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. A sub-menu offers the two selections "Constructing the Development Pattern of a Cone" and "Printing the Development Pattern of a Cone". It is the options provided under the second selection which have been added to MOTA. You can now print the development pattern of a cone and this may extend over several A4 pages. Of particular note, you can produce the pattern of a cone having either end or both ends angled to the cone axis. A set of explanatory diagrams with text can be displayed. You may also define a single straight cone and print the patterns of each of the pieces which, when welded together, will provide an equivalent bend section. The number of pieces and the overall bend angle are entered through the keyboard. A MOTA engine data file may also be accessed and the pattern of each section of the expansion chamber printed. Alternatively, any one section may be selected and patterns suitable for the construction of an equivalent bend section printed.
This new feature allowing creation and printing of Expansion Chamber sections is also included in the MOTA demo that is downloadable for free. Not all of the functions are included, but enough so that even if you do not purchase MOTA you can still create printed patterns of cones and save you having to buy other proprietary software to do this. Download it here ....... MOTA demo
We now have a simple 2 stroke expansion chamber design program. 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. It calculates the dimensions for both double and triple stage diffuser expansion chambers from a few basic engine dimensions. The information used in the program's calculations was taken from the books ‘The Basic Design of the Two Stroke Engine’ and the book ‘Design and Simulation of Two Stroke Engines’; both books are written by Professor G.P. Blair of Queens University Belfast, and published by the Society of Automotive Engineers. You are well advised to read at least one of the books mentioned above, since they contain the author’s academic lifetime of knowledge on the two-stroke engine.
There are several coefficients used in the design of the expansion chamber – these are a function of the engine’s state of tune. Those used in this program have been chosen for petrol engines, and are in the range 50cc up to about 500cc per cylinder. It is doubtful these formulae would work on small capacity glowplug engines, since the exhaust gas temperature is much lower, and the engine speed is much higher.
How it all began .......
MOTA® is the brainchild of Dr Julian Van Leersum, mathematics graduate from Monash University in Melbourne, Victoria. He is of Dutch/Swiss parentage, but now permanently resident in Australia.
With the successful MOTA® software, Dr Van Leersum has managed to combine his professional interests in computing & mathematics with his enthusiasm for karting and motorcycle racing.
"It occurred to me that most home tuners cannot afford the expense of hiring time on a dynamometer to check the viability of adjustments or special parts" said Julian, "yet many people these days have a home computer which could easily run a suitably designed tuning programme."
"Although there is really no shortage of books on the subject of 2-stroke tuning and preparation, I knew that an active software programme would be able to offer so much more." So, this is how MOTA® was conceived.
MOTA is an engine simulation program suitable for everyone from the enthusiast to the university researcher - from the beginner racer to the professional tuner. See testimonials. You can test your own engine and then re-test and compare your modifications - or build your ultimate engine right on the screen. Millions of fluid and thermo-dynamic calculations are made by MOTA representing the conditions inside your two-stroke engine throughout it's complete operating cycle.
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. Test your own theories on porting and exhaust pipe design; explore the limits of various intake methods; or just look for the highest power output from your own engine.
MOTA will accept a single-cylinder design, which will also cater for many multi's where 2, 3 or more cylinders of the same basic layout are repeated. Easy-to-operate, accurate and hours of fascinating results to enjoy! Excellent graphics you can analyse and compare. MOTA's "Two-stroke Dyno" will give you and your PC the equivalent of many experts knowledge.
MOTA and it's related set of programs have been developed to simulate the performance of high-output single cylinder two-stroke engines. It will simulate one of the cylinders of a multi-cylinder two-stroke engine provided that the cylinders are identical in layout and dimensions and each cylinder has a seperate exhaust and induction system. It allows simulation of engines with reed-valve, rotary-valve and piston port timed induction systems. Simulation of engines with either a box-silencer or an expansion chamber is also possible.
Because MOTA solves the equations describing the conservation of fluid and thermodynamic properties throughout an engine, it requires specification of the full engine geometry. This is accomplished through a menu driven environment, which prompts you for the required dimensions which are easily entered via the keyboard.
The output from MOTA is provided in two forms; a file, which summarises the engine geometry and performance, and a graphical interface which allows you to plot the various performance variables. The output file and these plots can be printed if you have a printer connected to your computer.
Where is MOTA different to other computer
programs and tuning manuals - and what can it do?
MOTA operates in the "real world" and it will:-
a) accept most any dimension and variations of dimensions.
b) operate on anyone's exhaust pipe theory by accepting almost all shapes.
c) operate within the limitations set under certain racing regulations.
i.e. A KT100S kart engine in Australia cannot be "ported" - so the ports physical dimensions cannot be modified.
MOTA will run on your own inputted physical dimensions, but allow the alteration of port timings without other physical variations.
d) accept that the data you input is from an engine that is running already, and will output it's predicted performance as a base for you to work from.
e) accept alteration to one engine dimension at a time - either real or imagined, and produce all of the new
outputs with the new dimension.
f) accept that ignition timing can be varied, and allows you to input such changes - possible or not, you can make the alteration to see what would happen.
g) does not ask complex technical questions - data inputs are easily measured and entered on the screen via the keyboard.
h) accept almost limitless variations, so you can test ideas beyond any current theories or practises.
So how does this help you?
Most everyone will have an actual engine that they wish to play with, or make perform better. MOTA can do that easily and quickly. It does not trouble you with the in-depth why's and wherefore's of two-stroke engine design theory - you are not trying to build an engine from scratch. You can do one alteration, or many, and MOTA works with that.
Some karting race results with MOTA.
The IWT "MR1" pipe for long circuit karting in the 100cc Non-gearbox class was designed using MOTA -- and it won the 2001 National Superkart Championship for our own team member Michael Rogers. It is an evolution of all of our earlier designs, that for the past 5 years have seen multiple state championships come our way, and at most meetings qualify at the front of the pack !!
The Mallala lap record for the 100cc Yamaha heavy class is now in the possession of Ian Williams, using this pipe as designed with the aid of MOTA.
The late model crankcase reed induction Yamaha YZ80
engine was "tuned" for Superkart racing using MOTA, to redesign the porting and
design a new reed and exhaust system -- before the first engine had even been
From the first time these engines hit the track they have been winning right across Australia.
The exhaust design for this has been used to win multiple State and National Championships, as well as the reed design now being used as "the" setup for all karts run in this class across Australia today.
Special features include
Price: AUD $255 Australian
Dollars including postage within Australia ...
or AUD $239 exported including airmail post to any country.
Details for purchasing upgrades ........... The current version of
MOTA is v6.10
MOTA version 6.10 for Windows® is now available , should you wish to upgrade.
The cost is AUD$125 if upgrading from versions 4.xx or 5.xx or 6.00 -- price is including postage.
Your program number must be quoted when ordering -- it is written on both your dongle and distribution disk(s).
The earlier version distribution disks are not required to be returned when ordering an upgrade.
If you want an order form to purchase the MOTA software , or an upgrade, we have two available.
In .pdf format to fax back ......... click here or an .xls file to email us ........ click here