DAVE Coleman is a man on a mission. The Mazda North America vehicle development engineer is a self-confessed car nerd who fell in love with the Mazda RX-7 when he was 10 years old after his dad brought one home; he later owned the car. Now he’s out to save the Mazda rotary.
While the development of the car expected to resuscitate the RX-7 nameplate is being led by Japan, Coleman and his small California-based team is playing a key role. “We’re all on the same page with what we want to build,” he tells Wheels. “Everything you expect in a rotary is enhanced.”
Controversially, though, Coleman says the new rotary will be more about driveability than revs.
“We’ve kind of hinted at where that [new rotary] engine is going,” he says, referring to the Taiki concept car from the 2007 Tokyo motor show, something he describes as a “big departure” for the rotary engine. Its 16X engine had a longer stroke with a barrel where the bring narrower rotor housing.
“[That] pushed it to be more torquey than the 13B. Bigger b – that’s a really big hint of whe we’re working towards with th rotary engine. We’ve tried to b the revs down somewhat.” e arrel ere he ring Coleman says fuel economy, typically a weakness of highrevving rotaries, is a major focus for the new RX-7, previewed as the RX-Vision concept (below middle) at the 2015 Tokyo show.
“At higher rpm the exhaust temperature runs a lot hotter. The RX-8, for example, you get into that fuel enrichment, where you’re throwing extra fuel into it to keep the exhaust temperatures down. If we can constantly have the engine where the exhaust temperatures are lower, that will give us a huge boost in fuel economy.”
Torque is something Coleman loves talking about. He was instrumental in the program to produce the lower-power/highertorque CX-9 that has just gone on sale. It was a gamble – especially with marketing departments fixated on numbers rather than real-world feel – but one that appears to have paid off.
He says technology will play bigger role in future Mazdas.
“We’ve got stuff you can’t even imagine that’s coming. You’ll be very surprised … new technologies that nobody else has been able pull off but everyone [is] trying to do,” he says cryptically.
“When we run Miller cycle at light load, that’s essentially getting y a n ies to o rid of some of the compression ratio but keeping the expansion ratio … so you still get really high efficiency. And we’re doing it with a much cheaper mechanism.”
Dave Coleman is not your typical engineer, because he started life as a car journalist. He even wrote an article for Wheels in the 1990s, so we know he’s a man with taste!
He also speaks his mind and isn’t afraid to call things out when they aren’t right.
“The last MazdaSpeed 3 [MPS in Australia] would have been better with the 2.0-litre engine rather than the 2.3; higher-revving rather than a whole bunch of torque,” Coleman explains.
That engine was an SUV minivan engine. It was car, but in a perfect it would have been a different car.” t e rathe rttorqu “Th and m aaa fun world wddiffer
The Mazda MX-5 impressed us so much we awarded it the coveted Wheels COTY last year.
But no car is perfect, and it has been noted the convertible has a fair bit of body roll.
Dave Coleman is quick to defend the roadster’s suspension.
“It’s a convertible and it’s not a very stiff M award zippy chassis, so you don’t want to put sharp inputs and start shaking the body,” he says. “We tuned that car to work well on roads, not tracks.”
Coleman says the lack of rigidity was part of keeping the weight down, and that the softer tune helps keep the tyre contact patch in touch with the road, increasing grip.