[WEC] Porsche Prototype Discussion

[cokata]

[Articus]

The level in boost in the Porsche is just unbelievable. I've been watching a few onboards and it looks quite hairy for the drivers especially when you they have to suddenly dart out from behind a car in order to avoid rear ending them such is the rate of acceleration.

If the 17 just narrowly missed rearending the Audi, imagine how crazy it must be if you make the mistake of following a GT car out of a corner. I think the Porsche is one of the most mentally demanding cars to drive for that reason. Just avoiding rear end collisions with slower classes looks dodgy.

[hcl123]

And better is the management of the all thing... i think the driver has a 'button' if he wants more in some particular 'launching' phase or the programmed, and it can be way far from the 'curve'. The system automatically re-programs the quantity for the other 'launching' phases in a lap... superb!... and superb specially that electric motor power ( its not all about the amount of energy but what you can do with it)

[ that is why some times we see the Porsche not able to pass those pesky Audis, when some laps before was easy(too many requests for additional boost in previous launches) ... its great, but its not infinite an stops abruptly... and next year when Audi passes to 6MJ and Toyota to 8MJ, i think we will not see those images like that and or that often (they to will have a special look at those electric motors)-> Porsche would be better with a V6 ]

[Spyderman]

If a V6 is coming (which is unlikely) then it will only be in 2017.

[Richard C]

I don't quite get why there is a push for a V6 by some. I can't say I know all of the details, but I would expect there is a real balance of trying to juggle displacement, friction, balance and number of cylinders. For example at one extreme you have a single cylinder, that may have fewer moving parts (less fiction) but with balance issues. On the other extreme you have V12 (or larger) that are nicely balanced, but with a lot more parts and more friction.

You can find articles online that talk about a trend toward 500cc cylinders as being optimal from an efficiency perspective...

http://blog.caranddriver.com/why-0-5...engine-design/

So that is why you are seeing more and more three cylinder 1.5L turbos these days in road cars. I can't think of a reason as to why this would not also apply to race engines. Especially race engines in which the goal is maximum power for a given amount of fuel (high efficiency) and that also includes a lower RPM (such as you see in both F1 and WEC these days). Maybe things are different if you are looking to get maximum power as you can crank up the RPM in a small package but you probably also give up fuel efficiency (how things have been done prior to fuel flow limits).

If that works, then I can understand Porsche using a four cylinder 2L engine. And given they have shown that the low displacement turbo works, why go larger? If the 500cc rule of thumb is correct then the optimal size for a six cylinder (V6 in this case) would be 3L. Do we see Porsche running a 3L turbo six?

Now if I was to try to tear down my argument, I would point to F1. Which is using a 1.6L V6 with a per cylinder displacement of 266cc. So Porsche could easily build a 2L V6 with a per cylinder displacement of 333cc (less than curent, but higher than F1's value). However, I suspect that F1 picked the displacement as part of the desired power cap and that the engine manufactures couldn't settle on a four cylinder solution (Ferrari I think didn't want a four cylinder?) so they settled on a V6. So the per cylinder displacement just happened to become 266cc and it also wasn't far (engineering wise) from the prior 2.4L V8 at a 300cc cylinder displacement.

Overall... I expect Porsche to stick with what is working for them for now. Maybe (as Spyderman says) they might consider a change in 2017 if it makes sense for some reason.

Richard

[cokata]

[Starfish Primer]

Originally Posted by Richard Casto

I don't quite get why there is a push for a V6 by some. I can't say I know all of the details, but I would expect there is a real balance of trying to juggle displacement, friction, balance and number of cylinders. For example at one extreme you have a single cylinder, that may have fewer moving parts (less fiction) but with balance issues. On the other extreme you have V12 (or larger) that are nicely balanced, but with a lot more parts and more friction.

You can find articles online that talk about a trend toward 500cc cylinders as being optimal from an efficiency perspective...

http://blog.caranddriver.com/why-0-5...engine-design/

So that is why you are seeing more and more three cylinder 1.5L turbos these days in road cars. I can't think of a reason as to why this would not also apply to race engines. Especially race engines in which the goal is maximum power for a given amount of fuel (high efficiency) and that also includes a lower RPM (such as you see in both F1 and WEC these days). Maybe things are different if you are looking to get maximum power as you can crank up the RPM in a small package but you probably also give up fuel efficiency (how things have been done prior to fuel flow limits).

If that works, then I can understand Porsche using a four cylinder 2L engine. And given they have shown that the low displacement turbo works, why go larger? If the 500cc rule of thumb is correct then the optimal size for a six cylinder (V6 in this case) would be 3L. Do we see Porsche running a 3L turbo six?

Now if I was to try to tear down my argument, I would point to F1. Which is using a 1.6L V6 with a per cylinder displacement of 266cc. So Porsche could easily build a 2L V6 with a per cylinder displacement of 333cc (less than curent, but higher than F1's value). However, I suspect that F1 picked the displacement as part of the desired power cap and that the engine manufactures couldn't settle on a four cylinder solution (Ferrari I think didn't want a four cylinder?) so they settled on a V6. So the per cylinder displacement just happened to become 266cc and it also wasn't far (engineering wise) from the prior 2.4L V8 at a 300cc cylinder displacement.

Overall... I expect Porsche to stick with what is working for them for now. Maybe (as Spyderman says) they might consider a change in 2017 if it makes sense for some reason.

Richard

I think the 1.6 Liter engine in F1 was linked to the Global Racing Engine idea, that 1.6 4 cylinder Turbo that could be used for WRC, WTCC... Then Ferrari and I think Mercedes pushed for something more glamorous than a 4 cylinder.

[Victor_RO]

Those GIFs of the Porsches demolishing everything under acceleration...

[Richard C]

Originally Posted by Starfish Primer

I think the 1.6 Liter engine in F1 was linked to the Global Racing Engine idea, that 1.6 4 cylinder Turbo that could be used for WRC, WTCC... Then Ferrari and I think Mercedes pushed for something more glamorous than a 4 cylinder.

Yes it was the Global Racing Engine idea. I can imagine that displacement working well for many different series and uses. While F1 abandoned the idea of the Global Racing Engine, I wonder why they still picked that displacement for F1?

Richard

[Richard C]

Regarding those GIFs...

Regardless of the technical discussion, those clips show how epic it must have been to drive those machines in that race. Especially at night.

As a fan, it's always hard to know when you are in a golden era. It generally is a hindsight thing. My love of prototype racing started in the Group C/GTP days. I had no idea then as I walked around the paddock at Mid Ohio (1985 +/-) as a youngster fresh out of high school that I was witnessing one at that time. I think the same is happening now.

Richard

[TF110]

Those gifs show you need 8mj. Thats like "power on demand" in a big way. I really hope Nissan, not just Toyota join that subclass next year.

[cokata]

Originally Posted by TF110

Those gifs show you need 8mj. Thats like "power on demand" in a big way. I really hope Nissan, not just Toyota join that subclass next year.

When the conditions were right for them, Audi were quicker outright and not by a tiny margin, but one more thing the hybrid system does for Porche is that it allows them to store a lot of energy and manually boost when needed to overtake traffic before a corner. Most of the Porsche drivers were using it excessively. The flywheel and supercap just can't hold so much energy.

[TF110]

Outright speed didnt win for Audi. Porsche could put together those consistent sub 3:20's when they needed it. Should be good next year to see how everyone responds. It will be more of a drag race next year imo.

[Articus]

I can't help but to draw parallels between the boost sytem on the Porsche and the Mushrooms from the old MarioKart games. Those Porsche drivers are having fun, simply put.

[Pole2Win]

Originally Posted by Articus

I can't help but to draw parallels between the boost sytem on the Porsche and the Mushrooms from the old MarioKart games. Those Porsche drivers are having fun, simply put.

That's pretty much it, except the mushrooms are random whereas the 919s always have boost at their disposal.

[Spyderman]

Originally Posted by cokata

When the conditions were right for them, Audi were quicker outright and not by a tiny margin...

What period was that? Lets see if the data bares this out.

I'll give you that the Audi's had a slight edge on race pace, but it was not by a large margin (as you claim) and it certainly wasn't consistent.

[hcl123]

Originally Posted by TF110

Those gifs show you need 8mj. Thats like "power on demand" in a big way. I really hope Nissan, not just Toyota join that subclass next year.

Better than 8MJ, you need the power and efficiency of the Porsche electric motor... thats the big differentiator. Usually when you start a straight with a great push, your momentum is higher down the all straight. Porsche didn't attain the top speed, the engine simply can't keep up, but has other posters stated, perhaps if you go for a V6 fuel consumption augments to a point that it isn't advantageous for varied strategies possible...

So it depends, if other contenders find the electric power levels of Porsche... even with only 6 MJ... i think they will be forced to adopt a V6 and find the necessary efficiency to stay at the top nosh... as earlier as 2017 (the wise would be to anticipate and already in 2016).

[ as example i think if Porsche didn't had the hybrid system functioning(imitate Nissan), it would be 5 to 6 sec slower at LM]

[Spyderman]

Originally Posted by hcl123

Better than 8MJ, you need the power and efficiency of the Porsche electric motor... thats the big differentiator. Usually when you start a straight with a great push, your momentum is higher down the all straight. Porsche didn't attain the top speed, the engine simply can't keep up...

This is a myth. The Porsche hit 340Km/h on the straight. That is more than enough considering the huge acceleration advantage they have from the electric engine.

Porsche's "weak spot" seems to be mechanical and aero grip. It has improved quite a bit in the twisty parts, but it still is not on par with Audi. It lost time in sectors 1 and 3. S1 is not too important (at Le Mans) because it is so short, but S3 is very important for overall lap time (especially in traffic).

The other area of "concern" are the brakes. Car #18 had a dreadful time throughout the race with this issue.

[Spyderman]

Just some data analysis to illustrate the advantage of Porsche's acceleration:

Audi # 7 did 35 laps equal or above 330Km/h
Audi # 8 did 62 laps equal or above 330Km/h
Audi # 9 did 53 laps equal or above 330Km/h
Porsche #17 did 219 laps equal or above 330Km/h
Porsche #18 did 199 laps equal or above 330Km/h
Porsche #19 did 256 laps equal or above 330Km/h

[Spyderman]

Originally Posted by Spyderman

It lost time in sectors 1 and 3. S1 is not too important (at Le Mans) because it is so short, but S3 is very important for overall lap time (especially in traffic).

Actually after further analysis , I would like to correct this: A comparison of quickest sector times (ideal lap) reveals that the slower S1 was the Porsche's Achilles heel. The best Porsche was almost half a second slower than the best Audi in that sector. As this section is composed of some slower corners, I will say that the mechanical grip is the deciding factor.

[cokata]

Originally Posted by Spyderman

Just some data analysis to illustrate the advantage of Porsche's acceleration:

Audi # 7 did 35 laps equal or above 330Km/h
Audi # 8 did 62 laps equal or above 330Km/h
Audi # 9 did 53 laps equal or above 330Km/h
Porsche #17 did 219 laps equal or above 330Km/h
Porsche #18 did 199 laps equal or above 330Km/h
Porsche #19 did 256 laps equal or above 330Km/h

That's again due to Lift and Coast, not acceleration. Once they get to speeds above 300kph the amount of boost that was used on the exit of the corner before that straight has very little bearing on the top speed.

It seems that the higher MJ classes also inherent allow you to stay on the throttle for longer. From the onboards i can tell that the Audis were lifting just infront of the 300m board on before the chicanes on the Mulsanne, while Porsches were doing it at the 200m board (with just 100m of coasting before they start breaking.)

Originally Posted by Spyderman

Actually after further analysis , I would like to correct this: A comparison of quickest sector times (ideal lap) reveals that the slower S1 was the Porsche's Achilles heel. The best Porsche was almost half a second slower than the best Audi in that sector. As this section is composed of some slower corners, I will say that the mechanical grip is the deciding factor.

Not really. Audis cornered a bit better (not a massive margin), it was down to the fact that Porsches boosted less in S1 like was the case back in 2014, and if you take away the hybrid advantage they have over the Audis, they are much slower.

[Spyderman]

Originally Posted by cokata

That's again due to Lift and Coast, not acceleration. Once they get to speeds above 300kph the amount of boost that was used on the exit of the corner before that straight has very little bearing on the top speed.

It seems that the higher MJ classes also inherent allow you to stay on the throttle for longer. From the onboards i can tell that the Audis were lifting just infront of the 300m board on before the chicanes on the Mulsanne, while Porsches were doing it at the 200m board (with just 100m of coasting before they start breaking.)

This has nothing to do with lift and coast. Audi often braked later than the Porsche's. It has to do with acceleration. Porsche are able to quickly hit their top speed (or close to it) on almost every lap, even if they were hindered by traffic.

Originally Posted by cokata

Not really. Audis cornered a bit better (not a massive margin), it was down to the fact that Porsches boosted less in S1 like was the case back in 2014, and if you take away the hybrid advantage they have over the Audis, they are much slower.

Look at the data. Audi were massively faster on the corners. I'll post the actual figures if you like.
Also- The hybrid system is part of the car. Saying that they would be slower than the Audi's without it, is like saying that the audi's would be slower than the Porsche if they didn't have an engine.....or if they had a 2L four cylinder diesel engine.

[hcl123]

Originally Posted by Spyderman

This is a myth. The Porsche hit 340Km/h on the straight. That is more than enough considering the huge acceleration advantage they have from the electric engine.

Porsche's "weak spot" seems to be mechanical and aero grip. It has improved quite a bit in the twisty parts, but it still is not on par with Audi. It lost time in sectors 1 and 3. S1 is not too important (at Le Mans) because it is so short, but S3 is very important for overall lap time (especially in traffic).

The other area of "concern" are the brakes. Car #18 had a dreadful time throughout the race with this issue.

IF others match the initial push of Porsche then the bar could be elevated to more than 350Kmh... and all of a sudden 340Kmh could appear really short (its all relative)...

And that isn't a weak spot, matter of fact Porsche has the best tire grip of all contenders... and they runs with less downforce to take advantage of it. Match Audi on the twisties is very very hard indeed, they have 'jupiter' levels of downforce that can only be effective if your engine is a monster torque... at least Nissan torquy V6 is on the right path (the rest, excluding straight aeros, is really bad)

[Spyderman]

Taking laps equal to or less than 3:25.0 (this eliminates yellow flags, safety cars and other anomalies), this is what we find when we look at average sector times between the fastest Audi and the fastest Porsche:

Audi #7:
S1 = 31.82 seconds
S2 = 77.4 seconds
S3 = 92.3 seconds
Total = 201.52

Porsche #19
S1 = 32.31 seconds
S2 = 76.8 seconds
S3 = 92.5 seconds
Total = 201.61

[Spyderman]

Originally Posted by hcl123

IF others match the initial push of Porsche then the bar could be elevated to more than 350Kmh... and all of a sudden 340Kmh could appear really short (its all relative)...

And that isn't a weak spot, matter of fact Porsche has the best tire grip of all contenders... and they runs with less downforce to take advantage of it. Match Audi on the twisties is very very hard indeed, they have 'jupiter' levels of downforce that can only be effective if your engine is a monster torque... at least Nissan torquy V6 is on the right path (the rest, excluding straight aeros, is really bad)

Down-force does not apply in slow corners.