McLaren P1 Clocks 7:04 Ring Time
09-16-2013, 11:27 PM
#31
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Oh I hate being right all the time! Check out the end of the video- what does he do? Stop! that's right, the batteries are dead, a one lap wonder. Now ask yourself when was the last time you saw a 'ring video where at the end of the hot lap they pull out the anchor- full stop?
09-17-2013, 12:34 AM
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09-17-2013, 04:59 AM
#33
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I raised this issue of battery discharge in a few forums with a few people who have driven the 918 and the answer is as follows.
The 6:57 lap was done in 'hot-lap' mode which means no battery charging, just drain it for power. The same laps can be done in re-charge mode in which case the battery does not exhaust itself and in that mode it's about 5 secs slower at the 'ring.
So the answer is that a 918 can do either one lap at 6:57 or lap endlessly at 7:02.
The P1 and LaFerrari are more affected as they have smaller batteries and less re-charging methods.
The 6:57 lap was done in 'hot-lap' mode which means no battery charging, just drain it for power. The same laps can be done in re-charge mode in which case the battery does not exhaust itself and in that mode it's about 5 secs slower at the 'ring.
So the answer is that a 918 can do either one lap at 6:57 or lap endlessly at 7:02.
The P1 and LaFerrari are more affected as they have smaller batteries and less re-charging methods.
09-17-2013, 05:47 AM
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GuyR, this is very helpful, but I have real trouble believing that the batteries can be regenerated here at the same speed they are used for a continuous 7:04 lap time and let me briefly state why. Someone here will know the precise approximations better than I, but the rate at which you "burn" energy I have heard is roughly proportional to the velocity cubed for reasonable speeds. I imagine it gets much worse as you go over 130mph and the air gets ever thicker. I know I burned a 1/4 tank in less than 30 minutes on my CGT on a autobahn in Germany near the Belgium border (where you could really just fly). In short, you are transforming "ordered" energy (nicely stored electrons in the batteries, carbon fuels in the tank) into "random" energy (heat and lots and lots of faster moving air particles which really add up -- they provide 70-80% of the energy transfer for a racing cyclist) at an incredible rate. To reorder that energy -- recharge your battery or take simple carbons from the air and make gasoline -- you need large amounts of energy. Where does that come from? Well the only source is some transfer from braking and your 600hp engine (which you need the energy from anyhow to keep you going fast), but with "minimal" efficiencies (I.e. much, much less than 1-to-1; which is why you use electricity lines which carry the energy from a large central plant than a portable gas generator). Porsche's large reliance on the size of their batteries for the extra horsepower here makes this ever more acute -- for racing a car at very high speeds, the battery is a short term power booster. As such, the statement here that the 918 can recharge itself and continue to maintain 7:04 lap times is like "you can cool your room by opening your refrigerator door." Now it would be nice to have all of the precise numbers as I am sure Porsche does (and I completely trust what they say, btw, and maybe their KERS has a much higher efficiency ratio than I can possibly imagine), and this doesn't take away their accomplishment here (it was the right direction to go and they did it right). I would guess, however, that after a few more laps like the one above, the 918 would become much slower as it would essentially be a 600hp car carrying around some 300kg(?) of dead batteries and associated equipment. Indeed, for an extended race, watch out in the rear for that ole howling V10 CGT! Cheers, Steve
09-17-2013, 05:57 AM
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Firtly two independent customers (one I know personally) have reported that during laps of Leipzig they returned to the pits with more energy than they left with.
Secondly and more importantly, the aspect of having less than 100% efficiency of re-charge is clear but is about the volumes it applies to. The 918 is creating kinetic energy based on all 887bhp, but is only needing to re-charge kinetic energy to drive 279bhp of electric motor. If therefore only needs to be able to retain 279/887 = 31% of the kinetic energy back into the battery to be able to keep it charged. This seems far more plausible, given that the 918 is re-charged during both coasting (by the engine) and during regenerative braking.
Neither the P1 or the LaFerrari have regenerative braking..........
09-17-2013, 07:28 AM
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GuyR,
Both good points!
The firsthand commentary is very interesting; and my only question would be wether these laps were done anywhere near the equivalent of a 7:04 lap time on the Ring? I.e. were they 150mph type of speeds or more gentler trips around the track. Again, the loss of "ordered" energy goes up exponentially at higher speeds as air becomes more like water and huge amounts of energy are lost to making those pesky air molecules (but lots of them) go a lot faster. I would believe their observation for lets say circa 80mph maybe (I am just totally guessing!). But above some point -- certainly approached by a 7:04 Ring time, its difficult to believe that the energy can regenerate itself (but this is perfect segway into your second point which is crucial).
On your second good point -- lets look at this as a closed system. Energy (ordered) is generated by both the V8 and the batteries -- it is transformed into (1) the velocity of the car (1/2 mv^2), (2) the heat produced by the car from the exhaust and tires and (3) the additional velocity of the air molecules being pushed out of the way (particularly intense when the boundary layer becomes so small at very high speeds). The energy transformed into heat (as defined here) doesn't vary that much compared to the speed of the car. However, the tradeoff between energy from the V8 and electric motors being transformed into (1) and (3) would depend dramatically upon the speed of the car. Thats why it takes so much more energy to go from 100-120 mph than from 180-200 mph. So at moderate speeds, where the energy from the V8 and electric motors is mostly transformed into kinetic energy of the car -- it makes complete sense that you can get enough of that kinetic energy back through the brakes to recharge the batteries. At very high speeds, where by far most of the additional energy from the V8 and the electric motors would go into moving air molecules out of the way, it is hard to believe that you get enough back from the extra input to maintain these high speeds to recharge the battery. Your point about all the regenerative energy going to the batteries is an important one although I would be surprised if it even got a 30% regenerative rate at normal rates given the inherent inefficiencies here -- but together with the V8 -- it would be enough to recharge the battery at reasonable speeds. It is at the very high speeds where the energy recapture rate from the brakes would probably drop fairly substantially (due to heat loss) and so your energy in (from the V8 and batteries) versus energy retained formula (first into the kinetic energy of the car and then back into the batteries) would be below one; the batteries would eventually lose out.
The real question is -- how fast does the 918 have to go before it crosses this equilibrium point? The statement that a 7:04 Ring track time is continuously repeatable and so is that "equilibrium point" seems awfully fast to me. But Porsche would know... Unfortunately, its just not very sexy to talk about fast do you have to go to drain your batteries and end up with a cutting edge supercar with a several hundred kilograms of "dead weight" on board; thats the stuff that good ole petrol heads have cold sweats about.
Even if the maintainable track time for the Ring (or other racing circuit) were well behind the CGT (with the new shoes), it still doesn't mean the 918 is not a big success. Far from it, it is the more practical car by some measure. It also is the fastest car (for a least a few good laps), etc. In short, it is a new way of approaching the car and they have done a fantastic job at it! Again, wtdoom's write-up does a really good job of trying to get your head around these two different animals. Since I only drive my car for adventure (the feel, the sound, the sight, the pure excitement, etc.), the CGT does it for me. Would I buy a 918 if it were not for the CGT -- maybe; it is just a bit high in price for my budget (but I hate people who slag something for its price because they can't afford it; the 918 is probably a bargain). Would I buy it later as a second -- hmmm practical --- car? Perhaps (budget permitting). But I think there maybe a lot more evolution here (with the whole battery powered concept being very new -- and we all know how fast the electronics industry changes -- although fortunately Porsche is trying to build in a way to avoid obsolescence here) where as the CGT is the ultimate expression of its design philosophy. I love its "bare bones" efficiency (but to such a high standard), btw.
Now who was it that complained that site might become dominated by a comparison between these two cars? (I'll have to change my moniker to "foot in mouth").
It is all very fascinating though and I look forward to more reports from the field on this latest super car.
Cheers,
Steve
Both good points!
The firsthand commentary is very interesting; and my only question would be wether these laps were done anywhere near the equivalent of a 7:04 lap time on the Ring? I.e. were they 150mph type of speeds or more gentler trips around the track. Again, the loss of "ordered" energy goes up exponentially at higher speeds as air becomes more like water and huge amounts of energy are lost to making those pesky air molecules (but lots of them) go a lot faster. I would believe their observation for lets say circa 80mph maybe (I am just totally guessing!). But above some point -- certainly approached by a 7:04 Ring time, its difficult to believe that the energy can regenerate itself (but this is perfect segway into your second point which is crucial).
On your second good point -- lets look at this as a closed system. Energy (ordered) is generated by both the V8 and the batteries -- it is transformed into (1) the velocity of the car (1/2 mv^2), (2) the heat produced by the car from the exhaust and tires and (3) the additional velocity of the air molecules being pushed out of the way (particularly intense when the boundary layer becomes so small at very high speeds). The energy transformed into heat (as defined here) doesn't vary that much compared to the speed of the car. However, the tradeoff between energy from the V8 and electric motors being transformed into (1) and (3) would depend dramatically upon the speed of the car. Thats why it takes so much more energy to go from 100-120 mph than from 180-200 mph. So at moderate speeds, where the energy from the V8 and electric motors is mostly transformed into kinetic energy of the car -- it makes complete sense that you can get enough of that kinetic energy back through the brakes to recharge the batteries. At very high speeds, where by far most of the additional energy from the V8 and the electric motors would go into moving air molecules out of the way, it is hard to believe that you get enough back from the extra input to maintain these high speeds to recharge the battery. Your point about all the regenerative energy going to the batteries is an important one although I would be surprised if it even got a 30% regenerative rate at normal rates given the inherent inefficiencies here -- but together with the V8 -- it would be enough to recharge the battery at reasonable speeds. It is at the very high speeds where the energy recapture rate from the brakes would probably drop fairly substantially (due to heat loss) and so your energy in (from the V8 and batteries) versus energy retained formula (first into the kinetic energy of the car and then back into the batteries) would be below one; the batteries would eventually lose out.
The real question is -- how fast does the 918 have to go before it crosses this equilibrium point? The statement that a 7:04 Ring track time is continuously repeatable and so is that "equilibrium point" seems awfully fast to me. But Porsche would know... Unfortunately, its just not very sexy to talk about fast do you have to go to drain your batteries and end up with a cutting edge supercar with a several hundred kilograms of "dead weight" on board; thats the stuff that good ole petrol heads have cold sweats about.
Even if the maintainable track time for the Ring (or other racing circuit) were well behind the CGT (with the new shoes), it still doesn't mean the 918 is not a big success. Far from it, it is the more practical car by some measure. It also is the fastest car (for a least a few good laps), etc. In short, it is a new way of approaching the car and they have done a fantastic job at it! Again, wtdoom's write-up does a really good job of trying to get your head around these two different animals. Since I only drive my car for adventure (the feel, the sound, the sight, the pure excitement, etc.), the CGT does it for me. Would I buy a 918 if it were not for the CGT -- maybe; it is just a bit high in price for my budget (but I hate people who slag something for its price because they can't afford it; the 918 is probably a bargain). Would I buy it later as a second -- hmmm practical --- car? Perhaps (budget permitting). But I think there maybe a lot more evolution here (with the whole battery powered concept being very new -- and we all know how fast the electronics industry changes -- although fortunately Porsche is trying to build in a way to avoid obsolescence here) where as the CGT is the ultimate expression of its design philosophy. I love its "bare bones" efficiency (but to such a high standard), btw.
Now who was it that complained that site might become dominated by a comparison between these two cars? (I'll have to change my moniker to "foot in mouth").
It is all very fascinating though and I look forward to more reports from the field on this latest super car.
Cheers,
Steve
09-17-2013, 08:55 AM
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Your point about pushing air vs accelerating mass is valid. I know a little about this as I've taken all my cars to their maximum speeds on Autobahns....
The extreme case would be that on a top-speed autobahn run, held at max speed, the battery can only drain and not be re-charged, since there is no braking and no engine capacity for charging. The top speed of any hybrid would therefore theoretically drop through time.
As you say though the issue is whether this impacts on normal tracks or not. This will depend on the track concerned eg Monza is a very high speed track and Spa/Silverstone are close behind. They are likely faster than Leipzig where the demo runs have been held.
I'm starting to think that this won't be a problem though, but only time will tell.
The extreme case would be that on a top-speed autobahn run, held at max speed, the battery can only drain and not be re-charged, since there is no braking and no engine capacity for charging. The top speed of any hybrid would therefore theoretically drop through time.
As you say though the issue is whether this impacts on normal tracks or not. This will depend on the track concerned eg Monza is a very high speed track and Spa/Silverstone are close behind. They are likely faster than Leipzig where the demo runs have been held.
I'm starting to think that this won't be a problem though, but only time will tell.
09-17-2013, 11:24 AM
#38
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Gentlemen, very intelligent posts, but here's about all I understood from the previous 5 or so posts........... "Cheers"
The moral of this is that I (and I'm ONLY speaking for myself) like things I understand. I read stuff I understand, I invest in stuff I understand and I buy stuff I understand. I understand a howling V10 mounted inside a lightly disguised racecar.
Spectacular as it is, I don't understand and can't get my feeble mind around this complicated new breed of supercars. I'll be keeping my cgt.
The moral of this is that I (and I'm ONLY speaking for myself) like things I understand. I read stuff I understand, I invest in stuff I understand and I buy stuff I understand. I understand a howling V10 mounted inside a lightly disguised racecar.
Spectacular as it is, I don't understand and can't get my feeble mind around this complicated new breed of supercars. I'll be keeping my cgt.
09-17-2013, 02:08 PM
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No worries bbs992tt! I think you'll be the better for it (well, I have certainly made the same decision but cannot criticise the 918 for this at all). Its a little like the continuing saga of man claiming that he has conquered nature... Really? The CGT is designed to best follow the simple principles of physics; the 918 has decided to use all of man's wizardry to confound them. Sounds a little Paul Bunyan-ish? The beauty of the 918 is that it can deliver so much -- very high fuel efficiency, low carbon emissions, oh and a killer track time at the Ring. Yes, and like a solid state amp -- where solid state circuity was never designed for amplification but only for 0-or-1 logic signalling which however looks completely perfect in any way you can analytically measure it (low distortion, linear frequency response, etc. -- sound familiar?) but a simple triode tube -- a very simple tube from the 40's actually -- can blow it away for sound in the way that we imperfect creatures can be astounded by.
The extra ingredient in the 918 is that it uses (aside from the electric steering, automatic shifting, computer programmed torque suspension etc) a huge amount of energy in the form of batteries. The beauty of a battery here is that it can deliver its stored energy in an extremely fast time; but it takes so much longer time to recharge. Massive torque, but little sustainability...
Anyhow, so all we were discussing (GuyR please correct me or comment if you feel differently) is at what average speed does the magic of the extra power from the batteries (with massive torque) fall victim to a heavy duty track or circuit drive? (where the batteries naturally dissipate). Well, Porsche has done everything possible to maintain the magic at "normal speeds" though using the engine and the brakes to recharge the batteries -- but at very high speeds and with few regenerative opportunities (GuyR points out an example that I recently experienced -- a freely open autobahn), the car will soon become a heavily overweight CGT (well, from a CGT owner's perspective, thats a fully respectful comment).
The difference is bewildering and will be commented on for a while; in my best guess, the 918 will slowly lose its batteries on any reasonable track with long enough race times (GuyR feels the opposite way -- that it will be remarkably self sustaining). And thats where the light weight CGT comes to the fore...
The 918 is an obvious choice for the many (well at least those who are wealthy enough to afford it), but the CGT is an obvious choice for the few (those who really want to master driving it)... Yes, and I know, they are producing about a 1/3 less of the 918s...
Cheers,
Steve
The extra ingredient in the 918 is that it uses (aside from the electric steering, automatic shifting, computer programmed torque suspension etc) a huge amount of energy in the form of batteries. The beauty of a battery here is that it can deliver its stored energy in an extremely fast time; but it takes so much longer time to recharge. Massive torque, but little sustainability...
Anyhow, so all we were discussing (GuyR please correct me or comment if you feel differently) is at what average speed does the magic of the extra power from the batteries (with massive torque) fall victim to a heavy duty track or circuit drive? (where the batteries naturally dissipate). Well, Porsche has done everything possible to maintain the magic at "normal speeds" though using the engine and the brakes to recharge the batteries -- but at very high speeds and with few regenerative opportunities (GuyR points out an example that I recently experienced -- a freely open autobahn), the car will soon become a heavily overweight CGT (well, from a CGT owner's perspective, thats a fully respectful comment).
The difference is bewildering and will be commented on for a while; in my best guess, the 918 will slowly lose its batteries on any reasonable track with long enough race times (GuyR feels the opposite way -- that it will be remarkably self sustaining). And thats where the light weight CGT comes to the fore...
The 918 is an obvious choice for the many (well at least those who are wealthy enough to afford it), but the CGT is an obvious choice for the few (those who really want to master driving it)... Yes, and I know, they are producing about a 1/3 less of the 918s...
Cheers,
Steve
09-17-2013, 02:16 PM
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Of course many 918 owners won't choose to replace a CGT, they may already have a CGT or will keep both. The 918 is afterall around 3x the price of a used CGT, so for a 918 buyer it's not a stretch to have both.
09-17-2013, 02:32 PM
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I raised this issue of battery discharge in a few forums with a few people who have driven the 918 and the answer is as follows.
The 6:57 lap was done in 'hot-lap' mode which means no battery charging, just drain it for power. The same laps can be done in re-charge mode in which case the battery does not exhaust itself and in that mode it's about 5 secs slower at the 'ring.
So the answer is that a 918 can do either one lap at 6:57 or lap endlessly at 7:02.
The P1 and LaFerrari are more affected as they have smaller batteries and less re-charging methods.
The 6:57 lap was done in 'hot-lap' mode which means no battery charging, just drain it for power. The same laps can be done in re-charge mode in which case the battery does not exhaust itself and in that mode it's about 5 secs slower at the 'ring.
So the answer is that a 918 can do either one lap at 6:57 or lap endlessly at 7:02.
The P1 and LaFerrari are more affected as they have smaller batteries and less re-charging methods.
09-17-2013, 02:36 PM
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It's never been so good for the super rich. Owners to be of the big 3 have a multiple of exotics in their stable
09-17-2013, 03:15 PM
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GuyR, generally agree on the economics but for CGT that is like new, I think the ratio is more like 2x (there is a huge thread here on the value of used CGTs). But the real issue is: if I walk to the garage, which one do I take? I can afford both, but can only drive one (and if I can afford both, my time is pretty damn precious). In the camera world, we have this dilemma all the time -- many great cameras and lenses, which to take? If you are honest, you eventually simplify. Simplification makes you a better photographer (you learn to use your tools better). In modest-to-good conditions, I know I would grab the CGT (after I had experienced the novelty factor of the 918); Why do I think so? Look at the video with wtdoom driving the 918 (and he rates the car very favourably). The CGT howl is just in a totally different league -- its just beyond belief. The 918 has an amazing growl, but the CGT just excites everyone single one of my caveman nerves. And it handles like an open wheel race car -- I can't be too praiseworthy of the CGT here in this regard. I have not driven the 918 -- and so everything here is somewhat ignorant -- but I do think I can see the basic differences already. Since I don't drive to work, etc., I am going to choose the car in the garage that is just going to give me more fun (its also kinda why I love when I see Morgan drivers on the Autobahn -- a big thumbs up salute from my car because I can see their enjoyment). I have been in many cars -- not the 918 yet -- and the CGT is just totally different; my shirt is often soaked with sweat when am I done driving. This doesn't take anything away from the 918 (phenomenal!), I just fell in love with my "beast" beforehand... And to be fair, she's still got the sexiest curves on the planet... But in the winter, alas, the CGT must hibernate and perhaps there is room for a heavier, more robust but rounder winter car with 4wd? Oh boy...
09-17-2013, 07:46 PM
#45
GuyR,
Both good points!
The firsthand commentary is very interesting; and my only question would be wether these laps were done anywhere near the equivalent of a 7:04 lap time on the Ring? I.e. were they 150mph type of speeds or more gentler trips around the track. Again, the loss of "ordered" energy goes up exponentially at higher speeds as air becomes more like water and huge amounts of energy are lost to making those pesky air molecules (but lots of them) go a lot faster. I would believe their observation for lets say circa 80mph maybe (I am just totally guessing!). But above some point -- certainly approached by a 7:04 Ring time, its difficult to believe that the energy can regenerate itself (but this is perfect segway into your second point which is crucial).
On your second good point -- lets look at this as a closed system. Energy (ordered) is generated by both the V8 and the batteries -- it is transformed into (1) the velocity of the car (1/2 mv^2), (2) the heat produced by the car from the exhaust and tires and (3) the additional velocity of the air molecules being pushed out of the way (particularly intense when the boundary layer becomes so small at very high speeds). The energy transformed into heat (as defined here) doesn't vary that much compared to the speed of the car. However, the tradeoff between energy from the V8 and electric motors being transformed into (1) and (3) would depend dramatically upon the speed of the car. Thats why it takes so much more energy to go from 100-120 mph than from 180-200 mph. So at moderate speeds, where the energy from the V8 and electric motors is mostly transformed into kinetic energy of the car -- it makes complete sense that you can get enough of that kinetic energy back through the brakes to recharge the batteries. At very high speeds, where by far most of the additional energy from the V8 and the electric motors would go into moving air molecules out of the way, it is hard to believe that you get enough back from the extra input to maintain these high speeds to recharge the battery. Your point about all the regenerative energy going to the batteries is an important one although I would be surprised if it even got a 30% regenerative rate at normal rates given the inherent inefficiencies here -- but together with the V8 -- it would be enough to recharge the battery at reasonable speeds. It is at the very high speeds where the energy recapture rate from the brakes would probably drop fairly substantially (due to heat loss) and so your energy in (from the V8 and batteries) versus energy retained formula (first into the kinetic energy of the car and then back into the batteries) would be below one; the batteries would eventually lose out.
The real question is -- how fast does the 918 have to go before it crosses this equilibrium point? The statement that a 7:04 Ring track time is continuously repeatable and so is that "equilibrium point" seems awfully fast to me. But Porsche would know... Unfortunately, its just not very sexy to talk about fast do you have to go to drain your batteries and end up with a cutting edge supercar with a several hundred kilograms of "dead weight" on board; thats the stuff that good ole petrol heads have cold sweats about.
Even if the maintainable track time for the Ring (or other racing circuit) were well behind the CGT (with the new shoes), it still doesn't mean the 918 is not a big success. Far from it, it is the more practical car by some measure. It also is the fastest car (for a least a few good laps), etc. In short, it is a new way of approaching the car and they have done a fantastic job at it! Again, wtdoom's write-up does a really good job of trying to get your head around these two different animals. Since I only drive my car for adventure (the feel, the sound, the sight, the pure excitement, etc.), the CGT does it for me. Would I buy a 918 if it were not for the CGT -- maybe; it is just a bit high in price for my budget (but I hate people who slag something for its price because they can't afford it; the 918 is probably a bargain). Would I buy it later as a second -- hmmm practical --- car? Perhaps (budget permitting). But I think there maybe a lot more evolution here (with the whole battery powered concept being very new -- and we all know how fast the electronics industry changes -- although fortunately Porsche is trying to build in a way to avoid obsolescence here) where as the CGT is the ultimate expression of its design philosophy. I love its "bare bones" efficiency (but to such a high standard), btw.
Now who was it that complained that site might become dominated by a comparison between these two cars? (I'll have to change my moniker to "foot in mouth").
It is all very fascinating though and I look forward to more reports from the field on this latest super car.
Cheers,
Steve
Both good points!
The firsthand commentary is very interesting; and my only question would be wether these laps were done anywhere near the equivalent of a 7:04 lap time on the Ring? I.e. were they 150mph type of speeds or more gentler trips around the track. Again, the loss of "ordered" energy goes up exponentially at higher speeds as air becomes more like water and huge amounts of energy are lost to making those pesky air molecules (but lots of them) go a lot faster. I would believe their observation for lets say circa 80mph maybe (I am just totally guessing!). But above some point -- certainly approached by a 7:04 Ring time, its difficult to believe that the energy can regenerate itself (but this is perfect segway into your second point which is crucial).
On your second good point -- lets look at this as a closed system. Energy (ordered) is generated by both the V8 and the batteries -- it is transformed into (1) the velocity of the car (1/2 mv^2), (2) the heat produced by the car from the exhaust and tires and (3) the additional velocity of the air molecules being pushed out of the way (particularly intense when the boundary layer becomes so small at very high speeds). The energy transformed into heat (as defined here) doesn't vary that much compared to the speed of the car. However, the tradeoff between energy from the V8 and electric motors being transformed into (1) and (3) would depend dramatically upon the speed of the car. Thats why it takes so much more energy to go from 100-120 mph than from 180-200 mph. So at moderate speeds, where the energy from the V8 and electric motors is mostly transformed into kinetic energy of the car -- it makes complete sense that you can get enough of that kinetic energy back through the brakes to recharge the batteries. At very high speeds, where by far most of the additional energy from the V8 and the electric motors would go into moving air molecules out of the way, it is hard to believe that you get enough back from the extra input to maintain these high speeds to recharge the battery. Your point about all the regenerative energy going to the batteries is an important one although I would be surprised if it even got a 30% regenerative rate at normal rates given the inherent inefficiencies here -- but together with the V8 -- it would be enough to recharge the battery at reasonable speeds. It is at the very high speeds where the energy recapture rate from the brakes would probably drop fairly substantially (due to heat loss) and so your energy in (from the V8 and batteries) versus energy retained formula (first into the kinetic energy of the car and then back into the batteries) would be below one; the batteries would eventually lose out.
The real question is -- how fast does the 918 have to go before it crosses this equilibrium point? The statement that a 7:04 Ring track time is continuously repeatable and so is that "equilibrium point" seems awfully fast to me. But Porsche would know... Unfortunately, its just not very sexy to talk about fast do you have to go to drain your batteries and end up with a cutting edge supercar with a several hundred kilograms of "dead weight" on board; thats the stuff that good ole petrol heads have cold sweats about.
Even if the maintainable track time for the Ring (or other racing circuit) were well behind the CGT (with the new shoes), it still doesn't mean the 918 is not a big success. Far from it, it is the more practical car by some measure. It also is the fastest car (for a least a few good laps), etc. In short, it is a new way of approaching the car and they have done a fantastic job at it! Again, wtdoom's write-up does a really good job of trying to get your head around these two different animals. Since I only drive my car for adventure (the feel, the sound, the sight, the pure excitement, etc.), the CGT does it for me. Would I buy a 918 if it were not for the CGT -- maybe; it is just a bit high in price for my budget (but I hate people who slag something for its price because they can't afford it; the 918 is probably a bargain). Would I buy it later as a second -- hmmm practical --- car? Perhaps (budget permitting). But I think there maybe a lot more evolution here (with the whole battery powered concept being very new -- and we all know how fast the electronics industry changes -- although fortunately Porsche is trying to build in a way to avoid obsolescence here) where as the CGT is the ultimate expression of its design philosophy. I love its "bare bones" efficiency (but to such a high standard), btw.
Now who was it that complained that site might become dominated by a comparison between these two cars? (I'll have to change my moniker to "foot in mouth").
It is all very fascinating though and I look forward to more reports from the field on this latest super car.
Cheers,
Steve
However, I'm going to have to go with GuyR on this as well.
The owners that I've spoken to, read about or listened to (along with Journalist), who drove the car in Leipzig, had as much if not more battery life coming back then when they went out.
I think we have to remember: The Ring is a huge incredibly, demanding track. Porsche was trying to set a record. And most owners will never drive it 8/10ths, mind you 9-10/10ths (unless their race car drivers) on a track to begin with. I can't see any owners need to use "Hot Lap Mode, unless they just wanted to try it. However, I see most owners having their handful just trying to master the car in Race Hybrid, while enjoying the benefits of keeping the battery charged (and HP/Torque benefits) doing so
The 918 Spyder should be fine in Race Hybrid mode on almost any track (unless they never have to brake). Lol. And even then, they would get engine regeneration in Race Hybrid mode as well (though it wouldn't be as much with the brakes working as well). And of course on a straight road, your driving for fun, and not lap times, so it shouldn't matter (along with Traffic and La Policia).
As Tamad mentioned, I think Porsche was smart (though it initially bewildered "enthusiast" making such BIG BATTERIES; which also provided "plug in" and "Zero emissions" ability), along with Regenerative Braking for concerns/customers just like you Stephen.
If you have a Carrera GT (which you do), and purchased the 918, I figure you would drive the 918 on the track for yourself. And after a while (whether you liked it there or not), you'd do it periodically, but not often, cause it's a $1 Million dollar car for Heaven's sake. Who would do that (unless you want to, and/or had the money to waste, and didn't care)?
So until we hear other wise. I don't think driving it on the road, or on a track, would be an issue for you, based off what I read--from you Stephen--about your driving habits. Of course there's only one way to find out (i.e. test drive in Leipzig).
Until we hear something to the contrary: It seems to be a fabulous, well thought out (though of course, "New Breed") car.
My Opinion: Like you; as long as it works, and does what it's supposed to, I wouldn't get hung up on (not saying you are Stephen) the Hybrid aspect. That's how you get all that crazy torque, complemented by that screaming engine.
It Kinda, reminds me of the RX7 several years ago. After a while, some people forgot, it was a Wankel/Rotary engine, when it became such a good car and handler. I think it was reliable for a good portion of it's run as well (why do I only think of the one with the small suicide rear door)? Lol
It's always good to read your comments Stephen.