Crown

No, I'm not mixing up anything. I was just referring to thermodynamics, not to the technology (water spraying per se), simply because I don't know of any scientific study about that (I guess Porsche has some sort of technical documentation about water spraying but I doubt they will publish it ). 

You don't seem to understand what I am referring to: Any change in temperature has a direct consequence for emissions. If you raise the power by lowering the intake temperature, the emissions will change. This is now the tricky part, to find the perfect balance between power, reliability, emissions and amount of coolant (water) you need.

It is possible to use the water spraying to control emissions. Of course Porsche could have raised the power of the engine to 700 hp without water spraying but then, they would have needed a different approach which would have required certain hardware mods. The water spraying solution was the most (cost) effective one in my opinion, without the need of a major engine overhaul and maybe different more expensive turbo chargers and intercoolers.

--

RC (Germany) - Rennteam Editor Lamborghini Huracan Performante (2019), Mercedes E63 S AMG Edition 1 (2018), Mercedes C63 S AMG Cab (2019), Range Rover Evoque Si4 Black Edition (2019)

RC:

No, I'm not mixing up anything. I was just referring to thermodynamics, not to the technology (water spraying per se), simply because I don't know of any scientific study about that (I guess Porsche has some sort of technical documentation about water spraying but I doubt they will publish it ). 

You don't seem to understand what I am referring to: Any change in temperature has a direct consequence for emissions. If you raise the power by lowering the intake temperature, the emissions will change. This is now the tricky part, to find the perfect balance between power, reliability, emissions and amount of coolant (water) you need.

It is possible to use the water spraying to control emissions. Of course Porsche could have raised the power of the engine to 700 hp without water spraying but then, they would have needed a different approach which would have required certain hardware mods. The water spraying solution was the most (cost) effective one in my opinion, without the need of a major engine overhaul and maybe different more expensive turbo chargers and intercoolers.

I get what you are saying and you're probably theoretically right but for official emissions testing the water spray will make zero difference as they are not carried out anywhere near the conditions where the water spray will be active   

997 GT2 2014 3.9 Mezger, 800PS @ 1.2 bar

2018 McLaren 720S 

993 Turbo, 2006 built 3.8, 577PS/797NM, 1440kg DIN sold to a worthy enthusiast.

TB993tt:

RC:

No, I'm not mixing up anything. I was just referring to thermodynamics, not to the technology (water spraying per se), simply because I don't know of any scientific study about that (I guess Porsche has some sort of technical documentation about water spraying but I doubt they will publish it ). 

You don't seem to understand what I am referring to: Any change in temperature has a direct consequence for emissions. If you raise the power by lowering the intake temperature, the emissions will change. This is now the tricky part, to find the perfect balance between power, reliability, emissions and amount of coolant (water) you need.

It is possible to use the water spraying to control emissions. Of course Porsche could have raised the power of the engine to 700 hp without water spraying but then, they would have needed a different approach which would have required certain hardware mods. The water spraying solution was the most (cost) effective one in my opinion, without the need of a major engine overhaul and maybe different more expensive turbo chargers and intercoolers.

I get what you are saying and you're probably theoretically right but for official emissions testing the water spray will make zero difference as they are not carried out anywhere near the conditions where the water spray will be active   

Of course it makes a difference since the water spraying is part of the car's legal certification. 

The reduced power makes no difference since this also means emissions go down.

It doesn't really matter but I just wanted to point out that the water spraying is not only related to a power gain but also to keep emissions at bay as an "easier" workaround. Otherwise the car would have required a different (more expensive I guess) approach.

The intercooler temperature drops by around 20°C...this makes a huge difference and increases thermal efficiency. 

--

RC (Germany) - Rennteam Editor Lamborghini Huracan Performante (2019), Mercedes E63 S AMG Edition 1 (2018), Mercedes C63 S AMG Cab (2019), Range Rover Evoque Si4 Black Edition (2019)

Doesn’t even seem possible that the water spraying would kick in in any of the tests done for emissions testing...

RC:

 

Of course it makes a difference since the water spraying is part of the car's legal certification. 

The reduced power makes no difference since this also means emissions go down.

It doesn't really matter but I just wanted to point out that the water spraying is not only related to a power gain but also to keep emissions at bay as an "easier" workaround. Otherwise the car would have required a different (more expensive I guess) approach.

The intercooler temperature drops by around 20°C...this makes a huge difference and increases thermal efficiency.

at which load? not at low rpm for sure and certainly not in the band of the certification process for emission...

there is a massive difference between spraying water to the intercooler (and bringing higher humidity to the mix) than directly spraying water in the chamber which is instantly vapor and allow better heat transfer, higher cylinder pressure and ignition timing. 2 massively different technology with 2 different goals. 

there is negligible emission advantage below 3,500rpm in term of NOx and worst emission of CO at that range, the combustion becomes incomplete... the system on the 2RS is just designed for track purpose which means pushing the car again and again while allowing stabilized temperature to maintain the HP at high load. same system on the 2RS Clubsport...I am pretty sure the system is not even functional at low load.

GT Lover, Porsche fan

991.2 GT3 manual, 991 GT3 2014(sold)

Cayenne GTS 2014

the-missile:

RC:

 

Of course it makes a difference since the water spraying is part of the car's legal certification. 

The reduced power makes no difference since this also means emissions go down.

It doesn't really matter but I just wanted to point out that the water spraying is not only related to a power gain but also to keep emissions at bay as an "easier" workaround. Otherwise the car would have required a different (more expensive I guess) approach.

The intercooler temperature drops by around 20°C...this makes a huge difference and increases thermal efficiency.

at which load? not at low rpm for sure and certainly not in the band of the certification process for emission...

there is a massive difference between spraying water to the intercooler (and bringing higher humidity to the mix) than directly spraying water in the chamber which is instantly vapor and allow better heat transfer, higher cylinder pressure and ignition timing. 2 massively different technology with 2 different goals. 

there is negligible emission advantage below 3,500rpm in term of NOx and worst emission of CO at that range, the combustion becomes incomplete... the system on the 2RS is just designed for track purpose which means pushing the car again and again while allowing stabilized temperature to maintain the HP at high load. same system on the 2RS Clubsport...I am pretty sure the system is not even functional at low load.

 

not only that but the system will also not kick in at low outside temperatures. Porsche even recommends to empty the water tank in winter to avoid damage to the system. 

997 GT3 clubsport | 991 GT2 RS

Gnil:

Whoopsy:

Gnil:

Why did you dismount  the springs ? Are you changing them ?

 

I got brand new springs from Porsche replaced under warranty. These are the worn down ones. 

Under warranty because you tracked the car a few times and got 1.7 lateral G's  ....... Maybe I should ask for new ones too 

You could. It is a known problem. But it's only a problem for a select few. Most people don't stressed their car till that point outside of factory drivers.

Have your mechanic inspect the spring protectors.

Kobalt:

Gnil:

Whoopsy:

I got brand new springs from Porsche replaced under warranty. These are the worn down ones. 

Under warranty because you tracked the car a few times and got 1.7 lateral G's  ....... Maybe I should ask for new ones too 

 

Whoopsy's?

Wait, the water can freeze in the winter? What if you garage heat fails?

Porsche states that the water spray system wont work at temeratures below 5c. because of that, 2RS will not be delivered with a full water tank and they only recommend to dealers to fill it with distilled water for deliveries on warm days. When used in winter or around freezing temperatures and when storing the car for a longer time Porsche recommends to empty the tank with a conventional manual pump. I will look for the text about it, but it will be in German 

997 GT3 clubsport | 991 GT2 RS

And you have to pump it out? Seriously, who has the time for all that...

Gnil:

Josef:

 

I was in Imola over the weekend for the Porsche Suisse Cup, 3 GT2 RS were on the track but I did not ask about water consumption. There are at least quite a few GT2 RS owners using the car on track which is a good sign. However, one had a crash with another car.

The problem with the GT2 RS on regular  tracks  is not the water , it' s the break pad wear 

Yes, that as well. Two days at Spa last fall at around 20 degrees. Ordinary tank empty after 3-4 laps and the pads totally fucked after that two days.... one of the pads was even split in two😱

SciFrog:

And you have to pump it out? Seriously, who has the time for all that...

Who has the time to go fish out the charging cable to plug a EV car back to the wall after parking? It's such an hassle to linger around longer to do that when one can just shut the door and walk away for a normal car. 

I don’t someone does it for me more seriously, that cannot compare...

The farmer:

Yes, that as well. Two days at Spa last fall at around 20 degrees. Ordinary tank empty after 3-4 laps and the pads totally fucked after that two days.... one of the pads was even split in two😱

Last year when I was at Imola with the Swiss sports cup , they were two GT2 RS doing the free training . They had to change at the end of each day the pads .  They were driving the car very fast and hard and had also switched to steel brakes . 

The car is a rocket ...... but also a bit heavy .

--

 964 Carrera 4 --  997.2 C2S , -20mm -- 991.2 GT3 RS 

SciFrog:

Doesn’t even seem possible that the water spraying would kick in in any of the tests done for emissions testing...

It kicks in once the boost pressure reaches a certain level. 

RC (Germany) - Rennteam Editor Lamborghini Huracan Performante (2019), Mercedes E63 S AMG Edition 1 (2018), Mercedes C63 S AMG Cab (2019), Range Rover Evoque Si4 Black Edition (2019)

it kicks in when the temperature reaches a certain level....

997 GT3 clubsport | 991 GT2 RS

rantanplan:

it kicks in when the temperature reaches a certain level....

Also this... 

RC (Germany) - Rennteam Editor Lamborghini Huracan Performante (2019), Mercedes E63 S AMG Edition 1 (2018), Mercedes C63 S AMG Cab (2019), Range Rover Evoque Si4 Black Edition (2019)

because i havent taken my GT2RS to the track yet, only to a drift day in cold and wet conditions and to a rally last November when it was cold here in Germany, I didnt have to refill the water tank in 5500km of driving the car. Only after a rally on very demanding pass roads in Switzerland at around 29C outside temp for 2 days in a row the car finally needed a refill last week. 

I drove the car fairly hard several times kicking it to 320kmh and used full boost pressure on many occasions but the 2RS really only seemed to use the water spray when driving hard in hot conditions. At least thats my own personal experience with it...

997 GT3 clubsport | 991 GT2 RS

RC:

SciFrog:

Doesn’t even seem possible that the water spraying would kick in in any of the tests done for emissions testing...

It kicks in once the boost pressure reaches a certain level. 

RC, you seem to think that EU emissions testing is carried out in the zone where the water spray is active, I had a look at the protocols and can only see "Motorways high speed" listed as one of the driving conditions, surely this will come no where near the water spray trigger points, do you have other info on the emissions testing or are you just being dogmatic ?  

997 GT2 2014 3.9 Mezger, 800PS @ 1.2 bar

2018 McLaren 720S 

993 Turbo, 2006 built 3.8, 577PS/797NM, 1440kg DIN sold to a worthy enthusiast.

TB993tt:

RC:

SciFrog:

Doesn’t even seem possible that the water spraying would kick in in any of the tests done for emissions testing...

It kicks in once the boost pressure reaches a certain level. 

RC, you seem to think that EU emissions testing is carried out in the zone where the water spray is active, I had a look at the protocols and can only see "Motorways high speed" listed as one of the driving conditions, surely this will come no where near the water spray trigger points, do you have other info on the emissions testing or are you just being dogmatic ?  

I can only tell you what I've been told when I talked about the water spraying system. Apparently it doesn't have only one purpose but I don't know when it kicks in otherwise (outside the maximum power/certain temp range).

RC (Germany) - Rennteam Editor Lamborghini Huracan Performante (2019), Mercedes E63 S AMG Edition 1 (2018), Mercedes C63 S AMG Cab (2019), Range Rover Evoque Si4 Black Edition (2019)

The water jet system is solely an external cooling system for the intercoolers. It only kicks in when IAT reaches a predefined level and the air to air intercooler can no longer keep up the cooling. 

If the water runs dry, the ECU simply reduces boost to keep IAT within the operating range. Hence the power deficit when there is no water.

Now if someone runs the car hard in cooler weather, or not running the car hard, the IAT may not even get to the trigger temp and spray will not be needed. The reverse is also true, if the ambient temperature is high enough, or the car is driven hard enough, the IAT could be above the trigger point and water spray is activated from the get go.

Track configuration also plays a role, if there are lots of stretches where the car is under full boost, i.e. lots of long straights, then the IAT will be above the trigger temp and water start spraying. But if the track don't have lots of long straights, then the time spent doing part throttle will be enough to keep the IAT below the trigger point and very little if any water is needed.

The intercoolers themselves have a specific heat dissipating capacity, if that number is not reached, it's pointless and useless to spray water to help cool the charge, as they do't need the extra help. 

The Porsche system is purely external, it has no effect on emission unlike the internal injection system employed by BMW.

So changing thermodynamics, this happens by changing the DET/intake charge temperatures through cooler temperatures (intercooler) by spraying water on the intercooler, thus preventing/suppressing detonation doesn't change emissions? Interesting. So emissions stay the same?  

I had a (retrofitted) water/methanol injection in my private Lancia Delta HF Integrale 16V and in a tuned Fiat Uno Turbo, so I know the difference.  Water spraying is actually the cheapest (easiest?) method to achieve a certain goal and I am still surprised Porsche didn't go a different route, even if it seems to be effective.

--

RC (Germany) - Rennteam Editor Lamborghini Huracan Performante (2019), Mercedes E63 S AMG Edition 1 (2018), Mercedes C63 S AMG Cab (2019), Range Rover Evoque Si4 Black Edition (2019)

RC:

So changing thermodynamics, this happens by changing the DET/intake charge temperatures through cooler temperatures (intercooler) by spraying water on the intercooler, thus preventing/suppressing detonation doesn't change emissions? Interesting. So emissions stay the same?  

I had a (retrofitted) water/methanol injection in my private Lancia Delta HF Integrale 16V and in a tuned Fiat Uno Turbo, so I know the difference.  Water spraying is actually the cheapest (easiest?) method to achieve a certain goal and I am still surprised Porsche didn't go a different route, even if it seems to be effective.

 

Are you being deliberately obtuse ? 

Of course the improved intercooling via the spray will have some effect of emissions, noone is arguing about that we are pointing out that for the official emission testing protocol ie on the chassis dyno and now on the road, the spray system will have zero effect as it will not be activated since it only kicks in at high IATs which will NOT be present during the official certification testing.

Porsche went this route 'cos its cheap and maybe it is logistically quite hard to get a big production run of the higher quality aerospace intercoolers which would have done the job better and more reliably. 

997 GT2 2014 3.9 Mezger, 800PS @ 1.2 bar

2018 McLaren 720S 

993 Turbo, 2006 built 3.8, 577PS/797NM, 1440kg DIN sold to a worthy enthusiast.

TB993tt:

RC:

So changing thermodynamics, this happens by changing the DET/intake charge temperatures through cooler temperatures (intercooler) by spraying water on the intercooler, thus preventing/suppressing detonation doesn't change emissions? Interesting. So emissions stay the same?  

I had a (retrofitted) water/methanol injection in my private Lancia Delta HF Integrale 16V and in a tuned Fiat Uno Turbo, so I know the difference.  Water spraying is actually the cheapest (easiest?) method to achieve a certain goal and I am still surprised Porsche didn't go a different route, even if it seems to be effective.

 

Are you being deliberately obtuse ? 

Of course the improved intercooling via the spray will have some effect of emissions, noone is arguing about that we are pointing out that for the official emission testing protocol ie on the chassis dyno and now on the road, the spray system will have zero effect as it will not be activated since it only kicks in at high IATs which will NOT be present during the official certification testing.

Porsche went this route 'cos its cheap and maybe it is logistically quite hard to get a big production run of the higher quality aerospace intercoolers which would have done the job better and more reliably. 

I try to be as subtle as possible why this system exists but apparently leaving a hint is difficult...  

Let it be how you guys say, so I don't have to write stuff over and over again. 

RC (Germany) - Rennteam Editor Lamborghini Huracan Performante (2019), Mercedes E63 S AMG Edition 1 (2018), Mercedes C63 S AMG Cab (2019), Range Rover Evoque Si4 Black Edition (2019)

Since VW swallowed Porsche, one should never expect high quality part (especially under the skin) will be installed any time soon

BiTurbo:

Since VW swallowed Porsche, one should never expect high quality part (especially under the skin) will be installed any time soon

You said it, not me.    

RC (Germany) - Rennteam Editor Lamborghini Huracan Performante (2019), Mercedes E63 S AMG Edition 1 (2018), Mercedes C63 S AMG Cab (2019), Range Rover Evoque Si4 Black Edition (2019)

OK I will take a jab at it. When the software detects an emissions test (we know they can do that) it sprays water on the intercooler to reduce emissions, ie “cheat”... In real usage, this does not happen except when hot and/or at the track   Else you would use water often and people do not want to have to refuel water on a $250k car. That would be very sneaky. Very very sneaky, but would that be surprising?

SciFrog:

OK I will take a jab at it. When the software detects an emissions test (we know they can do that) it sprays water on the intercooler to reduce emissions, ie “cheat”... In real usage, this does not happen except when hot and/or at the track   Else you would use water often and people do not want to have to refuel water on a $250k car. That would be very sneaky. Very very sneaky, but would that be surprising?

 Joking aside, no. There is no cheating involved (as far as I know), just using a simple solution for a more complex issue which could have been solved, incl. a higher output by using "better" parts. Or let me rephrase it: Maximum gain at lowest possible cost to achieve a "competitive" power output (vs. the 720S). As far as I heard, Porsche never planned to give the GT2 RS 700 hp, this happened pretty late in the development process. Now I shut up.

The GT2 RS is an amazing car but it didn't deserve the tech it got.  I still applaud Porsche for achieving what they achieved with the "limited" resources. This definitely speaks for their engineers, no doubt. 

--

RC (Germany) - Rennteam Editor Lamborghini Huracan Performante (2019), Mercedes E63 S AMG Edition 1 (2018), Mercedes C63 S AMG Cab (2019), Range Rover Evoque Si4 Black Edition (2019)

About 100 GT2RS delivered here in UAE. This system is just crap. You can’t drive on normal roads with our summer without emptying the tank. I can’t wait to see the guys trying to push on track days with 20L of distilled water sitting on the pit. I don’t know by what you are impressed but frankly this is typical cheap engineering. We can start talking thermodynamics all day long if you like...

GT Lover, Porsche fan

991.2 GT3 manual, 991 GT3 2014(sold)

Cayenne GTS 2014