2007 Volkswagen GTI, Honda Civic Si, and Mazdaspeed 3 Dyno Tests: The Truth in Numbers

Charlie Magee
2007 Volkswagen GTI, Honda Civic Si, and Mazdaspeed 3 Dyno Tests: The Truth in Numbers

Mazdaspeed 3

Journalists aren't exempt from the same childish giggle-fits that afflict regular car enthusiasts. All it takes is a loads of power (preferably enough to overwhelm the tires on command) and even the most jaded journalist will crack a smile. We think the normally aspirated Mazda 3 is a fantastic small car, so we just knew that the turbocharged Mazdaspeed 3 would be a guaranteed giggle.

The Mazdaspeed 3's engine puts out big peak numbers, and as expected, we loved its acceleration. Many of us noticed, though, that the turbocharged 2.3-liter sometimes felt like an on-off switch. At some speeds, it made amazing power. At others, it didn't. The dyno chart shows that we weren't imagining things.

Turbos, by nature, have reduced operating ranges, but the Mazdaspeed 3 seems to be particularly susceptible to that limitation. It has prodigious torque in the midrange, but the engine feels anemic below 3000 rpm or above 5500. Honda's normally aspirated Si makes at least 85% of its maximum torque from 2000 to its redline. That means that if you floor the Honda's loud pedal anywhere between two and eight grand, you'll have at your disposal at least 85% of the maximum quoted torque. VW's turbo GTI will hand over at least 70% of its peak number at any time from two grand to its own redline. The Mazda is far behind the others at 20%.

Of course, the 'Speed 3 makes a much higher peak torque number than either the VW or the Honda (in fact, its peak is almost twice what the Honda puts out). But the GTI's engine, which is 0.3 liter smaller than the Mazda's, actually makes more torque than the Mazda from idle to 2700rpm--and again from 5800rpm to redline. The result is that the VW responds to gas pedal inputs with proportional urgency while the Mazda is sometimes fantastically fast, and sometimes--quite surprisingly--not.

A dual-scroll turbocharger like the one in the Saturn Sky Red Line and Pontiac Solstice GXP would help the Mazdaspeed 3 in increasing its usable rev range. As you can see in the comparison graph between the 3 and the Sky Red Line, peak numbers are similar, but the shapes of the torque curves tell two very different stories. GM's dual-scroll turbo builds boost much earlier, and has almost reached its torque peak by 2000 rpm. At that speed, the Saturn's 2.0-liter generates 210 lb-ft, compared to the larger Mazda engine's 128. Torque is similar throughout the midrange once the Mazda finally wakes up at 3000. By 6000, Mazda's engine is running out of breath, putting out 138 lb-ft while the smaller GM engine still manages 168.

Punch the accelerator at 3000 rpm in a Mazdaspeed 3 and you'll probably smile, too. But if you compare it to the more sophisticated engines of the other cars here, you may find it lacking the linearity and broad-range power delivery that set apart the merely powerful engines from the truly magnificent.

Dyno Chart

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