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Room Ventilation

Ventilation is a commonly overlooked aspect of engine test cell room design. Proper airflow through the test cell is by far one of the most influential factors when assessing the power of your engine.

Fundamentally, air is a critical property of the combustion process. Without air it’s really hard to make any power. So why would you starve your engine of the one thing it needs most? It’s a lot of work to get your test cell to flow air correctly, let alone enough CFM. Realistically, most HVAC techs do not understand how much air is needed through a cell.

Typical guidelines are 10-15 times the cubic feet of your room in cubic feet of airflow per minute. Those requirements could be higher depending on your power level. A heat balance should be done to ensure you have enough airflow.

Below is a graph from a 493.9 HP alcohol circle track motor. As you can see, there was a 25.6 HP and 14.63 lb. –ft. gain by just providing adequate airflow through the room.

Performance Difference Graph

The difference in performance for correct room ventilation.

These discoveries almost cost an engine builder his life with the excess alcohol and exhaust fumes when he entered the test cell after only one run. Not only can there be power left on the table, it can be deadly. Understandably test cells cost money. There are also many ways to make your test cell usable and safe.

Ask the experts. Consult with a SuperFlow rep today.

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History of the Flowbench

An air flowbench is essentially a device that measures the resistance of a test piece – a cylinder head, manifold, carburetor, throttle body, exhaust systems – to flow air. Many different designs and models are on the market today that allow for comparison of flow results before and after changes in the flow path occur. Here’s a look at the history of this device.

Flowbenches and airflow data have been a part of the internal combustion engine development cycle for design, research and development for many years.

  • 1900s – Some of the first engine airflow studies, using some type of flow testing, occurred.
  • 1960s – Starting to study engine airflow and flowbench information and the relationship to performance in the racing industry

The foundry process and the associated compromises actually controlled most early cylinder head and manifold designs. These manufacturing compromises drove most designs – not the technical aspects or specific airflow requirements.

When SuperFlow Corporation introduced the first portable flowbench to the engine builders of the world in 1972, airflow science came to the kitchen tables, shops and garages everywhere. More elaborate and complex benches had been around for some time when the first SuperFlow model was available, but never in such an easy-to-use configuration. As market demand and understanding grew, many larger models were made available as racers began to compare flow information. Thousands of benches are in use every day, and engine component airflow technology is growing rapidly.

The first airflow benches in use at the Original Equipment Manufacturer (OEM) level were expensive, cumbersome and complex machines. They were applied in the late 1960s and early 1970s for some specific engine airflow development work.

  • Oldsmobile and Pontiac – used flowbench-guided designs early on
  • Chevrolet – did not have a flowbench lab in use until the 1970s
  • American Motors – used flowbench-guided cylinder head designs in the early 1970s
  • Chrysler – adapted a flow lab from elements that were used in air filter work, and the lab was developed in parallel with their introduction of the 426 Hemi engine
  • Ford Motor Company – flow labs date to the mid-1960s, where they supported their winning LeMans racing effort with their GT40 racing vehicles

Some of the OEM, specialty-engine manufacturers and professional race teams are now using Computational Fluid Dynamics (CFD) to assist in Computer-Aided Design (CAD) and flowbench-driven designs. Many of the OEM have abandoned their in-house airflow benches and outsource much of their airflow development testing. As a result, some well-established shops using SuperFlow or other flowbenches typically get involved in OEM development contracts because the programs are more time and cost-effective.

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