A few weeks ago, we got a surprise visit from the new BMW 335i coupe, one of the hottest cars of the year. We’d been quivering in anticipation for the 335i not because it’s a 3-series--although that pedigree doesn’t hurt--but because the mind-meltingly fast two-door offers BMW’s first turbocharged gasoline engine ever to be sold in the States.
With this in mind, we just had to take the new coupe to the dyno and see exactly how much power its twin-turbo powerplant puts to the ground. The results? 275 hp and 300 lb-ft of torque at the rear wheels--more than we expected. Rated by the Bimmer boys at 300 hp and 300 lb-ft of torque, it was pretty clear to us that the Bavarian masterpiece was a little underrated from the factory.
In the weeks since we first published the results of that test, we’ve heard some criticism of our conclusion that the 335i makes "closer to 350 hp" than the reported 300. We arrived at that verdict after some quick calculations, but since a chassis dyno only reports how many horses make it to the wheels, it’s admittedly a hard number to verify. We did four runs with that particular car, and the actual peaks were 276, 280, 280, and 283 horsepower. We published the lowest number to be sure there was no claim that we were exaggerating the engine’s output.
But what if this was a one-time fluke? What if that first 335i was a particularly strong example? Or--gasp--a ringer! The answer to that question appeared in the form of another 335i (this time painted space gray metallic) that BMW dropped off last week. Again, without hesitation, we grabbed the keys and headed for the dyno shop.
On the way, we were pleased to find intact the awesome midrange torque and incredible straight-six soundtrack. Reacquainting ourselves with the gauges, we noticed that, as with the original tester, the oil temperature stabilized at 240 degrees Fahrenheit while cruising in sixth gear at 80 mph. Lesser engines would melt at those temperatures!
Temperature? Wait! A quick look at the outside temperature display showed that it was only 78 degrees Fahrenheit outside. The last time we put a 335i on the rollers, it was 92. Everybody knows that engines make more power when they get cooler air--and that turbocharged engines are particularly susceptible to heat soak. We stopped worrying and started getting excited. This one might do even better.
We strapped the 335i down, started it up, and did three runs back to back to back. The results were very consistent, showing peaks of 285 hp, then 282 hp, and, finally, 287 hp. This 335i was even stronger at the top end than the last one, but not as strong in the midrange. Peak torque was stable through all three runs at about 285 lb-ft.
After the final run, we decided to grab audio of the 335i running from first gear through fourth. We expected to have the hairs on the back of our neck stand up at the sound of the 3.0-liter engine at full throat, but what we didn’t expect, of course, was a peak hp number nudging the 300-hp mark. That’s right--shortly after the shift into fourth, this second 335i peaked briefly at 299.93 hp.
Looking closely at the chart, there’s a likely explanation for that outrageous number. No, it wasn’t additional torque from a rough shift--the peak occurred too long after the gear change. Like most turbocharged cars, the computer allows a momentary spike of boost before stabilizing it at a prescribed level. We lucked out, as that spike happened right at the engine’s inherent power peak, so we got a little nudge in the final number. Whether the dyno numbers ultimately translate into 300 hp, 350 hp, or 327.543-to-the-fifth-power-hp, the results speak for themselves: this is one very powerful engine.
Read Article