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Mainstream Large Sedans Comparison

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Comments

  • captain2captain2 Posts: 3,971
    The Aura is a heavier car that rates slightly better than the LaCrosse 4 speed FE wise, despite more HP, an indication that the 6 speed helps in that regard. And then, of course, there is always the CVT, something that GM has avoided to this point, but good for efficiency, if somewhat disconcerting.
    But I'll obviously agree with you, after 50k in my Avalon, the 2GR Toyota engine sets the bar awfully high in all respects and remains unmatched for over 2 years now.
  • captain2captain2 Posts: 3,971
    I'm curious - what rpm is your 3.8 pulling at a constant 70 in 4th? Can't imagine that it is a whole lot different than the Avalon which is right at 2100 in 5th, and also well into the 30s (mpg wise) at that speed. It is possible to GAIN at least that 20% with hi-tech - my overall mpg is a solid 27!
  • joe131joe131 Posts: 972
    engines with narrow torque curves pulling a lot of weight are the ones that need extra gears in the transmission
  • dodgeman07dodgeman07 Posts: 573
    I'm curious - what rpm is your 3.8 pulling at a constant 70 in 4th? Can't imagine that it is a whole lot different than the Avalon which is right at 2100 in 5th, and also well into the 30s (mpg wise) at that speed. It is possible to GAIN at least that 20% with hi-tech - my overall mpg is a solid 27!

    In my '06 Lucerne, I'm just under 2,000rpm at 70mph in 4th gear. I agree that you can can gain 20% in mileage with the hi-tech engines, it's just that GM isn't getting that mileage now. If you're getting "well into the 30s (mpg wise) at that speed" in your Avalon, you're doing a lot better than most people.

    The Avalon's a great car but I wanted to stay under $25K (I got my used '06 Lucerne with 18,000 miles on the clock for $19K) and the Avalon's were all well over $25K with less warranty compared to Buick's 4yr/50,000 mile bumper-to-bumper zero deductible.

    I would never fault somebody for buying a Toyota as my company is a major supplier of engine components to them. ;)
  • captain2captain2 Posts: 3,971
    you sound like somebody that might know - not knowing which Toyota engines your co. makes components for.
    kind of like this?:
    back in 03/04 Toyota Corporate/Design (California) in need of a new V6, that would rival anything available and be strong enough to share with a multiude of Toyota/Lexus vehicles - approached their engine plant (in Missouri?) and challenged them not only to design the engine but also to knock $1000.00 of mfgr. cost out of each and every one of them. Believe that "Japan" had very little to do with it, and the co. exports the engine to Japan primarily for Lexus? The result now apparently saving Toyota hundreds of millions per year??
    Yep, as soon as you put leather in an Avalon (Touring and above) it is tough to keep it under even $30k given some rather nasty profiteering that's been going on with the distributors since day one. Despite that, however, it remains the cheapest car in this group to own over a defineable period of time, given the relatively astronomical residual values. A simple choice IMO - you can certainly save money now, only to effectively pay it back later. 32 or 33 mpg in an Avalon at a constant 70, BTW, I don't believe is unusual at all!
  • captain2captain2 Posts: 3,971
    understand the implication to which I would counter than none of the cars listed above 'need' the extra gears. These multiple gear trannies are a fad of sorts (of questionable virtue) for the consumer that thinks more is better. They may possibly (but not all the time) squeeze an extra mpg or two. Otherwise you might just have a hard time explaining 8 speeds in Lexus V8s, 7 speeds in 400 hp MBs etc. etc.. Incidentally, the VVTi (or even better CVVTi) systems in these better engines can and do serve to widen and flatten these torque curves that you pushrod guys hold so dear while you're sacrificing 50+hp and a whole lot of acceleration and smoothness/refinement. The 4 speed transmission and the smaller pushrod engines are dinosaurs that will go the way of the Powerglide, the Slant 6 and the 3.8 , inevitably replaced (2010 mandate) by these 5+ speed trannies in DBW systems so that the government can protect us from ourselves and screw up our cars in the process.
  • joe131joe131 Posts: 972
    I did not imply, but it seems you inferred.

    I just made a statement: "engines with narrow torque curves pulling a lot of weight are the ones that need extra gears in the transmission"
  • captain2captain2 Posts: 3,971
    to which I said, this doesn't apply to any of the cars in this group - so why bother talking about it, we are NOT comparing a bunch of pseudo sports small cars here with high strung 4 bangers are we?
  • joe131joe131 Posts: 972
    Doesn't necessarily matter how many cylinders a motor has. A motor with fewer cylinders can have a fatter torque curve than one with more cylinders, or vice-versa. Two motors with the same number of cylinders and the same displacement can also have very different torque curves.
    I do not have graphs on all the motors of all the cars mentioned in this forum. Some may be peaky (narrow torque band) compared to others here. If so, the peaky ones are the ones which will more likely derive a performance benefit from extra gears.
    Is the new Lexus with the 8 speed auto transmission one with a peaky motor? I don't know.
    Can you post all the torque curves of all the motors for us?
  • cobrazeracobrazera Posts: 352
    IMO an engine doesn't need to be peaky in order to take advantage of extra gears in the transmission.

    What's important is the " ratio spread " which is found by dividing the first gear ratio by the top gear ratio. The higher the number, the lower first gear can be for quick acceleration, and the higher top gear can be for economical cruising.

    If there are less gears in between the extremes, then the engine will require a wider torque spread to bridge the gaps.

    One of the reasons that CVT transmissions get better mileage than a conventional transmission is because of their very wide " ratio spread " - usually greater than a figure of 6.0 ( most automatics, even with six speeds, don't get much over 5.0 ). IMO, Lexus, Mercedes, BMW, etc. are pursueing the wide " ration spread " of CVTs by using more gears ( CVTs being questionable at transferring large amounts of torque )
  • captain2captain2 Posts: 3,971
    as a general rule more cylinders = more displacement = more torque spread over a wider band. Know of any 4 bangers over 2.5 liters or any V8s less than 4? Small truck V6s tend to be 'stroked' 4+ liter versions of some of the engines here - for a reason. And sure, different engine designs will certainly have torque curves and different HP outputs. And while torque can have an effect on drivability, it really has little to do with acceleration, otherwise cars in this class like the Lucerne 3.8 and the 500 DT 3.0 (DOHC) wouldn't be nearly so 'challenged'.
    The pushrod, however, is an antiquated 'technology' that would seem to only have applications in things like oversized V8s and is out of place in cars in this group. Not to worry, though, bet they will all finally be gone (except the V8s) within the next few years. Kind of depends on GMs ability to finance new engine production...
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,048
    >while torque can have an effect on drivability, it really has little to do with acceleration, otherwise cars in this class like the Lucerne 3.8 and the 500 DT 3.0 (DOHC)

    The extra torque works well to move a full-sized car because it's heavier. Put the 3800 that you know so little about into a light car and it moves because of the torque.

    Do you have any data to support your statement
    "oversized V8s and is out of place in cars of this group."? That sounds like an opinion.
  • captain2captain2 Posts: 3,971
    "oversized V8s and is out of place in cars of this group."? That sounds like an opinion
    of course an opinion, in deference to gas prices, weight imbalances, and TS issues in FWD cars!
    and yes the only thing I KNOW about that old 3.8 is that it won't hold a gear on even a gentle incline with the cruise set on 70 - so much for all that 'usable' torque you like to talk about. The Lucerne, in ths case, simply weighs too much for 200 hp and the available torque it does have.
  • rockyleerockylee Posts: 14,011
    W/E captain. The 3800 is more than adequate to move the Lucey. The Bonneville was around the same weight and the 3800 was in it for years. :confuse: If this is such a problem for you then step up and get a real car like the Buick Lucerne Super. That car will have more than just a set of grape fruits in the pants. :shades:

    Rocky
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,048
    >that old 3.8 is that it won't hold a gear on even a gentle incline with the cruise set on 70 -

    Strange that my cars all can handle inclines on Interstates between here and Nashville and rarely, I mean rarely, downshift into third. There are a couple between Cincinnati and Louisville that are steeper than typical.

    I think you don't know what you're talking about and are just making up stuff to have something negative about the 3800. No problem. Now I've read discussions about the weak sister OHC motors with low torque high horsepower shifting up and down in the cars that require 6- and more speed transmissions for driveability. Indeed the X3 I rode to the Reds games in beside being rough-riding kept shifting up and down and it was only a 5-speed IIRC.
  • tjc78tjc78 JerseyPosts: 5,025
    The Lucerne with the 3.8 is slow. The Bonneville for all its sporting pretentions was also not that quick either. In all boils down to progress. The 3.8 was fine 10 - 15 years ago when 200 HP in a large sedan was good. With the available technology the "bar" has been raised. Why would anyone want to drive an outdated slow to rev OHV engine, when you can get a free revving OHC engine with 70 more HP and better FE to boot. Its really a shame, the Lucerne is a nice vehicle but the powertrain options are just not there. Now, as I and other members of the forum have said, drop in the 3.6 and the six speed and you may have something.

    1999 Chevy S10 / 2004 Merc Grand Marquis / 2012 Buick LaCrosse

  • captain2captain2 Posts: 3,971
    then step up and get a real car like the Buick Lucerne Super
    assume that it then may keep up with an Avalon, Azera, or Maxima all at a penalty of a few mpgs? If I want a V8, then I sure as heck don't want FWD! Maybe the best thing to do is to wait for GM to replace the Lucerne with a V8 RWD model in 09/10 - just don't know if that will be before or after gas hits $5/gallon. :cry:
  • captain2captain2 Posts: 3,971
    The 3.8 was fine 10 - 15 years ago when 200 HP in a large sedan was good.
    this I'd agree with - because 10 or 15 years ago these cars didn't weigh near 4000 lbs. did they?
  • rockyleerockylee Posts: 14,011
    My 92' Bonneville SSEi weighed I believe 3800 lbs. but I could be wrong. :confuse:

    Rocky
  • rockyleerockylee Posts: 14,011
    Well the RWD Lucerne, will likely not make it to market until 2010, as a 2011 model. The Buick Velite Sedan could be here in 09' as a 2010 model built on the Zeta, archetecture. I would assume a Convertible will be out at the same time or the year after. ;)

    So yeah the 3.6 would be a better choice.

    The Lucerne should have this line-up.

    CX- 3800 V6 197-205 hp.

    CXL- 3.6 "High Feature" V6 with 255 hp.

    CXS- 4.6 Northstar with 292hp

    Super- 320hp Northstar V8

    -Rocky
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