Why do most performance cars have a longitudinal-mounted engine?
By performance cars I mean sports cars that typically develop at least 400hp and are usually coupes two seaters.
asked Jul 11, 2017 at 22:00
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1What are you classing as "performance cars" ? F1 or Rally??– Solar MikeJul 11, 2017 at 22:11
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Ford GT, McLaren P1, Mercedes SLS, Lamborghini Huracan...– Andrei RîneaJul 11, 2017 at 22:14
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2What Mike said and you probably want to flesh out your question a little bit better as well. In most cases performance cars have longitudinal engines because they are rear wheel drive.– Pᴀᴜʟsᴛᴇʀ2 ♦Jul 11, 2017 at 22:15
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Now we have a question with some boundaries. But do you mean two actual existing seats or that the floor pan was originally designed for two seats but the passenger seat has been removed to reduce weight?– Solar MikeJul 11, 2017 at 22:39
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I mean two-seater by design.– Andrei RîneaJul 11, 2017 at 22:42
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4 Answers
It's quite simply because a longitudinally mounted engine equates to less of an engineering challenge to achieve "balance". Imagine something like a large V formation engine, two banks of cylinders, two sets of exhaust headers, etc... The simplest way to divide this large heavy lump of metal and gaskets is along the centre-line of the crank. If that is aligned with the centre of the vehicle it is installed in, the vehicles balance left to right is near perfect.
Add a gearbox to the end of a longitudinally mounted engine plus a diff and prop-shafts that are all inline with the centre of the vehicle and you still have not only near perfect symmetry but likely equal length driveshafts. This is important as it avoids torque steer. With a 100bhp engine, torque steer is negligible, quadruple that figure and it becomes a big issue.
In transverse (typically FWD applications) it is usual to offset the bulk of the mass of the engine over to one side of the chassis and place the gearbox on the other side of this. At normal road speeds and relatively low power figures, this is a good compromise as it allows maximum cabin space. At higher speeds however and higher power figures, it significantly compromises the handling and indeed safety of the vehicle.
answered Jul 12, 2017 at 14:58
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If you mean how do we stabilise transverse, various ways but they're all a compromise. On the old Mini the gearbox was in the sump, under the engine. On a Lancia Delta, they use a dummy driveshaft so end up with equal length shafts at either side. Clever placement of the battery can offset weight distribution. However, everything is done to offset the inherent imbalance. Jul 13, 2017 at 5:45
And to add to @MeltingDog, there is also the concept of weight distribution - some cars even have the engine at the front and the gearbox / rear axle at the rear to improve the distribution.
answered Jul 12, 2017 at 5:30
I believe it's because of the idea that rear-wheel drive cars are more fun to drive, because burnouts and drifting and such.
Also, transverse engines (and typically front wheel drive cars) have traditionally been thought of as slow, economy cars. The original Mini was the first car to mass produce this design and was intended to be an economic small family car. Same with many hatchbacks in the 70s and 80s - it was all about space and weight saving over performance, which formed peoples opinions on the design.
Finally, it can be just hard to fit a large transverse engine.
answered Jul 11, 2017 at 23:55
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Golf GTI and Peugeot 205 GTI don't seem to have been designed for economy... All those "hot hatches" Jul 12, 2017 at 5:28
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Haha I was going to address that in the answer. These cars were never meant to be, really. The Golf GTI came about because some guys at the factory were mucking around and stuck a Bosch injection unit on a little Golf. This caught the eye of someone who convinced the execs to put it into production, almost as a kind of gimmick. To give you an idea of how odd this was at the time, the GTI wasn't even going to be sold outside of Germany, so ingrained people were (and still are) that sports cars be big engined, FR configurations. The 205 GTI wasn't even launched until the mid 80s. Jul 12, 2017 at 6:43
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Quite right - just shows that the marketing geeks don't always know what people want or need... Jul 12, 2017 at 6:52
Less torque on engine mounts. Transverse having the axle reduction in the engine and transmission structure then places drive axle torque on engine mounts. Subaru is different tho, more like transverse but it would at least have more length between torque couple.
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There is more than the engine mounts, usually a third mount (if not 4) to stop twisting from the torque reaction... Nov 4, 2018 at 16:13