Hooniverse Asks- What's the Most Under-Appreciated Straight Six Engine?

The straight six engine, despite its inherent balance, simple single head design, and economy of construction, has been mostly supplanted by the V6 in the automotive world. The V6, owing to its odd cylinder count per bank is not naturally balanced, but at 60° it’s typically narrower than a V8, and frequently shorter than an inline four. That’s a benefit in FWD cars, and those which need to meet pedestrian safety standards as the more compact designs allow for more hood crush-ability.
But the V6 lacks the above noted benefits of their straight six brethren, as well as the romance of a sleek inline. There have been a number of venerated straight sixes over the decades – the Jag XK, BMW’s glorious M-series, and Ford’s never-say-die Falcon six springing immediately to mind. And of course the Corvette was originally available exclusively with a straight six, the 235-cid Blue Flame Special.
Those are all well known and generally publicly acknowledged straight six engines, but what about the unsung heroes of the straight six club? Which engines do you think are deserving of veneration, but haven’t yet had their time in the spotlight? What in your mind is the most under-appreciated straight six engine?
Image: Hemmings

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  1. Maymar Avatar

    <img src="http://www.blogcdn.com/www.autoblog.com/media/2012/08/lead6-2012-volvo-xc60-r-design-review.jpg&quot; width=500 /img>
    If just because it's one of the few inline sixes left, and offered in every Volvo currently available (along with the Land Rover LR2), and it does seem to be a rather pleasant engine.

    1. Sjalabais Avatar

      I once overheard a discussion between a Volvo and a Lexus fanboy* on who had the calmest engine in their stable. Both threw technical terms and personal experiences around them. It ended when the Lexus fanboy said that you can balance a coin on its rim on a LS400 V8 while it's running…
      *Please don't ask.

      1. Maymar Avatar

        I'm not about to fault Lexus fanboys, as long as there's a bit of perspective. If it's RWD-based, it's moderately interesting. It's just the FWD-biased Lexii that, although sensible choices and all, haven't earned fanboys.
        I would muchly love one of those early LS400s, if I had the opportunity.

        1. Sjalabais Avatar

          Agreed. For all the Volvo love in my heart, I'd drive a LS400 V8 with the greatest implicitness. Unattainable vehicles in Norway though: A '91 model with 400000km for 10000$ is the only car currently for sale. Others I have seen are offered at similar levels of crazy.

  2. Dirty Dingus McGee Avatar
    Dirty Dingus McGee

    Pontiac OHC 6 from the mid/late 60's.
    Honorable mention; Mopar Hyperpack slant 6 from 1960

    1. Kris_01 Avatar

      Thank God someone mentioned the Hyper-Pak. I'll take one in 170 cid thank you very much… The thought of 6000 rpm in a /6 is music to my ears.
      Ever hear about the 225 with the 6-71 blower? Over 300 HP and smoooth.

  3. OA5599 Avatar

    "The V6, owing to its odd cylinder count per bank is not naturally balanced, but at 60° it’s typically narrower than a V8, and frequently shorter than an inline four."
    Clean sheet design V6 engines are typically 60 degree engines, but there are also numerous 90 degree V6's that follow the recipe of "take this already-tooled V8 and lose two cylinders".

  4. smalleyxb122 Avatar

    Atlas six, late of the Trailblazer.
    <img src="http://image.hotrod.com/f/31285295+cr1/ccrp-1108-hp%2Bturbocharged-vortec-inline-six.jpg&quot; width="500/">
    note: image not a Trailblazer.

    1. CABEZAGRANDE Avatar

      This. I have never understood why this engine didn't get more love. It really is just as good as the 2JZ, maybe better (yeah, I said it). Aluminum block and head keep it relatively light. The head is spectacular, it flows a ton. Large displacement for a DOHC I6. Several guys have turbo'd them and made 400 whp+ on very light boost. A few madmen had pistons and rods made for them to crank the boost and made more like 700-800 whp. It's a wonderful engine, and it got ZERO aftermarket love. A real shame.

      1. Devin Avatar

        I'd probably blame GM for that one, they didn't put it in anything outside of the Trailblazer and variants and nobody really liked those.

        1. CABEZAGRANDE Avatar

          They put a TON of effort into the Atlas family, and then only used it in the Trailblahzers and Canyon/Colorados. I have no idea why this didn't make it into the Silverado. I mean, I understand why it didn't make it into cars, it is about 3 miles tall, but it's a PERFECT base truck engine. I always thought the Colorado would get the same amount of love that the S10 got, and that parts for the Atlas engines would come as a byproduct of that. But it just never materialized, and the Colorado twins never got any love.

  5. geistkoenig Avatar

    The Pontiac OHC6 was a smart, sophisticated powerplant that was basically ignored in the age of thundering V8s. It deserved better.
    <img src="http://assets.hemmings.com/story_image/67418-500-0.jpg?rev=1"&gt;

    1. 7FIAT's Later Avatar
      7FIAT's Later

      Yes it did.

    2. Peter Tanshanomi Avatar
      Peter Tanshanomi

      True, but nowadays I wouldn't call it "under-appreciated." The ones that are left are quite sought after, and starting to significantly appreciate in value (no pun intended).

      1. geistkoenig Avatar

        Still kind of a cult motor. Collectors and the more astute speculators probably love the rarity and the story (Johnny Z!) that goes with it.

  6. JayP2112 Avatar

    Is it a straight 6 when it shares a common OHC?
    <img src="http://www.eurospecsport.com/products/engines/images/021-100-033-T.jpg&quot; width="600">

    1. Colonel Panik Avatar
      Colonel Panik

      Very nice looking engine, what is it and where can I order a dozen?

      1. Eric Rood Avatar
        Eric Rood

        Volkswagen VR6, I reckon. It's one louder than a VR5.
        <img src="http://data.motor-talk.de/data/galleries/700917/143137/bild-32444.JPG&quot; width="600">

  7. smalleyxb122 Avatar

    A shorter list would be straight sixes that are not under-appreciated. Topping the list would be the 2JZ, followed perhaps by the Cummins 6BT. BMW’s M50 and Jeep’s 4.0 probably would make the list, too. Not that they aren’t all excellent engines, and deserving of praise, but they can in no way be considered under-appreciated.

    1. sc296 Avatar

      Fords 300ci seems very appreciated.

      1. Wyowanderer Avatar

        I certainly appreciate the one that came in my 1984 Ford F-150. Best engine I've ever owned: powerful, reliable, if ubiquitous…

  8. Carter Avatar

    Inline sixes are the best. Down with the SBC.

    1. JeepJamey Avatar

      Huzzah! 4.Slow till death!

  9. 7FIAT's Later Avatar
    7FIAT's Later

    Got to give a shout out to Clifford, a company that made a good six even better.

    1. JeepJamey Avatar


  10. Jeff Avatar

    I have no rational reason to nominate this engine, other than it was in my Ford Maverick, and it never let me down. Ford 200 c.i. straight 6.

  11. Devin Avatar

    <img src="https://c2.staticflickr.com/4/3582/3520813736_8ab921f22f_b.jpg&quot; width="500">
    Ford's 300 straight six, durable, efficient, inexpensive, equipped in trucks so it was naturally overshadowed by V8 options.

    1. Carter Avatar


      1. Hatchtopia Avatar

        More important, what's that big yellowy thing on the side of the engine????

        1. Sjalabais Avatar

          Doesn't that look very much like an oil filter?

          1. Batshitbox Avatar

            It does, but you can just reach in there and grab it. Oil filters are always under or behind something really inconvenient, as a rule, aren't they?

          2. Hatchtopia Avatar

            Yeah, there's no way that's an oil filter. They go behind a manifold of some sort. Which is behind a heat shield. And underneath a frame member. Which is hidden by a plastic cover.
            What sorcery is this???

          3. Sjalabais Avatar

            Aaaah…and here I thought I could shine some brilliance over the conversation with my outstanding mechanical knowledge. Ha!
            On a side note: I have changed oil and filters on lots of Volvos, a Nissan and a Honda. It was only the Nissan that required a steady stream of four letter words to get the work done.

          4. nanoop Avatar

            "Very well! Sooo easy! Nice!"?

          5. nanoop Avatar

            It's booby-trapped.

          6. Wyowanderer Avatar

            With torque, nothing else. Hmmmm… I might be a Ford 300 six fanboy.

    2. PotbellyJoe ★★★★★ Avatar
      PotbellyJoe ★★★★★

      I miss mine. All it needed was proper gearing and in many applications it was equally capable to the 302.

    3. Roader Avatar

      My recently departed '88 F-250 300 EFI/5spd was everything you say except it wasn't terribly efficient. W/3.55 gearing I could eke out 18mpg @ 55mph, 17mpg@65mph, which isn't bad but not great either. It had no problem hauling 1000lbs over Vail Pass in 4th gear.

    4. Sjalabais Avatar

      Ad "overshadowed by V8": I very recently learned that one and another American classic could have been had with four cylinders…found that surprising!
      '61 Pontiac Tempest.

    5. CABEZAGRANDE Avatar

      Maybe it's just the circles I move in, but the 300 is revered by the people I know. Definitely no under-appreciation around here. Everybody knows it as an engine that's not gonna make a ton of power, but torque for days and utterly unkillable. A friend of mine finally had to call it quits a while back on the 300 in his 67 F100 after 440,000 miles with no major rebuilds.

    6. mac350 Avatar

      Had one in my old F150. Easy to work on. 180k miles when I finally sold it. Hauled horses all over central Texas. Only time it left me stranded was when the harmonic balancer cratered at about 150K. Replaced a fuel pump (two bolts, I think). What's not to like?

    7. boxdin Avatar

      It was said in the day the 300 six had more low end torque than a big block chevy.

  12. buzzboy7 Avatar

    What powers the FJs? The Toyota F engine, based on the Stovebolt 6, but bigger and torquier.
    <img src="http://bringatrailer.com/wp-content/plugins/PostviaEmail/images/1982_Toyota_Land_Cruiser_FJ45_Troopie_Troop_Carrier_For_Sale_Engine_resize.jpg&quot; width="600">

  13. Peter Tanshanomi Avatar
    Peter Tanshanomi

    <img src="http://www.hotrodders.com/gallery/data/500/CHEVY_250_INLINE_SIX.jpg"&gt;
    The '62-'88 Chevy six doesn't get mentioned as often as the slant-6 and the big Ford truck I-6s. Even though they can't make gobs of power (something about the intake and exhaust port shapes?), they were smooth, intelligently designed, incredibly durable engines. I had one in a '71 Malibu and I very much enjoyed making it go not terribly fast.

    1. BЯдΖǐL-ЯЄРΘЯΤЄЯ Avatar

      Well if you make em breath better they can go up in high power numbers, not talking about turbo or supercharge them.
      <img src="http://www.opalass.com.br/media/images/90/90/tmp/wmX-480x360x4-4c7054cdd5c5f3e63d1dc6a1bf99e41481c29d1d63542.jpg"&gt;

      1. Rover_1 Avatar

        And how it ended up in the Omega. Lotus developed EFI, the DOHC head also developed didn't make production.
        <img src="http://www.curbsideclassic.com/wp-content/uploads/2013/10/chevrolet-omega-41_key_6.jpg"width="500"&gt;

    1. Batshitbox Avatar


    2. Kiefmo Avatar

      I'll be in my bunk…

  14. Hopman Avatar

    Mopar slant-6. Virtually bombproof. That is all.

  15. Armand4 Avatar

    I'm gonna go with the Mercedes M130 and its relatives. Introduced at 2.2 liters and 80 horses in 1951, it lasted well into the '70s and was eventually punched out to 2.8 liters with fuel injection and 160 stout German ponies. It wasn't as exciting as the big six in the 300sl, or as sexy as the Twin-cam M110 that followed it, but it powered big luxury sedans, sporty Pagoda-roof SLs and Unimogs.

  16. Biker Joe Avatar
    Biker Joe

    4.0 L HO Six in the Jeep Cherokee, CJ, and Comanche pick-up trucks. Quiet, stone reliable, and with great fuel economy.

  17. JayP2112 Avatar

    The US Spec carb'd Triumph 2.5 made about 100hp.
    The UK Spec with FI made 150hp.
    <img src="http://www.classicandsportscar.ltd.uk/images_catalogue/large/triumph-tr6_10653.jpg&quot; >

    1. Piston Slap Yo Mama Avatar
      Piston Slap Yo Mama

      It its defense, the low compression and carb'ed American spec Triumph 2.5 version does lend itself well to being supercharged.

    2. Ate Up With Motor Avatar
      Ate Up With Motor

      To be fair, the 150 hp rating for the 2.5PI is a gross figure. Net ratings were 142 hp for the TR5 PI and early TR6 PI, 132 hp for Mk1 and early Mk2 2.5 PI sedans, and 122 hp (124 PS) for late injected TR6s and 2.5 PIs. The gross rating of the carbureted 2.5 in the TR250 was 111 hp, net was between 104 and 106 hp depending on the year.
      The Triumph six was pleasant enough if you weren't in a great hurry. It didn't breathe especially well and getting more than about 105 net horsepower out of it required a pretty radical camshaft, which wasn't much for flexibility or smoothness. (That's why the injected engine's power kept dropping — it was de-tuned to trade some peak power for a smoother idle and more flexibility.)

      1. JayP2112 Avatar

        Thanks for taking up the defence.
        I tore a US spec 2.5 down to the crank and found 11 tappets looking pretty flat.
        One wasn't flat. It had dished from wear. The tappet had failed. I first thought it was the tappet that looked porous failed. The cam lobe looked like an egg with the wear. But thinking later the entire oil system was clogged with paraffin and could have caused that failure.
        I later traded the '6 for bodywork on the MGB. Fair trade.

    3. BiTurbo228 Avatar

      Hear hear 🙂 not one of the greats by any means, but making more power than the SOHC I6 in a 240Z from an OHV engine with its roots in the 1953 Standard 8 803cc I4 is no mean feat. I know of at least one supercharged version making 235bhp, and you can get billet cranks from a company called Racetorations if you'd like more than that.
      I'm building one to go in my Spitfire that should hopefully make 180bhp and 200lb-ft on a standard TR6 PI cam so it should have reasonable driveability. Not massive numbers, but in such a compact package it's perfect for the dinky Spitfire.

      1. JayP2112 Avatar

        Awesome. 200lbft in car that weighs as much as a box of tissues will fly.

  18. CJinSD Avatar

    The Suzuki Verona transverse I6 isn't particularly appreciated, but I'm not sure that makes it under-appreciated.

    1. Sjalabais Avatar

      I just have to post this pretty East Asian blandness:
      <img src="http://www.gaddidekho.com/wp-content/uploads/2013/03/Suzuki-Verona-Rear-Side-View.jpg&quot; width="600">
      When in high school, I used to hitch hike home during the winter, when I wouldn't bike myself home. One day, I was picked up by a guy in a Grand Vitara V6. Car talk ensued. I was really surprised Suzuki even made bigger engines than I4's and may have hurt someone's feelings back then – just noticed, I am still every bit as surprised over the same info.

    2. Maymar Avatar

      It's the only thing that made it noteworthy, but it was also an unreliable pile. At least if they showed any longevity, trading a total lack of power or economy for smoothness would be reasonable.

      1. Sjalabais Avatar

        Would make a great Hooniverse asks on another day: What Japanese cars are not known to be reliable?

        1. Devin Avatar

          Technically a Korean car, that one.

          1. Maymar Avatar

            And the engine itself was developed with a lot of help from Porsche.

          2. Sjalabais Avatar

            Wasn't every engine? =8^)
            I have to say, it looks very Korean. But does that mean it wasn't a Suzuki to begin with?

          3. Rover_1 Avatar

            No, it was a Daewoo. Foisted on Suzuki by GM Corporate beancounters. Australasia got them as Holden Epicas. They were an Epic failure.

          4. Sjalabais Avatar

            Ah, I see. When in doubt, blame GM – never wrong. Thanks for the info!

          5. nanoop Avatar

            When they wanted something unreliable they out-sourced it?

  19. Joe Btfsplk Avatar
    Joe Btfsplk

    Toyota Land Cruiser 4.5l DOHC I-6. Purrs along at over 200k miles and uses ot a drop of oil between changes. Wonderful engine.

  20. BЯдΖǐL-ЯЄРΘЯΤЄЯ Avatar

    Don't know the quality of the six in line, but the world deserves more six in line motorcycles!
    <img src="http://data.motor-talk.de/data/galleries/183395/3706539/ben-076-1976-41-944×574-benelli-750-sei-32856.jpg&quot; width="600">

  21. Hank Avatar

    Here is one: http://en.wikipedia.org/wiki/Jeep_Tornado_engine
    I could swear Jeep made another, even more beautiful, inline six, but it may have just been a variation of this one.

    1. discontinuuity Avatar

      It looks like a Henderson or Indian F-head engine, but I don't think either made a six cylinder.

  22. 1977chevytruck Avatar

    My nomination is the Hudson Straight Six. Maybe not unappreciated today, but they sure as hell were when brand new. Just as powerful as a competing V8 and good for several NASCAR victories, but that was moot to the V8 crased public.
    <img src="http://upload.wikimedia.org/wikipedia/commons/c/c3/HerbThomasFabulousHudsonHornet.jpg&quot; width="600">

  23. Tim Odell Avatar
    Tim Odell

    Willys Overhead Cam Six, becuase Jeeps need to…rev?
    <img src="http://2.bp.blogspot.com/-3D_madNGc4E/UKv5KtBz79I/AAAAAAAAFPc/GmUkX7MJhb0/s1600/100_0624.jpg&quot; width=500>
    Wouldn't it be cool if that more sports-car-y I-6 made it into AMC's compact Rambler to make a bit of a fun sports car? That's exactly what Renault's Argentinian concern, IKA thought:
    <img src="http://bringatrailer.com/wp-content/uploads/2008/05/1972_IKA_Renailt_Torino_TS_Coupe_Front_1.jpg"&gt;
    via: http://bringatrailer.com/2008/05/16/south-america

  24. cc-rider Avatar

    Mercedes m104 from a w124. These engines can be boosted to 100hp and can be picked up for next to nothing all day long. I believe the toyota straight 6's were copied off the m103/m104 engines.

  25. dr zero Avatar
    dr zero

    Not too sure about being under-appreciated, other than it hasn't appeared as an answer yet, so I'll go with Nissan's RB series of engines. I wouldn't mind having one of these:
    <img src="http://upload.wikimedia.org/wikipedia/commons/7/7b/RB26DETT_R34.jpg&quot; width=600>

  26. mrfajita Avatar

    Another vote for that Ford 300ci/4.9L. A friend of mine had one in his 92 F150. He got it with 37x,000 miles and we wanted to turbo it (it was in a slammed redneck pro street truck) so we decided let's try to blow it up before rebuilding it with boost. 30k Very hard miles later with no maintenance, no oil change, nothing but a new belt and tensioner it still ran perfectly, with a slight lifter tick. Transmission lost 1st and 2nd twice and it would still roast the tires in third. Changed the oil and fixed the trans since he was selling it and the tick went away. We even took the fan off for better response and it never even got hot in traffic on a 105° day. You can not kill one.
    I've got a 4.0L in my jeep and other than my engine actually having some top end power, I had engine envy for that thing

  27. Rover_1 Avatar

    The old Falcon/Mustang/Maverick/Bronco/Econoline/Zephyr/Granada/Comet/Territory straight six.
    From 144ci (2.4 l ) and 84 hp/134 lb.ft on introduction as the Thriftpower Six. Quickly stroked to 170ci (2.8 l), then 200ci,((3.3l)
    <img src="http://upload.wikimedia.org/wikipedia/commons/e/e2/1962_Ford_Falcon_2-door_wagon_170_six_engine-1.JPG"width="500"&gt;
    To it's current, (& final?) iteration in Australia as the 242ci (4.0 l ) Barra Straight Six with the same iron block casting but with new alloy EFI 24v DOHC V VT head and intercooled turbo with a Euro IV emissions and Ford's durability testing pass, 416 hp/417lb.ft.
    The non-turbo versions still running up 1 million miles in Melbourne Falcon taxis.
    <img src="http://img.photobucket.com/albums/v642/gravelrash/DSC00102-1.jpg&quot; width="600">
    And 1400 hp/1000 lb.ft available with a little work, this one dynoed at 1163 hp
    <img src="http://www.australiastoughestcars.com.au/wp-content/uploads/2014/03/1901253_706159146101694_348412113_n.jpg&quot; width="600">

  28. Rover_1 Avatar

    The other great ex-USA Australian six.
    The Chrysler Hemi Six. From an unwanted truck engine in the US to at the time, the worlds most powerful six.
    No turbos, no multi-valves. Triple Webers and a 351 V8 beating 302+hp from 265ci in the June 1972 E49 Charger and a quarter mile production record that lasted for twenty years.
    The Hemi 265 six-pack OHV Six
    <img src="http://www.moparstyle.com/history/images/austra4.jpg"width="600"&gt;

  29. SajivW Avatar

    Nissan TB48DE as fitted to the last generation Patrol..
    280BHP and 295lb/ft out of the box and bombproof reliability. Add Boost and you get numbers that make things like this possible…

  30. jason carter Avatar
    jason carter

    Any American domestic cam in block Inliner. the AMC 258, which later on became the ole reliable 4.0l HO Jeep mill. those things are just keep on going and going and going.

  31. Benjamin Christopher Collins Avatar

    Well the Triumph and BMC’s spring to mind, SD1s short lived was deliberately choked so it couldnt match the v8. Remove the mismatched intake ports and its 160hp straight off.