our trial and test, the software was found to be official, secure and free. 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 history. Expansion chambers in pistonvalveless two stroke engines are useful for a variety of reasons. How twostroke expansion chambers work, and why you should care. There are a few software programs available for 2 stroke simulations.
Without a pair of really good chambers you will never get much power from you rd 350 ypvs. They fitted perfectly and sounded even better than expected. They often recover charged air which is passing into the exhaust, along with increasing cylinder pressure. Unlocking the secrets of 2 stroke expansion chamber exhausts e1. Enthusiasts, tuners, mechanics, gp, drag racing, mx, enduro. Once again, congrats on your ability the provide such a quality product and keep us two stroke lovers alive. How to plot two stroke expansion chamber cones on paper from software duration. The program takes your info and spits out a sheet with lengths and diameters. This program is not a part of mota, but it has been put together by. Racingsm software 2stroke exhaust calculator lufo youtube. 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. In a two stroke engine it is standard practice to calculate compression ratio based on the trapped swept volume i. Fourstroke expansion chambers general dirt bike discussion.
The program i used for most of the distances and diameters was the 2 stroke wizard pro version 3. Two 2 stroke exhaust expansion chamber calculator apps on. Two stroke tuners handbook 2 another mistake commonly made, sometimes even by those who have enjoyed some success in modifying two stroke engines, is to believe in a kind of mechanistic magic. So our starting point is deep expertise and knowhow. 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.
Simplified the good chamber works as described in the figures above giving lots of power over a wide rpmrange. For four stroke engines it is standard practice to calculate compression ratio based. Nov 17, 2017 this is the first video in a series looking at the science and mysteries of 2 stroke expansion chamber exhausts. How two stroke expansion chambers work and why you should care.
A complete two stroke pipe has properly tuned header, convergent, belly, divergent and stinger sectionsa difficult process. Based on design and simulation of two stroke engines written by dr. To preserve the original formulas, community editing will not be enabled on this page. This coefficient kh is called the horn coefficient, with typical values between one and two. Free 2 stroke exhaust expansion chamber calculator youtube. Dynomatontwostroke is a dosbased simulation that was originally released in the mid1990s.
A two stroke 125cc engine with standard exhaust system can combust no more than 125cc of fuel air mix. Bigger carburetors, higher compression ratios, altered port timings and expansion. Performance fabrications is dedicated to manufacturing the finest bespoke hand crafted exhaust systems available. We also have a simple 2stroke expansion chamber design program. Read my expansion chamber theory page to get a full understanding of how expansion chambers work and click here to read more of the details of this spreadsheet calculator. Specificaly written for gokarts engines, but will do any 2 stroke. The speed of sound is one of the main parameters involved in expansion chamber design as it governs the speed of the pressure pulses that affect the chamber. First we look at how the initial sonic compression wave is created during the blow. Once again before i start thanks to the author of the website. We shall send you a pdf document with the templates for manufacturing your exhaust.
This program calculates the dimensions for both double and triple stage diffuser expansion chambers from a few basic engine dimensions. Just a quick update on the progress of the freeware 2 stroke expansion chamber calculator software. Wrt1d1x2sw where wrt1 is the wave return time for the first part of the wave. Maximum average piston velocity calculator the average mean piston velocity is what most calculators. The two tuned lengths of the 2 stroke expansion chamber, photo of. The 2 stroke engine animation is a tool to help you understand the importance of port timing and exhaust waves in a 2 stroke engine.
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 center the progression curves of the. If you have any input or questions about our wizard performance tuning software please contact jp at one of the email addresses listed below. Ask our shadetree mechanics 2 stroke wizard pipe builder. Maximum average piston velocity calculator the average. So whether you have a 50cc road bike, a 500cc motocrosser or a classic racer, we will design the perfect exhaust system for you. A simple 3 stage two stroke exhaust calculator based on formulas of g. To edit a copy of this document, go to file at the top left of the page, and either download a copy.
Jan 15, 2005 ok, i had a question up a week or two ago about why two strokes have their expansion chambers in the pipes. Additions to the expansion chamber construction utilities the expansion chamber construction utilities have been extended considerably and are now accessed under a separate item on the main mota menu. This will get you started by providing, for your engine, the dimensions of an expansion chamber with a 2 stage or 3stage diffuser. The chambers is the single most important thing when it comes to tuning the 2 stroke engine. Free 2 stroke expansion chamber calculator software update. The one i have been using is call mota, from ian williams tuning. This of course is not even considering whether or not the exhaust and transfer port timings and outlet areas have been optimized for expansion chamber use. My expansion chamber calculator, how to obtain and use it. For a 4 stroke engine, the problem of loosing charge air to the exhaust is entirely neglectable. This software covers the 3 stage diffuser type expansion chamber exhaust as per equations provided in his book entitled design and simulation of two stroke engines published in 1996.
Improve the performance of your two stroke engine with a torqsoft designed exhaust system. The official home page of our 2 stroke wizard tuned pipe. But im curious as to how an expansion chamber would affect a four stroke engine. How to design a two stroke expansion chamber performance. Nov 27, 2018 2 stroke exhaust expansion chamber calculator is now ready for download follow the link to my software site and go to the 2t exhaust.
Notes on my free spreadsheet of mini 2 stroke calculators some of these calculators have never been available till now although engineering types have always been able to figure this stuff out. This small java applet uses design rules according to, and, to size a tuned pipe for a 2 stroke piston engine. So i put formulas based on that in an excel workbook file to. The calculated compression ratio is usually referred to as the trapped compression ratio. How twostroke expansion chambers work, and why you should. You know that changing the exhaust pipe and pipe length on your boat can have a marked effect on the engines power characteristics, but do you by how much and why.
When the transfer is complete, the piston is on the compression stroke but the exhaust port is still open, an unavoidable problem with the two stroke piston port design. They are so simple and fun that ive always enjoyed tinkering with them. The two tuned lengths of the 2 stroke expansion chamber, photo of compression wave formation. Srw team bafflecone calculator excel file to size, cut and construct the exhaust shapes correctly. This will get you started by providing, for your engine, the dimensions of an expansion chamber with a 2stage or 3stage diffuser. Download 2 stroke exhaust calculator for pc free download 2 stroke exhaust. Two stroke tuning by alexander graham bell excellent book. The arrangement of the intake and exhaust ports in a two cycle engine affords a unique opportunity to use the exhaust system to influence the intake sequence. My professional 2 stroke expansion chamber design software is more sophisticated than other programs that only use a few basic formulas.
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