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    Re: 918 latest news Thread Closed

    Jean:
    bluelines:
    reginos:
    RC:

    Reducing weight on street legal production cars is always a compromise regarding cost and safety, I'm glad Porsche found another way.

    Wasn't there an explanation of how  the Nissan GT-R's heavy weight helps its track times?


    --

    "Form follows function"

    Yes, it is a good laugh when Mizuno tries to explain this Smiley

    You don't have to be a physicist to understand that high weight is a disadvantage. No matter how well engineered the car is. Not seen many 2 ton F1 cars Smiley

     

    I still believe there is a good balance between a car's weight and mechanical grip (e.g. road tire's contact patch) to increase the traction for better handling.  

    Take Caparo T1 for example.  In theory, this car should be faster than almost all of road cars out there, however it is not, simply because you cannot get enough traction into the road legal tires without downforce in low speed corners.

    Mathematically it does not make sense. With more mass you get more friction, i.e. resistive force, but also higher inertia which will cancel it out assuming the friction coefficient is equal. The only thing that happens is that the forces are greater in all directions, which is why the GTR chews tires like noting else Smiley

    Low mass coupled with high aerodynamic downforce is the winner. This gives low inertia and high friction.

    That is the theory at least. I guess we could argue if it applies in practice or not.


    --

    Porsche 997 Carrera S in Carrara White with black leather interior. PASM-Sport Suspension (-20 mm), PSE.

    Audi S5 cabrio in Ibis White with black leather interior.


    Re: 918 latest news Thread Closed

    bluelines:

    Low mass coupled with high aerodynamic downforce is the winner. This gives low inertia and high friction.

    Always, the lowest mass-weight posible and the adecuate amount of downforce-weight to balance the traction and grip needed for the bends vs drag for the top speed for the straights for a given track and its course layout.

    Best example is F1 cars, and every kilo of mass they shed the faster the lap time, like during a race as they burn the fuel in the gas tank the lap times fall proportionaly. If they need more grip they dile in more downforce but if they would add mass instead, the opposite would happen.

    Mass increases the centrifugal force in the corners pushing the car outwards in the corner reducing corner speed, it increases weight tranfer loads, it decreases acceleration out of the corners, and decreased braking due to the increase inertias. Donwforce on the other hand puts weight on the tires just the same but does not affect centrifugal forces and actually helps braking. It does increase drag so too much downforce will affect top speed and acceleration at high speeds to a certain extent though, so there is a balance to be met depending on the track, though production street cars never reach those levels of downforce for it to be a problem.


    --


    Re: 918 latest news Thread Closed

    Yes yes you guys are right but this is good for race car design. Road cars have little or no aero. It doesn't take einstein to see that the GTR has very little downforce. 

    Even the GT3RS with its big rear wing doesn't generate much more than 200 kgs I think and that's at 250 kmh.

    So my two cent is that, on race cars, no question, mass as low as possible and loads of aero. For roads car, it's a more complex equation. 

    The Caparo maybe is too much like a race car, maybe it needs warm tyres to start generating lateral speeds at which the aero could work. Because this road car looks like it has loads of aero.Smiley

    What do you think Carlos? For road car, there is just so much more to take into account. 

    A car like the GTR relies on chassis (smart 4WD) and mechanical grip to smash a north loop time, not aero I think, hence the reason why it can be so heavy. Until the tyres and brakes give up.

    Given how low the 918 is and with its large wing, it should generate some aero, but not much.

    Its tyres will be state of the art too. First test on the northloop began with a Carrera GT with 300 kgs of weight added to it and those tyres and they were faster than the times the GT did in 04.Smiley

     



    Re: 918 latest news Thread Closed

    I completely agree for street cars the aero part is only a fraction of the factor it is on racecars, most don't even achieve negative bouyancy, but I still believe that even in streetcars were you can't have much downforce weight, any added mass weight is going to always do more bad than any good and hinder performance and handling.

    That said, modern cars have more and more things to help minimise more the negative effect of mass such as more complicated, albeit intrusive, 4 wheel drive systems coupled with electronic stability controls, better tire technology, etc. so you can see cars on the heavy side that are able to close the gap more and more and still perform. But with some drawbacks like cars being less in involving. greater wear and tear (tires, brake discs, etc). I the GTR would be 200kg lighter it would even be faster, the irony is that what allows it to be so fast inspite of the weight, all its 4WD mechanisms and such, is what contributes to all that weight.

    In the case of the 918 it has to make much less compromises for packaging compared to cars like the GTR were it has 4 seats, its big, has a big trunk, the engine on the front, etc while the 918 does not even need to compromise for anything except performance, not even in costs, so its has even more tools to its advantage to make that weight work, like very low centre of gravety for that weight, mid engine placement, very expensive parts and materials. Also there is the question of what "new" advantages the electric motor tech that the 918 innovatevely incorporates is going to bring to that as well (though I guess that the extra weight of the 918 is precisely because its showcasing such new technology). So IMHO, the extra weight in the 918 will be even less noticeable and especially for us mortals compared to walter rohrl lapping the ring.

    Its going to be a very special supercar IMO, and with that F40 you both ends of the supercar spectrum! max tech and sophistication vs most raw and lightweightSmiley


    --


    Re: 918 latest news Thread Closed

    Carlos from Spain:

     I the GTR would be 200kg lighter it would even be faster, the irony is that what allows it to be so fast inspite of the weight, all its 4WD mechanisms and such, is what contributes to all that weight.

    Smiley

    One of the peculiarities of the GT-R is that it has a front-mounted engine, rear-mounted gearbox and 4WD, so it needs the packaging space and weight of two longitudinal drive shafts: one to take the drive from the engine back to the transmission and then another to take the drive from the rear transmission forward to the front axle. This extra weight and space (which again translates into more weight by adding volume, or bulk, to the "body") have their price. The Nissan engineer (Mizuno?) was trying, unconvincingly, to make a virtue of a problem. 


    --

    fritz


    Re: 918 latest news Thread Closed

    Found this on the web angel

    76508_3232596953834_649144477_n.jpg


    Re: 918 latest news Thread Closed

    Interesting pic. Looks like some kind of "secret" launch in Leipzig


    --


    Re: 918 latest news Thread Closed

    2013 Porsche 918 Spyder testing...

    ...in glorious High Definition!

    Smiley SmileySmiley


    Re: 918 latest news Thread Closed

    Porsche 918 Spyder testing in the US...

    Porsche 918 Spyder testing in the US -- Article Link

    Smiley SmileySmiley


    Re: 918 latest news Thread Closed

    Great pic's! wink


    --


    Re: 918 latest news Thread Closed

    8000866283_4812c874c5_k.jpg8013209776_6b5116ab14_k.jpg


    --


    Re: 918 latest news Thread Closed

    Boxster Coupe GTS:

    Porsche 918 Spyder testing in the US...

     

     

     

     

     

     

     

     

     

     

     

    Porsche 918 Spyder testing in the US -- Article Link

    Smiley SmileySmiley

    This should be the "50.000€" Liquid Blue on the rear wing...

    Blueflame


    Re: 918 latest news Thread Closed

    I actually think it is sapphire blue.


    Re: 918 latest news Thread Closed

    Spyderidol:

    I actually think it is sapphire blue.

    It's a bit small to appreciate fully ;)


    Re: 918 latest news Thread Closed

    No doubt.


    Re: 918 latest news Thread Closed

    Saw this on another forum, probably manufacturer claim

    0 - 100: 3s
    0 - 200: 9s
    0 - 300: 27s
     


    Re: 918 latest news Thread Closed

    This car is stunning! Such a work of art!


    Re: 918 latest news Thread Closed

    Moser:

    This car is stunning! Such a work of art!

    Just 2nd that!

    Carrera GT was great but this one looks more refined, when it'll get it's definite light units at the back and sidemarkers it will still improve a great deal!

    Job well done porsche!

    Such a shame they didn't dare a bit more on the  991.


    --

    965 3.3turbo/  993 targa / 996 cab /997S cab

    Audi R8  //  Audi A5 S-line 3.0tdi Quattro/ RR 4.4i


    Re: 918 latest news Thread Closed

    Very beautiful.....is there any chance some of this design language is incorporated on the Panamera facelift due in 2013? kiss

     


    Re: 918 latest news Thread Closed

    Upsa:

    Very beautiful.....is there any chance some of this design language is incorporated on the Panamera facelift due in 2013? kiss

     

    Design elements derived from this car are sure to trickle down to every model sometime in the future. 


    Re: 918 latest news Thread Closed

    In the distant future, if you think how long it took for the Carrera GT door design to trickle down to Boxster 981.


    --

    "Form follows function"


    Re: 918 latest news Thread Closed

    Fact is Porsche is going more aggressive with their design.. I like these new rear vins on the side... those only showed up in recent images, some aero advantages there? This car I think will look best in flat white. I still like the CGT more, it's the best car ever.


    Re: 918 latest news Thread Closed

    Boyko23:

    I found this interesting additional info, regarding the Ring time:

    *The car had the Weissach package. 
    *Porsche had one lap to set a time.
    *Time was set from a standstill start.
    *One of the fastest times set by a street leagl car on standard road going tires.

    I guess Porsche wanted to demonstrate how quicky the car from standstill using electric motor assist with about 400ftlbs of torque available at 0 rpm Smiley. So very little effect in laptime.


    Re: 918 latest news Thread Closed

    918 meets the P1...


    --

    The secret of life is to admire without desiring.


    Re: 918 latest news Thread Closed

    just tweeted:

    CEO Muller sez 918's 7:14 'Ring lap can go lower. "If we are lucky, it will be under 7 minutes, but I don’t know, we’ll see…”

    http://blogs.motortrend.com/paris-motor-show-exclusive-porsche-confirms-sportturismo-cues-across-the-brand-hints-at-6-min-918-and-600-hp-911-26089.html

    wink


    Re: 918 latest news Thread Closed

    kiss


    Re: 918 latest news Thread Closed

    BiTurbo:

    Saw this on another forum, probably manufacturer claim

    0 - 100: 3s
    0 - 200: 9s
    0 - 300: 27s
     

    http://www.youtube.com/watch?v=98O5Zg9salo

    I don't think so. hahahaha
    It did 111 kmh-290 in 8.9 seconds (i timed it).
    Compared to the Agera r, it did about 10 seconds !!!
    http://www.youtube.com/watch?v=6WtlmpOKMG4

    (22 seconds through the video).


    Re: 918 latest news Thread Closed

    2:24 seconds in the video he did the hardest acceleration.


    Re: 918 latest news Thread Closed

    Porsche 918 Spyder on track at Leipzig...

    Porsche 918 Spyder on track at Leipzig -- Video Link

    Smiley SmileySmiley


     
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