From Naturally Aspired to Turbocharged Engines: BMW, Honda and Porsche Show Off Their Muscles

BMW, Honda, and Porsche have built some of the finest naturally aspired engines in the world. In the last two years, they have all turned their backs on tradition in favor of turbocharged engines for their most iconic models. So what have the M3, Civic Type R and 911 gained? And perhaps more important, what have they lost?

The BMW M3s

It’s hard for turbocharged engines to feel special, to have charisma, when by their very nature they can’t offer the same noise, response and high-rev drama. And that’s what we like about engines — the combination of our sense s being spiked matched to drivability both pulling in the same direction. Conversely, it’s when turbos have holes in their drivability that they tend to be exciting.


I drove a 1995 Audi RS2 recently. If you wanted to come out of the corner quickly, you had to accelerate before you turned in, then hold on tight and pray you got the timing right. It made me plan and concentrate, whereas the latest crop is designed to be as easy to use as possible. Maybe that’s where we’re going wrong — we ought to enjoy turbos for what they are, not hope they can impersonate an atmospheric engine so closely that we won’t be able to tell the difference.

Either way,we want to press the pedal and go, not sit around for a few seconds twiddling our thumbs and watching the overtaking gap narrow. Select Sport Plus in the BMW M3 and, provided you’ve been driving fairly sportily, it’ll notice this and use the engine airflow, even off-throttle, to keep the turbo spin ning at over 120,000rpm. So when you press go, youre ally do go. Fit the M Performance exhaust, and you counter almost all the noise criticisms, too.


The new M3 makes a fine fist of turbo-charging, almost too fine, because one of the things we‘ve criticized it for was making the performance too accessible. Picky, us? Now this is close to being a no-win situation, but it is true that we want an engine to have a sense of crescendo, to build and build as the revs climb, and as with most turbo cars, the M3’s torque curve is more convex, bulging lowdown and tailing off at the top, rather than developing through a concave arc into a screaming peak. In this instance, I’m not saying it tails off with a whimper rather than a bang, more that you’re already traveling so fast that holding on for the last 2,000rpm is not only unnecessary but might well invite the wrong sort of attention.


And in the case of the M3, it’s following on from twoofthe all-time greats—the E46M3’s 3.2-liter 343hp straight-six and the E92’s 414hp 4.0-liter V8. Of the two it was the older one that was my favorite — the six was a masterpiece: crisp, responsive, stunning to listen to. It took six cylinders as far as they could go, meaning BMW had to turn to eight for its re placement. BMW got that one pretty much bang on, too. It was always a relatively heavy drinker, but the way it revs through to 8,400rpm is pure magnificence, especially the arc over the last 2,000rpm.

It’s also a smoother, more consistent driving experience than the new one. I’ve touched on this before, but I believe BMW, concerned about how a turbo M3 would be perceived, deliberately made it challenging to drive quickly so it wouldn’t be se en as a cop out. Does that make it better?

No — by a slim margin, the old one gets my vote.

The Honda Civic Type Rs

In away, it’s surprising Honda held out for so long. When the red Civic Type R you see here was launched back in 2007, most of its rivals were already turbocharged. Take the MkV Volkswagen Golf GTI. It had the same power as the 198hp Civic, but over 80Nm more than the 192Nm the Honda could muster, delivered almost 4,000rpm further down the rev range.


Unsurprisingly the Civic, with its engine largely carried over from the 2001 EP3 TypeR, was criticized for being off the pace. But Honda held out, trusting in VTEC and high revs to do the business. And to a certain extent it did — and still does today. This naturally aspirated 2.0-liter is sharp and tingly. With intake and outflow of gases un impeded, response is immediate and it’ll happily so arround to 8,500rpm — thats’ easily l,500rpm beyond the upper reaches of the turbo’s range. It sounds eager and determined, with the engine building to a climax.

But the overriding impression is of a car that delivers much noise and drama for little progress. That’s not a criticism that can be leveled at the new one. The step-up in performance between the two generations is easily the biggest here — over 50% more power, over 100% more torque. Put your foot down at 50kph in fourth gear, and 10.7sec later you’ll have passed 160kph. The old Civic won’t be alongfor another 8sec.


But the initial lunge, that moment when you go for an overtake, there’s a lot less between the two. The new Civic suffers from considerable turbo lag. Side by side at 40kph on Dunsfold’s runway, old kept new honest for a four count before the turbo hooked up and thrust the monstrously winged Civic into the distance. At higher revs the issue is smaller,but it’s clear Honda still has to perfect turbocharging.

There is noise, but it’s flat and bland, lacks tonal definition or the sense that it’s working hard. The Civic’s blower is monoscroll, which means the impeller blades are fixed rather than having the variable geometry that allows carmakers to tune engine response and torque delivery via the turbos as well as the motor. Since the turbo behaves the same across the rev range, it allows you to feel some of the four-cylinder’s power characteristics, not least the step in performance when the VTEC kicks in. T urbos, especially variable-geometry ones, have a tendency to smother not just noise,but character — it’s one of our chief blower bugbears.


But because you don’t have to rev the knickers out of the new one to get places, economy is pleasingly strong — we had along-term car and it averaged 14km/L,where the old one returns around 11km/L. In saved cost and gained range that’s a difference worth having. As is the power and speed. This is relatively simple first generation turbocharging,and there’s a certain charm to its lag and heavy punch— the turbo Civic feels raw but rewarding. Yes, it’s missing the top-end snap and snarl, the aural pleasure, but of the two, old and new, it’s the one to have.

The Porsche 911s

The common beliefis that firms have been forced to adopt turbocharging due to emissions and wanting to improve economy. By and large that’s true. Only with the proviso that the benefits seen on the EU fuel cycle, which tests cars so gently that the turbo almost never wakes up, aren’t then matched by the reality.

However, there’s another reason: power.


When I went on the launch of the new, turbo Porsche 911,one of the engineers openly told me that if they didn’t turn to turbos, they wouldn’t be able to match the power figures of their rivals. Forget noise, lag and all the rest, it’s the headline figures of speed and economy th at sell cars and at least until the official tests get a makeover, turbo cars fare better on a spec sheet.

Theeveryone-else-is-doing-it-so-we-must-too mantra is a powerful one — no one wants to be left behind on technological development,so we all follow each other down the same paths (or cul-de-sacs, depending on your perspective). But what does that matter when it comes to actual driving? Do you actually notice that the new car runs from 50kph to 160kph in fourth gear in 10.6sec, where the old one took 14sec?

You can see the difference in the figures alright,but in reality it’s the old one that feels faster at the top end. And more special. The old 3.8-liter flat-six is mesmerizing. It’s guttural at low speed, chuntering around, then as the revs rise it clears its throat and starts to howl, the noise developing with every single revgained. It’s multifaceted magnificence.


To a certain extent, Honda and BMW have managed to alleviate the concerns about the move away from natural aspiration with, in Honda’s case, a massive power increase, and in BMWs, by focusing on noise and minimizing turbo lag. Porsche has followed BMW’s example and in isolation the new twin-turbo 911 is a responsive, noisy thing.

And yet, compared to its predecessor, it’s now not an engine you feel particularly inclined to play with. It feels more professional, smooth and hushed, where the old one was so charismatic and enthusiastic about getting places you couldn’t help but join in. It made the whole driving experience come to life. The counter-argument is that turbocharging improves everyday drivability. Overtaking becomes more effortless, you can run longer gearing and still have plenty of mid-range urge, noise levels are lower. For 90% ofthe driving you do, it makes more sense. But these are sports cars, and the 10% matters. And that’s why I’d have the original: the engine, the car’s heart, was a classic.


We haven’t learned anything new here,but the comparison has allowed both turbos and natural breathers to reveal the strengths and weaknesses of each other. Put most people in a naturally aspirated car and they’d miss the torque, update them to the turbo and they’d protest about the noise and delay. Legislation and the very real need to lower emissions ensures turbocharging is here to stay, but it’s incumbent on the car firms to make it the best it can be, so that turbo can not only imitate natural aspiration, but actually move the game on.

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