By on March 15, 2016

1991 Mazda MX-3, Image: Mazda

Reader Brian Tai writes:

I’ve been an enthusiast and part-time DIYer for years now. I love to learn about everything automotive.

My question for you: why are cars with small engines always inline-fours? Why do manufacturers not put 2.0-liter V6s into cars? I know they don’t usually use big displacement inline-fours because of NVH issues, but what about the other way around?

Thank you for your question, Brian. I’ve been wondering about this very aspect of engineering for a while and you just gave me enough push to go sniffing for answers.

The current landscape of modern, non-pushrod, direct-injection engines is one of patterns. Chances are that the four-cylinder engine humming away under the hood of your Generic Corp. Compact displaces the same volume as a large bottle of Coke and has all the aural bliss of a vuvuzela filled with stadium hot dogs. Add two cylinders and arrange them all in two rows of three, and that engine is more likely to displace 3.0 liters today than it ever has in its history. Add two more cylinders and you see the growing crop of 4.0-liter V8s. The pattern: 500 cubic centimeter cylinders.

C/D tackled this topic not too long ago. 500 ccs per cylinder provides for a nice blend between efficiency and power, especially when paired with turbocharging and a number of other whizbang technologies. Additionally, with global taxation schemes aimed at vehicles with certain displacements — such as the additional tax paid on vehicles with engines that displace over 1.5 liters in China — it makes more sense to build engines with half-liter cylinders.

However, you might remember the small K-series motors from Mazda. The K8 V6 displaced a whopping 1.8 liters in the MX-3. Even the bigger V6s from Mazda of that generation, which many tuners wedge into the MX-3 in order to boost performance, measure in at a paltry 2.5 liters.

So, we asked Mazda: Why aren’t small displacement engines still a thing? The answer was simple.

“Making a piston costs about the same amount, whether it’s a big piston or a little one,” explained Mazda engineer Dave Coleman. “Boring a cylinder costs about the same whether it’s big or small. Casting and machining two three-cylinder heads costs almost twice as much as one four-cylinder head. Making four variable cam timing actuators costs exactly twice as much as making two. Six injectors costs 50 percent more than four.”

When you’re developing a car to a price, that overall price and profit is directly related to the amount it costs to build said car. Why build a V6 if you can engineer a four-cylinder engine with the same displacement and similar output at a lesser overall cost?

And to drive the point home even further, there’s not much practical point in building a V6, as they “take up more space than four-cylinders, making a bigger, heavier car,” continued Coleman.

So, if you are one of those owners of a Mazda MX-3 with its diminutive 1.8-liter V6, you could be sitting on a historical artifact for years to come.

[Image: Mazda]

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131 Comments on “Ask The Editor: What Happened to Small-Displacement V6s?...”


  • avatar
    CoreyDL

    Interesting, something I’ve never really pondered. Though I was aware of the little tiny 6-cyl engines Mazda was doing in the early ’90s. I just figured “It’s a weird Mazda thing.” like the Millennia’s auto swivel vents, or any rotary they ever made.

    I like that you got an answer from a real person who works there, and they were speaking to you in plain conversational English. I don’t feel other manufacturers would take this approach. I’d expect more, “Please refer to press release 435A-C.9 where profit margins are explained vis a vis materials quantity.”

    • 0 avatar
      bunkie

      It helps to understand history. In the late 1950s, Moto Guzzi stunned the motorcycle racing world with V8 bikes. Honda did the same with 250CC in-line sixes in the 1960s. Why? The reason was simple: high RPM (a 16000 redline for the Honda) operation pumped a lot of air from that small displacement per piston, making for insane power-to-displacement ratios. The small piston sizes worked well with the less-advanced metallurgy of the time and the lower mass of all of the valvetrain components. The price was complexity. Complexity is expensive. An interesting holdout is Ducati’s continuing use of desmodromic valves (which forgo springs in favor of mechanical closing of valves, adopted to allow for higher RPM operation beyond the ability springs to reliably close the valves).

      These days, it’s the electronics and software that are complex, but from a manufacturing perspective, they are cheap once the development cost is amortized.

      • 0 avatar
        CoreyDL

        Thanks – bikes are something I know little of.

      • 0 avatar
        st1100boy

        I think production cost (and packaging) is one of the reasons you’ll see motorcycles with a focus on low costs typically running parallel twins rather than v-twins. One head, one set of cams, a simpler timing chain & tensioner set up, etc. With the exception of Suzuki SV650-based engines, it seems the Japanese have largely moved to parallel twins: Kawasaki, Honda and Yamaha have all introduced middleweight parallel twins in recent years, BMW too. V-twins are largely confined to cruisers and more premium and larger displacement sporting bikes. Even KTM is said to be working on an 800-class parallel twin now.

        • 0 avatar
          Lou_BC

          st1100boy – agree. Cost and packaging is a big advantage with parallel twins. It is narrower fore/aft so it could sit further back improving centre of gravity.
          Counterbalancing is much better now than in the past so a parallel twin can run as smooth as any other twin.
          The Ducati 90 degree twin has perfect primary balance. Harley’s 45 degree twin on the other hand is a “vibrator”. I read that the reason why Harley is a 45 degree twin was because their original bike was just that, a bicycle with a motor in it. The 45 degree twin fit best.
          Inline 4’s tend to have more “brutal” power delivery because there is always a cylinder firing coupled with a flat plane crank. Yamaha went to a cross plane crank with the R1 to give it more of a “V-twin” like power delivery. Most if not all modern litre class sport bikes would be next to impossible for us mere mortals if it wasn’t for traction management systems.

          • 0 avatar
            st1100boy

            I’ve had two v-twins (a 60 degree Aprilia/Rotax and a 75 degree KTM) and they both shake to a moderate degree. Someone used to solid mount Sportsters would probably think they’re glassy smooth, but most of my riding career has been on Honda V-fours, a four cylinder Gold Wing, and a pair of Yamaha FJRs. I don’t mind the vibes too much myself, certainly not enough to give up that twin sound and character.

          • 0 avatar
            rocketrodeo

            The V4s are the best solution to multicylinder power and low-vibe smoothness. Rev like fours, narrow like twins, torque like twins. I’ve had a bunch of them, including five V65s and an ST1100. Honda, Ducati, and Aprilia obviously think highly of them.

      • 0 avatar
        Sam Hall

        The desmo valvetrain was better than valve springs for high-rpm running 50 years ago. But springs (and valve seats, and valves themselves, and anything else metallic that had to live in a high-temperature world) sucked back then.

        Modern metallurgy has fixed the springs so that they work as well or better than the desmodromic setup, though it has yet to make a Honda–any Honda–sound like Duc.

        • 0 avatar
          sportyaccordy

          I think the desmo reigns supreme, even over pneumatics. Duc’s rocketship MotoGP bike demonstrates this every time it hits the track in the most entertaining way. Watching it outdrag everything on the main straight lap after lap never gets old. It’s expensive and complicated though.

          • 0 avatar
            pbr

            for the last 2-3 years Ducati ran in the “Open” MotoGP classification that gave them more fuel, more engines per season, and access to softer compound tires in exchange for using a DORNA-supplied ECU and giving up access to the hardest compound tires.

            The extra fuel permitted them to make more power for longer, thus the visible acceleration advantage. The tires were a help in qualifying usually, and an advantage for the early part of most races.

            This year (2016) the Open-class concessions are all around engine freeze and quantity of testing. Everyone uses the same DORNA-supplied ECU, tires and fuel allocation. Here’s a more complete rundown:

            http://www.asphaltandrubber.com/motogp/2016-motogp-rules-summary/

            and Kevin Cameron on Desmo & Ducati:
            http://www.cycleworld.com/2014/04/25/cw-tech-valve-control-history-and-why-ducati-is-committed-to-desmodromics/

          • 0 avatar
            sportyaccordy

            The softer tires only came into play during qualifying. Ducati has never had problems with fuel usage:

            http://www.crash.net/motogp/news/217340/1/ducati-fuel-cut-makes-no-difference.html

            I can’t find the 2016 engine allocations, but I don’t think Ducati had too many problems there.

            Long and short of it is Ducati hasn’t had a huge advantage due to the Open/Factory 2 concessions. Even back when Stoner was riding it the Desmo was an absolute rocket. It was Honda (remember Marquez’ 100M dash during qualifying?) and Yamaha (remember Lorenzo complaining about the choppier throttle when Yamaha got limited to 20L?) who are hamstrung by engine limitations.

            Part of it is differences in layout- for example I think only the Yamaha has a balance shaft, which sucks fuel and costs HP (hence Yami’s lower top speeds/acceleration), and the rest is due to choice (Honda has a 90 deg L4, but it is too aggressive, so it is prob as powerful as the Duc but doesn’t get any drive). Even if it did give them an advantage, no matter, still no post Stoner/Rossi wins.

      • 0 avatar
        USAFMech

        <– See avatar, @CoreyDL, @bunkie That there is a 500cc V8 Moto Guzzi.

  • avatar
    PRNDLOL

    MX-3 Precidia with its 1.8 V6, I remember it was the spunky ‘it’ car in 93.

  • avatar
    bball40dtw

    Answer: The four cylinder, 2.0L, turbocharged, direct injection engine.

    • 0 avatar
      MattPete

      I always thought BMW lost their soul when they went with that configuration.

      I can possibly understand going with a turbocharged smaller displacement engine, but they should have stuck with an inline-6 as a way to distinguish themselves from other manufacturers.

  • avatar
    gtemnykh

    Mark I think the magic number for naturally aspirated engines is closer to 600-650cc as of late: Midsize 4 cylinders are all either 2.4 or 2.5L, V6s are almost exclusively 3.5-3.7L, with a few deviations (Hyundai 3.3, Chryco 3.2).

    Fewer cylinder engines are cheaper to make and have less friction (ie better mpg), it is as simple as that IMO.

    I rather like the idea of a big torque 4 in truck applications, like Toyota’s 2.7L in the Tacoma, although with the latest generation’s weight gain that sounds like a losing combination.

    • 0 avatar
      Scoutdude

      The lower frictional losses of fewer cylinders are the main reason you don’t see small displacement V6 or smaller V8 engines. It is also why the Geo Metro had a 3cyl and why Ford is making 3cyl engines.

    • 0 avatar
      3XC

      I can attest to the Toyota 2.7 I-4 being a gutsy little engine.

      My dad and I towed back a VW Thing from Massachusetts to Maryland with his crew cab 2WD 2013 Tacoma. No issues at all, you could barely tell you were towing anything at highway speeds.

    • 0 avatar
      Sigivald

      Depends on where you look.

      BMW, Mercedes, Audi, and Volvo all have a 3.0L turbo 6; I think that’s what Mark was talking about – the “performance” end of the market, not the “we need some form of 6 in this thing” market.

      (And of course the 2.0L turbo 4 is the default “hot” four and really does replace the “smaller than 3L 6” very well.)

      • 0 avatar
        John Horner

        Volvo is rapidly phasing out everything except 4 cylinder engines. Check out the new V90, XC90 and S90 flagships. Volvo is obscuring the matter by using designation like “T5” and “T6” which used to mean turbo 5 cylinder and turbo 6 cylinder for engines that in fact are all 4 cylinders.

        See for yourself:
        http://www.volvocars.com/us/cars/new-models/all-new-xc90/specifications

  • avatar

    I always thought that the original Lincoln Continental would be a cool vintage car to own but the idea of maintaining a 292 cubic inch/4.8 litre engine with 12 cylinders just seems like a bad idea. Apparently the 1948 Continental was the last time a major US automaker sold a V12 so that must indicate something. The DB9 I rented had 5.9 litres of displacement but also produced 503 hp compared to the Continental’s 110.

    • 0 avatar
      bball40dtw

      Old Contis, provided that they need to restored anyway, are begging for a 6.2L Boss V8 Swap.

      • 0 avatar
        ajla

        Why won’t Ford put the 6.2L into a large car?

        • 0 avatar
          Sigivald

          Because who’d buy it?

          They can’t sell a Taurus as it is, with the 3.5 EB – the 6.2 has to be heavier and larger, and I don’t know what the point of the 6.2 would be except even worse fuel economy.

          (The 3.5 EB in Navigator trim has more torque than the 6.2 and I believe slightly more horsepower – and the torque is almost certainly available faster.

          Hell, I wouldn’t mind a 3.5 EB swap for the 5.4 in my old SuperDuty – it’d be a step *up* in every regard.)

          • 0 avatar
            ajla

            Well I’d buy one…

            Judging from this post the 6.2L would be much cheaper to build than the 3.5EB so that’s something. The 6.2 also sounds like a war machine while the Duratec35 family sounds like a Dyson.

            The 6.2L in the Raptor was rated [email protected] and [email protected] So better peaks, but higher RPM than on the present EBs. That said, I dont think Ford has maxed out the potential of either engine yet.

          • 0 avatar
            bball40dtw

            I’d buy a 6.2L Ford sedan/coupe. I’d also buy a Navi/Expedition with a 6.2L. The 3.5TT is a great engine, but the 6.2L makes glorious noises. It may be beat in torque by the Ecoboost V6, but part of the problem is that Ford hasn’t spent money on their biggest V8. Upgrade it like they have the Coyote, and I’m sure you’d see some gains in power.

        • 0 avatar
          bumpy ii

          Because it’s an old-school truck engine designed to run at modest outputs for a bazillion hours.

          • 0 avatar
            ajla

            Well, Ford failed at that because when you put your foot down it biltzes harder than what is offered by FCA or GM. The 6.2’s family is a big-displacement LS killer stuck in a fleet truck.

            Ford should go back to putting boring engines in trucks like they did from ’97-’10.

  • avatar
    Kyree S. Williams

    It’s true. Most V6 engines don’t tend to be smaller than 3.0-liters these days, while most V8s stay above 4.0-liters. Then again, Maserati sells a 3.8-liter V8 in the Quattrporte. And Aston Martin’s 5.9-liter N/A/ V12 has been replaced in the upcoming DB11 with a comparatively-tiny 5.2-liter twin-turbo V12 (which may or may not have been partially-designed by Mercedes-AMG).

    • 0 avatar

      I think when you start getting into the upper echelons of cost, efficiency kind of goes out the window.

    • 0 avatar
      Xeranar

      Those engines are designed to use smaller pistons with less displacement in favor of forced induction for the most part. Less stress because you’re moving less up and down but on the same token all of those vehicles have huge profit margins and those engines are almost guaranteed to be hand-assembled or partially so. There is no need to worry about shaving $50-100 per unit in parts because they aren’t selling enough units to really save any profit nor is their profit so slim that those numbers matter.

      V6s are also terrible things, inherently unbalanced and a mess. In the modern era they serve as a marketing gimmick rather than an actual difference maker. They offer a step up but separate the V6/V8 step up deals with Luxury brands.

      • 0 avatar
        wmba

        Gosh, I thought I was the only one who knew or cared about the 60 degree V6 unbalances. They really need a balance shaft. Still, with complicated motor mounts, and good detail design, the Honda and Toyota 3.5 V6s are pretty good. The Audi 3.0 liter 90 degree V6 with offset crank throws is better. Then you start up a straight six BMW and blip it. Oh.

        Yes, there’s a difference.

        • 0 avatar
          Sketch

          I think you’re confusing 60-degree with 90-degreee. 60-degree V6’s are inherently balanced. True, they’re not as smooth as a straight 6, but they don’t need a balanace shaft and are typically much smoother than 90 degree V6’s. For omre info:

          https://en.wikipedia.org/wiki/V6_engine#Balance_and_smoothness

          • 0 avatar
            Xeranar

            Anything that throws odd numbers of pistons needs correction. They use a complex set of internal crankshafts to off-set the off-balance, but it’s still inherently unbalanced. They resolved most of the core issues 40 years ago but it’s a technically complex engine when an I6 or V8 will do the exact same job with slightly different parameters. If anything, this goes back to why we don’t see tiny V8s (cost per cylinder) or I6s (length). It’s not necessarily a good decision but it is practical.

          • 0 avatar
            bikegoesbaa

            Don’t inline 3-cylinders throw an odd number of pistons smoothly without additional correction?

  • avatar
    92golf

    The first Ferrari V12 was 1497cc.

    It geeks me out to imagine the 12 tiny pistons (according to the almighty Wikipedia bore and stroke were 55mm X 52.5mm) and the engine spinning away at 6,800 rpm.

    I remember those little Precidias’ too. Though there were never very many of them around.

  • avatar
    bumpy ii

    The small-displacement V6 (and I6 and V8) was a meeting point between displacement taxes and the perceived prestige and smoothness of higher cylinder counts. Hence, you ended up with Japanese I6s and V6s at 2 liters or less, and a 3-liter BMW V8.

    • 0 avatar
      Featherston

      If I recall correctly, British taxes once were based on bore but not stroke, hence undersquare engines like the XK6.

      The Mazda engineer is absolutely right regarding costs. Something like Toyota/Lexus’ 8AR-FTS must entail a lot of cost per cylinder, and upping those expenses by 50% matters, regardless of displacement.

      • 0 avatar
        Kyree S. Williams

        I’m glad the 2.0T (which isn’t *quite* as good as what the Germans or Americans offer) replaced that 2.5-liter V6 in the IS, which—in addition to costing more money to build—was anemic.

        • 0 avatar
          Featherston

          It’s a little unfair to call the 2.5 “anemic.” For its price point and era, the IS 250 is down on power. But it isn’t a slow car in a real world sense. I do agree that the 2.0T’s output is more class appropriate.

          The real sin of the 4GR-FSE is carbon build-up, as a result of having only direct injection. It seems to be the only engine in Lexus’ (admittedly brief) history that’s been genuinely problematic.

          There doesn’t seem to be much internet chatter about carbon problems in the dual-injected 3.5 V6. We’ll see if the 2.0T follows suit. My guess is that 10 years from now, we’ll look on it as a better engine than its DI-only German and US competitors, if only for reasons of reliability and longevity. But that jury will be out for quite some time yet.

          • 0 avatar
            wmba

            Yes sir. That 2.5 V6 DI only Toyota is as good a carbon sludge generator as any pre ’08 VW/Audi 2.0t. Little known fact until you visit the forums as I did years ago.

            Great comment.

          • 0 avatar
            30-mile fetch

            The Lexus 2.5 isn’t anemic, it generates plenty of power for 2.5 liters and sounds and feels refined while doing it. I thought the problem was the 3600lbs of IS it had to haul around.

  • avatar
    Lampredotto

    The designer in me understands the efficiency/power and cost/benefit considerations.

    But the gearhead in me casts a wary eye to the new world order.

    Sure, a 2.0T inline four is more efficient and economical to build than a 2.5L N/A V6. But it will never sound better than a Mazda KL-DE.

    At least in terms of Japanese automotive design, it really feels like we’ve emerged from an engineer- and enthusiast-driven golden age (1995-2005-ish) and have entered into one that’s far more compromised.

    • 0 avatar
      a5ehren

      That may be true for Subaru/Honda/etc, but the current Mazda lineup is pretty dang good.

      • 0 avatar
        sportyaccordy

        Bleh, the 3 rental I have now begs to differ. Don’t believe the hype. The Golf TSI is more fun to drive, and is still nowhere near something like an old Civic. I don’t believe anything the media says anymore since I have driven this car. It drives like any old economy car.

      • 0 avatar
        Lampredotto

        No question that of the Japanese manufacturers Mazda is the most engineer- and enthusiast- driven, and we should take some comfort in that fact.

        But compare the current Mazda engine lineup to that of twenty years ago and it looks dispiritingly homogenous.

        2016:
        -2.0L four
        -2.5L inline four
        -3.7L V6 (CX-9 crossover only)

        1996:
        -1.8L four (Miata)
        -1.8L V6 (MX-3)
        -2.5L V6 (MX-6)
        -2.3L Miller-cycle V6 (Millenia)
        -1.3L twin turbo rotary (RX-7)

        etc.

        • 0 avatar
          Uncle Wainey

          1996 is also the year that Ford bought a controlling stake in Mazda to keep them from going bankrupt.

          Those old engines were fun, but I’ll take homogeneity if it keeps them in business.

          • 0 avatar
            mazdaman007

            ^^ This. The engineers in Hiroshima were running amok in the mid 90’s with nary a bean counter to be seen. (Insert some lame sake joke here).

            I am very glad they are still around today to give us the Miata and other products, I don’t see any other company around that could produce it with the fun to drive factor, reliability and cost.

            And yes, I am biased :)

            PS: Even the new CX-9 is now a 2.5L turbo.

    • 0 avatar
      sportyaccordy

      This are definitely more regulation driven these days, to the detriment of anything related to design and character. If Mazda’s offerings are indicative of the “enthusiast’s choice”, working class enthusiasts are in serious trouble.

      I realized things were in really bad shape when it dawned on me that the only new 6+ cylinder sedans with stickshift are the 340i, the M3, the M5, the SS and the ATS-V. I’m almost certain that is IT. It will make more sense for them to better develop those “sound symposers” as that will be our only possibility for “good sounding” engines. What a bummer. Buy up all the 6 banger sedans you can now

      • 0 avatar
        CoreyDL

        I’ve always liked the low stress sounds of V8 engines. Low revs and a build of speed with little noise. I don’t want the engine to sound like it’s straining to do something. Sort of like the “power reserve” gauge in a Phantom, always plenty left.

    • 0 avatar
      Sigivald

      “Good sounding” is more a matter, I think, of what people are *trained to expect or think is good* than some inherent thing.

      (People try to tell me an old-school V8 burble is great; I don’t see the appeal.

      Those people with fart-can mufflers on Civics are *sure* they sound awesome, too.

      People who grow up with the sound of a turbo-4 as “fast” will think that “sounds good”.)

      • 0 avatar
        CoreyDL

        *Taps chin*

        Then what sir, sounds “good” to you with regard to car engines?

        • 0 avatar
          krhodes1

          I find there is no correlation between cylinder count and how good an engine sounds. There are great sounding 3s (new BMW 1.5T), 4s, 5s, 6s, and 8s, and those that sound like poo. The Viper V10 sounds like crap, but I have never heard a V12 that didn’t sound nice, though most don’t make much noise at all.

          My strong preference is for inline 6s, and I seldom like the sound of American V8s. I generally hate the sound of V6s other than Italian ones. I’m not sure the Italians are capable of making a bad sounding engine no matter what the configuration, even a single-cylinder Piaggio sounds pretty good!

          • 0 avatar
            bunkie

            The F-Type has a lovely V6 snarl that is befitting a car named after an athletic cat.

          • 0 avatar
            wmba

            But the Jag V6 is a 90 degree bank angle with offset crank throws like the VW/Audi 3.0 V6. I believe krhodes refers to regular cooking 60 degree V6s.

    • 0 avatar
      pbr

      [retracted]I don’t think I’ve ever heard a V-6 that really sounded good. MAYbe the KL-DE, but that’s been out of production since … 2002? Don’t see Probes every week anymore.[/retracted] I’ve only ever owned one V-6, a Cologne 4.0L in a Ranger. OK for what it is, I guess, but the sound of it reminds me of the V-6 NASCAR Busch Grand Na

      Update: busted by “heavy handle.” The Alfa V-6 in GTV-6/Milano/164 does sound very good indeed.

      • 0 avatar
        heavy handle

        The classic Alfa V6 of the 70s, 80s and early 90s was awesome (especially through straight pipes).

        • 0 avatar
          heavy handle

          PBR: thanks for your update. That engine is still one of the finest things I’ve ever heard.

          True story: a friend calls me up one day in the 90s, “get over to my shop now!”

          He had a 164 in for an exhaust job and was driving around the lot with no muffler. Mamma Mia! Que macchina!

          • 0 avatar
            vrtowc

            Must fully agree about Busso V6. The turbo in my Alfa Romeo 166 V6 2.0TB takes some of the sound away but its hum and roar are still a much enjoyable sound stage for a daily commute. On top of that it is one of the prettiest engines as well. No plastic covers in engine bay, just raw aluminium head covers and six chromed&polished intakes.

      • 0 avatar
        Lampredotto

        The old Acura NSX’s engine also sounds quite lovely, especially when the VTEC kicks in, yo.

      • 0 avatar
        derekson

        The V6 in the 2016 Camaro sounds pretty damned good, especially considering it’s the same V6 as in whatever Cadillac model and probably will end up in Impalas and Traverses in a few years.

  • avatar
    carguy

    Packaging and weight also have a lot to do with it. 4 cylinder engines are more compact and weigh less than than V6 of similar displacement. That makes an inline 4 a much better choice – particularly for FWD cars.

    You can also turbocharge Inline 4s with a single turbocharger while V6 engines usually require two.

  • avatar
    Zackman

    Simple answer: Cost. No sense making a small V6 if the same displacement 4 cyl. will do.

  • avatar
    05lgt

    Can’t remember where, (maybe the old SCC mag’s?) I read that 500cc cylinders provided some advantage to clean burn over smaller, usually less square cylinders. I think it involved both the chamber shape for flame propagation and surface to volume for quench. Could have been pure BS, I have nothing to check it with.

    • 0 avatar
      Sketch

      The overall size of a cylinder doesn’t affect how square it is. You can have a square 500cc cylindder and a square 250cc cylinder, the 250cc will just have half of the 500cc’s bore X stroke. That’s probably not practical, as it’s not going to have much room for valves, I’m just trying to illustrate a point. There’s no reason a 1.8L and a 2.0L can’t both be square.

      My guess on the real reason: parts sharing. If your various-number-of-cylinder engines are all the same bore and stroke, you can use the same pistons and connecting rods everywhere.

  • avatar
    John Horner

    Cost is the #1 issue, fuel economy #2. The smaller the bore, the greater the thermal losses and friction losses. A few companies have made families of inline engines of 4, 5 and 6 cylinder configurations. Volvo probably did this in greater volume than anyone else with the “white block” family of 4, 5 and 6 cylinder inline engines. They were generally about 2, 2.5 and 3 liters capacity. It was a cool idea because many components were the same from one to the next (pistons, rods, valve train, water pump, starter, etc.). Now Volvo is moving to an all 4 cylinder lineup for fuel economy reasons.

    Today a base design goes up and down the power curve depending on how much (if any) turbocharging, electric hybrid and/or fancy engine management is used.

    Today 4 is the new 6, 6 is the new eight, and sometimes 3 is the new 4 (i.e. Ford 1 liter straight 3). Fuel economy is the big driver of this trend, not cost. The technologies being used to get more power out of smaller engines are often costly.

    If you want a silky smooth 3 liter V-6 in a new modest sized sedan or coupe, buy one now because they are fading fast.

    • 0 avatar
      turf3

      If you want a silky smooth 6 cylinder engine you need to get an inline 6 (still the best layout – designed along with the Jaguar E-type 1st series by God Himself on His own drafting board). Good luck with that, though.

      • 0 avatar
        Sigivald

        You can still get an S60 T6.

        And BMW and Lexus will still sell you a straight 6, I believe.

        In the non-luxury market, the straight-6 is dead, yes.

        • 0 avatar
          CoreyDL

          The 3.5 in Lexus is a V6. ***REDACTED***. Not sure if it’s what you meant, but the S60 T6 is a 4-cylinder.

          • 0 avatar
            gtemnykh

            “Don’t believe Lexus ever had an I6”

            You owned an older GS series for Chrissakes!! You’re killin me Corey. Lexus used the 2JZ in a number of 90s-2000s applications, the non-turbo variant of the Supra I6. Specifically in the GS300 and IS300. Smooth, overbuilt and reliable motors, but not particularly efficient and not super powerful either.

          • 0 avatar
            CoreyDL

            Suckah mine was a V8! I wasn’t shopping the 6-cylinder ones!

          • 0 avatar
            tjh8402

            Lexus used the sainted 2JZ on the IS300, the SC300, and the first two generations of GS300.

          • 0 avatar
            gtemnykh

            Oh I know yours was a V8, but having owned a particular model, I simply assumed you would know more about that generation of GS in general. Toyota is absolutely famous for their JZ series of I6s, the 2JZ is particularly well regarded for how much boost it can take on stock internals.

            The 7M family is well known as well, it’s the precursor to the JZ family. Some headbolt/headgasket issues but once that is sorted once they too are solid motors.

          • 0 avatar
            CoreyDL

            I probably knew at one point, I always research extensively before buying. But once I realized I wanted a 01+ 430 model, all the prior 300 knowledge fell out.

          • 0 avatar
            derekson

            The AWD S60 T6 is still a 6 cylinder for one more MY, IIRC.

          • 0 avatar
            CoreyDL

            Good grief, turns out we’re both right. Depends -which- S60 T6 trim you meant, I think. Some are 4, others still have the 6. I’m not clicking through all these to figure it out.

            This lineup…
            T5 Drive-E
            $34,150
            T5
            $35,650
            T5 Drive-E Premier
            $36,800
            T5 Premier
            $38,300
            T6 Drive-E
            $39,450
            T5 R-Design Special Edition
            $39,900
            T6 Drive-E Platinum
            $43,300
            T6 R-Design
            $44,200
            T6 Drive-E R-Design
            $44,400
            T6 R-Design Platinum
            $47,700
            T6 Drive-E R-Design Platinum
            $47,900
            T6 Polestar
            $59,300

    • 0 avatar
      Scoutdude

      You are contradicting yourself. In one sentence you say that cost is the main driver and in another you say it is fuel efficiency. Fuel efficiency is the #1 reason for mainstream automobiles.

  • avatar
    dwford

    Also, remember that back in the day the Mazda 1.8 V6 only put out 130hp and the 2.5 about 170, easily beat by today’s 4 cylinders. Even back then those outputs weren’t that exciting when the integra gs-r 1.8 4 cylinder had 170hp and many regular 1.8s had around 130

  • avatar
    Fred

    Daimler had a small V8 (2.5l) it was a pretty sweet little engine. When Jaquar took them over they got rid of it in favor of their huge 3.4l I6 mostly for political reasons.

  • avatar
    eggsalad

    500cc per cylinder? Bah!

    Let’s go back to 1970, when the Cadillac V-8 came with 1025cc per cylinder!

    • 0 avatar
      Featherston

      There’s a great line in GO LIKE HELL where Enzo Ferrari likens the GT40’s cylinders to wine bottles. To which America might have shrugged its shoulders and said, “So?”

  • avatar
    George B

    What happened to small displacement V6s? Four cylinder engines improved. A well designed I-4 with balance shafts is smooth enough so that the marginal improvement in NVH isn’t worth the cost. My current daily driver has a Honda K-24 2.4L I-4 with power output very close to that of the Honda J30 3L V6 in the previous car. The V6 has much less vibration at idle. The lighter weight of the I-4 improves handling. The I-4 easily wins on fuel economy.

    • 0 avatar
      Russycle

      Odd. My 07 Honda 2.4L is so smooth at idle you can’t even tell it’s running with the radio on.

      • 0 avatar
        CoreyDL

        Lol! Is that meant to be funny?

        • 0 avatar
          gtemnykh

          It’s all relative. When we sold our ’90 Civic Wagon and first bought our Fit, the only way I could tell it was running at idle was by the tachometer. Fresh engine mounts and 10+ years of NVH engineering make a big difference.

          • 0 avatar
            CoreyDL

            I just meant that having the radio on as a requirement to cover up engine noise is no great thing!

      • 0 avatar
        zososoto

        Surprisingly, my 2.0L 88 Prelude is just as quiet as well. I’ve “good morning vietnam!”-ed that car a few times.

        The 82 RX7 was very smooth after I fixed the exhaust leak. Mazda used to demonstrate the smoothness of the rotary by putting a glass of wine on top of the air cleaner at 5000RPM+

  • avatar
    tjh8402

    Where does Ford’s 2.7 EB V-6 fit in this? I love small six cylinders and would always prefer one over a 4, which is why I’m (pleasantly) surprised and confused by Ford’s introduction of that engine. Is it only because fullsize pickup buyers won’t accept an I-4? It’s power numbers are awfully close to the 2.3 EB I-4.

    • 0 avatar
      dal20402

      “Is it only because fullsize pickup buyers won’t accept an I-4?”

      That and high-end CUV/SUV buyers.

      I’m also glad it’s there. I’m buying in a different direction now but would still have a long and serious look at a 2017 Fusion Sport.

      • 0 avatar
        tjh8402

        The Fusion sport is seriously appealing. Brilliant Chassis, fantastic engine. Should be a 335i on a budget. the only disappointing feature is the lack of a manual transmission.

  • avatar
    cgjeep

    All things being equal would a 2.5 4cly have more torque than a 2.5 6cly due to the larger displacement of the individual cylinders? Somethng I have always wondered.

    • 0 avatar
      bumpy ii

      The six usually has a better torque curve, due to the extra throw and additional power cycles. Depends a lot on the details, though.

      • 0 avatar
        tjh8402

        I think a lot of these bigger I-4s (the 2.4s and 2.5s) are long stroke giving them a low to midrange advantage over a similar displacement six. engines with fewer cylinders seem to rev lower and have more torque than engines of the same displacement with more cylinders, which are less torquey more rev happy.

  • avatar
    Chan

    Materials engineering has made significant advances, and a V6 is inherently more complex than a straight-four.

    Consider that in the early 90s, V6-equipped cars were barely pushing 180 hp.

    Today, a blown four can provide 300+ hp with the OEM’s most aggressive tune, and 240+ hp in typical tune. On top of that, low-RPM peak torque is a staggering advantage for turbocharged engines. I would believe that turbocharging an I-4 is cheaper than designing and manufacturing a V6.

    • 0 avatar
      sportyaccordy

      Yea, a tiny snail on a 4 makes for real world oomph. Golf TSI had way more low end urge than my old 3.0L Maxima, which weighed the same and had a stickshift rather than an AT like the Golf. Doesn’t prompt you to wring it out but it does make highway driving a lot more fun.

  • avatar
    FreedMike

    All I remember about the MX-3 is that I once got a letter to C/D about it published. As I recall, they claimed something to the effect of “the car begs you to dance with it and take it home.”

    Approximately reply: “So does that really ugly girl with the hairy legs at the corner bar…I’ll pass on both.” Even got a reply from the fabled “Ed.” for that one.

    Japan made some seriously ugly cars in the early ’90s, between that and the Del Sol.

  • avatar
    gasser

    The I-4 may be cheaper to make, but is it cheaper to maintain? How will these stressed engines do at 100K and 150K miles? The V6 and V8 engines seem to loaf themselves along for years. Will this be the case for the newer I-4s?

  • avatar
    dal20402

    This topic makes me feel like an old man.

    The newer turbo fours are objectively better engines in every respect than the previous generation of naturally aspirated V6s. There’s a reason the only NA sixes left are the 3.5+ versions where a replacement four would be big and unrefined.

    But I still prefer the six-cylinder sound even though it doesn’t actually bring any concrete benefits. My preference is purely an aesthetic thing, but it’s enough of an aesthetic thing that I look hard for six-cylinder options. It will be a major reason for the purchase if I buy an Infiniti QX50 as planned, even though the VQ is one of the ugliest-sounding sixes in existence. It’s why my toy car has the growly, pleasingly rough, rev-loving Honda C32A.

    The difference between six and eight is far less important. I’d be perfectly happy if someone swapped the V8 in my Lexus for an equally powerful turbo six with more low-end torque.

    • 0 avatar
      tjh8402

      Haha I feel the same way and I’m only 32. I remember all the lovely smooth snarly rev happy sub 3 liter normally aspirated sixes on the market (especially from the germans), forget the old 60s sports cars with 3.0 V12s and the like.

    • 0 avatar
      derekson

      At least you admit that your preference for larger, NA engines with a higher cylinder count is just an aesthetic preference. Most of the posters around here like to claim that their luddite tendencies are actually grounded in rational thought processes.

      Self awareness is depressingly rare these days.

      • 0 avatar
        Chan

        Before you make broad generalisations that a turbo-four is better in every way than a NA-six, remember that it’s easier to control your actual fuel consumption with an NA engine.

        With the turbo, you’re forced to tread the fine line and stay off-boost, otherwise you gain no real-world MPG compared to the bigger engine.

        Yes, with cruise control on, that 2.0T will return better highway numbers.

        I have a car with a 1.4T in a car that is an aerodynamic brick. My wife averages 31-32 MPG on it. I average 28, and I can probably do the same with a modern V6, while having a more responsive powertrain.

        • 0 avatar
          dal20402

          I find it comes pretty naturally to stay out of the boost except when I really need it. My wife has a far more binary approach with the throttle. In our Jurassic-tech 4-speed turbo Forester I get 19-20 mpg and she gets closer to 17.

  • avatar
    dividebytube

    Loved the straight six 2.5L in my departed MY04 325i – so smooth and such a quick revver. Sure it has as much hp as a Dodge 2.5L, but the BMW wins for smoothness and broader torque. And when you hit the top of the RPMs, it never got thrashy.

  • avatar

    Cost of production-I’ve always thought it interesting that the last option they give you is power…yet most of the time, the faster engine isn’t necessarily more expensive. Displacement is free, at least in the USA…it costs more money to turbo, etc…

    Taxes-displacement isn’t free elsewhere, so that is why we are seeing more and more big cars with small fours, usually turboed to make the power. Now that you can make the same power with less pistons….and lastly

    NVH/marketing. Just so it does not vibrate, no one (except us) really cares how many squirrels are under the hood.

    If I want to see great engineering, a classic bike mag is way more interesting.

  • avatar
    stuntmonkey

    I’m surprised combustion efficiency wasn’t mentioned. Today’s engines are so much more efficient that before. A modern 2.4l K-series Honda puts out 185-ish bhp, about the same territory as what a V-6 did 20 years ago.

    The other extreme is the Porsche 944 S2, 3-litres 208bhp, bigger than some V-6’s at the time. Pretty sure a modern Di engine would produce the same but with better torque and with a smaller displacement.

    • 0 avatar
      wmba

      The factory claims 207 lb-ft torque or 69 lb-ft/litre. What you see nowadays for NA DI engines is about 72 to 75 lb-ft per litre. That old Porsche engine was right up there for port injection, comparable to all the mass production engines of three years ago. And it was over 25 years ago.

    • 0 avatar
      dal20402

      I think the comparison that may illustrate the relative merits of old sixes and new fours best, turbos notwithstanding, is the current DI K24 (in fully realized 206-hp Acura TLX form) versus the 200-hp J30 of 18 years ago.

      K24: 206 hp @ 6800, 182 lb-ft @ 4500, 24/35
      J30: 200 hp @ 5700, 195 lb-ft @ 4700, 18/26

      That’s almost indistinguishable output numbers and an absolutely monster (~40%) fuel economy advantage for the four. On top of that, it’s cheaper to maintain.

      Subjectively, the K24 is quieter, smoother, has a broader and flatter powerband, and vibrates less.

      The *only* thing the J30 has going for it is that it doesn’t sound like a four. But that’s a surprisingly big deal.

  • avatar
    quasimondo

    What happened to small displacement V6’s?

    The same thing that happened to high-revving 4-bangers, and turbocharged engines that were tuned for power instead of fuel economy. Buyers were convinced by autojournos that these are “bad” characteristics to have in an engine. Perhaps they were too impatient to let an engine rev to the upper end of its power band or wait through the lag, but either way, they were described as peaky, laggy, and requiring too many gear changes to get the power you want. You dn’t want that man! You want, lazy torque (never mind that all of these engines are wheezing at 6K now) disguised as a “fat” powerband.

    Imagine that, a lazy fat engine. Makes me regret selling every sport compact and hot hatch I ever owned.

  • avatar
    tjh8402

    quick update on cost being a main motivator here:

    Toyota recently released details on their 2016 WEC LMP1 car and it features a small (2.4L) V6 twin turbo. Noteworthy because LMP1 has pretty liberal engine regulations as far as cylinders, displacement, and configuration (Porsche won last year with 2.0 V-4, yes a V not inline 4). Audi is sticking by their 3.7 V-6 TDI. Point is, racing doesn’t award points for which engine sounds the best or runs smoothest (otherwise Toyota’s glorious howling normally aspirated V8 would’ve kept going); it rewards the engine that offers the most performance with the best efficiency, and Toyota clearly believes the small displacement V-6 offers that. If a 4 cylinder of similar displacement would’ve been the better powertrain, they would’ve gone for it. The one that top level works LMP1 projects don’t really care about? Cost.

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