2012 Midsize Shootout: Dyno Day

By Mark Williams; photo by Joe Bruzek

Understanding how and where each midsize pickup engine makes power is probably the most important personality trait and defining characteristic.

Our group consisted of five V-6s, one V-8 and one inline-five-cylinder. All have part-time four-wheel-drive systems except for the all-wheel drive Honda Ridgeline, which meant six of our test vehicles could be tested on the same K&N inertial dynamometer for rear-wheel vehicles, while the Honda would need to use the all-wheel-drive dyno (that’s why the chart looks different), which is usually reserved for Subaru WRXs, Mitsubishi Lancer Evolutions and other European performance sedans.

K&N assured us both dynos were standardized within fractions of a percentage point of one another, in terms of accuracy. In addition, each unit was calibrated and recalibrated on a regular basis to guarantee accuracy. Each truck was run in 2nd gear to keep the curves relatively consistent, giving us the engine power band info we need between 2,500 and 6,000 rpm.

Here’s a quick explanation for those who might not know how a chassis dynamometer works: K&N uses inertial dynos to determine the estimated SAE-corrected horsepower of their intake kits and manufacturer replacement air filters. This type of dyno does not actually measure horsepower; it measures acceleration. This measured acceleration is multiplied by the mass of the drum (a minutely measured constant mass) to obtain the force being applied to the drum as it spins. When the exact force to move the drum is known, determining the exact torque is a straightforward calculation. The torque is calculated by multiplying the calculated force by the radius (again, a finely measured constant) of the dyno’s drum. Once you have the torque number, horsepower is just a calculation away:

• Horsepower = torque x rpm / 5,252

All of our vehicles were tested on the same morning of the first test day, with almost identical weather conditions throughout. Each computer sensor sends its data through an SAE correction factor inside the software. K&N’s top technician conducted each set of dyno runs with the precision and repetition worthy of a skilled surgeon. This is necessary to remove as many variables as possible. He was quick to tell us that, as good as he is, even identical vehicles can have slightly different results for many reasons.

And indeed, we did find some relatively significant fluctuations between the Nissan and Suzuki, which had the same engine, transmission and ring-and-pinion ratios. Those differences worked out to a 3 percent better horsepower peak and close to a 6 percent better torque number with the same powertrain. Our K&N expert said the difference could be explained by the way in which each computer is adjusting and sensing the various atmospheric conditions before and during the dyno tests (see K&N disclaimer at the bottom). Regardless, our main goal was to make sure each truck was tested with the exact procedures to keep the playing field as level as possible.

NISSAN FRONTIER

SUZUKI EQUATOR

Our dyno results didn’t give us too many surprises. We knew the GM V-8 would lead with the most horsepower, and we knew all the modern V-6s were going to rate at or near the 200 hp threshold, but what we didn’t see coming was how well (or poorly) the various engines produced torque and where. Although this category only considers peak horsepower (vehicle horsepower numbers are divided into the winner’s horsepower rating, in this case 239.4), it’s worth noting that for how much less power the Ford Ranger made (165 hp), it produced much more torque (186 pounds-feet) than the more modern and lively Ridgeline engine (184 pounds-feet).

FORD RANGER

HONDA RIDGELINE

Credit also seems due to the GMC Canyon for producing good horsepower (192 hp) and decent torque (184 pounds-feet) with one and three fewer cylinders. However, we were most struck by the fact that the Tacoma, which made less than 200 hp, could produce the flattest torque curve of the group, making more than 200 pounds-feet just after 3,000 rpm all the way up to 5,500 rpm. The Toyota torque curve looks more similar to the Colorado’s V-8 than it does to the other V-6s.

GMC CANYON

TOYOTA TACOMA

In the end, the Colorado had the best horsepower number (239 hp) over the second-place Suzuki Equator (216 hp), but only by a margin of 11 percent. Likewise, it was no surprise the Ranger came in last place, but it offered a good, strong torquey feel. Interestingly, the Honda uses a different strategy to compensate for its average horsepower and torque output with a 4.53:1 ring-and-pinion and five closely knit transmission gears.

CHEVROLET COLORADO

In the end, the charts tell the whole story, giving the win to the biggest engine with the most cylinders. The Colorado won the event and was awarded 100 points. The remaining peak horsepower numbers were divided into the winning horsepower to get an adjusted score (rounded to the nearest tenth) out of 100 points. For example, the Ridgeline’s peak horsepower was 202.2, so it received an adjusted score of 84.

K&N Disclaimer

K&N has noticed that SAE-corrected horsepower values will vary from day to day while testing the same vehicle, due to the manner in which the vehicle’s on-board computer adjusts for varying climate conditions, among other variables. In other words, if a vehicle is tested at 6,000 feet on a hot day, the dyno will apply an SAE-correction factor to adjust the conditions to a standard temperature and pressure (STP), yet the vehicle’s on-board computer will also apply certain set of operating parameters as well. If that same vehicle is tested at sea level on a cold day, the dyno will again adjust to STP while the vehicle may adjust to a different correction factor. Furthermore, some vehicles have required almost 100 miles to be logged on the engine to allow the on-board computer to reset itself to obtain more accurate input readings.

2012 Midsize Shootout

Overview
Track Day
Fuel Economy
Off-Road Day
Judgment Day
Results