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2008 Sienna Hybrid - Do you want 4 cylinders or 6?



  • timothyhtimothyh Posts: 11
    The Dept of Transportation just published their proposed CAFE minimums for 2011-15. Toyota is supposed to average 26 mpg for their light trucks in 2012, rising to 28mpg in 2015.

    The current Sienna averages 19mpg according to the EPA.

    Come on Toyota. Give us a more efficient van for our families!!
  • wwestwwest Posts: 10,706
    [quote name='diver1972' date='Tuesday, Apr 22, 2008 @ 03:36 PM' post='146287']
    Exactly how much safety are you trying to achieve? What exactly are you wanting to protect against?

    The Tundra is RWD and therefore will be significantly safer in overall operation on adverse, ice or packed snow, roadbed conditions.

    Yeah, I've heard rumors ranging from 2010 MY to 2012 MY. Like the other hybrids, it's likely to achieve real MPG gains only in stop-go-stop-go-stop-go traffic conditions (i.e. where the ICE can shut off). Since the ICE is still needed to push it down the road on the interstate, highway MPG isn't likely to improve much,

    Well, not really. With the "electrics" along to act as an ICE SuperCharger the ICE can not only be downsized (lower frictional losses), but made more efficient at fuel "burn" using the Atkinson Cycle technique or simply derated as in the HL and RX.

    if any, over what it is now. No matter how you look at it, it's still a 4,000-pound vehicle with a 3.5L 6-cylinder, not a 2,500-pound Cavalier with a 2.2L 4-cylinder. More liters drink more fuel. :sad:

    "..with a 3.5L 6-cylinder, not a..."

    That's the point, or at least partially so...

    The turbocharged 2.3L I4 in the Acura RDX produces 260HP....

    Think about what could, MIGHT, be done with a hybrid 2.0L I4 using the Miller Cycle via an engine driven Supercharger. But with the positive displacement composite (carbon fiber) SC speed/boost controlled independently of the engine RPM using the Toyota HSD CVT concept. During hwy cruise the ICE would just "loaf" along with the SC providing enough, "just" enough, the exact right amount (NO throttle plate), of intake airflow for the level of engine performance required/needed.

    Okay, now put your foot "into it", the lightweight carbon fiber SC spools up virtually instantly putting the ICE "on boost" and the electrics "kick in" their extra TORQUE.

    Zoom, ZOOM,....ZOOM...!!

    And all with absolutely STELLAR FE.

    Now just add a CNG conversion kit w/tank (carbon fiber) and refill the CNG tank overnight at home using PHILL.

    Using CNG (~100 octane equivalence) would not only increase the "standard" ICE's HP/torque substantially, but would allow the compression ratio to be increased to an even higher level..

    Maybe we wouldn't need a LARGE 2.0L ice, maybe a 1.5L would suffice.
  • timothyhtimothyh Posts: 11
    VERY unfortunately, Toyota is not going to put an Acura (Honda) engine in one of its vehicles.

    It should.

    The Camry 4-cylinder (2.4L) gets 155hp. As you noted, the 2.3L Acura turbo charged 4-cylinder gets 260hp. The Acura TSX without a turbo gets 207hp.

    When I first started this thread, I was hoping that SOMEONE at Toyota would focus on a highly efficient large vehicle. The Highlander falls short. And as Atexeria pointed out, it would not be for everyone. If you need to tow something, don't get a hybrid. If you want good acceleration, get a Highlander hybrid or don't get a hybrid.

    As they did with the Prius, would Toyota make a large vehicle that focuses on fuel economy. The Prius has a 1.1% market share of all vehicles sold in the US. Every other hybrid combined also has a 1.1% market share.

    Fuel efficiency doesn't turn everyone on. But if its very important to 1% of the new car buyers - one's with families -

    Come'on Toyota!! Let us have it!
  • ateixeiraateixeira Posts: 72,587
    CAFE uses unadjusted EPA fuel economy numbers.

    They've been lowered twice, yet CAFE still uses the very outdated higher numbers from the 1980s.

    The Sienna would probably get 23-24mpg on that old scale.
  • V-6's are rough enough, especially in 90 degree configuration and without counterbalancers. Coming from my last three cars with rotary, inline 6, and V-8 motors, the current Sienna motor doesn't feel particularly smooth to me. The last thing I'd want is a large unbalanced inline 4 booming away under the hood. Inline fours are not in primary balance, nor are 90 V-6's. The only way to get them to be truly smooth is use counterbalancers, which add weight and mechanical complexity. At least a decent V-6 is smoother than an inline 4.
  • wwestwwest Posts: 10,706
    "The only way to get them to be truly smooth...."

    Yes, that's likely very true for I4/inline, but what about "boxer" style..??

    Wouldn't those be even more "perfectly" balanced vs any "V" engine..??
  • jim314jim314 Posts: 491
    There is negligible additional complexity in having twin counter rotating balance shafts to smooth out an inline 4-cyl. I know Chrysler used them on its now superceded 2.5L 4-cyl. I suppose that the European mfgrs use them on their 2.0 L 4-cylinder engines.
  • ateixeiraateixeira Posts: 72,587
    The chain-driven 2GR V6 isn't exactly known for being quiet. The 3MZ was actually more quiet.

    It's worth the trade-off for all the extra horsepower, but still.

    FWIW Toyota added sound insulation to the fire wall and along the door sills to offset the extra noise from the V6.

    Hybrids often shave weight by removing sound deadening, though.
  • ateixeiraateixeira Posts: 72,587
    People are asking for an AWD descrition in this thread:

    Can you please hop over there?
  • timothyhtimothyh Posts: 11
    Toyota introduced an updated version of its Japan-only minivan, the Alphard, last week. The Alphard did have a hybrid version from 2004-08. The 2009 drops the hybrid version. Toyota is introducing a V-4 and a V-6 version of the Alphard in Japan. The V-4 is said to get 27mpg. Does anyone know whether that's highway or combined?

    Does any one know if this means no hybrid system for the Sienna?
  • surjn98surjn98 Posts: 34
    When does the next generation Sienna come out? Just curious!!
  • timothyhtimothyh Posts: 11
    The speculation is 2010.
This discussion has been closed.