The 2014 Accord Hybrid has been a hot item in Honda's local press fleet (and apparently in showrooms), so it took us a little while to get our hands on one. We couldn't wait to dyno test Honda's most powerful Hybrid to date, as it has an all-new two-motor hybrid configuration, and essentially no traditional transmission. Instead, it has what Honda refers to as an e-CVT, with the "e" standing for "electrical". And if you didn't already know, CVT stands for Continuously Variable Transmission, but in this case we like to say it merely emulates the operation of a CVT, as unlike a conventional CVT, there is no mechanical change in gear ratios.
In Honda's "two-motor" hybrid system, one of the motors is a large, powerful (rated at 166hp) traction motor which directly drives the front wheels. The 2nd motor is coupled to a 2.0L gasoline engine and serves as a motor/generator. In motor mode, it is used to fire the engine for the start/stop function, and in generator mode, it takes the output of the gasoline engine and converts it to electricity, in order to recharge the onboard 1.3kWhr battery pack or to power the traction motor directly.
Three modes of operation
With these components, the Accord Hybrid can operate in one of 3 modes: EV (Electric Vehicle), HV (Hybrid Vehicle), and Engine Drive (ED). EV mode is pretty self explanatory. The engine is shut off, and the traction motor is powered by the battery pack. The Battery pack is said to be able to deliver around 60hp (45kW), so the Accord Hybrid can travel at reasonably high speeds in EV mode, but not for very long durations as the battery capacity is rather limited. The HV mode typically means the engine is running, generating electricity and powering the traction motor and/or recharging the onboard battery pack. ED mode is where the engine is coupled directly to the wheels in a direct drive fashion (with a single overall gear ratio of 2.45). This typically engages at speeds in the 40-70mph range, and while Accord Hybrid lacks a tachometer, with an Obd-II scan tool you can see that it churns about 1800rpms at 50mph. Also, according to Honda engineers, there's a 4th case where Engine Drive can be assisted by the electric motor, but you might not notice this mode.
For our purposes of dyno testing the Accord Hybrid, the important thing to note is that for maximum power output, the Accord's system operates in HV mode. The engine spins up to its peak rpm (6225rpm on the scan tool), invoking its "power" cam profile (as opposed to the "lo-rpm" lobes, which operate on an Atkinson cycle) delivering a rated 141hp to the input of the motor/generator. This juice is passed on to the traction motor, and supplemented by the battery (if available). Keep in mind that this means the theoretical maximum output of this system to the wheels is 166hp. The 196hp quoted figure is actually a little bit misleading. It is indeed the maximum output of the system (defined as MAX power output from the engine/generator pair and the battery pack), but you can only pour a gallon of milk into a gallon jug. Because, remember, in HV mode, the only thing connected to the wheels is the traction motor. And that is rated at 166hp. Conveniently, most cars in the 200hp range typically put down around 165-170hp to the wheels, so you could think of the 196hp as a "crank" rating and the 166hp as the whp (wheel horsepower) rating.
Throw out those correction factors
The good news is that the Accord Hybrid actually made more power than the 166hp rating on Dynolab's Dynojet (UPDATE: Unfortunately, Dynolab seems to be permanently closed.). The other interesting consideration is that the SAE "correction factors" typically applied by the dyno testing software do not apply for EVs (or HVs running purely from a traction motor, as is the case here), and should be ignored when dyno testing these types of vehicles. Correction factors are there to scientifically correct for changes in oxygen density in the air due to elevation, humidity, and temperature conditions, all benchmarked against a set of ideal conditions. This is only relevant for combustion engines. In this case, sure, there's some combustion variation for the ICE, but the 60hp output capacity of the battery should be able to swallow up any difference or shortcoming of the 141hp engine due to elevation, heat, humidity etc. Under "ideal" conditions, when the engine is able to generate 141hp, all that's technically needed from the battery is an additional 25hp of energy, so that leaves 35hp of headroom for less than ideal combustion conditions.
No RPMS or TORQUE on the plot?
There is no torque plot on these graphs because on dynojets, torque is always calculated by first determining the power output and then plugging that data into a standard equation (HP=TQ*RPM/5252) along with the measured RPMs, but this method relies upon a fixed gear ratio to plot Torque against RPMS on the x-axis. With CVTs, you can get a torque reading against speed (on the x-axis), but only when the dynojet's RPM pickup is working, and apparently we were unable to get a good RPM reading from this Accord Hybrid, so no torque graphs.
Click the image below to view the full-size dyno sheet and page_number=2">continue on to the next page to see the video of the dyno pass.