[WEC] Porsche Prototype Discussion

[Breitling24]

Originally Posted by Gingers4Justice

The sound issue will sort itself out. If a lack of sound turns people away, then the organising bodies and manufacturers will bring the sound back. So we'll just have to see.

Exactly. Also, just as the aero has evolved since the commencement of testing, so too has the exhaust system, I am sure.

[hcl123]

Originally Posted by hcl123

Porsche being 4 cylinders but turbo is not to worry , they can still derive lots of power and torque from that engine ( even so i think a V6 would had been much more elastic, better).. F1 4 cylinders turbocharged used to have sometimes over 1000 hp in qualifying and over 500 Nm... of course the higher the boost the stratospheric the fuel consumption is, and this is restricted, nevertheless it can be only in certain parts of a circuit, in overall they can catch up with the fuel flows allowed..

Yes i know what is coming, max fuel flows are not permitted to be passed in any circumstance.

well, the last point of measurement is just after the high pressure fuel pump, and all turbos invariably have a return tank, or a return rail that drops in the main tank(usually from that high pressure pump itself) . A return tank of sorts can very well be after the last fuel flow metrics... the more you economize on braking and on approach a slow corner the more you have available for acceleration boost after the corner.

If ppl think no one will try to bypass FAI/ACO restrictions are sorely mistaken... that is why freedom and simplicity are so valuable... that is why a single fuel flow metering just after the main fuel tank, or integrating to the main tank, very precise ( its possible) and not allowing more flow than allowed ( and only monitored to prevent tampering), is more than enough to assure fuel flows and consumption in average for all circuits.

[ then fuel flow penalties would be only one... disqualifying... because the metric pump would had been tampered with ]

Then the more you economize below that value the more is available to boost past the value, yet fuel flows and fuel consumption would remain exactly in what is set, and an "efficiency" fuel flow formula doesn't have to be about economy but can be also about power at the same time ( best of both worlds).

[gustavobamba]

"The hybrid systems are very parameterizable. They can choose release the electric power on the straights or at corner exits, depending on the track characteristics."
Neel Jani interview.



Are he telling the electric power could influence top speed???????

[hcl123]

IIRC there is no restriction when and where, better said after what point ( 14), you release hybrid power... and the release strategy can vary from corner to corner or from point to point ( from more intense to shorter time and vice versa, to right after corner to much later), has it was possible in 2013 already... yes it can influence top speeds with some strategies.

[ it can be even "gapped", after a slow corner you kick it right away in 1th, 2th and 3th gears... then save a little for later(gap)... and then in 6 and or 7th gear give it another push for top speed.. the higher the top speed the more you can recover next on braking... *all is computer controlled* driver doesn't have say here really ]

[FxL]

Originally Posted by deltawing

How did they resolve the vibrations issues?

According to Fritz Enzinger (head of LMP1 development), they had to change the firing order of the engine and therefore needed a couple of new components, including a new crankshaft, which had a delivery period of 16 weeks. Furthermore, he says that they never questioned the V4 and didn't spare a thought about switching to a 6 cylinder engine. The vibrations are not a problem anymore since they are gone completely.

[gwyllion]

In case people want to read the rest of the article, that mentions the new crankshaft: http://www.motorsport-total.com/wec/...-14030701.html (in German).

[deltawing]

Originally Posted by FML

....The vibrations are not a problem anymore since they are gone completely.

Vibrations gone completely? On a V4? With all due respect I am not going to believe that.... "Reduced to certain extend" I can believe and hope for. "Gone completely", I will pass ...

[hcl123]

Perhaps *almost completely*... you still have balancing shafts to play with... and this is V not linear, crankshaft is shorter... difference for a V6 in that respect very minimal.

[FxL]

Originally Posted by deltawing

Vibrations gone completely? On a V4? With all due respect I am not going to believe that.... "Reduced to certain extend" I can believe and hope for. "Gone completely", I will pass ...

Of course you always have vibrations in any kind of combustion engine to a certain degree, visible and/or measurable. What Enzinger tried to say is in my opinion that neither the drivers nor the car or engine itself are affected by the problem anymore.

A literal translation (see gwyllion's link):

Originally Posted by Fritz Enzinger on motorsport-total.com

I remember when we had installed the modified engine in Portimao on friday night. We all were very excited. Then it was fired up - and suddenly the vibrations were not only less, but they were gone.

Maybe the word "completely" I used before was a bit too much, but strictly speaking there is no difference between "gone" and "completely gone" since they are either gone or not (there are of course still vibrations to a certain degree, you are right. But I think it is clear what he was trying to express).

[Velociraptor]

You can weed out most vibrations with a clever crankshaft design - case in point, the inline-3 petrol in VW UP! that doesn't use any balancing shafts.

[deltawing]

The inline 3 in the UP! is suspended on bushings. The V4 in the Porsche LMP1 is bolted directly to the structure, it is stressed element. Two very different scenarios.

[PascaLM]

And what about a "simple" change in the ignition order of the cylinders ? Could this affect the vibration mode ?

[gwyllion]

Another (very short) video of the Sebring test: https://www.youtube.com/watch?v=iwRyQRkLu30

[hcl123]

Originally Posted by PascaLM

And what about a "simple" change in the ignition order of the cylinders ? Could this affect the vibration mode ?

It was (it must ) be a question of balance of the crankshaft... when you change the "balancing" ( so to speak becasue it might not only be due to the counter weights) of the crankshaft you change the firing order... remember its the crankshaft that commands the positioning of the pistons its not the spark plugs lol... to change ignition ordering invariably you must change crankshaft ( very so in symmetric engines).

[PascaLM]

Originally Posted by hcl123

It was (it must ) be a question of balance of the crankshaft... when you change the "balancing" ( so to speak becasue it might not only be due to the counter weights) of the crankshaft you change the firing order... remember its the crankshaft that commands the positioning of the pistons its not the spark plugs lol... to change ignition ordering invariably you must change crankshaft ( very so in symmetric engines).

Well, at least you can choose 1-3-4-2 or 1-2-4-3 sequence on the same engine configuration. You can modify the ignition advance timing (if correct expression in English).
They can change small details to avoid a complete re-architecture of the engine which should have taken too much time, no ?

[FstrthnU]

I've got a really quick question here, does anyone know whose Electric motors the Porsche 919 is using? I've had a hard time finding the specific company.

[Bandicoot17]

A123 systems are responsible for the batteries iirc

[FstrthnU]

Originally Posted by Bandicoot17

A123 systems are responsible for the batteries iirc

I know that (what used to be) A123 is supplying the batteries, my original question is on the motors which put that electricity on the ground.

[MyNameIsNigel]

Originally Posted by FstrthnU

I know that (what used to be) A123 is supplying the batteries, my original question is on the motors which put that electricity on the ground.

Considering the partnership with Schaeffler, I wouldn't be surprised to hear that they also supply the whole MGU and differential unit for the front axle.

[hcl123]

Originally Posted by PascaLM

Well, at least you can choose 1-3-4-2 or 1-2-4-3 sequence on the same engine configuration. You can modify the ignition advance timing (if correct expression in English).
They can change small details to avoid a complete re-architecture of the engine which should have taken too much time, no ?

well lets consider a linear... still used like this (privileges torque)... 1 4 (firing) 2 3 (exhaust) - 1 4 ( exhaust ) 2 3(admission) - 14 ( admission) 2 3 ( compression ) - 1 4 (compressing) 2 3 ( firing) ... from 2 to 2 revs there are 2 revs without firings-> tends to rev low, not good for power ( play reverting order 2 up 2 down on the *same stroke* and see it leads to the same 2 by 2 order).

Since a piston goes up to compress or exhaust you can revert half of cylinders from firring or exhaust to the contrary( no more 2 cylinders on the same stroke but reverted) ... *this without having to change the crankshaft*... but then you'll have to change the top valve "camshafts", then you'll have something like 1234 (what ever, that is what some Tunning kits do that include new camshafts) but there is never this change the firing order without changing nothing else (else is as if you start counting from the cylinder 2 firing instead of 1 but the sequence is the same).

[ right balancing changing the crankshaft, usually is 1234 (whatever) but the spacing can vary a lot, can be even spaced or 2 by 2 pistons can be closer ]

[PascaLM]

Interesting.

Did Porsche publish any information about the angle between cylinders ?

[hcl123]

Originally Posted by FstrthnU

I've got a really quick question here, does anyone know whose Electric motors the Porsche 919 is using? I've had a hard time finding the specific company.

Ha! ... no one tells, not only Porsche... and you can bet they are purpose build, as well the controls... for up to 1MJ event, there is a lot of energy that can go from more torque to more revs ( power) and even during one event it can change ( from torque to power or vs versa) according to a specific release point ( controls are software).

[hcl123]

Originally Posted by PascaLM

Interesting.

Did Porsche publish any information about the angle between cylinders ?

The angles of least friction are 86º or ~180º (boxer)... since its not a boxer we can guess its called a 90º angle ( 86 to 90 they will claim the same).

[ even linear engines are mounted tilted ( varies according to spacing) to try to "approach" points of least friction ... boxer is a little better but its a pumping headache (can incur plenty of losses) that is why is bad for NA petrols ]

[carbon_titanium]

Yes surely will be around 90º, no sense to build it with a 60º design and of course can't be 180º. By the way, I expect to see V4 replace the B6 in next future, in "cheaper" porsche cars like cayman or boxster.

[hcl123]

Those box engines perhaps will never go to a prototype... not enough space to the underfloor (perhaps Mazda someday will surprise with a small turbodiesel, box .. placed a little higher )

The same with 60º, prototypes will never be that narrow... no need for them and is worst.

[to replace the B6 doubt... V6 sells... for consumption just rev lower(limit)... power is never the same of motorsport( revs very high always)... and a production car like the Cayman is way much heavier, it will appreciate plenty the more torque of a V6 specially at low(er) revs... ppl still has this notion of seeing everything by the "max" power (hp) rating... its very wrong (what about in between max ?)... its oil selling marketing... ]