Simple Tech: Engine installation explained

Shashank Singh  /
05 Jul 2016 17:34:14 IST

The chassis is the skeleton of thecar. It provides the structure to which all theother bits are mounted so that they canfunction as they are designed to. Obviously,there is no one fixed place where the engine,for instance, can be installed. And that iswhat we will explore this time in SimpleTech. Installations are normally classified bywhere the engine is in the chassis, sometimesusing the front or rear or both axles asa reference. Each kind of installation bringsdifferent benefits and issues to the completedautomobile. Which is the balancethat the manufacturer decides upon at thedesign stage with the intended role andfunction of the automobile in mind. At themost simplistic level, for instance, an engineunder the front bonnet - a front-engineinstallation - is easy to produce in terms ofcost and logistics and that is why it's themost favoured place to mount the engine intoday's cars. The front-wheel drive layout, asan extension also makes the rest of thedrivetrain compact and easy to produce andinstall which is why almost every hatch inthe world today uses the front-engine,front-wheel drive configuration.

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The placement of the engine, alsoinfluences how the motor's weight sits onthe wheels of the car - it determines asignificant chunk of the weight distributionof the car - and that, in turn, determineswhat the car will handle like to a greatdegree. To take an example, a mid-mountedengine - mounted between the two axles butalmost never at the centre of the car - allowsmanufacturers to come close to a 50:50weight distribution (exactly half the weightof the car sits on the front axle and exactlyhalf on the rear) which is considered theperfect weight distribution for the ultimatehandling experience. Even distribution alsomakes the car stable and its handlingpredictable, adding to the driver's ability tofeel secure and confident as well as toextract maximum handling performancefrom the car. Obviously, mid-mountedengines tend to intrude into the passengerspace - a perfectly mid-mounted engine,would in theory, be mounted between thetwo front seats, more or less.

At the other extreme, Porsches used toplace the engine at the rear, initial 911s hadthem behind the rear axle. Which is why theoriginal 911s were considered such ferociouscars to go fast in. The extreme engineposition would give them the handlingcharacteristics of a pendulum in effect,allowing the car to oversteer (as in the tailwould slide) easily and these slides were veryhard to control even with skilled hands at thewheel. Today's 911s place the engine muchcloser to the rear axle or directly over it,allowing the oversteer tendency to be curbedand the cars to handle phenomenally. Again,rear-engine configurations can lead to greatspace in the cabin and the odd sensation ofloading your luggage in the front trunk ofthe car. Many of the greatest handlingsportscars today use mid-rear engineinstallations where the engine is mid mountedbut ahead of the rear axle. Andtaking a leaf from that book, many cars alsouse a front-mid-engined installation - theengines sits behind the front axle - allowingsome benefits of the mid-configuration, plusa shorter drivertain if rear-wheel drive. Manyhigh performance GTs, like the 599 GTBfrom Ferrari favour this configuration.

Motorcycles, thanks to how small thephysical dimensions are, offer a lot lessflexibility. Early motorcycles did someinteresting work with engine mountings buttoday, the engine is usually mounted in allmotorcycles just behind the front wheel.Which places the considerable weight closeto the centre of gravity of the motorcycle,crucial for its handling.

But we also talk about the actualorientation of the engine in the installation.A longitudinal engine is mounted with itslong axis parallel to the length of the chassiswhile a transverse mounting (very good inmaximising cabin space) mounts the longaxis of the engine across the chassis, parallelto the axles. Motorcycles tend to favour thetransverse layout for space efficiencyalthough most V-Twins and some tripleslike the Triumph Rocket III still use alongitudinal configuration.

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Tags:  | simple tech  | engine installation  | Engine  | mounting

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