| Drag racing is a fast and furious sport. Thousands | | | | part, including measuring it with a ruler by hand. |
| of horsepower are unleashed in the blink of an | | | | But more sophisticated methods are available; |
| eye and have to be harnessed safely down the | | | | these are called CMM, (Coordinate Measuring |
| track in a matter of few seconds. In comparison, | | | | Machines). More specifically a portable CMM, which |
| an average road car might have one or two | | | | is in essence an articulated arm with a probe, was |
| hundred horsepower and take about 20 seconds | | | | required in the case of the engine block. A high |
| to cover that distance. Needless to say, it takes | | | | precision rotary encoder (a high precision position |
| some clever engineering and manufacturing | | | | sensor) for all 6 or 7 axis enables the part to be |
| technology to achieve a reliably performing drag | | | | measured to an accuracy of within 0.02mm. You |
| racing car. | | | | can measure any point on the part in full three |
| Drag racer Paul Carey of AERO Racing drives a | | | | dimensions (X, Y and Z) by simply touching the |
| Mazda RX-7 in the 'Supercharged Outlaw' class of | | | | probe to it. Otherwise laser scanning attachments |
| ANDRA's National Drag racing series. The AERO | | | | are available which enable the full three dimensional |
| Racing team have been using an advanced | | | | surface to be digitised. This is more useful for non |
| quad-cam Toyota V8 engine to power the RX-7 | | | | geometric shapes and contours like the dashboard |
| down the 400m drag strip. Not only has this given | | | | of a car for example. |
| them a point of interest, as it is unique to have a | | | | In all cases, an experienced technician is needed |
| Toyota V8 among the legions of American V8's, | | | | to operate such a high precision machine, as even |
| but also enables them to be running sub 8 second | | | | the movement of an operators breathing can |
| 400m times. | | | | give vastly varying results. There are techniques |
| During the 2008 season, reliability problems with | | | | to help against this happening, such as taking |
| the engine were not letting Paul and his team | | | | more data points and averaging the results. |
| achieve the best performance from the car. The | | | | A full survey of the existing engine block's |
| extreme pressures from the big PSI supercharger | | | | features was performed and then used to |
| were frequently splitting cylinder bores in the steel | | | | produce an initial CAD model or point cloud model. |
| block, leading to expensive and time consuming | | | | The tool enables the user to create surfaces, |
| engine rebuilds - not to mention the loss of points | | | | circles, points and lines in the 3D model |
| in the competitive series. | | | | representing the real part's surfaces, cylinder |
| The solution was to develop a completely new | | | | bores and bolt holes. Generally this won't be ready |
| engine block from a billet of Alumec 89 which | | | | to send to the machinist straight away as a whole |
| could withstand the rigors of competition. But | | | | host of post-processing is required to create a |
| without starting from scratch and re-inventing the | | | | finished CAD model. This is where an experienced |
| wheel, or engine even. The next best thing was | | | | engineer is required to take the measured |
| to manufacture a better version of the standard | | | | features and produce a finished solid model with all |
| block, stronger and more durable and at the | | | | the dimensions accurately specified and tolerances |
| same time retain the ancillary systems that were | | | | set out. This whole process requires a large |
| already developed for it, such as the PSI blower, | | | | degree of precision and attention to detail to |
| heads, camshafts and bell housings. One of the | | | | maintain the critical geometric tolerances required |
| aspects to improve on was to remove | | | | by this 1500 HP engine. |
| un-necessary water coolant passageways in the | | | | The model can then be passed on to the machine |
| block, which are not required when runs are | | | | shop for manufacture. High precision machining is |
| typically less than 10 seconds and using Methanol | | | | another article in itself, but needless to say CNC |
| fuel. | | | | (Computer Numerically Controlled) machines are |
| The need for some reverse engineering was | | | | used across all manufacturing industries to |
| obviously there. Reverse engineering is a process | | | | produce components of very high accuracy, |
| where a physical part or complex shape is | | | | complimenting the accuracy of the CMM quite |
| digitised to create a CAD (Computer Aided | | | | nicely. |
| Design) model on sophisticated computer | | | | The finished product is identical to the CAD model |
| software. Ultimately using this CAD model to | | | | produced by the reverse engineering process. The |
| re-engineer, update or add to the original design. | | | | block is made stronger and able to withstand |
| Other uses of reverse engineering are in cases | | | | larger cylinder pressures and temperatures with |
| where the CAD models or manufacturing | | | | reduced warping. Remember this engine produces |
| drawings for the original parts may not exist and | | | | 1500 Hp from 282 cubic inches capacity! All the |
| need to be re-created, such as re-creating parts | | | | ancillary devices like the PSI supercharger, cylinder |
| for historic cars or machinery or additional parts | | | | heads and gearbox bolt back on as per the |
| to accurately interface to existing parts. All the | | | | original engine. Reliability has also been improved |
| automotive manufacturers and even top | | | | and with that the elapsed times have fallen to a |
| motorsport teams utilise such technology to | | | | personal best of 7.367 sec, all thanks to some |
| speed up the design process. | | | | clever engineering. |
| There are several ways to reverse engineer a | | | | |