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Distribution: why does Ferrari stick to belts ?

Discussion in 'Technical Q&A' started by ze_shark, Mar 5, 2004.

  1. ze_shark

    ze_shark Formula 3

    Jul 13, 2003
    1,273
    Switzerland (NW)
    Anyone has a theory for the reason why Ferrari sticks to timing belts instead of gear trains like on F1 engines or motorcycles (Honda's V4s for instance).
    Gear trains are maintenance free, highly reliable, more compact (shorter engine).
     
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  3. Enzo

    Enzo F1 Rookie

    Feb 14, 2002
    4,077
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    Pat Pasqualini
    I'm not positive but I think it has to do with Belts the engine can rev more freely and also the weight reduction. I'm not 100% positive.
     
  4. AEHaas

    AEHaas Formula 3

    May 9, 2003
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    Ali E. Haas
    I agree with ENZO however it is just a guess.

    aehaas
     
  5. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    7,299
    Ferrari got into belts in the late 1970s, at that time, one could make a belt cam system lighter in an absolute sense and lighter in a rotational inertia sense. One can still engineer a blet based system that is both lighter and has less inertia than a chain based system. The only real difference now, is that the cost of labor has changed the equation of replacement maintanence. The 360 engine block traces its roots all the way back to the 308 block. It was imply easier to keep the belt system than to re-engineer the whole cam arrangement.

    The Maserati block is chain based, you can expect the Ferrari engine based on this block to follow suit (chains). Unlike belt based systems that need to be kept away from engine oil, chain based systems have to be bathed continuously with engine oil. Changing from one to the other without re-engineering the whole block is <ahem> quite difficult.

    Gear based cam drive systems are so noisy that they are unworkable in automobile applications unless you use dual helical cut gears, which basically tripples the cost of the system.

    Chain based systems have failure modes, and the failure modes are different than the failure modes on belt based systems. So there is reasonable trepidation for the engine design team at Ferrari from changing things that could wipe out a years profits in a short period of time. Belts work, and if replaced at regular intervals, belts are reliable for the durable life of the engine.
     
  6. Newman

    Newman F1 World Champ
    Professional Ferrari Technician Consultant Owner

    Dec 26, 2001
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    Another advantage to belts is there are less vibrations transmitted to the valvetrain from the crank. This is one reason jessel developed a belt system for domestic pushrod v8 engines like a SBC. There are other advantages to the jessel system that are specific to the SBC but vibration is one of them that applies to any engine really. I also think the rotational mass is a good reason. I dont mind changing belts every 5 years or so.
     
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  8. Diablo

    Diablo Formula Junior

    The Enzo is chain based...off of the Maserati... Say it ain't so......
     
  9. Bill Sawyer

    Bill Sawyer Formula 3

    Feb 26, 2002
    2,108
    Georgia
    My understanding is that it usually isn't the belts that fail, it's the tensioner. If they stick with belts it would sure help if they could improve the tensioner system and lengthen the time between engine-out belt services.
     
  10. Dale

    Dale F1 Veteran

    Oct 7, 2003
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    Dale Juan
    Theres no better cam drive than gears,
    why dont ferrari use them-cost to much,

    Dale.
     
  11. Newman

    Newman F1 World Champ
    Professional Ferrari Technician Consultant Owner

    Dec 26, 2001
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    helical gears made of titainium to drive the cams, throw in needle bearings on the cam journals and roller followers on the buckets.
    Wonder if ferrari will jump on the solenoid actuated valve band wagon?
     
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  13. ChrisfromRI

    ChrisfromRI Karting

    Jan 28, 2003
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    Chris F
    There's no technical reason that Ferrari can't utilize a "Honda-VTEC" like system where you get low RPM drivability with one cam profile (lift/duration/overlap), and you also get high RPM performance by switching over to a better breathing cam profile (lift/duration/overlap).

    The Honda S2000 engine uses a timing chain, and it red-lines at 9K RPM (Model Year 2000-2003). It makes 240 HP per liter because of its high RPM breathing, yet it is pleasant to drive around town at low RPMs. This, in a $33K roadster.

    However, it just doesn't sound like a Ferrari -- nothing does!

    Kind Regards, Chris
     
  14. ChrisfromRI

    ChrisfromRI Karting

    Jan 28, 2003
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    Oops, that's 120 HP per liter, 240 HP for 2 liters...
     
  15. Newman

    Newman F1 World Champ
    Professional Ferrari Technician Consultant Owner

    Dec 26, 2001
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    Newman
    yes its 240HP but has no torque, cant pull a sick whore off a toilet with an S2000. no offense intended.
     
  16. ChrisfromRI

    ChrisfromRI Karting

    Jan 28, 2003
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    Chris F
    Newman,

    Take a look at the results from the SCCA Solo2 Nationals, under B Stock -- where the S2000 and many other sports cars reside (including the 308, 328, Boxster, Z4, Z3, M Roadster, M3, TT, 911, 928, 944, Espirit, Elan, 350Z, RX-8).

    You will note that the S2000 clearly dominates the class, despite it's low torque. It just does enough other things better than the other cars in the class!

    Kind Regards, Chris
     
  17. MikeF

    MikeF Karting

    Nov 4, 2003
    127
    Bloomington IN
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    Mike Fisher
    Belts are a guaranteed cash cow for Ferrari Service Departments!!
     
  18. stephens

    stephens F1 Rookie
    Lifetime Rossa

    Feb 13, 2004
    4,483
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    Stephen S
    Unfortunately they also taught Ducati this trick!
     
  19. Auraraptor

    Auraraptor F1 World Champ
    Lifetime Rossa Owner

    Sep 25, 2002
    11,486
    MO
    Modern Ferraris are using continuous valve timing to in effect get a Vtec everywhere in the range. Its far more efficient then Honda's old 2 setting approach, as it is always optimal with continous variable. Vtec was great...5 years ago before continously variable came out. In fact, Ivtec is just that.
     
  20. ChrisfromRI

    ChrisfromRI Karting

    Jan 28, 2003
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    Auraraptor,

    How does "continuous valve timing" change the duration of the valve cycle, or in other words, how long the valves stay open and closed in the cycle compared to the time they spend opening and closing? There are only four valve states: open, closed, opening, closing. The amount of the valve cycle dedicated to each state is determined by one thing; the physical shape of the eccentric cam lobe.

    My understanding is all that the continuous timing systems change is the advance of the cam cycle relative to the crank cycle, which is certainly something, and clearly better than nothing. However, this means that the cam profile, or shape of the cam lobe, stays exactly the same. So that the really important criteria affecting performance like duration and lift stay exactly the same. These critical characteristics are what makes engines breathe at high RPMs, and are exactly what characteristics are changed by a race team when they change cams to optimize performance. Basicly, all that the continuous systems do is what a degree wheel does, just with the added "twist" of it being continuous.

    That's why Honda gets more HP per liter than anyone else from a naturally aspirated sports car (120 HP per liter). They don't have to compromise with a single cam profile. They have a regular cam profile for good drivability at normal RPMs, and a high RPM cam profile that opens the valves wider and for a longer part of the cycle -- thus improving high RPM breathing and performance.

    The new Honda iVTEC adds the continuous cam/crank timing adjustment to the high/low RPM cam profile, but resides in their more economical and lowest emission vehicles (which really benefit from this). However, their highest performance automobile engine with respect to HP per liter is still the S2000's engine. That is because the lion's share of the performance gains come from breathing at high RPMs by changing the cam profile, rather than only shifting the valve cycle relative to the piston cycle.

    Just look at the numbers. Who else makes a 120 HP per liter naturally aspirated sports car?

    Kind Regards, Chris
     
  21. Auraraptor

    Auraraptor F1 World Champ
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    Sep 25, 2002
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    Well for one, they don't anymore, as current S2000s are 2.2L with a lower redline.
     
  22. ChrisfromRI

    ChrisfromRI Karting

    Jan 28, 2003
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    Chris F
    You've got me there. They did through 2003, but for 2004 they responded to what buyers wanted with a higher displacement re-optimized engine that delivers some more torque at low RPMs.

    I take it that I was able to correct your misconceptions on how modern engine valve systems work. Your welcome.

    Kind Regards, Chris
     
  23. ze_shark

    ze_shark Formula 3

    Jul 13, 2003
    1,273
    Switzerland (NW)
    Variable valve timing is now a common techno, BMW has had its Vanos then double-Vanos system on the old M3 (but not in the US where former M3s has a paltry 240hp instead of the euro 321hp), Porsche has it too, Toyota (VVT), etc ..
    I am skeptical about the argument on belts, after all chain or gear driven cams on bikes reach easily 14'000 rpm.

    Btw, another thread on the topic: http://ferrarichat.com/forum/showthread.php?t=6782
     
  24. ChrisfromRI

    ChrisfromRI Karting

    Jan 28, 2003
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    Chris F
    Yes, that was an excellent thread. Unfortunately, the conclusion was that the continuously variable valve timing ONLY shifted exhaust valve timing relative to a constant piston and intake valve cycle. Lift and Duration (cam lobe profile) are NOT affected. The end result is improved economy, emissions, and drivability, with less than a 1 percent improvement in performance. This is good since it is important to meet economy and efficiency rules, but would NOT be noticeable from a performance perspective.

    OTOH, when VTEC kicks in you actually feel it!

    Kind Regards, Chris
     
  25. Auraraptor

    Auraraptor F1 World Champ
    Lifetime Rossa Owner

    Sep 25, 2002
    11,486
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    Chris, no you haven't, I want to check my information and will get back to you.

    BTW I am not a anti honda blah blah whatever, I had a gen 5 prelude and a NA 2 NSX both with Vtec. So when it comes to Vtec, its a been there thing for me. (Oh and I do remember it fondly...):D

    I am just trying to comfirm that indeed what you say is true or not, as I was under the impression that it did affect lift and duration.
     
  26. ChrisfromRI

    ChrisfromRI Karting

    Jan 28, 2003
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    Foster, RI
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    Chris F
    Auraraptor,

    Please check, and by all means please correct me if I am not right. This thread is a good place to start your research:

    http://ferrarichat.com/forum/showthread.php?t=6782

    The deeper you research, the more you are going to find that Honda's dual cam profile approach is the way to go when it comes to actually delivering performance improvements to the driver. This is why I am surprised that Ferrari doesn't utilize this approach, since it would compliment everything else that Ferrari does so well for the driver!

    Instead, Ferrari and other makers tout their continuously variable cam/crank timing as the "end-all" in response to the question of where they are at improving their breathing technology, but when you boil it down by looking at what and how much it does, their continuously variable technology doesn't actually deliver performance to the driver, the real raison d'etre. Until they can affect the cam lobe profile characteristics such as Duration and Lift, there is no meaningful improvement to the driver.

    Kind Regards, Chris
     
  27. PeterS

    PeterS Three Time F1 World Champ
    Silver Subscribed

    Jan 24, 2003
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    PeterS
    It's all in the big plan to see that mechanics make a lot more money when the belts go and Ferrari sells the mechanics expensive parts. Jimmy Hoffa had all of this information is a briefcase.
     

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