By on July 25, 2006

Aston V8.jpgAll cars should have a V8.  For one thing, the modern eight cylinder engine is inherently balanced; it has completely overlapping power impulses.  In other words, one cylinder fires before the previous cylinder has finished contributing, creating a much smoother power delivery with fewer impulses. That’s why a V8 can use the same drivetrain components as a much smaller four cylinder engine with half the displacement.  There is no need for secondary balance shafts, and no unpleasant vibrations to annoy the passengers and reduce the life of the exhaust system and other accessories.  It’s the smoothest engine configuration money can buy.

In contrast, inline four cylinder engines are inherently unbalanced.  Because of the geometry of the crankshaft and rods within the engine, fours shake in both the horizontal and vertical planes.  There’s only one way to mitigate the effect: add unbalanced shafts to create counter-vibrations. This “fix” adds weight, complexity and cost.  Even so, the inherent vibrations from a four cylinder engine wreak havoc on accessories and require extra mass in all the mounting brackets and related parts.  In fact, by the time a four cylinder engine is tamed, it weighs and costs almost as much as a V8.  And the customer still suffers the noise and vibration penalties that come from skimping on cylinders. 

V6’s also have inherent imbalances, though not nearly as severe as a four. Depending on the block angle, V6 engine operation creates vertical or horizontal forces.  The most sophisticated V6 engines also have balance shafts, again adding to complexity, cost and weight.  Fives, threes and twos have even worse vibrations, some beyond simple analysis.  V10’s add the vibrations of two five cylinder engines together, which is better at some speeds, worse at others.  Turbocharging or supercharging four or six cylinder engines to get to V8 power levels simply adds more complexity and weight to an already challenged engine design, and sacrifices the low end torque of a naturally aspirated powerplant.  (Just ask Mercedes’ AMG division, who’ve recently switched from supercharged eights and sixes normally aspirated 6.3-liter V8's.)

Odd numbers of cylinders, like three or five, are inevitably the result of cost-cutting.  Sometimes there’s no time or money to tool for a smaller engine, so a few cylinders are lopped off an existing engine.  That’s why GM’s lackluster small pickup trucks and the Hummer H3 sport a five cylinder engine. Ten cylinder engines, currently deployed in Vipers and some Dodge and Ford trucks, are another cost-cutting move.  Engine not powerful enough?  Add two more similar cylinders and call it good.

The provision of V12 engines in luxury cars is even more perverse.  V12’s are no smoother than a V8 and add (you guessed it) weight, complication and cost.  While that may be the manufacturer’s intent, it still makes little engineering sense. Jaguar gave up on V12’s a while ago.  Aston Martin passed on their V12 to offer a V8 in their latest car.  In fact, thanks to the V8’s relatively light weight, good power output and compact packaging, the engine configuration is, belatedly, making gains in the European market.  BMW, Mercedes, Volvo and Audi all offer Euro-spec V8 passenger cars. 

Once you’ve committed to a V8, there are a lot of reasons for making it a pushrod.  A single camshaft simplifies a lot of things, and the narrow heads associated with pushrod engines allow greater flexibility in vehicle packaging. Thus smaller cars can enjoy a V8 engine.  Before the outraged techno-comments start dropping at the feet of this post, it should be noted that the most powerful racing engines in the world are pushrod V8s, with two valve heads to boot. Some of the fastest cars you can buy in America have pushrod, two valve V8’s. The Chevrolet Corvette is only the most prominent example.

So why don’t all cars have V8’s?  The answer lies in marketing, rather than engineering.  Marketing has declared that V8 engines are best suited to high-end, high performance cars, while the masses should get by with “economical” fours and sixes.  The public now believes that V8 means bad mileage.  The opposite is true– at least potentially. Mileage depends on two factors: the weight of the car and how fast you go.  Engine size and cylinder count have little to do with it.  Of course, bigger engines encourage people to accelerate and drive faster, but that’s not the engine’s fault.  And new technology is mooting the V8 as gas-guzzler argument.  Multi-displacement systems (a fancy way of saying that four cylinders go on vacation when not needed) have the potential to dramatically increase V8 mileage under light load conditions.

In short, for pistonheads at least, the five saddest words in the English language are still “I could’ve had a V8”.

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67 Comments on “V8’s Rule!...”


  • avatar
    Lesley

    Aaaaah yes… You’re probably one of the few guys that can understand why I had a pushrod V8 on an engine stand in the mudroom off my kitchen for over 2 years (I have no garage). Eagerly awaited hop up parts were like pieces of art, examined, photographed, drooled over – each one arriving like another piece of the puzzle. The day it finally departed my back door to be dropped in the awaiting engine bay of my beloved dodge… and hearing its first bark on turnover, gawd, I felt like handing out cuban cigars!

  • avatar
    Stephan Wilkinson

    As Don Sherman pointed out in Automobile a couple of months ago, a Saleen S7 Twin Turbo will probably go just about as fast as a Veyron, will probably get to that speed first, costs half as much, and has a pushrod 16-valve V8. “You don’t need four turbos, sixteen cylinders and 64 valves to go fast,” Dyno Don wrote. “All you need is too much horsepower propelling too little curb weight.” the Saleen’s engine is basically a blown Nextel Cup engine.

  • avatar
    Sajeev Mehta

    Well said! The LS-series of GM small-blocks are the best example: make disturbing amounts of power in a pretty light (all aluminum) and compact (OHV) package. Good low end torque, rev freely, cheap to modify.

    I for one want to see an LS2-powered Honda S2000. If they can put it in a Miata, why not? That would be sick.

  • avatar
    pariah

    Pros and cons of horizontally opposed engines?

  • avatar
    chandler

    Bob refers to the vibrations and imbalances inherent in an inline four or V6 engine. How much of this is addressed by the horizontally opposed (boxer) configuration?

  • avatar

    I note the absence of the even smoother and vibration-free Straight Six from your argument there Mr. Elton!

    Besides, nothing is prettier than a twin-cam inline six with a polished aluminum head. Engine bay nice and neat with flammable stuff on one side (intake) and hot gases on the other (exhaust)… it just seems so… orderly.

    A V-8 looks ungainly and boxy in comparision.

  • avatar

    Lesley writes:
    Aaaaah yes??? You???re probably one of the few guys that can understand why I had a pushrod V8 on an engine stand in the mudroom off my kitchen for over 2 years (I have no garage). Eagerly awaited hop up parts were like pieces of art, examined, photographed, drooled over – each one arriving like another piece of the puzzle. The day it finally departed my back door to be dropped in the awaiting engine bay of my beloved dodge??? and hearing its first bark on turnover, gawd, I felt like handing out cuban cigars!

    Lesley, forget what I said about trucks being a turnoff in the thread on cars and sex. Any woman with this kind of appreciation for the machinery and these skills can drive anything she damn pleases.

  • avatar
    phil

    Bob, i really appreciate the description of the inherant balance or lack thereof in various engine designs. makes we wonder why volvo has peristed with 5 cyclinder engines for so long when they could clearly have gone any direction they wanted. interesting that they finally put a v8 in their SUV. makes me admire the japanese even more for making such smooth 4 bangers.

    when i bought my 2004 X5 i drove the 6 and the 8, the 6 would launch with surprising verve, but ran out of accelerative power pretty early, compared with the awesome 4.4 that just seemed to get stronger as you climbed the rev ladder. needless to say i got the 4.4 and was SO GLAD i did. over the 67K miles i owned the car i averaged 19.7 mpg and always drove it to enjoy it, cruising at 80+ on the freeway (most of the miles were freeway). I think the 6 speed auto (new in 04) was a big reason for the surprising mileage. i wouldn’t have cared if it got 15 or 16 because of the tremendous pleasure derived from that engine. tranny started to slip at 60k miles and i sold it to russian mafia (really, they saw the ad on autotrader, arrived in a Dinan stage 3 M3, cash only, didn’t test drive the car, never took off their sunglasses, thick accents, quite an experience).

    can’t wait to drive the next M3, even without pushrods i’ll bet it can scoot.

  • avatar
    gbh

    The most inherently balanced ICE standard configs are the I6 and the V-12. What engineering textbook, study, or lab test has ever suggested otherwise in the last 40+ years? Please, I’m really curious.

    I have absolutely no idea where the author of this article is getting his info, but to call it incomplete and misleading would be generous.

    Yes, a crossplane V8 can be balanced pretty darn well. Sure, 12 cylinders add weight, and one can make a convincing argument in favor of a V8 over a V12 for complexity and packaging.

    However, as much as I detest posting links, below is a link to a more thorough and educated discussion of the above topic. I’m not going to put up a ton of SAE links, or try to put up graphs of firing order input to the crank, or explain the Otto cycle. Just Google up something regarding V8 V12 inherent vibration.

    http://forums.atlasf1.com/showthread.php?s=c8514b3d7340b8d0b98088a0ab084b0c&threadid=81573&goto=nextnewest

    There’s hundreds of experienced powertrain engineers out there. I’ve never met one in 25 years who suggested for a second that somehow a V8 could possibly have lower inherent vibration than an I6 or V12 config. Never. It also defies any logic, but hey, why let the truth get in the way of reassuring the owners of scythes that they can keep up with the Yazoo.

    If the author is referencing nitro-drag engines for his high-hp pushrod v. ohc scenario, that’s like comparing Saturns to JATO units.

    Pushrods are inherently inaccurate compared to OHC. The very existence of pushrods forces huge compromises on intake design. Last time I played with CFD (computational fluid dynamics), a round tube flowed a lot more air than a same cross-section of oddly rectangular runner. Perhaps the laws of physics have been changed.

    If you like pushrods, great. But the realities are that a well designed SOHC engine height is *maybe* 1″ taller than the same block with pushrods. There’s a LOT more friction with pushrods than there is with one cam per head actuating the valves. Not to mention the inherent inaccuracy of pushrods v. OHC.

    There’s a reason designers choose OHC whenever they can. Pushrods are as outdated as carbs. GM and Ford use them because it saves them money. There is no other reason.

    Last time I checked, you could put an OHC motor under the hood of a ‘Vette.

    Honestly, most of the above is a rather moot point. Fully electronic valve actuation is coming and will be required to meet emissions and driveablity targets in the future. Oh yeah, and you’ll get more HP/TQ than any mechanical valve actuation scenario.

  • avatar
    stanshih

    Ummm… I’m not an automotive engineer, but wouldn’t there be weight distribution and structural issues related to shoving a V-8 into a compact car?

    And, I’m not an actuary, but wouldn’t car insurance rates (and car passengers) go through the roof if V-8s were standard fare? Accident rates/severity would increase in a V-8 world, methinks.

    I care about cars, but safety and people’s lives trumps exciting driving for me.

  • avatar
    Johnny Canada

    “The public now believes that V8 means bad mileage. The opposite is true, at least potentially”

    Is that the same as saying,”The public now believes that gas is expensive. The opposite is true- at least potentially” ?

    Smooth no doubt, but at an ever increasing cost.

  • avatar
    Yuppie

    Have never owned a V8 or any vehicle having a pushrod engine. But most automotive engineering textbooks state that the I6 configuration is the most balanced, but necessitates the use of a longer crankshaft compared to a V8 of the same displacement.

    Simple is not always better. The DOHC system, which allows for variable timing of the intake and exhaust valves independently, is the way to go.

    Re: fuel economy and cylinder deactivation (where one bank would become inactive) leaving a V8 operating as an I4, wouldn’t counter-spinning balance shafts be needed then? This messes up the whole “weight, complexity and cost” argument.

    Further, from what I have read on the Hemi multi displacement system as well as Honda’s cylinder deactivation technology (Accord V6 hybrid), the pistons remain connected to the crankshaft even on deactivated cylinders. Not to mention that, on Honda’s system, the camshaft on the deactivated bank is still spinning, I think. That’s a lot of dead weight to be moving. The only solution would be to somehow decouple the deactivated cylinders from the crankshaft, once again messing up the whole “weight, complexity and cost” argument.

    Regardless of cylinder number and arrangement, a small displacement engine with an appropriately-sized turbo is optimal for commuting. But I am biased by my ownership of an Audi A3 2.0T FSI.

  • avatar
    ronbo456

    I’m kind of partial to the Ferrari V-12, myself. Smooth, torque-y, powerful, quiet enough to *require* an aftermarket exhaust, and not very heavy for the output. A pig at the pump, but you can’t have everything.

  • avatar
    gbh

    I seem to have somehow posted the wrong link.

    Mea culpa.

    http://64.233.161.104/search?q=cache:Ol_Vmj3YsiEJ:forums.atlasf1.com/showthread.php%3Fs%3Dc8514b3d7340b8d0b98088a0ab084b0c%26threadid%3D81573%26goto%3Dnextnewest+v8+v12+inherent+vibration&hl=en&gl=us&ct=clnk&cd=9&ie=UTF-8

  • avatar
    Moparman

    I own V6 a straight 6 and a pushrod V8 and my V8 (small block Mopar) is every bit as smooth (smoother actually) as my straight 6 (2004 Jeep 4.0). As for everyone owning a V8, those who grew up from the late 50s to late 70s grew up in a world of V8s Nearly every car on my block had a V8. My neighborhood was populated by Impalas, LTDs, Furys and Delta 88s. Every falmily car had a V8 engine which were all quite powerful. I used to beat 280Zs in impromtu drag races with my Father’s 455 C.I.D. Pontiac Grand Safari station wagon.

    Pushrods exist in the modern world for cost and simplicity reasons, but are pefectly acceptable for the operating RPMs of most V8s, but I too prefer OHC. As or V8s in smaller cars, V8’s can be made in small displacements. My not a 2.5 or 3.0 litre V8?

  • avatar

    I have a Volvo T5 wagon. This has one of the wierdest engines of modern times, a sideways mounted straight five (front wheel drive), which is then turbocharged. I believe the five cylinder configuration was dictated by making the engine fit sideways, rather than other considerations. I will say it drives well; has the usual turbo lag but is quiet powerful and considering the size of the car and usual loading of five noisy kids, pretty economical with gas, too…

  • avatar
    starlightmica

    gbh –
    Wow, nice writeup. Keep writing like that and Farago will have to pay you to comment!

  • avatar
    JSForbes

    But is it smoother than a rotary?

  • avatar
    vallux06

    Hey Bob,

    I dunno but my M88/3 engine in an early model BMW M6 might be hard to beat when it comes to smoothness AND power.

    My limited experience I had with (american built) V8’s was when my wife brought home the company car on occasion It was (be still my pace maker!!) in ’95 when she got an Oldsmobile Aurora as a daily driver!!

    Now THAT engine, a derivative from the vaulted Northstar engine, did not realy convince me at all!!

  • avatar
    C.D.Weir

    Yuppie: I think your logic is reversed on the V-8 cylinder deactivation concept. If you detached the inactive four pistons, then you would have vibration issues. But as it now is designed, the inactive four pistons and rods continue to counterbalance the active four, so nothing changes much with the balance of the moving parts of the engine. The inactive cylinders, remember, are simply acting as air springs while deactivated.

    True, the power pulses are different, which is mostly an aural resonance issue…which is why Honda runs noise cancellation through the stereo system of the Odyssey when the V-6 is in ECO mode.

    I don’t know what Chrysler does in this regard with the Hemi system, but it is likely very similar since nobody says much about hearing anything when driving them on 4 pots.

  • avatar
    mbslk350

    After reading the story, I was going to say that I now forgive GM for leaving a pushrod engine in the Vette. But after reading the comments I’m not so sure I forgive them after all.

    And I’m still wondering why they put in a 4-speed automatic when cars at half the price have a 5-speed. Maybe that’s a topic for another story. (I know…why would anybody buy a Vette with an automatic in the first place…)

  • avatar
    Lesley

    Cylinder de-activation, such as DCX’s MDS, doesn’t leave one bank operating, but shuts down every other one. The cylinders still actually travel up and down, but the system uses extra oiling channels which plump up and detach the pushrods from the lifters so corresponding valves don’t open and close. There’s no detonation, since the ‘puter also tells the associated injectors not to um, inject.

  • avatar
    steronz

    I’m also not sure where Bob is getting the fact that “tamed” I4s weigh almost as much as V8s. I know a decent amount about honda 4 bangers, and I know that your average 1.6-1.8L civic/integra long block weighs about 180 lbs with all accessories attached. Prelude/Accord/S2k motors are gonna be roughly 220 lbs. Add on another 100 lbs if you attach a tranny. I don’t know much about V8s, so I looked up the weight of an LS1 crate engine. 390 lbs, the internet tells me, and since that’s a crate engine I’m guessing you’d be into the 400s after accessories. Just a hunch, but a larger, beefier Camaro tranny is probably a bit heavier than 100 lbs. So all told, you’re looking at about twice the weight for a pushrod V8 that makes 350hp vs a 240hp I4 S2000 motor. Might not seem like a lot in a 3500lb car, but it’s hardly an insignificant difference for a 2450 lb Fit or a 2800 lb Civic.

  • avatar
    thx_zetec

    V8’s are good for some uses but not good everywhere.

    Depends on power requirements. Would you put a V8 in a weedwhacker? No, you’d use single cylinder. Would you use a V8 for a 2000 HP aircraft engine? No, you’d use an 18 cylinder.

    V8’s can produce more power per weight, but not much more. My car (1999 Ford Contour) weighs 2,700 lbs and has a 120 HP I4. A 120 HP V8 would be too complex and much heavier.

    As for I4’s being marketing . . . . can you name a V8 econobox that gets 32 city, and costs the same? Maybe this is a conspiracy and you should make a movie “who killed the ubiquitous V8”.

    I *do* agree that GM’s pushrod V-motors (V6’s and V8’s) are under-rated. If I want a 250 hp V6, give me a GM pushrod V6. Likewise if I want a 350 hp motor give me the pushrod V8. Great torque, durability and fuel economy for these size motors.

    About vibration: the trick for I4’s is not to make’em too big – 2 liter I4’s are fairly smooth.

  • avatar
    carlisimo

    If we all wanted heavy cars, sure. But we don’t. Some of us (well… some of them to be honest) don’t even want more power.

    No way a V8 is ideal for the urban car market (where the ideal engine takes up very little physical space). Look at the interior room in the Fit, in a small, easy to park footprint; only possible with a transverse inline engine.

    Nor for the 40mpg market. Fuel consumption is a function of (wait for it…) fuel volume injected into an engine, ie largely a function of power. A lot of people are somehow happy with

  • avatar
    ChartreuseGoose

    Idiotic. I’m interested in economy, doing the most with the least, not chest-thumping. What does Bob propose we all do when gas (in the real world, not some alternate universe where economy doesn’t matter) reaches $4 a gallon? What about those of us who prefer small, nimble, light cars? Or those who have to drive in a city?

    This article is guaranteed to give a nice little warm fuzzy to all the wannabe hot-rodders, but I’m not sure it has much of a connection to reality.

  • avatar
    morphwvutuba

    That was the most preposterous thing that I have EVER read. Not a damn thing in that article has any engineering or scientific basis. I find it insulting. RF, please don’t invite him back.

  • avatar
    Sasquatch

    So the V10s used in the new M5/M6 and new Audis is a cost cutting move?

    I thought it was because they wanted to be like Formula One?

  • avatar
    Jonny Lieberman

    For the record, I do agree with the first sentence.

  • avatar
    discoholic

    Bob,
    With all due respect to your love of big honkin’ V8s, the most inherently balanced engine design is not a V8 but an inline 6. Listen to the old BMW sixes (before they switched to four-valve heads) and you will instantly know what I mean. There isn’t an eight-banger in the world that matches its silky note.

    Besides, an econobox with a V8 would not only get single-digit gas mileage (yeah, right, you won’t ever step on the gas and use the power…) but would also have about 75% of its weight on the front wheels. Makes for superb driving dynamics – oh, and don’t forget to buy new front tyres every 5,000 miles or so.

  • avatar

    My third Crown Vic, a ’91, got 28.5 MPG on the highway. Granted that was with the cruise control at a whopping 55 mph, probably pissing off quite a few on I-77, but I clocked 420 miles on the trip odometer that weekend. Went down to visit my mother in West Virginia and then back, didn’t have to refuel until I got back to the last gas station before my house, less than a mile away, even went and visited my grandmother when I was down there too.

    I can’t wait to get back in a V8. I’ll do so as soon as one or both of my fords die.

  • avatar

    My ’62 Comet has an I6 engine, naturally internally balance. If I wanted to go to a V8 I’d have to get a different *externally* balanced flexplate.

    The V8, while an excelent motor in some regards fails to be the ‘smoothest’ engine as you claim. Please in the future make sure your science is sound if you are going to base your article on science.

  • avatar

    Startled that no one’s brought up the difference between a 60-degree V6 and a 90-degree V6. The former, I believe, is as inherently smooth as a V8.

    IIRC, the V6 fitted by GM into the Chevy Citation and the rest of its compact FWD cars in 1980 or so was 60-degree, but thereafter they wanted to make V6es on the same line as 90-degree V8es. So they lopped off 2 cylinders and henceforth their V6es had all the usual vibration problems from the “missing” sequence of firing, requiring balance shafts etc.

    IIRC more, Lancia was known for its 60-degree V6es.

    Then there are the various narrow-angle V-engines from Volkswagen (V5, V6) and the “W” engines (W8, W12, W16) and so on. And narrow-angle V10s like Connaught’s (22.5 degrees) … sheeesshhhh.

  • avatar
    Simone

    If you want to see something really special and European with a V8, search via Google using: Lancia Thema 8.32

    Nice Poltrona Frau italian quality leather and one of Modena’s finest cavalino rampante powerplants just in one Q-ish styled package.

  • avatar
    vallux06

    Simone

    I had that engine in its original package!! Lol. The ’77 Ferrari 308. In black with burgundy interior. My, how times change!! Today a I4 turbocharged GTI gives you better performance (and easier maintenance too).

    But, for sheer looks…… Nothing better!! I ran up 2 major services on this car, at 12,000 and 25,000 miles the timing belts were changed as a precaution.(They are supposed to last all of 15,000(!!) miles) That was what ultimately turned me off the Ferrari. Hey if I’d wanted high maintenance, I could have stayed with my 1st wife!!

  • avatar
    geozinger

    JV:

    I had to comment on the differences between the types of the GM V6’s…

    The 60-degree V6 is alive and well, in fact a new variant is the ‘global high-feature’ 3.6L OHC V6 that is starting to show up in more mainstream (domestic) GM vehicles. The latest version of the original V6 is the 3.5L ‘high-value’ OHV V6 now made in China… See this link for more info:
    http://60degreev6.com/view.php?pg=familytree

    The 90-degree (Chevy) V6 was indeed a small block missing two cylinders, I think it was a 4.3L for it’s production life. A lot of those went into RWD Caprices, S-10 and C-10 pickup trucks. Our shop truck had one, a pretty decent motor.

    The other 90-degree (Buick) V6 was an odd-firing V6 which was a 3.8L size for it’s production life, which was incredibly long. (close to 40 years, IIRC).

    I got the feeling from reading your post that the 60-degree motors weren’t being made, but that may be just my interpretation.

    Otherwise, I love V8’s, I just don’t want to feed one right now. Maybe something with a LS2 in the future…

  • avatar
    Drew

    I’m an Engineer, SAE member, ASME member, and auto enthusiast. After reading the post by Bob I had to sign-up just to point out that there is no supporting evidence for nearly all of the statements he’s made. It is totally irresponsible and disgusting to see someone pass along supposed “facts” that are plain and simple fabrication–a biased invention of someone’s mind. This one is especially laughable “(V-8) It???s the smoothest engine configuration money can buy.”

    Hey Bob, if the V-8 is so perfect, why do think all those million mile over the road big rigs all have straight sixes? What engine format do you think diesel-burning industrial co-gen systems use? What engine format do diesel-electric locomotives use–you know, the ones that they startup and run 24-7 until it’s time to tear them down and rebuild? Here’s a hint, it’s not a V-8, pushrod or otherwise.

  • avatar
    xargs99

    Yeah, Drew has some good points. I’d like to address some of the silliness in this article myself. I have about 15 years experience in building engines. Mostly motorcycle, but a fair number of cars as well.

    A counterbalanced four can be quite smooth, and the ‘weighs almost as much as a V8’ is nonsense. You use the engine/packaging that’s appropriate for the vehicle.

    I’ve put inline fours where flat fours once were (VW Transporter with a 3TC Toyota engine), V6es where straight sixes were (AMG postal jeep), and a single cylinder engine where a tiny V-twin was (XR600 in VTR250 frame).

    I’m a fan of the GM 3800 series 2 V6 as well, it’s a marvel of engineering.
    Split-pin crank that has a 60 degree balance with a 90 degree block, a counterbalancer for the secondary vibes from the rod offsets, and it’s made out of cast iron (which is good or bad, I suppose) and makes 275hp with a supercharger:

  • avatar
    eslai

    Well, I guess Bob’s not going to respond to this one. Robert, I would seriously question whether this article should remain online without some huge disclaimer at the top…

  • avatar
    jjdaddyo

    You want smooth? How about a nice 12-cyclinder radial? Torque-y, too. Now if we could only fit it in the engine bay of something smaller than a Peterbilt….

  • avatar
    Stephan Wilkinson

    I don’t remember why, but radials all have an odd number of cylinders, at least per “bank.” In other words, you can have an 18-cylinder radial, but it’s made up of two nine-cylinder banks.

    Biggest radial I ever flew–actually four of ’em–was the Wright R-3350 (cubic inches, in other words, and indeed they were 18 cylinders each) in the Lockheed Connie. Turbocompounds, meaning they had turbochargers that not only pressurized the induction air but shaft-drove, through gears, the crank as well.

  • avatar
    Yuppie

    To: C. D. Weir

    You are right about my logic being backwards re: I4 mode imbalance being worse if the inactive 4 cylinders were decoupled from the crankshaft. But my point re: moving dead weight being inefficient is still valid, right? So an I4 w/ a turbo is superior in this respect.

    To: Sasquatch

    With regard to use of V-10’s by BMW and Audi, it is unfortunately due to the misconception by unsophisticated consumers (the vast majority of the car buying public in North America) that more cylinders is better, not in terms of hp or torque or engineering, but that having more cylinders somehow places the vehicle in a higher “class”. So BMW and Audi would have to put V-10’s in the flagship model, even though a well-engineered V-8 would have done the job just as well or even better.

    To: THX-Zetec

    I agree, having driven my A3 2.0T, my wife’s Acura RSX, my mechanic’s Mitsu Lancer Evo, my friend’s S2000, all 2.0L I4’s. The biggest I4 I have driven was the 3.0L on a Porsche 968 (early 1990’s model). I don’t know if it’s the age of the vehicle, but that was definitely not as smooth.

    To: Drew

    That’s why I registered for an account too!

  • avatar
    Jack Shry

    Bob,

    Your article certainly strikes an emotional cord for us that paid $0.25-$0.50 cent gas. The growl of a Chevy and the honk of a GTO at WOT. Those are, however, times gone by.

    And hey folks; it will be $5.50 – $6.00 gas very soon. We will fall in line with the other global users of gas. Heck, we aren’t even the largest single consumer of fossil fuels. China will soon crack the Hydrocarbon fuel whip, along with about everything else.

    My son drives a Legacy 250 GT, talk about a quiet, low profile, reliable, powerhouse. He has put several great sounding Mustangs (V8’s) to shame.
    As for your technical references; leave that to the engineers.

  • avatar
    xargs99

    S.Wilkinson
    Re: Radials
    I think radials need odd numbers of cylinders beacuse of the master/slave connecting rod system. If the engine had an even number of cylinders, there would be an odd number of connecting rods on one side of the crank, given the master rod has all the slave rods bolted to it.

  • avatar
    Steve_S

    Come on not one mention of a Rotary! Sure their gas mileage and power are not great but they are very smooth. Just think of what some serious research money poured into rotary design might do.

  • avatar
    gbh

    Just to put a merciful bullet in the last glaring factual lame horse of this piece…

    “Mileage depends on two factors: the weight of the car and how fast you go. Engine size and cylinder count have little to do with it.”

    Even before the 1940’s, the importance of aerodynamics was realized by the automotive community (if not always appreciated or acted upon).
    The implicit suggestion that a wind-cheating design is not important verges on the surreal.

    Further, even a cursory glance of the physics of having more reciprocating mass than you need 90% of the time, shoots lots of holes in the ‘number of cylinders’ being irrelevant argument. Regardless of one’s cylinder deactivation scheme, those pistons and rods and unused sections of camshaft need energy to keep turning. Oh yeah, they add frictional losses too. Only a few HP to be sure, but it takes around ~15-20 HP to run an average sedan at 60MPH n level ground. Those extra few wasted HP count.

    Coup de gras – The author states that number of cylinders and displacement really don’t matter much to mileage. Then he extolls the virtues of cylinder deactivation as a way to save fuel with a V8.

    Anybody else see the rip in the fabric of the space-time continuum forming?

    The final what-the-hades suggestion is that ‘displacement has little to do with it’ either. So an 8L V8 can be packaged to be as small as a 2L I4? Really? Same internal frictional losses, same inertial mass? I can just slot a 3406 Cat in place of the 225 slant-six in an old Duster? Keep the radiator and everything, right?

    It’s a diesel, the mileage is sure to go up.

    Methinks this article must have been either an elaborate prank, or testing the depth of reader knowledge.

  • avatar
    imageWIS

    Mercedes put some serious money into Wankel (Rotary) research and could not make the technology viable for all the applications they wanted to use the engine for. Also, if you recall the RX-7 (last gen) had some serious engine problems. These problems seem to have been fixed with the new RX-8, but only time will tell.

    Jon.

  • avatar
    imageWIS

    I have to agree with GBH…it is much more complex than simply those two variables. The friction of the engine, the transmission, the gear ratios, etc???all play important parts in not only the speed of the car, but the gas mileage as well. Also, manufacturers have to take into consideration wear and tear and longevity (re: just see how many production cars that utilize turbochargers also have anti-lag systems).

    Jon.

  • avatar
    bripab007

    To steronz and others that think 4-cylinder engines are lighter than in reality:

    They’re not as light as you seem to think. The 2.0L F20C S2000 engine weighs over 320lbs., not including the transmission. The 1.6L B6 engine in the ’90-’93 Mazda Miata weighs just at 300lbs. sans tranny.

    An interesting place to find out about engine weights is the engine conversions forum at http://www.miata.net . People have been putting Ford 302s, GM LS1/2/6s and the 3.5L, all-aluminum Buick/Oldsmobile/Pontiac/Rover V8 into Miatas for some time.

    The 3.5L BOPR and LS1 V8s are so light, that the balance of the finished Miata is identical to when it had the original 4-cylinder engine.

  • avatar
    NVHGuru

    What a great way to increase site traffic – put up false editorials so all the engineers and pistonheads have to sign up just to complain! Worked with me too, although I may not come back if you put many more of these factually incorrect posts on the site.

    And Elton calls himself an engineer; I guess GM is paying him more than TTAC!

    Come on Farago, get the site back on track with some TRUTH.

  • avatar
    steronz

    bripab007:

    I guess you’re right about the F20C… it took a long time to get a weight on it, so I just guessed that it weighed about the same as an H22. But the other engines I know more about, and I know that I’ve personally picked up and put a d16y8 long block in the back of my crx, so I figure that can’t weigh much more than 125 lbs for 127 hp. And the shipping receipt for my 160hp b16 was for 225lbs with tranny attached. But I can see where the truck and roadster engines might have to weigh quite a bit more.

  • avatar
    esoterica

    Just to pile on, gbh, you’re right about Bob neglecting to mention aerodynamics, but what’s more is that weight, for all intents and purposes, doesn’t matter at all in constant-speed (i.e. highway) driving, just as it doesn’t affect top speed (with the minor exception of marginally increased tire friction).

    And, yes, it’s ridiculous to state that “engine size and cylinder count have little to do with [economy].” In fact, the reason that cylinder deactivation makes the engine more efficient is not because you’re just pouring fuel into half as many cylinders, but because cylinder deactivation shuts down the valves, reduces pumping losses (it takes a lot of energy just to pull air in and push it back out of the cylinders), and basically turns the unused cylinders into air springs.

  • avatar
    leondraw

    While there is, for the most part, no substitute for cubic inches, and much as I love the visceral punch of a V8, they are not the end-all be-all Bob suggests.

    With three turbocharged 4-cylinder Saabs sitting in my driveway, I can tell you they are smooth, fast (130 to 150 mph), and provide excellent local and highway fuel economy. Sure they have balance shafts. Big deal. Those last the life of the engine as long as you change the oil. Are they more complex? Sure, but they still last a long time.

    I also think of my friend’s well-tweaked Mitsubishi Eclipse with its turbo 4 cylinder that was cranking out a healthy and reliable 400 bhp while embarrassing a few Corvettes on track days at VIR.

    The only advantage pushrod V8s have is that they are relatively simple engines and they do provide great torque for towing. These are good things. But in performance terms they are no longer necessary to propel cars on regular roads. Even high performance cars. And as fuel prices climb they will gradually disappear from the mainstream except in trucks where the torque is necessary.

    Saying “all cars should have a V8 is like saying all cars should be hybrid. Use the right technology for what you are trying to do. And you don’t need a V8 to go fast or even accelerate quickly.

  • avatar
    Carzzi

    I’ve recently acquired my first V8 automobile. Yes: it’s powerful, thirsty and in a premium luxo car. Kinda the epitomy of the stereotype that drives the uninformed away from V8s.

    It is a BMW. And it burbles. It is, ladies and gentlemen, the E39 M5.

    Think about getting one. Legacy, heritage and power, all for less than $40K if you look carefully. Get one with CPO and you will be the envy of Hemi drivers.

  • avatar
    Sasquatch

    To Carzzi: Excellent choice on the e39. The high revving wail of the new V10 M5 is intoxicating. Bt give me the muscular growl of a V8 any day.

    Maybe the new 4 litre V8 M3 will be the best of both worlds?

  • avatar

    I LOVE V8’s & always have, I won’t own a vehicle without one, and they have come a LONG WAY BABY! But, I have driven my wife’s car w/a four banger & I appreciate it for what it is, a good around town,
    grocery-getter for the simple inexpensive life in the city. It gets good mileage, is nice to drive, relatively economical & all that. But on the highway I want a V8 & a car that has some serious manuevering & stopping capabilities.
    There is one big item missing from all this back & forth on mileage & what affects it, the drivers style of driving. In my experience no other factor has so much room for improvement or to affect positive change on mileage, I can get 28mpg or 12mpg depending on the style of my driving.
    The aggresive driving habits in North america are the one of the largest contributors to low gas mileage I can think of, and are just so easy to change. Drive with economy in mind, not to beat that other guy to the next stoplight, or to take out our frustrations in some Mini-Indy rush. Of course on a sunny spring day, all of us get a little exuberant in the foot.
    We must also realize that just like Chevy versus Ford versus Honda, 6 cylinder people will likely always be 6 cylinder people, there are always gonna be V8s, 4s, 6’s in engines, whatever, and each of them has their benefits & drawbacks. But the evolution of the small, efficient V8 is still to me, one of the great automotive engineering achievements. Best balanced or not.
    I have put a LOT of miles on many different variations of them and nothing comes closer for me to the near-perfect, all-around package for a cars engine.

  • avatar

    Hey, What can I say, I’m a V8 guy!

  • avatar
    fishiftstick

    First, I love V8s. My first car was a Chevy Nova (the 4-door Camaro, not the Corolla clone) with a 350 V8. Sure it had bench seats and bias-ply tires, but it went like stink.

    Second, one thing that GM did relatively well was V8 rwds. When they switched to front-drivers and 6-cylinder engines in the 80s, they lost credibility with their market and reliability went down the drain.

    One of GM’s big sellers was the G-body, especially the Cutlass and Regal. In ’88 they replaced it with the 6 or 4 cylinder fwd W-body, a sales catastrophe. The fugly styling didn’t help either. GM’s 6-cylinder fwd sedans were never as good or as reliable as the V8 rwds they replaced, and in luxury applications they were laughable.

    Finally, Bob misses the point on pushrods. Take his example of the Corvette engine. Sure the LS2 makes 400 hp, but that’s because it’s a 364, and there’s no substitute for cubic inches—except maybe liters (6.0). The LS2 makes 66.67 hp per liter. The LS7 does a bit better: 505 hp from 7 liters = 72.14 hp per liter.

    Now compare that pushrod V8 with a DOHC V8: the Audi 4.2. Sure it “only” makes 335 hp, but it’s got smaller displacement. If we compare apples to apples, the Audi wins: it makes 79.76 hp per liter. With the LS2’s displacement, the Audi mill would yield 479 hp; with the LS7’s, it would make 558 hp.

  • avatar
    jml

    I am/was a loyal reader. Knowledgeless rants like this serve only to bring the collective intelligence of readers down a few notches. Read a introduction to automobile design book next time.

  • avatar
    Carzzi

    Sasquatch:

    Here’s hoping the M3’s V8 will have a 90?? crank, not a 180??.

    The former has the NASCAR growl I love.

    The latter can be as good as a Ferrari 360’s howl, but then again, it can be as bad as the Lotus esprit-V8’s relatively characterless drone. Good exhaust tuning is important.

  • avatar
    EnnNorak

    Bob Elton is so right about V8 engines.  My hobby horse is to help stamp out 90-degree V6 engines as they are inherently out of balance.  In-line 6 engines are in as perfect balance as one could hope for and we should have more of them.  I drive a leased Audi A6 and its 90-degree V6 growls at certain RPMs.  Unfortunately, Mercedes also uses 90-degree V6 engines and I don't like BMW cars because they have no side protection from parking lot door dings.  Porsche has a nice horizontally opposed 6 but I can't use a sports car so I have nowhere to go for a German car.  My next car will probably be a Buick Lucerne with the Cadillac Northstar V8 — that way I can have a luxo interior and a smooth V8 without having to pay for an overpriced Cadillac.  I always knew that if I waited long enough, GM would bounce back and offer a sensible product like the V8 Buick Lucerne.

  • avatar
    Bob Elton

    Well, take a vacation and 61 people write in to lambast me for the latest editorial.

    To respond to some of the reality based comments,

    !. Marks' Standard Handbook for Mechancial Engineers has a concise analysis of internal combustion engine vibrations vs cylinder layouts. Mine is the Tenth Edition.

    2. The inline 6 is balanced rotationally, but with only 6 cylinders the power impulses do not overlap as well as those of a V8. I didn't discuss the I6 because there are so fewof them anymore, BMWs excepted. And, even BMW admits that their V8 weighs less than their current 6s. Also, the longer crankshaft of an I6 tends to introduce vibrations of its own at high revs.

    3. I never said that a V12 wasn't as smooth as a V8. What I did say was that it was no smoother, and had the added weight and expense associated with 12 cylinders.

    4. A boxer engine, 6 cylinders, is basically a V6 with a 180 deg angle. If it has a 6 throw crank, it is pretty good, but there are still rotating vibrations when looking in a plan view.

    5.  Rotary (Wankel) engines are smooth because their vibrations are at a much higher fequency, and hence harder to detect. Plus, Wankels tend to be smaller diaplacement. The reason the Wankel is a dead end, technically, is that they have an inherent disadvantage thermodynamically. That means that they use more fuel to get the same amount of power. Sort of a fatal flaw today.

    6. MDS, while it decreases the power pulse overlap, does so only at very light throttle. The rotating balance of the V8 remains. The DC system momentarily disables cylinders from the center 4, never the end 4, and then only momentarily for any given cylinder. If the cylinder were deactivated for more than a few power strokes, it would cool off and, when reactivated, emissions would be unacceptable.

    7. Engine weights are hard to come by, accurately. I've researched weights a lot for the last 40 years. I stand by my conclusions. Similarily size. Compare widths of engines, as installed. Again, I stand by my conclusions.

    8. Engine smoothness vs car smoothness. A rough engine that is well insulated from the car will lead people to think it is a smooth engine. To some degree it may not matter, but a rough engine subjects its accessories to a lot of strain, and can break exhaust systems after a while. 4 cyl engines tend to have expensive hydraulic motor mounts these days to further isolate the engine. Think your engine is smooth? Put you coffee cup on the valve cover and rev to the redline. Let me know how much coffee is left.

    9. Volvo uses a 5 cylinder engine transversely because their 6 was too long. Volvos are better cars with a 6 or an 8.

    10. Antique cars wioth inline 8, V12 or V16 engines are outside of the scope of this article. As are antique V8 engines with a single plane crankshaft.

    11. As someone mentioned, weight doesn't matter in steady state travel. But it does matter in acceleration and deceleration, which are a large, perhaps the largest, part of vehicle operation in the real world. Hiow quickly you choose to accelerate determines, to a large degree, the mileage you will get. I neglected to mention aerodynamics, but that is affected little, if at all, by engine type. And, aero effects are very limited in normal use, short of steady high speed travel.

    12. V10 engines usually come about when carmakers don't have a big enough V8. That's the case with Dodge. Ford followed suite because marketing drove engine design. Ditto at Audi, et al.

    13.Many big rigs have V8s, some V12s, though they have been fading in popularity. Mack and Detroit and Caterpillar have all offered V8s. Sixes are cheaper and simpler, and truckers are willing to live with the drawbacks.

    14. I never saw a car with a radial engine. Have you?

    And, finally, you may think I'm a crackpot, but but remember, Farago is the enabler!

    Bob Elton

  • avatar
    Bob Elton

    Oh, I should mention that I don't work for GM, or Ford or DC. My garage currently has 3 Fords, 3 DC cars (Hudsons are DC cars these days), and 5 GM cars. (big garae). But 3 of those are antiques.

    Bob Elton

  • avatar
    gbh

    Bob,

    While Marks’ is a ‘display text’ to have on your coffee table while you’re still in school, it’s hardly something degreed engineers ever use (at least that I’ve ever known). “Concise analysis” is a gross understatement. Marks’ is a VERY general tome, designed to give you an idea where to look to get to the next step.

    When Marks’ is used, it’s to garner a vague idea about a long-forgotten subject, or general formula that has slipped out of top-of-mind.

    Relying on Marks’ to provide insight on any topic is akin to basing your doctrinal thesis entirely on two entries from the Encyclopedia Britannica down at your local library. You might get in the ballpark, but you have no clue where your seats are.

    It is also worth noting that the 10th ed. is also 10+ years old. Irrelevant to this topic, but not to others.

    If you were to read some in depth analysis of V8 v. V12 configs you would find that indeed a V12 is inherently smoother than a V8. I do not necessarily disagree with the conclusion that a V12 is not worth the extra effort. But I do disagree that it is no better than a V8. Scientifically speaking, this is just simply not correct.

    If you want to know what engines really weigh, get out of your house and go down to a junkyard. If you have a decent one near by, they’ll have hundreds of engines in the back room complete. Then you can actually measure a few dozen. Since they ship a lot of those engines, the yard guys can even tell you what lots of powerplants actually weigh.

    I stand by conclusions.

    Weight doesn’t matter too much in steady-state travel. Problem is, climbing hills or changing speeds – not steady state.

    I agree Wankels are probably never going to be efficient enough to be widely adopted. Too many inherent thermo issues. Someday with highly optimized cermets, maybe.

    V10s are more of a marketing exercise than anything else. You can get the more HP and less weight doing a force-inducted V8, at least with the crappy domestic offerings.

    I haven’t seen a 12v71 in a truck in 10 years. Have you?

    I haven’t seen any production cars with a radial engine lately, but there have been several cars done with radial engines- start with the Monaco Trossi.

    There have also been a coupla radial-engined motorcycles as well, but I think they were strictly (functional) but show bikes.

  • avatar
    dfg

    Further to gbh’s comments:

    This:
    “10. Antique cars wioth inline 8, V12 or V16 engines are outside of the scope of this article. As are antique V8 engines with a single plane crankshaft.”

    is cheating. Your article holds up the V8 for all manner of “inherent” engineering advantages. many of which have been successfully countered by the posters here.

    4. A boxer engine, 6 cylinders, is basically a V6 with a 180 deg angle. If it has a 6 throw crank, it is pretty good, but there are still rotating vibrations when looking in a plan view.
    Err, you mean rocking couple? Of what amplitude? “rotating vibrations in a plan view” – so that’s how you describe the picture from Marks that you still appear to be attempting to get your head around?

    “4 cyl engines tend to have expensive hydraulic motor mounts these days to further isolate the engine. ”
    As do almost all engines, of whatever configuration….
    If you’re going to whinge about the demise of the V8, why not base the article on why they became unpopular and why and how marketing pushed the car manufacturers in that direction.

    No mention of an I8?

  • avatar
    KingElvis

    I’m convinced, although you are preaching to the choir.

    I wish to God I could’ve bought a Charger with a 260cid V8 of roughly the same horsepower (250) as the big V6 . I have the 3.5L version. It has good power – at high rpm of course, and you can feel the vibration of it at idle easily from the driver’s seat. I’m sure you would get about the same gas mileage under the same conditions too – and with a small V8 you don’t have the need for cylinder shutdown. MDS doesn’t really do much for real world gas mileage – it’s just to trick the EPA computer for CAFE compliance.

    Good point about weight too. You can quibble, but the most basic physics of the situation say lots of weight is going to take lots of energy to move.

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