Understanding
Hybrid Turbos
Turbo Technics have been making hybrid performance turbochargers since as early as 1985. The term ‘hybrid’ simply refers to the fact that a ‘hybrid turbo’ consists of a mixture of parts from different turbochargers, usually based on an original unit for a specific application. Originally, this was simply a case of mixing and matching components between different configurations of the same type of turbo, to achieve a desired performance characteristic.
Over the years, the number of turbo models (and manufacturers) has increased, and with it the number of different components on offer. These days it is possible to build hybrid performance turbos vastly different to their original spec with dramatic changes in performance. This is something that Turbo Technics excels at, with expertise in component modification and the design and manufacture of bespoke parts.
The term ‘Hybrid’ covers a very wide range, from a minor uprate to a completely redesigned turbo. The essential point to remember is that a hybrid turbo by itself, will not necessarily give a significant power boost. Typically, an appropriate ECU tune is required at the very least, along with upgraded components for any restrictive elements of the induction or exhaust system. Older engines also tend to require modification to handle high boost pressures, though most modern turbocharged engines respond well to increased boost pressures in their standard form.
Increasing the boost pressure also increases the internal loading within the turbocharger, and often requires a change to the bearing system usually incorporating a 360° thrust bearing. Turbo Technics have developed a manufacturing process to make these precision parts from solid, giving a greater bearing contact face to withstand the high loads, which would otherwise destroy a standard bearing very quickly.
Turbo Technics will occasionally specify a “cut-back” shaft wheel. This is the exhaust-driven turbine wheel inside the turbocharger, and to improve the gas flow the outlet part of the blades are sometimes ground. However, it’s effectiveness is dependant on the blade geometry of the standard part, and can have a detrimental effect through reduced efficiency if used inappropriately.
Many hybrid turbochargers will look identical to standard units from the outside. The changes occur inside, by using different aerodynamic configurations, both in the compressor and turbine wheels, and different bearing systems to support the increased loads.
There is always an element of compromise between power capability and low speed response, and the engineering challenge is to find the optimal balance. By selecting the most suitable components or if necessary a bespoke design, it is generally possible to arrive at a combination of good drivability with the required power output.
In Detail
THE ANATOMY OF PERFORMANCE
Which parts are typically changed or modified in a hybrid turbo and why? Below is a quick guide for a basic level of hybrid:
| Compressor Wheel | This is usually the first part to be changed on a hybrid turbo and is responsible for drawing fresh air into the turbo. It is normally changed for a wheel of larger size to increase flow and, if the original is cast, is often upgraded to billet construction for increased strength. |
| Turbine Wheel | The turbine wheel takes energy from the exhaust gas to drive the compressor wheel, which is connected to the turbine through a shaft. It is sometimes replaced with a wheel of larger size or, for a lower cost solution, the blades are ‘trimmed’ or ‘cut-back’ to increase exhaust flow capacity, although this may compromise turbo response. |
| Bearings and Shaft | Put simply, the bearings and shaft support the turbine and compressor wheels and hold them in a steady position. As the size of the compressor and turbine are increased, so does the volume of gas flow and this in turn increases the forces on the shaft and bearings. The bearings and shaft are sometimes increased in size or otherwise modified to help cope with these increased loads. This may include the application of a ‘360°’ thrust bearing if the original turbo is not fitted with one, or a bearing with increased capacity. |
| Compressor housing & backplate/seal-plate | These components fit snugly around the compressor wheel and consequently require modification if a larger compressor wheel has been fitted. |
| Turbine Housing | This component fits snugly around the turbine wheel, and will also require modification if a larger turbine wheel has been fitted. |
| Actuator | This component controls the boost pressure of the turbocharger and is sometimes adjusted or changed to achieve a higher basic boost level. |
TURBO TECHNICS HYBRIDS
Although this guide is based on a typical hybrid turbocharger, most of Turbo Technics’ hybrid turbochargers are not typical hybrids and carry many more features and modifications for optimal performance. To find out more about the performance turbos available from Turbo Technics for your vehicle, contact our experienced Sales Team
