Testing cars for power ratings is a tough and tricky business - accounting for different conditions, locations, equipment and techniques can make it tough to generalize results. And to make matters worse, there is often a lot of guesswork employed to get between real, delivered wheel horsepower and output at the crankshaft, or vice-versa. A recent test of Nissan's GT-R has answered some of the ongoing questions of how it performs so well, however, and taken a good bit of the fiction out of the process.
Rumors and reports
from around the web have been claiming Nissan's stated figures for the GT-R's twin-turbo V6 are understated ever since it began its remarkable climb
up the many performance charts. All-wheel drive and tons of rubber just couldn't make up for the massive power deficit, they claimed. But it turns out Nissan's claimed 473hp (353kW) figure isn't far from the truth at all, according to MotorTrend
. The torque numbers are about 40lb-ft (54Nm), or roughly 9%, larger than Nissan's 434lb-ft (588Nm) rating, and could help explain a little of the car's low-end acceleration abilities.
The key to this latest round of testing is the use of Hyper Power Dynamometer's DYNOmite, which allows testing not just of engine output, but of powertrain drag. After a dyno pull, instead of ceasing to record data, the machine records the slow-down period, and measures the drag due to the car's powertrain, including engine, transmission and wheels.
The end result? As physics would suggest, the parasitic losses of the drivetrain increase with speed, varying from 23hp (17kW) at 50mph to 84hp (62kW) at 100mph. That works out to a real-world inefficiency ranging between 5-17%, depending on speed - quite good for an AWD car.
One thing to keep in mind, however, is that this is just one particular example of the car - power figures can and will vary from vehicle to vehicle. It will simply take time and repetition to see if these results are more or less representative of the general population of Nissan GT-Rs than previous tests. The method, however, is a definite improvement.
2009 Nissan GT-R