Dynamic numbers – i.e. frame Dynos – are not an exact science when it comes to the power actually produced by an engine. A chassis dynamometer measures the power at the wheels, and that’s always a lower number than what you’ll get at the engine crankshaft. This is because the power goes from the crankshaft to a transmission, transmission shafts, axles, hubs, wheels and finally tires. In the process, these components absorb some power, the transmission being the biggest horse thief.
For decades, the average power loss for manual transmissions has fallen in the range of 15%. The automatics were even worse at 20, but these days we have more than a few cars fitted with dual-clutch gearboxes. The loss of power in these transmissions is still a mystery, with some saying it is similar to a standard manual and others saying it is better.
This long introduction is at the heart of this McLaren 720S showdown against the Ferrari 488 Pista hp from Dragtimes. We mention this because the clip attempts to unravel the mystery of stray power loss in a dual-clutch gearbox, while offering a power comparison between apples. To this end, the 720S and Pista presented here have been tested on the same chassis dyno, and would be original. Officially, both cars have engines with a nominal power of 720 hp, but the results of the dynamometer show that the McLaren puts a lot more power on the ground. Either the 720S makes a lot more power than expected, or the Ferrari loses a lot more power between the engine and the tires.
Here’s where it gets interesting. The video also refers to a Dynojet plot allegedly sourced directly from Ford, showing 577 horsepower for a 2018 Ford GT. The company is reported to have tested all of the new GTs on this particular dynamometer to verify power before shipping cars to customers, so presumably, 577 hp on a Dynojet dynamometer at sea level is the magic number for power at the wheels. Given the official SAE rating of the GT of 647 hp in the crank, this means that the car suffers only 11% of transmission loss.
In other words, provided the Ford connection is correct. We asked Ford to confirm if it is running new GTs on a test stand before shipping, and if 577 hp of wheel is an approximate number. In response, we only received SAE horsepower figures of 647 hp for the previous EcoBoost GT and 660 hp for the 2020 models. So this 11% theory is just that – an unconfirmed theory.
That said, here’s where it goes really interesting. When applied to the dynamic layout of the Pista, the engine power at the crankshaft is 721 hp. It’s almost dead on what Ferrari claims, giving credit to the theory. Plug that same number into the McLaren and the power of the crankshaft is 786 hp – well beyond what McLaren claims. However, given the crazy acceleration we’ve seen time and again since the 720S, many believe it is underrated from the factory. This 11% theory also seems to confirm this.
So yes, that is a lot of calculations and bench racing, but the results are certainly intriguing. Could 11 percent be the new standard for calculating transmission loss on cars with modern dual-clutch transmissions? Of course, not all dual-clutch transmissions are created equal, and the chassis dynamics numbers can fluctuate based on many variables beyond stray power loss. Results may also vary between different types of chassis dynos, although for this video (and the Ford GT connection), all dynos were of the Dynojet variety.
At the end of it all, the point to remember for this video is that the McLaren 720S puts absolutely more power on the ground than the 488 Pista, despite official engine ratings.
Dynamic numbers – i.e. frame Dynos – are not an exact science when it comes to the power actually produced by an engine. A chassis dynamometer measures the power at the wheels, and that’s always a lower number than what you’ll get at the engine crankshaft. This is because the power goes from the crankshaft to a transmission, transmission shafts, axles, hubs, wheels and finally tires. In the process, these components absorb some power, the transmission being the biggest horse thief.
For decades, the average power loss for manual transmissions has fallen in the range of 15%. The automatics were even worse at 20, but these days we have more than a few cars fitted with dual-clutch gearboxes. The loss of power in these transmissions is still a mystery, with some saying it is similar to a standard manual and others saying it is better.
This long introduction is at the heart of this McLaren 720S showdown against the Ferrari 488 Pista hp from Dragtimes. We mention this because the clip attempts to unravel the mystery of stray power loss in a dual-clutch gearbox, while offering a power comparison between apples. To this end, the 720S and Pista presented here have been tested on the same chassis dyno, and would be original. Officially, both cars have engines with a nominal power of 720 hp, but the results of the dynamometer show that the McLaren puts a lot more power on the ground. Either the 720S makes a lot more power than expected, or the Ferrari loses a lot more power between the engine and the tires.
Here’s where it gets interesting. The video also refers to a Dynojet plot allegedly sourced directly from Ford, showing 577 horsepower for a 2018 Ford GT. The company is reported to have tested all of the new GTs on this particular dynamometer to verify power before shipping cars to customers, so presumably, 577 hp on a Dynojet dynamometer at sea level is the magic number for power at the wheels. Given the official SAE rating of the GT of 647 hp in the crank, this means that the car suffers only 11% of transmission loss.
In other words, provided the Ford connection is correct. We asked Ford to confirm if it is running new GTs on a test stand before shipping, and if 577 hp of wheel is an approximate number. In response, we only received SAE horsepower figures of 647 hp for the previous EcoBoost GT and 660 hp for the 2020 models. So this 11% theory is just that – an unconfirmed theory.
That said, here’s where it goes really interesting. When applied to the dynamic layout of the Pista, the engine power at the crankshaft is 721 hp. It’s almost dead on what Ferrari claims, giving credit to the theory. Plug that same number into the McLaren and the power of the crankshaft is 786 hp – well beyond what McLaren claims. However, given the crazy acceleration we’ve seen time and again since the 720S, many believe it is underrated from the factory. This 11% theory also seems to confirm this.
So yes, that is a lot of calculations and bench racing, but the results are certainly intriguing. Could 11 percent be the new standard for calculating transmission loss on cars with modern dual-clutch transmissions? Of course, not all dual-clutch transmissions are created equal, and the chassis dynamics numbers can fluctuate based on many variables beyond stray power loss. Results may also vary between different types of chassis dynos, although for this video (and the Ford GT connection), all dynos were of the Dynojet variety.
At the end of it all, the point to remember for this video is that the McLaren 720S puts absolutely more power on the ground than the 488 Pista, despite official engine ratings.