OPTIMUM Power Logo graphic


In a series of articles, in issues 2 and 3 of the influential Race Engine Technology magazine, the authors Prof. G.P. Blair (Prof. Blair & Associates) and Melvin Cahoon (Volvo-Penta of the Americas) discuss The Design Parameters for Airbox Restrictors in Race Engines.

Virtual 4-Stroke along with 4stHEAD and Fluent were used in the creation of the entire data for a one litre racing engine for this design discussion and show such output data in the form of pressure, particle velocity or mass flow rate at significant crankangle locations within the engine and its ducting throughout the engine cycle.

Such data are single instantaneous snapshots taken from the entire data computed over the 720° crankangle of the complete engine cycle. It is possible to show such data as a movie, but obviously not within a magazine article. Some of the movies that the authors used in obtaining their snapshots for the Figures for the design discussion in the magazine are uploaded on to this website.

They are either animations of the Virtual 4-Stroke output or of the CFD output from the Fluent software. They are clearly marked and titled in the list below. The full relevance of what you are looking at will only be apparent if you have read the article in issue 2 of the Race Engine Technology magazine.


Pressure - Unrestricted Pipe - 9000rpm (416 kb)
Pressure - Unrestricted Pipe - 12000rpm (339 kb)
Pressure - Unrestricted Pipe - 15000rpm (276 kb)
Mach Number - Unrestricted Pipe - 9000rpm (212 kb)
Mach Number - Unrestricted Pipe - 12000rpm (196 kb)
Mach Number - Unrestricted Pipe - 15000rpm (168 kb)
Pressure - Restricted Pipe - 9000rpm (419 kb)
Pressure - Restricted Pipe - 12000rpm (390 kb)
Pressure - Restricted Pipe - 15000rpm (276 kb)
Mach Number - Restricted Pipe - 9000rpm (237 kb)
Mach Number - Restricted Pipe - 12000rpm (225 kb)
Mach Number - Restricted Pipe - 15000rpm (173 kb)


Mach Number - Straight Pipe - 9000rpm (114 kb)
Mach Number - 90deg Bend - 9000rpm (193 kb)
Mach Number - 90deg Bend - 12000rpm (124 kb)
Pressure- Straight Pipe - 9000rpm (83 kb)
Pressure - 90deg Bend - 9000rpm (116 kb)
Pressure - 90deg Bend - 12000rpm (79 kb)