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design:engine_gasket_case_study

Case Study: Engine Gasket

A case study of miscommunication between engine designers.

In a major automobile manufacturer, the engine design group worked by distributing major engine component responsibilities to individual senior designers. One designer was in charge of each of the crank, block, cylinder head, valve train, etc.

The design process in place at the time (around the mid 1990's) called for the engine block designer to specify a number of key parameters about each engine block. The values of these parameters would be distributed to other designers as required. One such parameter was the block deck height, which is the height from the bottom of the engine to the top of the block. This parameter is needed by the cylinder head designer.

Given the block deck height and the overall specification for the engine height, the cylinder head designer can determine how much vertical space there is to “fit” in a cylinder head.

On one occasion, a block designer and a cylinder head designer who had never worked together on an engine before, were teamed up. They each did their assigned tasks, per the process described above. But when a wooden prototype of the engine was constructed, it was found that the engine was too tall.

The two designers carefully checked their work, but could not find the error in their calculations.

Two weeks passed before they finally discovered their error. The block designer had assumed he was responsible for specifying the engine gasket (which goes between the block and the head), and so he included the thickness of the gasket in the block deck height. This had always worked for him in the past.

But the cylinder head designer thought that the engine gasket was his responsibility; so he included the thickness of the gasket in the height of the cylinder head. This had always worked for him in the past.

The engine had two engine gaskets, which made it too tall.

It took two weeks to find this error for various reasons.

  1. The two designers were working on two slightly different design problems, but they did not know it.
  2. There was no standard engine model and design process that was universally known by the designers.
  3. The designers were unaware that most design errors occur between components, not inside them.
  4. Neither the designers nor the engineering management realised the importance of properly executed teamwork.
  5. There was inappropriate management of the design team, and ineffective means for the designers to communicate pertinent information.

What lessons can we learn from this case study?

  • Even the simplest things can be done badly.
  • Most errors are obvious ones.
  • Nothing can replace a good design process.
design/engine_gasket_case_study.txt · Last modified: 2020.03.12 13:30 (external edit)