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Yeah it was posted on the big P1 thread thats now been locked, these are Ron's comments people are referring to
 

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I sent a Tweet to the author letting him know that the 'mood board' slide that got everyone in a tizzy was shown to foreign media at the MTC, not to potential P1 customers - that's what the article stated when I could give it a glance this afternoon and that isn't accurate. He thanked me for the clarification and I assume he has or will correct the article to clarify that point.

The other issue I caught while skimming was the one about the P1 needing two recharges to make one lap of the Ring. That's not explained very well either, as those recharges amount to a cumulative total of power spent over the course of the lap with the EMachine (in McLaren-speak) regenerating the power required to recharge the batteries using excess torque from the engine along the way. At no point is the P1 ever completely out of battery assisted power nor do you have to stop to plug it in - some power goes out, some power goes back in. Only when you add up all the electrical power used over the length of the lap do you see that it is equal to twice the capacity of the battery and not having the battery capacity to do a complete lap on one charge is essentially a good thing as it means the car carries less battery weight. It's also impressive that the P1's power regeneration capabilities can manage restoring that much power when being driven flat out. Perhaps the only negative here is to fuel economy versus the strategy employed by others to recover kinetic energy through the brakes, but as we know McLaren have their reasoning on this.

I'll read the rest later - I only caught bits of it when a friend flagged me for being referenced in the text. Sort of expected Jalopnik to run with the story and they did manage to draw a little more information from McLaren to clarify their current position as a result.

>8^)
ER
 

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No Moncho - we are newsmakers. ;) :D

>8^)
ER
 

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Sorry... The myopic, leading the blind.
 

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I think this Jalopnik story sums things well but one thing I am struggling with.

the EMachine (in McLaren-speak) regenerating the power required to recharge the batteries using excess torque from the engine along the way.
and

It's also impressive that the P1's power regeneration capabilities can manage restoring that much power when being driven flat out
Reminding people of basic conservation of energy whatever goes to the battery is obviously negative for forward propulsion. I'm happy to accept McLaren have an ability but they can't redefine first principles.

So now watch any number of on board Nurburgring videos and listen to the motor. The 918 lap is as good as anything. Where on the lap - and for how long - do we see any part throttle events? Not many right? So can someone explain how this system works and manages to re-charge itself 2x on a lap?
 

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So now watch any number of on board Nurburgring videos and listen to the motor. The 918 lap is as good as anything. Where on the lap - and for how long - do we see any part throttle events? Not many right? So can someone explain how this system works and manages to re-charge itself 2x on a lap?
In almost any of the 73 corners ? :confused:

I'm certainly not a racing driver as you are, just did some tourist sight seeing laps there but having a hard time to imagine that the P1 (or 918 for that matter) is going flat out at Hatzenbach, Quiddelbach-Flugplatz, Aremberg, A'Forst, Metzgesfeld, Kallenhardt, Miss.Hit.Miss, Wehrseifen, Breidscheid, Bergwerk, Klostertal, Karussel, Hoche Acht, Wippermann, Brünnchen, Eiskurve, Pflanzgarten, Schwalbenschwanz and Galgenkopf ?

So if it's not all flat out, then it must be part throttle ? So time to regenerate ?



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I read this:-

The battery charges using surplus power from the engine, or it can be plugged in and charged in two hours on a standard charge or 10 minutes on a fast charge. The V8 engine can also be used as a generator in preparation for electric use. McLaren took the decision not to recoup power from the brakes, as it felt the loss of brake feel far outweighed the benefits

Not a lot of balanced throttle at the 'Ring i'm afraid when flat out... so when are we re-charging? I don't pretend to be an engineer on this stuff but I can see its actually pretty complex especially if we start introducing this balance element. Thing is balance on or off power is the same thing in terms of importance?
 

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I'm sorry but there is very little part throttle in driving a fast lap... I can't really convince you here beyond asking you to look and listen to the lap of the Porsche 918 on Youtube.

In the main you are throttle or brake - doing nothing is very very seldom seen. Of course there are "balanced" throttle phases but as I asked before if there is a question of balance then you are really just transferring the issue of balance from braking phase to part power...

Its an interesting point - and one that is i'm convinced behind the silence - but without understanding how it works beyond the marketing BS its tough to know.

Of course my contention is that this would make more interesting reading in Autocar / EVO if they were to do a better job.
 

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Discussion Starter #13
In the main you are throttle or brake - doing nothing is very very seldom seen. Of course there are "balanced" throttle phases but as I asked before if there is a question of balance then you are really just transferring the issue of balance from braking phase to part power...
Phil, why wouldn't the car just keep the revs up when you're on the brake and let up on the gas in a turn? There are a *lot* of turns on that track. For the 918 run, it didn't sound like he was "on it" in all the turns to me.


Listen at 1:03, 1:10, 1:21, 1:28, 1:38, 1:45, etc. etc. You hear the engine winding down as he approaches a lot of turns.
 

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I'm sorry but there is very little part throttle in driving a fast lap... I can't really convince you here beyond asking you to look and listen to the lap of the Porsche 918 on Youtube.

In the main you are throttle or brake - doing nothing is very very seldom seen. Of course there are "balanced" throttle phases but as I asked before if there is a question of balance then you are really just transferring the issue of balance from braking phase to part power...

Its an interesting point - and one that is i'm convinced behind the silence - but without understanding how it works beyond the marketing BS its tough to know.

Of course my contention is that this would make more interesting reading in Autocar / EVO if they were to do a better job.
I have to disagree.

I'm not saying at all "doing nothing", we were talking about part throttle or "balanced" throttle phases as you call it. A situation where the P1 would be able to re-charge by overreving the engine, IF that is how it is supposed to work.

And there's quite a lot of part/balanced throttle even on the 918 hot lap.

I'm referring to this video with a VVBOX overlay:

http://www.youtube.com/watch?v=pV8aNwEBPTQ

Please check the boost gauge. How often on that lap is the car under full boost and the engine under full throttle ? I would say less than 40%. Maybe even less than 30%.

7 minutes for a lap of 22km means an average of 188 kph which is not that much for a 900hp car. Of course there is up and downhill but that numbers make clear, that the car spends quite some time beeing not driven under full throttle.




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Phil, why wouldn't the car just keep the revs up when you're on the brake and let up on the gas in a turn? There are a *lot* of turns on that track. For the 918 run, it didn't sound like he was "on it" in all the turns to me.
Yes that's why I'm asking about the control laws for the hybrid system. What is known is that they will not re-charge in the braking phase - and that will take out a lot of the areas you call "winding down".

Lets take a 90deg corner. You will be 100% throttle approaching, then 100% throttle to 100% braking initially and then only part throttle in the mid corner before 100% throttle. Now of course there are periods when you bleed off the brake and have zero throttle just as you may have periods of part throttle as you balance the car mid-corner. However doesn't that give a balance problem but instead of braking in the part throttle / balance phase??

I would find it incredible if when coming onto the throttle and trying to accelerate any engine power was going to re-charge the battery as it wouldn't make sense simply from a physics sense. In the de-acceleration phase I stuggle to see any significant off throttle deaccel without braking.
 

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Discussion Starter #17
Yes that's why I'm asking about the control laws for the hybrid system. What is known is that they will not re-charge in the braking phase - and that will take out a lot of the areas you call "winding down". .
I'm not sure this is correct. I believe they have no regenerative braking. However, the engine will opportunistically seek out times when it can keep revs up beyond what is needed an divert that to the battery. Just to clarify, just because they do not have brake regen does not mean they would not use engine regen during a braking event. I haven't seen anything to suggest that they will not use the engine to regen during braking, and think your information is incorrect on that, but would happily be corrected if my understanding is wrong.
 

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I'm not saying at all "doing nothing", we were talking about part throttle or "balanced" throttle phases as you call it. A situation where the P1 would be able to re-charge by overreving the engine, IF that is how it is supposed to work.

And there's quite a lot of part/balanced throttle even on the 918 hot lap.

Please check the boost gauge. How often on that lap is the car under full boost and the engine under full throttle ? I would say less than 40%. Maybe even less than 30%.
Yes I hear this "over -revving" concept but when can that happen? It can not happen in acceleration because that creates the same "balance" issues as if you harvest under braking - except now you managing it on the power side not braking. Maybe that IS how it works but I would be surprised. Why? Because you will have times when 100% throttle is not 100% and so on... you'd have a varied throttle response to a consistent input - which is never a good thing in any machine be it car, motorbike, helicopter or aeroplane.

So now all we are left with are these part throttle (and yet NO brake because they tell us it doesn't harvest under braking) that is a rare event on a race track. hence your comment

How often on that lap is the car under full boost and the engine under full throttle ? I would say less than 40%. Maybe even less than 30%.
needs refining - how many times is that whilst in deacceleration and with no braking.....
 

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Discussion Starter #19
Lets take a 90deg corner. You will be 100% throttle approaching, then 100% throttle to 100% braking initially and then only part throttle in the mid corner before 100% throttle. Now of course there are periods when you bleed off the brake and have zero throttle just as you may have periods of part throttle as you balance the car mid-corner. However doesn't that give a balance problem but instead of braking in the part throttle / balance phase??

I would find it incredible if when coming onto the throttle and trying to accelerate any engine power was going to re-charge the battery as it wouldn't make sense simply from a physics sense. In the de-acceleration phase I stuggle to see any significant off throttle deaccel without braking.
This is a really good question and one I can't answer. I know generally you like to keep revs up in a car even through a turn if you can, and generally that doesn't seem to upset the inertial balance of the car. But it certainly could! Particularly if the car jets the heck out of the throttle. This is an unknown, and you would think McLaren would consider this. Perhaps they have a solution as magical as their hydraulic suspension. And perhaps you are 100% correct in that it limits how much excess throttle could be applied. Is that 0 throttle excess? I'd say likely not, but perhaps so.

I don't understand fully how it all works either.

That said, after McDc posted the video with the boost and after noting the spots to you when you hear the engine isn't on it, I've changed my own mind on being dubious if there is enough juice to get around the track. I'm pretty certain there is more than enough opportunity to juice the battery and get through the lap and think the sectional stuff, while legitimate speculation, is now off the mark. The car has the juice to make it. I could still be wrong, particularly if you are correct that there is no opportunity to give a little rev boost in the turns, but I think that very likely there is without messing up the balance (probably more a question of degree, some small percentage over what is needed, say 10-15% would likely not upset the balance but still provide plenty of juice for the battery)
 

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I'm not sure this is correct. I believe they have no regenerative braking. However, the engine will opportunistically seek out times when it can keep revs up beyond what is needed an divert that to the battery. Just to clarify, just because they do not have brake regen does not mean they would not use engine regen during a braking event. I haven't seen anything to suggest that they will not use the engine to regen during braking, and think your information is incorrect on that, but would happily be corrected if my understanding is wrong.
I'm just reading this:-

The battery charges using surplus power from the engine, or it can be plugged in and charged in two hours on a standard charge or 10 minutes on a fast charge. The V8 engine can also be used as a generator in preparation for electric use. McLaren took the decision not to recoup power from the brakes, as it felt the loss of brake feel far outweighed the benefits

If I read your view correctly (and great conversation guys - remember I don't know the workings of this system either! I'm just putting a view across) you saying you are off throttle and on the brake and the engine is via a controller opening the throttle while you braking??
 
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