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  1. #101
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    That 88 Honda F1 was a VERY different engine, much bigger. We are talking about a 1600cm3 R4 and imho it`s quite impressive, where we are today (not only WRC, but also small cm3 turbo engines on std. road cars but still we can see more reliability issues, like small TSI engines for example).
    Last edited by Tarmop; 2nd February 2017 at 20:56.

  2. #102
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    Bigger? OK, it was V6 but still 1500ccm...

  3. #103
    Senior Member Mirek's Avatar
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    Quote Originally Posted by J_n_z View Post
    Bigger? OK, it was V6 but still 1500ccm...
    Yes, F1 is different, rules, materials, area of use, fuel, the engine had only 50 mm stroke (closer to motorbikes of today than to cars). The point is that it is better not to use high rews when You don't need to do so. High rews mean also high friction losses (they grow with the square of engine speed) and therefore less efficiency (not only engine but also gearbox).

    Quote Originally Posted by Tarmop View Post
    but also small cm3 turbo engines on std. road cars but still we can see more reliability issues, like small TSI engines for example).
    In this case it's mostly about design flaws. It's possible to design totally reliable small turbo engine for decent price, the best example is 1.0T Ford EcoBoost
    Stupid is as stupid does. Forrest Gump

  4. Likes: itix (5th February 2017)
  5. #104
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    Quote Originally Posted by Mirek View Post
    Jan, it might sound weird but I am sure that the problems with broken valve springs on S2000 cars were real and not that uncommon.

    On the other hand I think that only few times Fabia (the car with the longest stroke - 92 mm) suffered from broken conrod and that was due to a faulty batch of them. Otherwise even with brutal overrewing usually something else broke.

    The long stroke actually doesn't apply to 1.6 WRC engines built from scratch (usually bore/stroke around 83/73). The only 1.6 WRC engine with long stroke was Mini due to the fact that it was the only one based on production unit (PSA/BMW EP6CDT).
    That makes sense on the "custom" engines...there IS a need for enough room to have valves of a certain size.....
    The valve spring failures well that sound just plain wrong calculations and what I call "getting greedy design/choice wise.

    I wonder how many guys here actually build and modify motors for competition???
    John Vanlandingham
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  6. #105
    Senior Member itix's Avatar
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    Quote Originally Posted by Mirek View Post
    I'm sorry, my English is probably not good enough, but I don't know what You mean by valveflow.

    Anyway I don't know the exact WRC rules.

    AFAIK the problem with S2000 valves was that they had to be made of steel, i.e. they were heavy. With such high engine speed the valve springs had to cope with very high valve inertia. For me it is an example of a wrong idea how to make things cheaper.

    Dim: That's exactly what I though - if the higher top speed as the only clear benefit is worth the effort to make the engine reliable at so high rpm. Maybe they simply set the limiter to lower value than what is allowed by the rules.
    Sulland meant valve float I am quite sure. It is when the valve springs are not strong enough to close the valve properly given engine speed, boost pressure and cam profile, meaning that the valve and lifter is "floating" above the cam leading to a very abrupt close and valve failure.

  7. Likes: dimviii (5th February 2017),Mirek (5th February 2017)
  8. #106
    Senior Member Mirek's Avatar
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    Thanks, I didn't know the English term.
    Stupid is as stupid does. Forrest Gump

  9. #107
    Senior Member Fast Eddie WRC's Avatar
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    Quick one on aero and gearing...

    I heard that on a long road in Monte there was a 10kph max speed difference between the new cars (202-212kph).

    The Fiesta was fastest, then i20 and Yaris was slowest. Will this be mostly gearing or aero, or some of both ?

  10. #108
    Senior Member KKS's Avatar
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    That story about when engine works on limiter, that always about gearing. No?

  11. #109
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    You could hear them on the rev limiter in some videos from Monte, that is definitely rev limiter. Aero should just effect how fast you get to the rev limiter based on drag. But that's just one element, there is also all the usuals like grip, torque, gear ratios and bravery...

  12. #110
    Senior Member Lundefaret's Avatar
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    Quote Originally Posted by KKS View Post
    That story about when engine works on limiter, that always about gearing. No?
    Its a combination of gearing and revs (on what rpm the rev limiter is set).
    https://www.facebook.com/noseendfirst?ref=hl#

  13. Likes: Mirek (8th February 2017)

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