Comparison tests Porsche 918 vs McLaren P1 vs LaFerrari
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F355
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All these claimed downforce numbers of McLaren and Ferrari are net. Simply the car's resulting downforce overall (consisting obviously of all lift and downforce areas of the car).
Ferrari e.g. has published a diagram which shows a bit of lift (negative downforce values) for the 328 of 1985 and the 348 of 1989 and then marginal downforce (positive value) for the 355 of 1994.
Ferrari e.g. has published a diagram which shows a bit of lift (negative downforce values) for the 328 of 1985 and the 348 of 1989 and then marginal downforce (positive value) for the 355 of 1994.
Evidence of 'net' downforce?
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- The measurement of the vertical force on a car in the wind tunnel and of the quasi-static suspension deflection/force when running on track or road give obviously the car's overall downforce (net) or lift.
How would a separation of the various areas which produce downforce and lift even be possible?
- In the fluid dynamics calculation the forces corresponding to the calculated pressure distribution over the car's surface are finally summated (roughly speaking). This again gives the car's overall downforce (net) or lift.
How would a separation of the various areas which produce downforce and lift even be possible?
- In the fluid dynamics calculation the forces corresponding to the calculated pressure distribution over the car's surface are finally summated (roughly speaking). This again gives the car's overall downforce (net) or lift.
kingjr9000
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I'm wondering who are these two new members 
kingjr9000
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Are any of you on fchat or mclife
kingjr9000
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I thought you were on fchat the way you were arguing with the other guy, have fun you two.
, have fun you two.
kingjr9000
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Not really. I spend most of my time over here.
kingjr9000
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You would think so but manufacturers had a history of stating gross downforce for marketing value. Basically they measured downward force at zero downforce and then take the difference in downward force with maximum downforce. I am convinced that neither the LaFerrari nor the P1 has less downforce than an Enzo or 458 at any speed. It wouldn't be logical from the perspective of technological evolution.
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Many cars for which the manufacturers claim downforce values have neither a wing nor active aerodynamics. So the difference between "zero downforce" and "maximum downforce" is zero. Clearly 0 kg is not the downforce claimed for these cars!
Yes, unlikely that a 458 Italia has more downforce than LaFerrari at any speed - because like the P1 and Enzo also LaFerari will stay in maximum downforce configuration beyond 200 km/h.
Yes, unlikely that a 458 Italia has more downforce than LaFerrari at any speed - because like the P1 and Enzo also LaFerari will stay in maximum downforce configuration beyond 200 km/h.
I don't follow your logic on that one. Basically at 160mph you have a few hundred kg of uplift or more. Remember the early Audi TT before the boot-lid spoiler was added? Even with the spoiler it had zero net downforce and likely still negative, but nevertheless the spoiler added some downforce.
This article suggests 500kg at 135mph for the Enzo, that would be more than the LaFerrari even assuming no aero trimming. Clearly can't be right. Also doesn't tally with a v^2 relationship to value at 300kph.
http://auto.howstuffworks.com/enzo3.htm
So how come the Enzo's downforce was quoted at 300kph, after which, aero was trimmed, whereas the LaFerrari is quoted at 200kph? Like I said, maximum downforce is always quoted for marketing purposes. Perhaps Ferrari were trying to improve inline speed to mask the real weight. There's only so much drag that DRS will cure. Or maybe aesthetics played a part.
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As explained before, Ferrari gives all downforce numbers at 200 km/h in recent years, e.g. 123 kg for the F12 which produces far more downforce at higher speeds. Not in line with the argumentation that max levels would be claimed.
In the link it says almost half a ton at 135 mph. In fact the claim was about 400 kg. Net. But the claim was optimistic for the Enzo.
In the link it says almost half a ton at 135 mph. In fact the claim was about 400 kg. Net. But the claim was optimistic for the Enzo.
Bucketslash11
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i've heard 700+kg of downforce at 300kph on the laferrari
I've heard 360kg.
it's also incorrect to assume a completely accurate v^2 relationship in any case. At higher speeds, the angle of the lift vector changes and there are also lots of other effects wrt to boundary layer build-up on underbody venturis. v^2 is a very loose approximation and was really introduced for the purpose of non-dimensionalising drag and lift coefficients. In reality both Cl and Cd do change with speed.
As a point of note, peak downforce is actually stated as occurring at 156mph at 4:00.
The F12 likely doesn't produce much downforce because it's a GT and as a heavier car it's unnecessary for stability. Given that a LaFerrari weighs over 1600kg kerb, who knows how much an F12 weighs? The claim was gross not net for the Enzo. Downforce has probably been curtailed beyond 200kph in recent years as a result of perceived necessity and usability. The other key thing to note is that, as the heavier car, the LaFerrari would need proportionately more downforce to be on par with the P1.
it's also incorrect to assume a completely accurate v^2 relationship in any case. At higher speeds, the angle of the lift vector changes and there are also lots of other effects wrt to boundary layer build-up on underbody venturis. v^2 is a very loose approximation and was really introduced for the purpose of non-dimensionalising drag and lift coefficients. In reality both Cl and Cd do change with speed.
As a point of note, peak downforce is actually stated as occurring at 156mph at 4:00.
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