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CAN YOU HEAR ME NOW?

THE CONTROLLED fury of Formula 1 racing has been affected this season by discontent over the sound of the cars’ exhaust. To me, this is misguided acoustics, much ado about nothing, and in ignorance of motorsports history.

Granted, to others, including F1 impresario Bernie Ecclestone, engines of the 2014 Technical Regulations are sounding too quiet, too tame and lacking the spine tingle of their most recent counterparts. In response, Mercedes-Benz AMG Petronas team has been given the assignment of evaluating a megaphone exhaust system, the point being to assess whether it carries any significant performance detriment—and, more important, any improvement in sound.

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The Mercedes-Benz AMG Petronas F1 car, as fitted with a megaphone exhaust.

One thing is certain: It will make a car louder. This, after all, is why wind instruments have their shape. A trumpet’s bell or race engine’s megaphone directs the sound and reduces some of its inherent backflow. A video from KClassScienceChannel describes the working of a megaphone (http://goo.gl/jHov6l).

As any horn player will admit, though, a megaphone doesn’t change the character of the sound; this comes from the other end of things, the player’s embouchure in the mouthpiece.

Lots of things affect F1’s 2014 sound, each responsible for part of the diminuendo. By regulation, 2014 F1 engines are 1.6-liter V-6s running no more than 15,000 rpm (http://wp.me/p2ETap-24d). Last year’s F1 2.4-liter V-8s ran to 18,000. Today, there are simply fewer and smaller explosions per unit time.

Also, and crucial in the analysis, unlike their immediate predecessors 2014 F1 engines are turbocharged: They extract energy (and noise) from the engines’ exhaust. What’s more, today’s F1 engines have EGER, exhaust gas energy recovery. These units reside downstream of the turbo and transform some of the remaining exhaust energy—and thus some of the noise—into electricity.

This energy recovery is added to KERS, kinetic energy recovery of braking energy that’s been part of F1 for several years now. Unlike EGER, though, KERS doesn’t affect engine sound.

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Mercedes-Benz AMG Formula 1 power unit, as viewed from the right. A lot of the technology here doesn’t make noise; it reduces it.

So we have smaller engines running at lower revs and extracting energy in two different ways from their noisy bits. No wonder their sound character is different.

Besides, if you want real spine tingle, check out Gerard Berger’s win at Estoril, Portugal, in the 1989 Ferrari F640 (http://goo.gl/49UBcX). The normally aspirated V-12 engine had real character, not just sound level. It’s also interesting to recognize an era when drivers weren’t quite so aggressive bouncing from apex to apex.

What about megaphones and their effect on F1 performance? Some worry that altering the direction of exhaust flow could adversely affect rear aerodynamics. Others suggest an optimized megaphone might enhance an engine’s exhaust tuning (though it seems rather far downstream to have much effect in a modern F1 power unit).

Not that megaphones haven’t been used in motor racing. The first 500-cc Formula 3 cars, originating in England not long after World War II, were all powered by motorcycle engines. See http://wp.me/p2ETap-kq.

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A modest megaphone is a feature of this Cooper Norton Formula 3 car. Image by Hmaag.

Many of these Formula 3 cars featured megaphones, said to be part of the engines’ exhaust tuning. They certainly gave the cars an exhaust blat far greater than their diminutive size would suggest.

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Maybe this Cooper Formula 3 driver has fond memories of megaphone exhausts.

The driver in this particular Cooper is identified as Bernard Ecclestone. ds

© Dennis Simanaitis, SimanaitisSays.com, 2014

One comment on “CAN YOU HEAR ME NOW?

  1. Bill Urban
    May 16, 2014

    Early megaphone research from “The Scientific Design of Exhaust & Intake Systems”, Philip H. Smith and Dr. John C. Morrison, third edition, 1971: “. . . because of the continuous reflective action of the megaphone in comparison with the instantaneous action of a plain pipe-end, the total period over which scavenging waves arrive at the exhaust valve is considerably prolonged.” An accompanying chart describes one megaphone experiment – compared to a straight pipe – yielding a 40% longer negative pressure period, with an ideally shaped megaphone.

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