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Timing an engine

  • 04-08-2018 08:01AM
    #1
    Grueller
    Registered Users, Registered Users 2 Posts: 5,647 ✭✭✭


    All the threads about timing belts, chains and failures of them got me thinking.
    I drive an 06 Isuzu Dmax. It is certainly an "agricultural" driving experience. However the engine is timed by gears and is a lifetime maintenance free solution.
    Is there any good reason why this can't be done in more engines? Does it make an engine noisier or less refined which would make little difference in a pick up but a big difference in a car?
    Are there many any other engines that have this solution out there?


Comments

  • #2
    tabby aspreme
    Registered Users, Registered Users 2 Posts: 4,538 ✭✭✭tabby aspreme


    Timing belts are lighter , have less resistance, so better fuel economy, less noise, gears are ok for a single cam, lower revving engine


  • #3
    Hotblack Desiato
    Registered Users, Registered Users 2, Paid Member Posts: 40,870 ✭✭✭✭Hotblack Desiato


    tabby aspreme wrote: »
    Timing belts are lighter , have less resistance, so better fuel economy, less noise, gears are ok for a single cam, lower revving engine

    Honda VFR750 bike engine was DOHC (actually quad cam - a V4 with two DOHC heads) and far from low revving

    The reasons they went back to chains were production cost and noise.

    Also the head can't be skimmed unless thicker head gaskets are available to compensate.

    I'm partial to your abracadabra
    I'm raptured by the joy of it all



  • #4
    Henry Ford III
    Moderators, Business & Finance Moderators Posts: 18,175 Mod ✭✭✭✭Henry Ford III


    Timing chains aren't bullet proof either.


  • #5
    Grueller
    Registered Users, Registered Users 2 Posts: 5,647 ✭✭✭Grueller


    Henry Ford III wrote: »
    Timing chains aren't bullet proof either.

    Gears are fairly bulletproof though


  • #6
    [Deleted User]
    Posts: 17,925 ✭✭✭✭ [Deleted User]


    A decent valvetrain design and a 90k mile timing belt interval shouldn't be problematic.

    Timing chains even when in fairly poor applications do generally give plenty of warning signs.

    If timing gear sets were more common you can be sure a manufacturer or two would make a mess of it somehow resulting in plenty bad press.

    The added cost to gear the timing in a quadcam, 24v, v6 engine would be eyewatering.

    You might reckon a gear timed engine is bulletproof but there's moving parts aplenty & contact so there's inherent wear.... conceptually it's not at all bulletproof :)


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  • #7
    dr.fuzzenstein
    Banned (with Prison Access) Posts: 16,575 ✭✭✭✭dr.fuzzenstein


    Henry Ford III wrote: »
    Timing chains aren't bullet proof either.

    They would be, but then some engineer says "well, we can save €0.05 per engine if we make them just a tiny little bit thinner and lighter"


  • #8
    mickdw
    Registered Users, Registered Users 2 Posts: 23,985 ✭✭✭✭mickdw


    dr.fuzzenstein wrote: »
    Henry Ford III wrote: »
    Timing chains aren't bullet proof either.

    They would be, but then some engineer says "well, we can save €0.05 per engine if we make them just a tiny little bit thinner and lighter"
    Not only cost. Engine efficiency drives a lot of the decisions. If they can use light weight materials with reasonable lifespan, they will cause it will help the push towards lower emissions. They don't seem to give a damn once components are good enough to get them over the warranty period.


  • #9
    Grueller
    Registered Users, Registered Users 2 Posts: 5,647 ✭✭✭Grueller


    Augeo wrote: »
    A decent valvetrain design and a 90k mile timing belt interval shouldn't be problematic.

    Timing chains even when in fairly poor applications do generally give plenty of warning signs.

    If timing gear sets were more common you can be sure a manufacturer or two would make a mess of it somehow resulting in plenty bad press.

    The added cost to gear the timing in a quadcam, 24v, v6 engine would be eyewatering.

    You might reckon a gear timed engine is bulletproof but there's moving parts aplenty & contact so there's inherent wear.... conceptually it's not at all bulletproof :)

    Good response. Am I incorrect in thinking geared setups would be superior to chains or belts?


  • #10
    tabby aspreme
    Registered Users, Registered Users 2 Posts: 4,538 ✭✭✭tabby aspreme


    dr.fuzzenstein wrote: »
    They would be, but then some accountant says "well, we can save €0.05 per engine if we make them just a tiny little bit thinner and lighter"

    Fixed that for you


  • #11
    CJhaughey
    Registered Users, Registered Users 2 Posts: 14,670 ✭✭✭✭CJhaughey


    Augeo wrote: »
    A decent valvetrain design and a 90k mile timing belt interval shouldn't be problematic.

    Timing chains even when in fairly poor applications do generally give plenty of warning signs.

    If timing gear sets were more common you can be sure a manufacturer or two would make a mess of it somehow resulting in plenty bad press.

    The added cost to gear the timing in a quadcam, 24v, v6 engine would be eyewatering.

    You might reckon a gear timed engine is bulletproof but there's moving parts aplenty & contact so there's inherent wear.... conceptually it's not at all bulletproof :)

    The Honda engine in the VFR is no different, Quad cam V4, only two extra pots per bank.
    They rev a lot higher as well and had no difficulty with longevity.
    It comes down to noise as well, timing gear engines tend to make more mechanical noise than belts or chains which engineers/manufacturers are trying to reduce as well.
    I think its cost driven though.
    d-gear.jpg


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  • #12
    kona
    Registered Users, Registered Users 2 Posts: 7,522 ✭✭✭kona


    Chains gears and belts are a waste of time. Camless engines are the way to go but i dont think they will make it to mainstream with the impending obsolescence of the I.C.E


  • #13
    [Deleted User]
    Posts: 17,925 ✭✭✭✭ [Deleted User]


    Grueller wrote: »
    Good response. Am I incorrect in thinking geared setups would be superior to chains or belts?

    Superior in what way?
    A belt & pump change on a 4cyl is €300/500 ......I don't see the need for a geared setup :)


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