Current ver. 5.1.1
History of changes

Let us introduce you to the Excel based software. Bimotion is currently the dominating software for analytic engine tuning, i.e. time-area and parameter controlled. The program generates state of the art pipes with respect from exhaust- and transfer ports time-area and shape design. Since the exhaust port and the exhaust pipe should be regarded as one unit, this is the optimum user friendly way to do it with full control. The ports is simply mapped on paper and measured in figures, entered into the program and converted for 1D flow calculations.

This unique program contains, except from all Excel functions, more than 10 000 lines of custom developed code.



The unique Bimotion features are:

* Arbitrary port shapes
* Dual exhaust port
* Auxiliary exhaust ports
* Parametric Port Design with guidance
* Port mapping translation
* Exhaust pipe and exhaust port dependence
* 3 to 8 ports
* Blair Pipe (Pre-parameterized 5-coned pipe)
* Custom pipe (2 to 6-coned pipe)
* Comparison of 2 exh. port sets (e.g. stock - tuned)
* Height- and width port offsets for fast scenario analysis
* Inside parameter recommendations dependent on
  engine size and tuning degree based on massive
* Port layout development plot
* dxf cad drawings output on developed cones,
   hydro form and roll form.
* Language translation file import
* 4 years free support and updates.
* Portable, no hardware lock

System requirement:
MS Windows with installed MS Excel 2003 or later
except any trial-, or cloud version (Excel 365)

The program is divided into different pages that are accessed from the 'Pages' button. Different program sections makes the actual dimensioning work more efficient and less time is spent on searching after parameters in the program.

Two identical sections ('Exhaust Port #1' and 'Exhaust Port #2') are intended for one modified configuration (#1) and one original configuration (#2). These two pages are transparent to each other in red and blue color, see below.

'Transfer Ports' handles 2-5 scavenging ports shape design.

'Custom Pipe' is a fully parametric flexible pipe model. Blair Pipe' is an auto-generated racing pipe with predefined built in dependencies for state of the art race engines.

'Port Mapping' is a table set to convert a paper mapped measure into a projected flow measure.

'Development Plot' is page where a developed plot can be printed for all ports or selected.

'About...' page connects and shows the latest released version, online manual access, etc.


The different pages are:

Exhaust Port, one of two identical sheets. Two transparent configurations with auxiliary ports, arbitrary shapes.

Transfer Ports, 2 - 5 ports, arbitrary shapes.

Port Angles Design.

Custom Pipe, a flexible model with built in parameter recommendations.

Blair Pipe, a pre-parameterized 5-coned pipe for race engines.


Port layout plot. Two exhaust port configurations are overlaid for comparison in this plot example.

General Pipe manage pipes with coned header, 3-stage diffusor and 2-stage baffle for which any custom dimensions can be used. The user are guided by a lot of detailed recommendations from well known designs in real life. This works more or less as a 'pipe lab' page.

Bimotion Pipe

Design & Simulation of Two-Stroke EnginesThe other exclusive pipe model is suggested by prof. G.P Blair (QUB). This theoretically elegant pipe is described in the book "Design & Simulation of two-stroke engines" and is also designed from a time-area designed exhaust port. The program uses the mathematics and recommendations described in chapter 6 in the book.


The exhaust- and transfer ports shape design are made in a table and plotted in real time in a chart. For a chosen tuning degree, the port should be designed to reach the time-area target (decided by the tuning degree).

The exhaust port can be mapped inside the cylinder on a piece of paper, developed, measured, and entered in a column to be transformed to the port shape in flow direction. The reverse can also be done, i.e. adjust the port shape in flow direction and plot it as developed. The program also produces manufacturing templates as sheet cone developments in the same time. Very user friendly !! 

The plots are changed in real time when values in green cells are changed.
The modeling is very flexible with a lot of options to view the ports in charts.

         Dual exhaust port


Read the KX500 case study and the manual for further insight in how to calculate high performance 2-strokes with Bimotion software!


the manual:

The print function also include dxf cad drawings output of exhaust pipes !

- Ordinary layout drawing
- Cut out template for hydro forming
- Developed cones cut out templates for roll forming
- Customized compensation for TIG weld seam width and sheet thickness.


US $ :249.00

Order is to be placed from Contact.