Why do F1 cars have such high RPMs?

Discussion in 'F1' started by Cavallini, Feb 20, 2004.

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  1. Cavallini

    Cavallini Formula 3

    Nov 2, 2003
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    Only newly initaited to the televised pleasure of Formula One racing, I often wondered why F1 cars have such incredibly high revs. Couldn't the same level of thrust be achieved with more torque, considering the cars already have 800+ horses from only 3 liter engines (at least the F-2000)? Does it have something to do with greater control, as opposed to big cc engines or boosted autos? Or is it something unique to the racetracks that demands such a rev band, as opposed to the big ovals?

    CART and Indy cars don't seem to have anywhere near the rev range, but I'm sure they approach the same top speeds, if not higher.

    I've ruled out the idea, though sensible to me, that F1 teams simply enjoy that unequalled metal symphony. ;)

    Many thanks for your expertise,

    JPR
     
  2. 62 250 GTO

    62 250 GTO F1 Veteran

    Jan 9, 2004
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    I'm sure an F1 car can reach 230 mph if the aero was adjusted. Not quite sure about the revs. Maybe it has to do with their acceleration?
     
  3. rdsherman

    rdsherman Rookie

    Feb 20, 2004
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    In an internal combustion, torque is approximately
    proportional to displacement. However, power is
    the product of torque times the maximum
    angular speed of the motor (Max RPM). So
    doubling the RPM doubles the power.

    rdsherman (physicist)
     
  4. PSk

    PSk F1 World Champ

    Nov 20, 2002
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    Hmmm, okay lets start from the top.

    In a race series where the rules stipulate a maximum engine size this also in all reality stipulate the amount of torque the engines are going to produce, thus the only advantage you can gain on the opposition is more power via extra engine revs ... which leads to gearing advantages and actual torque improvements at the rear wheels (via the gearbox ratios, etc.).

    Torque is simply, T = F x D, where F = force, and D = distance.

    In a reciprocating engine, force equals the combustion force and distance is the radius of the crankshaft.

    Thus an engine designer can play around with bore stroke ratios, and a larger bore will give a larger force (due to increased surface area on top of the piston), but in reality they all probably are not that different in bore/stroke ratios and there would be a practical limit on the maximum combustion bang you could get for a 10 cylinder engine of 3000cc. Thus torque will be basically the same for all teams and engines of that size, that breath as well, etc.

    Thus if you can pull say 500 rpm more than the other team, that means that you can gear your car so that at the similar top speeds your engine is revving 500 rpm higher. So what you say well, what that extra rpm means is that you have a better ratio in the gearbox that allows slightly higher engine torque to push the driving wheels ... thanks to the mechanical advantage of a gearbox.

    On top of that you get that same advantage with all the intermediate gears and thus will have a slight acceleration advantage!!!

    Pete
    ps: Why do CART engines not rev the same. COST!, far tighter engine rules to keep the cost down ...
     
  5. Gilles27

    Gilles27 F1 World Champ
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    Do any of you know how or when the FIA check the team engines to ensure they don't exceed the 3 liter capacity?
     
  6. beast

    beast F1 Veteran

    May 31, 2003
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    Jack,

    I have read that the FIA will perform checks of engine swept volume at the Mfg. facility for the engine. Then at random on race weekends they can go and and insert a depth gauge and a device that expands to measure the cyl bore thru the spark plug hole and calculate swept volume of the engine.

    Rob
     
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  8. Cavallini

    Cavallini Formula 3

    Nov 2, 2003
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    Thanks Pete, I forgot about the size constraints. Higher RPMS would be the only and best way to increase performance.
     
  9. Skelter

    Skelter Rookie

    Nov 1, 2003
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    The top speed of an F1 car is limited by aerodynamics, so while they may aproach higher top speeds they couldn't possibly turn the way F1 cars do, i'm pretty sure given the aerodynamic eficiency of F1 cars that they would have no trouble going faster than an indy car if setup of an oval.
     
  10. Gilles27

    Gilles27 F1 World Champ
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    Thanks Rob. That's interesting. I figured it would be too easy to try and slip an illegal engine past the Regs, right? Another thing that interests me that I'd like to see on TV is a step-by-step piece on the actual post-qualifying impound and pre-race release of all the cars. As a fan, I see the cars on the track qualifying. Then I'll see the occasional impound photo of all the cars neatly arranged. The next time you see the cars, they're in their respective garages. It would be interesting to see them "fill in the blanks" and show what actually transpires in the interim.
     
  11. Fede Ferrari

    Fede Ferrari Formula Junior

    Jan 5, 2004
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    I want to add that the maximum speed reached by a F1, besides the aerodynamics, comes in function of the combination of its box of changes and of the circuit. If you put I aim a F-1 under conditions, and you give him a straight line of 15Km, it will surely reach the 400Km/h, but this in a race is impossible, for blame of the adjustments in the car, which should enter in curved slow and closed, in open and quick and the longest straight line in a circuit, never reaches the 2Km.

    To take as example the adjustments of the F2003-GA of Schumacher in the bereavement against the Eurofighter. The Scuderia prepared it to achieve the 273Km/h, in a long straight line of an airport and if it didn't achieve its objective, it was by reason of the rain that didn't allow him to achieve the one it grabs correct.

    Greetings
     
  12. beast

    beast F1 Veteran

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    Jack,

    In the book by peter Wright "Formula 1 Technology" Chapter 19 is all about the impound and inspection procedures that go on in F1.

    But i do agrre with you i would like to see them in action inspecting the cars that would be very interesting, but i hate to say it that the teams would say no since it would possibly allow the competition to see what they are doing under the skin of the car.

    Rob
     
  13. robinh

    robinh Formula Junior

    Jan 3, 2004
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    The cars are scutineered all of the time. The other teams rat on each other if they think anything is outside the rules (Ferrari barge boards for example) and the cars have things built into them to allow checks to be done. For example the ride height is controlled by the rules and to check it all F1 cars have a piece of timber under them. If it wears (I think by more than 2mm but could be wrong here) during a race the car ride will be deemed to be outside of the rules and will be disqualified.

    There is a great of money sloshing around, rules, breakinf them and forcing others to adhere is a big thing.
     
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  15. F360@20

    F360@20 Karting

    Nov 24, 2003
    244
    San Diego
    Does it also have to do with the amount of power coming out of a turn? Meaning you have the extra RPM's to run a gear out threw a turn so you have a constant accelartion?(without have to shift)
     
  16. ART360

    ART360 Guest

    I heard that Honda, in the 80s claimed they were running a 500cc motorcycle engine with oval pistons. I also heard it was about 650ccs, and they didn't get caught. The factory 500cc Suzukis were also rumoured to be a bit oversize also. I wouldn't be surprised if some of the engines were a little large. Especially on the slower teams.

    Art
     
  17. JeffMN

    JeffMN Rookie

    Jan 18, 2004
    28

    Speak of the devil... This is a great pic of the oval-piston internals. Each oval piston has two connecting rods. IIRC, Honda was actually going to sell a few of these for street use but I'm not sure that ever happened.

    http://www.sportbikes.dhs.org/index.cfm?fuseaction=displayit&Picture_ID=20217

    -Jeff
     
  18. beast

    beast F1 Veteran

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    The problem Honda had with the oval piston engine was the fact that the rings were very difficult to produce and properly seal against the cylinder wall. From what i understood the rings had to be made and fitted to the cylinder and piston by hand. One other problem the engine had was the crankshaft would twist slightly from inertia if the rider down shifted to quickly or the rear wheel left the track surface under power. The crankshaft would twist and now the piston was running in the bore crooked and would scuff the piston and cause rings to break.

    A very brilliant design but i feel way to ahead of its time. One side note when Honda stated that they wanted to get into Champ car racing. CART went and put into the rule book "No oval pistons allowed!" almost instantly.
     
  19. PSk

    PSk F1 World Champ

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    Okay I have to disagree that the Honda Oval piston engines was a great feat of engineering or clever design.

    First of all it was produced to get around a rule that limited the manufacturers to a maximum of 4 cylinders.

    Second of all the only reason it produced more power is because it effectively is a v8 and we all know that the more cylinders the more volumetric efficient an engine will be. This engine has more piston surface contact area than a v8 (compare the oval pistons to 2 round pistons) thus more friction, has the same number of conrods, same number of valves and spark plugs ... and negatively has a dead period in the combustion chamber which would be hard to effectively fill for complete and efficient combustion ... also as already mentioned extremely difficult to seal that shape for the piston rings.

    Thus very clever that they could actually build it at all ... but again if the rules had allowed Honda to build a 2 pistons firing at the same time v8, Honda would have built one and made MORE power and had normal reliability.

    A white elephant that proves nothing IMO.
    Pete
     
  20. bluekawala

    bluekawala Formula Junior

    Jan 22, 2004
    430
    Pittsburg, KS
    Is this true... I thought the number of cylinders has little, to nothing, to do with volumetric effeciency? My understanding is that its more about... well theres lots of factors like cams and intake etc almost anything, but not the number of cylinders. I'm confused
     
  21. PSk

    PSk F1 World Champ

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    The more cylinders an engine has the more pumping efficiency it will have ... but there are many negatives too, like cooling, etc.

    Basically it is because the revolving mass will be lighter, because the pistons, conrods/valves, etc. will be lighter, etc.

    Pete
     
  22. bluekawala

    bluekawala Formula Junior

    Jan 22, 2004
    430
    Pittsburg, KS

    Interesting, thanks!
    You never know what you'll learn on the marvelous F-chat!

    Happy driving
     
  23. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    5,768
    At any given displacement, more pistons means smaller pistons (lighter) and a shorter stroke (more revs) this comes at the cost of weight and added friction.
     
  24. ferrarifixer

    ferrarifixer F1 Veteran
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    The First V10 Ferrari F1 engine in the 310 was called an 046. This is because it's stroke was only 46% of it's bore.

    The names now follow on in sequence, but not indicative of the bore/stroke ratio.

    Typically, most road cars stroke is 90-110% of it's bore.

    The 1997 310B I looked after, idled at about 4500rpm at revved to 16,000 in "customer" spec. You needed nearly 10,000 rpm to simply pull out of the pit garage.
     
  25. teak360

    teak360 F1 Veteran
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    It's very simple, for a given displacement higher revs equal MORE HORSEPOWER. GP engineers don't striverfor higher torque, they go after the Holy Grail of racing......HORSEPOWER
     
  26. tvrfreak

    tvrfreak F1 Rookie
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    They go after both, actually. And then they try to finagle the torque curve so that it's "manageable" Typically they strive for lots of it across a broad rev range and a gradual falling off at the upper limits of the rev range. This allows the driver to ease off just a bit, or not at all if he's very good, whenever the tyres lose traction and the engine revs rise quickly.

    Higher rpms mean more horsepower, but torque (especially the useable kind) wins races.
     
  27. 62 250 GTO

    62 250 GTO F1 Veteran

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    With as much power as they have and all of the areo downforce, wouldn't they need like an extra 20 hp to get just a mile ot two per hour out of the straightaway sections?
     
  28. tifosi69

    tifosi69 Formula 3

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    They did produce the limited-production NSR repli-racer superbike for sale to the public, with the oval pistons, not sure of the year, if memory serves it was around '94-96 in that time frame and it was I believe 900cc. It was more than Ducati expensive at the time however.
     
  29. beast

    beast F1 Veteran

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    Downforce is not the issue here. it is more the drag bring produced by the tires out in the open that requires more horsepower from the engine. This is why you see aero devices like winglets, barge boards, and flipups near the tires. they are there to channel air away and to also to redirect air around the turbulance being produced by the tires. If a F1 car was able to place on a sports prototype car (Le mans) body onto it you would see a dramatic increase in straight line speed.

    Take a look at the pictures for the front wing end plate on the F2003-GA. The secone picture is the same as the first with comments added in.
     
  30. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    5,768
    F1 engines close the valves with high pressure nitrogen instead of with springs. It seems that the mechanism of valve closure is limiting CART engines (ala 2001 before RPM constraints). The high pressure nitrogen has the property that the pressure between the cam follower and the cam is rather constant, whereas a spring has increasing force with increasing lift. The net result is that a pneumatic valve can A) open faster, B) close faster, C) follow the shape of the cam better, D) as long as you don't run out of high pressure nitrogen. The major reason this technology has not penetrated road cars is the leakage of nitrogen and the requirement for pressureizing the valve train before cranking the engine over at startup.

    Then, of course, the valves are made of titanium, as are the retainers and the pneumatic cam followers. Before 2000, the engines used berylium vavle seats. These seats transfer heat better than other machinable materials, weight nothing, and are toxic to the machinists who cut the seats and lap the valves onto the seats.

    Current valve timing for F1 engines hovers around 40/80-80/40 or 300 degrees of duration, and 80 degerees of valve overlap. In fact, the valves are only closed for 200 degrees of rotation out of 720 degrees, compression getting 100 degrees and the power stroke getting another 100 degrees.

    Ok, The pneumatic valve springs got rid of the RPM limit from the valve train or at least moved it into the 22K-25K RPM range. So the engine designers sought to make use of the newly found rev range. This lead to a shortening of the stroke to keep the reciprocation motion from limiting the RPM reach of the engines. Shorter storkes lead to bigger pistons. The combination of bigger pistons and shorter strokes makes is harder to develop a combustion chamber that has both high compression and a fast flame front.

    At this point (late 1980s), the valves were inclined in pairs of intake and exhaust in a roof-like chamber. If was found that arranging the valves in a squashed pyramid and adding squish at the ends of the combustion chamber, that the combusion could be compressed into the inner 70% fo the combustion chamber, resulting in the fast flame fronts necessary to burn a mixture at 18,000 RPMs and higher.

    Compression ratio hovers in the 13:1 to 14:1 and is more limited by the specification of useable gasoline than by the ending designers and constructors. Current F1 race gas is a mixture of 112+ octane compoments (Tolulene, Xylene,...) and some 80- octane components (heptane) so that the mixture will look like 101 gasoline in terms of knock in the testing 'research' engine. If F1 engines were restricted to actual pump gasoline power outputs would be reduced 50-75 HP. If the fuel for the F1 engines were obtained randomly from a gas station in the town at which the race was to take place and everybody got fuel from the same tanker, F1 engines output would be have to be reduced by 75-100 HP just so that the engine would survive on the uncalibrated fuel.

    As the RPM band gose higher, the size and weight of the intake velocity stacks and exhaust headers both get smaller and simultaneously it becomes easier to extract energy from the harmonics of pulsing pressure, giving a self-superchargin effect. At peak TQ a typical F1 engine is around 115% volumetricly efficient! Modern F1 engines have the velocity stacks on a servo mechanism in an attempt to move the TQ resonance in concert with the engine RPMs so the engine always operates at TQ approximately equal to peak TQ.

    On the header size, the current RPM band of best header operation has header tubes that are so short that packaging all 5 tubes into a single collector requires a tube bending genius. The collector masquerades as the big tibe from the juction of the header pipes to the slashcut exhaust.

    To recap:
    A) pneumatic valve train
    B) fast burn combustion chambers
    C) excellent breathing
    D) complete utilization of pulses of pressure in header and intake
    F) expensive fuel masquerading as gasoline
     
  31. 62 250 GTO

    62 250 GTO F1 Veteran

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    :)
     
  32. fasthound

    fasthound Formula Junior

    Nov 23, 2003
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    Mitch - I've been looking for pictures of the head assemblies on ANY car with a Pneumatic valve train with not much luck. I would really like to see what the assemply looks like and how it works. Do you have any source for pictures, or better yet, exploded engineering drawings showing how it all goes together?

    Anyone have anything like that?

    THANKS!
     
  33. kirill

    kirill Formula Junior

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  34. macca

    macca Formula Junior

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    Honda wanted to race & win in the 500cc GP bike class with a 4-stroke, and since a two-stroke has twice as many firing strokes (so even though it's not as efficient it produces more power per cc) decided that if they could get more revs and build a bike with a very light weight they would stand a chance, so they went for oval pistons so that the weight of the con-rods and valves would be less of a constraint on revs.

    They were wrong. The NR500 appeared in 1979 and by 1981 had got to be as good as it could, and had a seriously fast rider in Freddie Spencer, but still couldn't cut it. It revved to 20,000 and had lots of torque, but was still heavier than a two-stroke and had only about 110 hp when the Suzuki and Yamaha were around 130 hp.

    So then they did a 750cc version, which was raced in some endurance events where engines didn't have to be based on production bikes, such as the prestigious Suzuka 8-Hours (at Honda's own track), and since it made 155 bhp and loads of torque it was quicker than the ordinary v-four which had about 130 bhp. Then they did the NR750 road bike, but it was the priciest thing on the road so only sold to curious millionaires!

    And they went to two-strokes for racing, and won the 500 and 250cc WCs with Fast Freddie.............but now Moto GP is all 4-strokes, currently 990cc with sliding weight limits for the number of cylinders, and the V5 Honda gives over 240 bhp, which is still less than the 300bhp/litre of F1 engines.


    Paul M
     
  35. Gatorrari

    Gatorrari F1 World Champ
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    When I started following F1, the engines were developing about 400 HP out of the same 3 liters, with peaks at about 10,000 RPM. So the more-than-double horsepower nowadays is due, at least in part, to those super-high revs.

    But I liked the way the cars sounded better when the revs weren't so high. If they want to slow the cars down, a rev limit of not more than 14,000 RPM would do that, and the sound wouldn't be so painful!
     

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