Subaru's PZEV's

Discussion in 'Community Discussion' started by silbeej, Nov 9, 2008.

  1. silbeej macrumors 6502a

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    Feb 3, 2007
    #1
    So i'm looking into a Subaru as one of my other threads had made clear, but i'm not so clear on the pzev. I know it is partial zero emissions, so fuel is shut off if the car is moving faster than the engine wants to go etc, but there are some things i'm not so clear of. First off, why does the PZEV engine make 175hp vs the standard engine making 170hp? Is there any adverse effect on fuel economy, cuz i have an 08 Outback which doesn't have the PZEV, and i'm getting 27/33 for my MPG, and i don't want it to go down a ton if i get a PZEV one. Any info on this topic would be nice.
     
  2. Lord Blackadder macrumors G5

    Lord Blackadder

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    #2
    A bit off-topic, but you can also consider the diesel Subarus coming out next summer.
     
  3. silbeej thread starter macrumors 6502a

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    #3
    I don't think the US versions are coming until 2010. I have heard that there are going to be new Outbacks and Legacys soon as well, but cant find any information about them. And i don't have to have a PZEV, just in my state thats how they are sold, so i want to find out whats different about them.
     
  4. Lord Blackadder macrumors G5

    Lord Blackadder

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    #4
    The diesels are coming as 2010 year models, which arrive in summer/fall '09. Not sure what they've done to make the PZEV version...probably different valve timing programming (current non-aspirated Subaru 2.5L engines have variable valve timing) and additional emissions scrubbing apparatus.

    Increasing engine efficiency increases both power and economy, though it doesn't necessarily affect emissions. Conversely, emissions control shave a history of strangling power and economy. As emissions controls have gotten better, they affect power and economy less.
     
  5. Counterfit macrumors G3

    Counterfit

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    #5
    Current 2.5l normally- (or naturally-, if you prefer) aspirated Subaru engines have variable valve lift. i-AVLS, Active Valve Lift, because it's not even that variable. On one intake valve per cylinder, there are two cam lobes and rockers. At low RPM, the low-lift rocker is used, while at higher engine speeds, a solenoid locks the two rockers together, using the high-lift lobe. It's either on or off, no middle.



    non-aspirated means it doesn't breathe :p



    Edit: According to Cars101.com (great site for anything you want to know about Subarus), here's what goes into a a car being a PZEV:
    1. A charcoal cannister catches unburned gas left in the engine when it's turned off so it doesn't just evaporate.
    2. Fuel injectors that close tighter when they're not in use.
    3. A finer mesh in the catalytic converter, as well as optimized placement of its precious metal.
    4. The engine's electronic brain is tuned to run the hot at start up to help the catalytic converter heat up so it can start doing its job faster.
     
  6. silbeej thread starter macrumors 6502a

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    #6
    So bottom line i'm asking now is: Does the PZEV mean it restricts the engine more, thus giving me worse fuel economy? Subaru rates it the same as the regular engine, but i need to know if i will still get my crazy good MPG in an 09 as i do in an 08.
     
  7. Counterfit macrumors G3

    Counterfit

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    #7
    I don't think the cat would add too much, and I think the evap system and injectors could probably make up for the loss.
     

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