A decade of downsizing - why did the 5 cylinder not thrive?
Discussion
As ICE development starts to wane, I find myself questioning why, in a world of constant downsizing, the 5 cylinder did not finally find the market that always alluded it?
The trend over the past 15 years has been towards modular inline engines with swept capacities of 500cc per cylinder, and this has led to the widespread standardisation of 1.5 3-cylinder, 2.0 4-cylinder and 3.0 6-cylinder units, all turbocharged. It would seem obvious to me that a gap is present that could be filled easily by a 2.5 5 cylinder in any engine family.
Both Audi and Volvo have tried to use a 5-cylinder configurations in the past as their answer to both the efficiency of a 4 and the refinement and power of a 6, which they arguably failed to achieve wholesale, but probably managed quite well as a compromise of both.
Benefits of a straight-5 include easy mounting transverse and longitudinally, which considering the increasing prevalence of cab-forward transverse cars at ever growing scale, would have allowed a larger engine to be fitted, instead of having to rely on ever more extreme 4-cylinder builds to take the massive boost.
I think if I was a premium marque in the mid 2000's, knowing that I'd soon have to start selling smaller engines at higher price points to traditional buyers, I would have done anything to avoid fitting the same engine configuration that every run-of-the-mill car has, and the straight-5 might have been the answer.
Thoughts on a postcard...
The trend over the past 15 years has been towards modular inline engines with swept capacities of 500cc per cylinder, and this has led to the widespread standardisation of 1.5 3-cylinder, 2.0 4-cylinder and 3.0 6-cylinder units, all turbocharged. It would seem obvious to me that a gap is present that could be filled easily by a 2.5 5 cylinder in any engine family.
Both Audi and Volvo have tried to use a 5-cylinder configurations in the past as their answer to both the efficiency of a 4 and the refinement and power of a 6, which they arguably failed to achieve wholesale, but probably managed quite well as a compromise of both.
Benefits of a straight-5 include easy mounting transverse and longitudinally, which considering the increasing prevalence of cab-forward transverse cars at ever growing scale, would have allowed a larger engine to be fitted, instead of having to rely on ever more extreme 4-cylinder builds to take the massive boost.
I think if I was a premium marque in the mid 2000's, knowing that I'd soon have to start selling smaller engines at higher price points to traditional buyers, I would have done anything to avoid fitting the same engine configuration that every run-of-the-mill car has, and the straight-5 might have been the answer.
Thoughts on a postcard...
at first, id say it was because V6s make more power and are easier to package in just about anything.
nowadays its because of turbocharged 4 cylinders.
don't get me wrong though, i'd quite like an inline 5 cylinder, they sound awesome. but i'd want it longditudinally mounted driving the rear wheels, and BMW have that niche covered with a straight six.
i'd like to see someone swap a 5cyl into an MX5, or something like that.
nowadays its because of turbocharged 4 cylinders.
don't get me wrong though, i'd quite like an inline 5 cylinder, they sound awesome. but i'd want it longditudinally mounted driving the rear wheels, and BMW have that niche covered with a straight six.
i'd like to see someone swap a 5cyl into an MX5, or something like that.
Probably a case of "one more in the lineup."
The vast majority of sales are 3/4 cylinder engines, a trend which has only reinforced with time; a premium manufacturer needs a middling luxury/cooking engine (I6 has been the flavour for recent from-scratch designs) and a range topper (a V8) and doesn't want to build anything in addition to those two, considering their modest sales volumes.
There's also the packaging & noise issue. Having more than 4 cylinders is increasingly reserved for very fast or large, luxurious (or both!) cars, plebmobiles are 4-pots at most. In that market there's no place for a 5' - their "character" translates to roughness in a luxury car that would otherwise have an I6, and a V6 or V8 is a better package in a sports/super car (esp. as a stressed member.)
I'd suggest the VW I5 really only soldiers on because it's a workable way to package more poke (when your 4' is out of ideas) in modern fwd packages (hence the baby RS's)
The vast majority of sales are 3/4 cylinder engines, a trend which has only reinforced with time; a premium manufacturer needs a middling luxury/cooking engine (I6 has been the flavour for recent from-scratch designs) and a range topper (a V8) and doesn't want to build anything in addition to those two, considering their modest sales volumes.
There's also the packaging & noise issue. Having more than 4 cylinders is increasingly reserved for very fast or large, luxurious (or both!) cars, plebmobiles are 4-pots at most. In that market there's no place for a 5' - their "character" translates to roughness in a luxury car that would otherwise have an I6, and a V6 or V8 is a better package in a sports/super car (esp. as a stressed member.)
I'd suggest the VW I5 really only soldiers on because it's a workable way to package more poke (when your 4' is out of ideas) in modern fwd packages (hence the baby RS's)
From wikki
[/i]Five-cylinder engines have a crankshaft with 72 degree angles.[3] amongst four-stroke engines, an advantage of engines with five or more cylinders is that the power strokes are overlapping (if the engine has an even firing order).[1]
On the other hand, the odd number of cylinders in a straight-five engine results in imperfect primary and secondary engine balance (unlike a straight-six engine). Counterweights on the crankshaft (also used in straight-four engines) can be used to reduce the vibrations from these imbalances.[4][5][/i]
Is it just the small advantage of a smoother motor outweighed by a three, four, six or v6 having better balance inherently?
Sounds contradictory that a five can be smoother with firing overlap, but also less balanced due to primary and secondary vibrations. Big advances in modern cars is reducing VNH (vibration noise and harshness) and engine vibration a big part of it here.
[/i]Five-cylinder engines have a crankshaft with 72 degree angles.[3] amongst four-stroke engines, an advantage of engines with five or more cylinders is that the power strokes are overlapping (if the engine has an even firing order).[1]
On the other hand, the odd number of cylinders in a straight-five engine results in imperfect primary and secondary engine balance (unlike a straight-six engine). Counterweights on the crankshaft (also used in straight-four engines) can be used to reduce the vibrations from these imbalances.[4][5][/i]
Is it just the small advantage of a smoother motor outweighed by a three, four, six or v6 having better balance inherently?
Sounds contradictory that a five can be smoother with firing overlap, but also less balanced due to primary and secondary vibrations. Big advances in modern cars is reducing VNH (vibration noise and harshness) and engine vibration a big part of it here.
Edited by Tyrell Corp on Thursday 11th January 14:13
SweptVolume said:
The trend over the past 15 years has been towards modular inline engines with swept capacities of 500cc per cylinder, and this has led to the widespread standardisation of 1.5 3-cylinder, 2.0 4-cylinder and 3.0 6-cylinder units, all turbocharged. It would seem obvious to me that a gap is present that could be filled easily by a 2.5 5 cylinder in any engine family.
I'm not sure your statement here stacks up...500cc per cylinder has, for many decades, been a typical value in Euro market cars. 6s were usually about 3l, 8s about 4 and 4s about 2.
Sure, some were larger, some were smaller, it's never been a hard rule and still isn't; VAG's 3 cylinder is 1.0, and they make a lot of 1.5 4s. Hondas 3cyl is 1.0, and I bet they sell more 1.5 4s than 2.0s. Toyota make 4s with various capacities.
So the reason not to make 5s anymore is simply that they're unnecessary. White goods buyers won't care how many cylinders their car has, those who simply refuse a 3cylinder can buy a 4, and petrolheads will almost always strive for more cylinders.
5s have packaging benefits - you can usually shoehorn one into a car designed for I4 engines, where an I6 is too long and a V6 is too wide. You don't get many transverse I6s, but Volvo made them for their bigger cars. Their transverse I5 fitted into the Focus platformed Volvo and, as they were under Ford's ownership it was used in the Focus too. Note that the next Focus ST had a 4 cylinder and made more power, hence... Unnecessary.
I'm sure the majority of people who bought a car with a 5 cylinder bought it because that's simply the engine that came with the sporty model, not because they wanted to have a 5. Whereas V8, V10 and V12 engines are a thing that people want (to a lesser extent six cylinder engines too)
I've always loved the sound and smoothness of a five. Even the D5 in our XC90, once you get above the typical idle clatter, makes a decent noise, and it doesn't lose its refinement or smoothness with revs which I can't say has applied to any four pot diesel I've driven.
The petrol version in my old S60 sounded lovely and was creamy smooth under all conditions.
In Volvo's case, neither engine is particularly fuel efficient though, which I suspect played a part in their demise.
One of the things I love about 5 cylinder engines is how the sound is offbeat and a little "rough" (in a good way), but the delivery feels so smooth.
The petrol version in my old S60 sounded lovely and was creamy smooth under all conditions.
In Volvo's case, neither engine is particularly fuel efficient though, which I suspect played a part in their demise.
One of the things I love about 5 cylinder engines is how the sound is offbeat and a little "rough" (in a good way), but the delivery feels so smooth.
Reason being that by the time downsizing became a thing most OEMs didn't have heritage/know how in 5-cylinder enginees and they really aren't necessary compared to updating your 4 or 6-cylinder range or adding mildhybrid/PHEV tech for more power. Powertrain engineers tend to really only think about efficiency (both power and CO2), packaging, reliability and compliance. Anything else is only relevant if it is really going to sell your car. Niche enthusiasts are quite a small group. Also - by the time downsizing became a major pressure it was clear that the ICE was running out of road so not a good time to invest in another powertrain.
The next all-new RS3 is reportedly an EV and with the TT RS now dead, and the engine's only other use being the RSQ3 (same MQB platform) - I would suggest the 2.5 TFSI won't be around much longer.
The next all-new RS3 is reportedly an EV and with the TT RS now dead, and the engine's only other use being the RSQ3 (same MQB platform) - I would suggest the 2.5 TFSI won't be around much longer.
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