Diesel engine warm up

Discussion in 'VW Mk4 Jetta, Golf, New Beetle, Passat TDI forum' started by Pete, Jul 13, 2011.

  1. Pete

    Pete New Member

    Joined:
    Mar 14, 2011
    Messages:
    23
    Car:
    2005 VW Jetta TDI
    I have been asking around this question for a long time now, but I still don't have a good answer for it.
    Why does it take longer for a diesel engine to warm up an interior of a car in comparison to a gasoline engine?
    login to remove this ad
  2. Cogen Man

    Cogen Man Member

    Joined:
    Jun 27, 2011
    Messages:
    387
    Car:
    Golf TDI/2011
    Location:
    Kingston, Ontario, Canada
    Mods:
    Window tint, window vent visors, ScanGauge II.

    Diesels don’t run as warm as gasoline engines and many drivers still remember how long it took the interiors of 1970s and 80s Mercedes and Volkswagen diesels to warm to a comfortable level. That's why the 2011 Golf TDI that I have have heated seats. And boy do they work.
  3. chittychittybangbang

    chittychittybangbang Administrator

    Joined:
    May 23, 2007
    Messages:
    21,852
    Car:
    2006 Jetta TDI
    Location:
    CT
    Cast iron block and beefier components = more mass to warm up.
    Less waste heat = less heat transferred to engine coolant (engine coolant warms the cabin).
  4. Keithuk

    Keithuk Super Moderator

    Joined:
    Aug 29, 2010
    Messages:
    5,449
    Car:
    2010 Golf GTD (170) CBBB
    Location:
    Stoke on Trent, England
    Diesel engines have an higher thermal efficiency that petrol so more heat from the fuel burnt does work and isn't absorbed into the cooling system. This is mainly due to the higher compression ratio of a diesel. A petrol engine has a thermal efficiency of 25% a diesel has a thermal efficiency of 35% thats why you get more miles per gallon. Thats why for every $1 of fuel you put in a petrol you get 25 cents of power out of it and 35 cents of power from a diesel.

    VW know that diesels take longer to warm up thats why they fit an auxilary heater in the heater system thats burns diesel in its own chamber to warm the inside of the car in colder countries.

    Thermal Efficiency

    Diesel Cycle

    Diesel Engine
  5. Turbo Lag

    Turbo Lag Member

    Joined:
    May 6, 2011
    Messages:
    150
    Car:
    99 Jetta TDI
    Location:
    Knoxville
    Don't worry, with global warming you wont have to worry about heating the interior of your car :panic:
  6. vwman

    vwman New Member

    Joined:
    Jul 14, 2011
    Messages:
    2
    Car:
    volkswargen/1985
    I have heard, that it is because a diesel engine, is made of thicker metal.

    Another theory I have, is that a gasoline engine takes more rpm than the diesel engine, which means that petrol makes more burns
  7. Turbo Lag

    Turbo Lag Member

    Joined:
    May 6, 2011
    Messages:
    150
    Car:
    99 Jetta TDI
    Location:
    Knoxville
    What you mean by take more RPM's? You talking about idle or cruise speed?
    Either one i'm going to have to bust that theory. :) Unless you mean that a gas engine requires more fuel to burn to mantain a set rpm then a diesel? Diesel fuel dose burn cooler.
  8. Keithuk

    Keithuk Super Moderator

    Joined:
    Aug 29, 2010
    Messages:
    5,449
    Car:
    2010 Golf GTD (170) CBBB
    Location:
    Stoke on Trent, England
    They are slightly more robust because of the higher combustion pressures involved thats why they don't generally rev higher than a petrol.

    I think he means that petrol engine tend to rev higher than diesel engnes and therefore more fuel is burnt.
  9. chittychittybangbang

    chittychittybangbang Administrator

    Joined:
    May 23, 2007
    Messages:
    21,852
    Car:
    2006 Jetta TDI
    Location:
    CT
    The speed of fuel combustion is also a limiting factor. There is a window to inject the fuel and burn cleanly.

Share This Page