Turbocharger systems are a complex combination of many different parts. From the turbo itself and intercooler to the fuel management system and the quality of the engine’s internal components, a vehicle must have many different things just in the right order to run properly.
One of the most important aspects to a well designed turbo system is choosing the right compressor and turbine wheel correctly the first time. When the right wheels are selected you can be confident that the turbocharger is going to perform exactly as it should without complications from surging, excessive lag, or overspeeding. There are a few key mathematical formulas and general information points that you should be familiar with before choosing your wheels.
This section is intended to provide general turbocharger sizing information, not specific turbocharger-vehicle-engine solutions. Typical turbocharger matches are the result of engine dynamometer testing and installed vehicle performance evaluation. Often, compromises must be made to arrive at a match that yields satisfactory response and power.
Actual power produced by any gasoline-fueled engine is a function of how much air flows through the cylinder head and engine itself, regardless of whether it is naturally aspirated, supercharged or turbocharged. The best rule to gauge how much airflow an engine will need to make a certain amount of power is to use a factor of 10. This is based upon the rule that it generally takes 1 lb. of air to make 10 HP. Thus, if an engine makes 500 HP then it flows 50 lbs. of air per minute. It is also important to note that cubic feet per minute or cfm, is not a valid value to use in measuring air for turbochargers. Once a turbocharger has compressed air, the air has density. This density gives the air weight and must be measured in lbs./minute. The conversion formula from cfm to lbs./min. is to multiply or divide by 0.0691 depending upon the conversion direction. For example 500 HP or 50 lbs./min equals 723.59 cfm (50 / 0.0691) and 723.59 cfm equals 50 lbs./min. (723.59 x 0.0691). Keep this conversion in mind when selecting a compressor wheel, as this is a key point in selecting a compressor wheel for a turbocharger.
After the HP is converted to airflow in lbs./min., a compressor wheel selection can be made by matching the air flow plotted on the compressor map,with the associated pressure ratio. Pressure ratio is defined as absolute compressor discharge pressure P2, divided by the absolute inlet (ambient) pressure. For example: (boost pressure in psi + ambient pressure in psi; ie. 15 psi of boost + 14.7 psi (1 atmosphere) / 14.7 (1 atmosphere) = 2.02 pressure ratio. The pressure ratio, shown as P2/P1, is located on the left hand vertical axis of the compressor map. Select a compressor map where the air flow and the pressure ratio intersect at a flow rate where the plotted efficiency is no less than 65%-70% for a street application. There will probably be more than one compressor which will satisfy your requirements – in this case, pick the compressor which has the LOWEST surge air flow limit at the selected pressure ratio – this will provide the widest range of performance at the boost pressure your vehicle will be operating at.
Turbine selection must also be considered for a successful turbocharger match. Most turbochargers described in this catalog are designed for use with an external wastegate or other device to bleed off excess exhaust energy when a desired boost is attained. TURBONETICS Inc. offers four different external gates matched for various HP outputs.
Turbine selection is a variable based on intended use, weight, and desired response. Turbine power available to drive the compressor wheel can vary in two ways: 1) The area to radius (A/R) ratio of the turbine housing can be changed to alter turbine inlet pressure; and 2) The turbine wheel trim can be specified to affect an increase or decrease in turbine pressure for a given turbine housing A/R (see A/R Ratios & How To Choose A Turbocharger for determining the proper A/R ratios).
|60-1 Compressor Map||10 KB|
|62-1 Compressor Map||7.42 KB|
|HP76 Compressor Map||4.14 KB|
|T3 Super 60 Compressor Map||8.87 KB|
|T04B Super H Compressor Map||10.16 KB|
|T04B Super S Compressor Map||9.19 KB|
|T04B Super V Compressor Map||10.11 KB|
|T04E 40 Trim Compressor Map||8.76 KB|
|T04E 46 Trim Compressor Map||9.6 KB|
|T04E 50 Trim Compressor Map||9.94 KB|
|T04E 54 Trim Compressor Map||8.02 KB|
|T04E 57 Trim Compressor Map||8.49 KB|
|T04E 60 Trim Compressor Map||9.84 KB|
|T58 Compressor Map||7.87 KB|
|T61 Compressor Map||9.36 KB|
|T64 Compressor Map||10.97 KB|
|T66 Compressor Map||11.44 KB|
|T70 Compressor Map||9.17 KB|
|T72 Compressor Map||8.71 KB|
|T3 40 Trim Compressor Map||6.91 KB|
|T3 45 Trim Compressor Map||6.91 KB|
|T3 50 Trim Compressor Map||8.33 KB|
|T3 60 Trim Compressor Map||9.42 KB|
|Y2K T88 Compressor Map||221.19 KB|