There is no such thing as the average vintage 2 cycle bike or rider. Two stroke cylinder porting tips watch this before you start cutting. How would you scientifically go about tuning a 2 stroke to run perfect. Exhaust and main transfer timing can be entered by mouse click on graph, or typed. For manufacter and tuner of four stroke engine, ntproject has developed a series of software to help in the development of the engine and its components. Basic 2 stroke tuning by eric gorr changing the power band of your dirt bike engine is simple when you know the basics. Tune pipe edit with a convergingbelly sectiondiverging type tune pipe the goal is to have the diverging section create a returning rarefaction wave and the converging section create a returning pressure wave. Oct 21, 2017 6 excel spreadsheets for designing an expansion chamber, a heads squish band, a boost bottle, a balanced crank, correct fueloil ratio, and correct port dura. I didnt really like many of the pipes but a few were ok but i wanted more. 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. Minimum to maximum acceptable exhaust pulse widths are. The displacement, exhaust valve size, induction system, cam profile, exhaust port design and rpm range all factor into deciding what form the exhaust system should take. How twostroke expansion chambers work, and why you should care.
Nov 05, 2011 a simple 3 stage two stroke exhaust calculator based on formulas of g. However, you shouldnt just pick any business that you can find anywhere. Nov 02, 2019 for further investigate of the operation of two stroke engines with tuned exhaust pipes it is most appropriate to analyze actual test data. Improve the performance of your twostroke engine with a torqsoft designed exhaust system. Twostroke waveaction engine simulation motion software. It is called a twostoke engine because there is a compression stroke and then a combustion stroke. Follow the link to my software site and go to the 2t exhaust calc menu item and download either the stand alone program or a installer package. This is an important process to understand and is the reason why not only the cylinder decides the tuning degree but also the exhaust pipe, cylinder head and ignition. It will simulate one of the cylinders of a multicylinder two stroke engine provided that the cylinders are identical in layout and dimensions and each cylinder has a seperate exhaust and induction system. Mutts nuts 2 strokes provide a range of services for 2 stroke bikes, from a simple oil change to a full 2 stroke motorbike restoration service. The difference between the pressure in the cylinder and the pressure at the cylinder end of the exhaust duct determines whether gas flows from the cylinder into the exhaust duct or into the cylinder from the exhaust duct.
Kaaden understood that there was power in the sound waves coming from the exhaust system, and opened up a whole new field in twostroke theory and tuning. Thanks to the software two stroke design instead you can enter the data of your cylinder with extreme facility and precision, and then analyze the port areas and the timing area in the engine cycle timing for each phase. Acceptable piston stroke is 28mm to 81mm in version 27 and 29. Jan 19, 2008 he will do one of two things,hang up, or if he is a good one,start explaining the complex nature of fluid dynamics, sonic wave pressures and the effects temperature on the speed and timing it takes to hit an open exhaust port at 6500 rpmsthis being said. Two stroke engine and exhaust design software north. You can also save and load the data by using the provided functions. Improve the performance of your two stroke engine with a torqsoft designed exhaust system. The exhaust designer programme enables the user to design a two stroke exhaust system with ease, then with one click of the mouse, create a pdf document in any of the common paper sizes a4, a3, letter. Feb 16, 2017 two stroke cylinder porting tips watch this before you start cutting. However, optimization of a particular design using such software is often difficult and time consuming. Two stroke moped tuning two stroke timing moped tuning. On the other hand, while the twostroke engine does not commonly require large. Moreover you can have advices for the development of the engine thanks to the help of tested formulas for intake, exhaust. With that we have categories that cover most riders.
The charging efficiency is dependent on the pulse energy created from. For performance two stroke engines, the second solution is most often employed by means of a tuned exhaust pipe known as a tune pipe. On the other hand, while the two stroke engine does not commonly require large. North american two strokes general two stroke discussion two stroke engine and exhaust design software this is the place to talk about anything related to two stroke road race bikes.
Tuning an exhaust system to a given application is a casebycase basis challenge. We use computer design software to maximize power and torque at any elevation. I found most other software work on outdated blair and jennings formulas. The exhaust tuning of a 2stroke is designed to preserve the positive pulse going down the pipe and reflect that positive pulse back up the pipe. We cant afford to waste any of it by having it escape out the exhaust port. The most common mistake is to choose the wrong combination of.
Ive also heard that people who race karts will use a egt to tune there motors. For a 2 stroke with expansion chamber and no boost bottle then everywhere. Motax contains all the features found in mota plus expansion chamber. In contrast, a twostroke engines valve timing may be altered simply by reshaping the holes in its cylinders, and its power output markedly changed by utilizing inertia and resonant effects in its intake and exhaust tracts. Millions of fluid and thermodynamic calculations are made by mota representing the conditions inside your two stroke engine throughout its complete operating cycle. Adding a performance exhaust system can be a great way to increase power andor alter the power delivery of. Exhaust tuning theory and system design weve all heard the magazines talk about back pressure and most of what they say is utter cac so how do we ensure we have a good, efficient, exhaust system bearing in mind that back pressure, any back pressure, is a. General rules of thumb are easy to grasp, but applying them correctly is where things get tricky. Software for fine tuning and design of two stroke engine. In my last post, i shared details about how the two stroke cylinder works, in todays post i want to provide an overview of how a performance two stroke engines exhaust system works. The calculations are assuming a speed of sound in the exhaust gas, which is not known exactly. After our trial and test, the software was found to be official, secure and free.
Do you want it to be full range, still strong at low rpm or do you want it for higher power at rpm even if that means you will loose some low rpm. Knowing the category of rider you are helps to choose the right modifications to best suit your riding and budget needs. Free 2 stroke exhaust expansion chamber calculator youtube. Mota and its related set of programs have been developed to simulate the performance of highoutput single cylinder two stroke engines. This is a module for complex 2stroke exhaust calculation having in account several variables according to lufo racing tuner philosophy. The intent of the competition is to provide universities with an.
It will simulate one of the cylinders of a multicylinder twostroke engine provided that the cylinders are identical in layout and dimensions and each cylinder has a seperate exhaust and induction system. Advanced two stroke tuned exhaust system the challenge the society of automotive engineers clean snowmobile challenge 2002 sae csc 2002 is an engineering design competition for college and university student members of the society of automotive engineers sae. No previous knowledge of the two stroke cycle engine is required just input the required data and then run mota to set in motion this powerful process. You could create a hardcopy of the program window, though, using your. The port duration should not exceed the recommended value. We shall send you a pdf document with the templates for manufacturing your exhaust. A tuned pipe has a set of cones divergent meaning the cone gets bigger and convergent meaning the cone gets smaller. An engines exhaust port can be thought of as a sound generator. This 2 stroke engine animation is accompanied by an excellent article with several 2 stroke engine diagrams and indepth explanations of the 2 stroke engine cycle. Optimization of exhaustpipe tuning on a 4stroke engine. A racing engine exhaust system uses an expansion chamber at the end of the pipe which is basically two cones that reverse themselves prior to the end stinger where the spent exhaust is allowed to exit the chamber. They are so simple and fun that ive always enjoyed tinkering with them. Small values of kh are best suited to grand prix engines with narrow power bands, larger.
Dec 17, 2019 for a 2 stroke engine the tuned pipe is the section of the exhaust system that 2 stroke wizard tuned pipe design software ian williams tuning 15 replies. This 2 stroke engine animation, article and diagrams are courtesty of. Because tuning a 4 stroke is nowhere near as complex but still requires additional tools more money since the current setup, especially if its stock, unlikely provides enough tuning differential to compensate for the new system. If you are aiming for these qualities, modifying your 2stroke engine is a great strategy.
In designing a two stroke engine, you want to extract the combustion gases as quickly as possible and then plug the exhaust. How to design a two stroke expansion chamber performance exhaust step 2 duration. Just a quick update on the progress of the freeware 2 stroke expansion chamber calculator software. When the exhaust port shape is decided from time area targets etc. North american two strokes general two stroke discussion. From the optimization of the engine head, at the studied of the cams, at the sizing of intake and exhaust manifolds, until to the balance of the crankshaft, thanks at our software you could. My professional 2 stroke expansion chamber design software is more sophisticated than other programs that only use a few basic formulas. Two stroke engine porting, head mods and pipes two stroke tuning advice from the experts at bimotion. Assign fixed relationships between transfers and exhaust port. Calculates port heights from durations, or durations from port heights. Kaaden understood that there was power in the sound waves coming from the exhaust system, and opened up a whole new field in two stroke theory and tuning.
Each time the piston uncovers the exhaust port which is cut into the side of the cylinder in two strokes, the pulse of. Here is the official description for 2 stroke wizard tuned pipe. Yes, at about this point youre probably wishing youd stuck with the old exhaust system or owned a 4 stroke. Basic 2stroke engine tuning information joe hunt rc. Read my expansion chamber theory page to get a full understanding of how expansion chambers work and click here to read more of. Pro circuit has built a reputation around our exhaust systems. 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. Tom turner, master two stroke tuner, pipe builder, and the man that developed tsr two stroke racing software designed and built his 424cc yamaha rd400 dragbike to develop and prove his racing design software and prove it, it did. For port work, one company that will help you is 2strokeporting. Software for fine tuning and design of two stroke engine by. Engineering acousticssonic supercharging of 2 stroke. The official home page of our 2 stroke wizard tuned pipe. Once the piston makes it to the end of the compression stroke, the spark plug fires again to repeat the cycle. Mota software, 2 stroke engine simulation software, 2 stroke exhaust design.
The way a two stroke motor works causes them to be f. A 2 stroke is different of course since there is only a finite amount of fresh mixture available in the crankcase to be transferred up into the cylinder. Two stroke performance tuning chapter 3 porting and cylinder scavenging today, when we take a look down the cylinder of a two stroke engine, we find its walls literally filled with ports to handle the induction, transfer and exhaust phases of gas flow through the engine. Engineering acousticssonic supercharging of 2 stroke engines. How twostroke expansion chambers work, and why you should. But because of the limited worldwide activity in two stroke engine development, program sales were limited and further development was curtailed. Other books to his credit are modern engine tuning, twostroke performance tuning and forced induction performance tuning. The exhaust blowdown target is a statistical value for the tuning degree decided by the bmep target braked mean efficient pressure. This coefficient kh is called the horn coefficient, with typical values between one and two. You should only rely on the experience of the very best. Racingsm software 2stroke exhaust calculator lufo youtube. For this we can go to the tfx website where they demonstrate their testing and data analysis software, or read the paper referenced below titled exhaust gas flow behavior in a two stroke engine. The cylinder pressure drops, and the fresh charge transfers thru the transfer ports, over the top of the piston, and out the.
Split your calculated 2stroke exhaust up to 42 sections with regular length or even more with irregular lengths. Optimization of exhaust pipe tuning on a 4 stroke engine using simulation 200202 engine performance simulation software has become an integral part of the engine designers toolkit. There are many ways to boost the power, one of which is by installing a tuned pipe. A myriad of different aftermarket accessories is available for you to custom tune your bike to better suit your needs. Free 2 stroke expansion chamber calculator software update. In a fourstroke engine, there are separate intake, compression, combustion and exhaust strokes. We offer two stroke exhaust for all of the popular motorcycles and atvs. Bimotion 2 stroke software has been commercially available and in professional use since 1991. Great tool for those who are building exquisite format exhausts, one of the largest benefits of this module is that it can be used with any exhaust formula results. The first thing you need to do when tuning a two stroke is to determine its characteristics. In a 2 stroke, we want to maximize the retention of that finite fuel charge. Those of us who have grown up in the japanese two stroke.
The exhaust port opens and combustion gas starts down the pipe at supersonic speeds. This small java applet uses design rules according to, and, to size a tuned pipe for a 2 stroke piston engine. In contrast, a two stroke engines valve timing may be altered simply by reshaping the holes in its cylinders, and its power output markedly changed by utilizing inertia and resonant effects in its intake and exhaust tracts. Exhaust and intake tuning this article describes the principles involved in using tuned exhaust and intake systems on two cycle and fourcycle engines. The mechanic who got lucky stan stephens autobiography 2020 edition republished with extra chapter after selling an amazing amount of copies of my book i completely sold out.
The software does complete cycle simulation of the whole internal combustion process including the gasdynamics in the pipesducts, ports and plenums air boxes, boost bottles, exhaust boxes etc. Our goal is to achieve the biggest power gains as possible, while maintaining reliability on your 2 stroke engine. Mota and its related set of programs have been developed to simulate the performance of highoutput single cylinder twostroke engines. Software for optimal setting and design of engines and racing. Torqsoft twostroke exhaust system designer programme.
Click here to download a spreadsheet that will let you figure out your engines exhaust pulse width. Scientifically tuning a 2stroke motorcycle jetting. The way a two stroke motor works causes them to be fairly noisy and a bit inefficient. There are pipes and silencers for racing, recreation, quiet riding and even usfs approved spark arrestors. Properly tuned systems can increase the charge of fuel delivered to the cylinders and a related phenomenon can aid in the extraction of exhaust gases from the cylinders. I have been into 2 stroke bikes for over 28yrs and i have bought and tested many exhaust pipes on all the bikes i have owned to find the best one for my needs. Graham bell is an acknowledged expert on engine tuning, with many years experience in this field. Mutts nuts 2 strokes two stroke motorbike servicing.