Barra Turbo Selection – Finding the Best Size
To find the optimum Barra turbo size we’ll use the calculators on StrikeEngine and follow the usual turbo selection process.
Step 1
Step 1 is to find the volumetric efficiency of the engine. We’ll use this calculator and the data points from this dyno graph
| cc | BHP | RPM | VE | Boost |
| 3900 | 327 | 5390 | 0.61 | 25.7 |
| 3900 | 335 | 3830 | 0.74 | 31 |
Step 2
Step 2 is to bolt the VE numbers into the turbo size calculator with our boost target. For this article we want 30 PSI at 3830 and 5390 RPM.
| PR | CFM | lbs/ft | Boost | RPM | Power Predicted |
| 3 | 688 | 52.9 | 30 | 5390 | 552 |
| 3 | 593 | 45.6 | 30 | 3830 | 476 |
G30-900
Barra Turbo Analysis
The G30-990 seems very well suited to the Barra at 30PSI. The two points are close to the efficiency island and additionally, there is headroom to improve the volumetric efficiency of the engine while maintaining the same boost pressure and improve the performance of the turbo.
In short, for stock engine efficiency, the 990 turbo is a good fit and if we improve the engine later, the turbo will still be suitable. And one more plus with the G-Series, there is some room to turn up the boost to 35PSI.
