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what do these engine terms mean?

Discussion in 'Motors Archive' started by izoneiz, 20 Oct 2002.

  1. izoneiz

    Wise Guy

    Joined: 18 Oct 2002

    Posts: 2,333

    Location: London, WC1

    DOHC (direct overhead cam)
    Common rail Diesel
    Twin cam

    Also, how does a V5 unit work? becuase surely it would have 3 on one side, and 2 on the other?

    If i think of more questions ill add them

    cheerz

    IZONEIZ
     
  2. PurDunamis

    Wise Guy

    Joined: 18 Oct 2002

    Posts: 1,179

    Location: Messing with a Nd:YAG, DCM and a Raman Shifter

    Overhead Cam
    The cam shaft is dicectly above the valves and opens them directly - as opposed to a side cam where the motion is transmitted via followers, pushrods, and rockers

    Common Rail Diesel
    Errr - not sure (have a fair idea - but I'm sure someone will be along with the definative answer soon enough:))

    Twin Cam
    Just what it sounds like - Two cam shafts, typically part of the overhead cam design, one for inlet one for outlet - useful for higher numbers of valves per cylinder

    :)

    [edit] Missed the V5 bit

    Your right it does have different numbers of cylinders in either bank - you balance the load by having an flywheel that if not symetrical, that way the engine is rotationaly balanced

    [/edit]
     
    Last edited: 20 Oct 2002
  3. Bill101

    Soldato

    Joined: 18 Oct 2002

    Posts: 5,550

    Location: Liverpool

    DOHC is double overhead Cam
    Common rail diesel is the newer way to inject fuel into the cylinders
    Twin cam...well there are two of them (so they only lift half the valves so they can,in theory spin faster while only doing half the work of a single cam.
    V5 is a bit of a fudge, I think they are not true V engines, they will have a banencer shaft or similar to smooth out the enging
     
  4. Chabsy

    Hitman

    Joined: 18 Oct 2002

    Posts: 655

    Location: London

    i think common rail is like a turbo diesel but air is injected into the cylinder at very high pressure increasing the compression
     
  5. tigerstyle

    Sgarrista

    Joined: 18 Oct 2002

    Posts: 8,963

    Location: UK

    or as in almost all the big ford V8s still and other oldish engines,

    the camshaft sat at the bottom of the engine (well it wasnt really a camshaft) and the pushrods went all the way up through the block to the top, then connected with linakges at the top

    this was very clumsy, and you can imagine all the stress and force it took to push the ahem, push rods, a light spinning cam is much lighter, simpler

    so this should kinda enlighten you as to how having a camshaft at the top is much simpler :)
     
  6. Lopéz

    Man of Honour

    Joined: 17 Oct 2002

    Posts: 27,543

    Location: Leicestershire

    What is Common Rail?

    A common rail engine is designed to supply constant fuel pressure to electronically controlled injectors through a shared fuel reservoir. This means that the fuel supply is not dependent on the engine revs. A common rail system is built around four basic components:

    A high pressure pump with pressure regulator and inlet metering valve.
    A rail which contains a pressurised reserve of fuel.
    Injectors which inject precise amounts of fuel into the combustion chamber as required.
    A Diesel Control Unit – the ‘brain’ of the system, which precisely controls injector flow and timing as well as rail pressure while continuously monitoring the operating conditions of the engine.
    Benefits of Common Rail:

    Accomodates all planned emissions legislation
    Opportunity for pre-injection and post-injection
    Modular system
    Compact
    Full electronic control
    Fuel Economy
    Enhanced reliability and performance
    Cover’s a variety of vehicle applications.

    Taken from:
    http://www.delphidieselsystems.com/diesel/uk/UKDDSproductitems5940.asp
     
  7. nutcase

    Sgarrista

    Joined: 18 Oct 2002

    Posts: 7,625

    Location: SX, unfortunately

    Some useless did u know info: Did u know that it is impossible to totally balance a 4cyl inline engine? Can't rememebr why, did it in dynamics a few yrs ago. 3cyl, 5cyl, 6cyl etc. can be balanced totally tho'
     
  8. PurDunamis

    Wise Guy

    Joined: 18 Oct 2002

    Posts: 1,179

    Location: Messing with a Nd:YAG, DCM and a Raman Shifter

    I knew that - can't remember why either:p :D
     
  9. Sharknose

    Wise Guy

    Joined: 18 Oct 2002

    Posts: 1,772

    You may find this useful :)

    http://autozine.kyul.net/technical_school/tech_index.htm

    Got a section on engine layouts, such as V5, W12, W16, V8 etc etc.

    Also lots of stuff on VTEC (mmmmm, VTEC :D), VVC, VANOS, VVTL-i, SAABs variable compression.

    .... and theres stuff on suspension, chassis etc as well.
     
    Last edited: 20 Oct 2002
  10. Dogbreath

    Capodecina

    Joined: 18 Oct 2002

    Posts: 16,651

    Location: Devon

    DOHC = Double Overhead Cam = Twin Cam. Two cams, located in the head are used to control the valves, one cam is used for exhaust valves, the other for inlet valves.

    Yes, a V5 would have 3 and 2 cylinders per bank. I imagine that VW have to use a balancer shaft to get the engine as smooth as it is reputed to be.

    The "Common rail" system is more like a multipoint injection system on a petrol engined car, although the fuel is injected directly into the cylinder rather than the intake manifold. Previous systems used mechanical injectors that were all fed independantly from a mechanical/electro-mechanical pump and distributor.
     
  11. pinkaardvark

    Soldato

    Joined: 18 Oct 2002

    Posts: 6,705

    Location: Cambs

    Re: Re: what do these engine terms mean?

    Do VW do a V5 engine then? I know they do a 5V which is actually a 20Valve 4 cylinder unit.
     
  12. Ev0

    Capodecina

    Joined: 18 Oct 2002

    Posts: 13,842

    Yup they do a V5 engine.

    Its in the Golf V5 (model down from the 4motion), Bora and Beetle.

    As said , common rail diesel I always thoguht meant that the fuel rail was under constant high pressure and directly injected into cylinder, rather than swirl pot.

    the high pressure causes the fuel to be injected in a better way, think of it as spitting water out of your mouth. If you just kind of open your mouth , the water just runs out in a big lump as such, if you put your lips together and really push it out with some pressure it comes out as a fine spray, which in an engine will combust easier.

    Dunno if that sounds right, couldnt think how to put it into words, been a long weekend :).
     
  13. IainB

    Man of Honour

    Joined: 18 Oct 2002

    Posts: 1,951

    Location: Hertfordshire

    So my 'Camshaft' isnt a camshaft - explain ya self pedster :D
    Me's all confused now :p
     
  14. Dogbreath

    Capodecina

    Joined: 18 Oct 2002

    Posts: 16,651

    Location: Devon

    Although of course, it's not really a proper V engine as the con rods of adjacent cylinders do not share a common crank journal.
    A swirl pot is something completely different. It is used mainly on cooling systems to ensure any air bubbles in the coolant are removed. It is occaisionaly used on a fuel system for a similar reason, but only ever on the low pressure side of system, i.e. a lift pump will pump fuel into the swirl pot, and then the high pressure pump will deliver the fuel to the fuel rail.

    The fuel HAS to be injected at very high pressure on a diesel system, irrespective of wether it uses a convetional or common rail system, because the fuel is directly injected into the cylinder, which is at high pressure to start with (due to high CR). A diesel injection system may have peak pressures of 20,000 PSI, a typical petrol injection system runs at around 30-45 PSI.