918 [Official] Porsche 918 Spyder

[F40 LeMans]

My doubts with that 240-300 kph in the 918 are:

-it is faster than the more powerful car, the P1
-it was tested in a windy day
-it was tested during a day with higher temperature than the P1, worst for combustion
-it weight more than the P1
-it seems has more drag at high speed than the P1
-it has larger tires than the P1

...anyway it was faster than the P1 to 300kph by a full second.

Who is more competent than me explain why...I am curious to a good explanation. It seemed there were many here.

 

[Mafalda]

My doubts with that 240-300 kph in the 918 are:

-it is faster than the more powerful car, the P1
-it was tested in a windy day
-it was tested during a day with higher temperature than the P1, worst for combustion
-it weight more than the P1
-it seems has more drag at high speed than the P1
-it has larger tires than the P1

...anyway it was faster than the P1 to 300kph by a full second.

Who is more competent than me explain why...I am curious to a good explanation. It seemed there were many here.

...and don't forget 918 lose and e-engine after 265kph...

 

[Mafalda]

I repeat: if this is an usual performance for 918, autocar's p1 is one of the most unlucky test ever, and LaFerrari really can confirm the claimed 15s

 

[RS2000 4X4]

It used to be easy, testing a car. Just hop in, shift decent and try to hang on while making the best time possible.

Now the suspension need to be in X setting, the spoilers need to be in X setting, make sure the batteries are in X setting, blablabla you know what I mean. Problem is that it is often mentioned how the car was set up by the tester in order to achieve their numbers.

I think the Porsche has full power to 300 or more, I dont see them do it that fast with 129 bhp less.

 

[RS2000 4X4]

I shall say it differently, if Porsche shuts off the e-engine in the front, we should be able to see it in the graph. A 129 bhp loss at 265 km/h should make it viewable on the graph, instead we see nothing. Its like doing the numbers full throttle and half throttle after 265, it should be less lineair after that.

 

[Sunny]

It used to be easy, testing a car. Just hop in, shift decent and try to hang on while making the best time possible.

Now the suspension need to be in X setting, the spoilers need to be in X setting, make sure the batteries are in X setting, blablabla you know what I mean. Problem is that it is often mentioned how the car was set up by the tester in order to achieve their numbers.

Couldn't agree more.

 

[F40 LeMans]

I think the Porsche has full power to 300 or MORE, I dont see them do it that fast with 129 bhp less.

This is exactly what I mean from the first post. Even the full power does not sounds me enough.

 

[Rolf]

Another factor to take into account is gear ratios and torque produced at the speed range from 240km/h to 300km/h and gearchange speed and driver reactions, this could also affect the acceleration of the P1 compared to the 918 during testing conditions. I don't have a comparison showing the gear ratios/speed per 1000rpm for each gear for both cars and torque produced at those speeds but it would be another interesting comparison to evaluate.

 

[Mafalda]

I made a comparison graph. Both were tested with full tank of fuel and two persons onboard.

ememmh thanks, but watching the graph 918's 0-300 seems 16.2s...

 

[Mafalda]

My bet is
this 918 WS package has a longer front-ratio: it'd explain why, compared with claims, 100-200 is a bit slower (4.8s, vs 4.6) but 200-300 is really better (11.7s 12.7s)
EDIT
...oopps, it's 100-300

 

[F40 LeMans]

Another factor to take into account is gear ratios and torque produced at the speed range from 240km/h to 300km/h and gearchange speed and driver reactions, this could also affect the acceleration of the P1 compared to the 918 during testing conditions. I don't have a comparison showing the gear ratios/speed per 1000rpm for each gear for both cars and torque produced at those speeds but it would be another interesting comparison to evaluate.

Exactly. I tried to calculate some numbers days ago and guessing the intermediate gear for the 918 (it was not mentioned on the gear specs, so I used the total ratio using the rear tires) I concluded that the P1 was also in advantage of torque produced down to the road at about 300 Kph looking at the factory engine numbers claimed.

 

[F40 LeMans]

ememmh thanks, but watching the graph 918's 0-300 seems 16.2s...

Mafalda, the graph shows 100-300 kph, not the 0-300...

 

[Mafalda]

Mafalda, the graph shows 100-300 kph, not the 0-300...

 

[Bridster]

My doubts with that 240-300 kph in the 918 are:

-it is faster than the more powerful car, the P1
-it was tested in a windy day
-it was tested during a day with higher temperature than the P1, worst for combustion
-it weight more than the P1
-it seems has more drag at high speed than the P1
-it has larger tires than the P1

...anyway it was faster than the P1 to 300kph by a full second.

Who is more competent than me explain why...I am curious to a good explanation. It seemed there were many here.

While there is a lot of focus on the Porsche being too fast, it might as well be that the P1 was too slow. Autocar is often one of the slowest magazines when it comes to acceleration numbers.

Also:
- 887 PS vs 916 PS; depending on drive train losses, the 918 could potentially deliver more power to the road.
- The time was an average of two runs in opposite directions, so it doesn't matter.
- At high speeds higher air temperature seems to be more important than combustion losses (as evidenced by the fact that the Veyron SS's top speed run was deliberately conducted at the highest possible temperature of the day). It remains to be answered, of course, if 240-300 is fast enough.
- It most likely weighs only about 50-70kg more.
- That is not at all sure, we don't even know in what mode the P1 was run for the acceleration test.
- Well, yeah...

And, as mentioned, with the cars being hybrids and computers in them controlling a lot of their characteristics, including how much power is delivered, it may very well be the case that in the P1 a full power was not being delivered for the whole duration of the acceleration test. Or, quite possibly, either the DRS, or the IPAS, or both, need to be activated for the best results in the P1, and they weren't...

 

[Deckhook]

I would have honestly have thought aerodynamic drag would have as much of an effect on acceleration at these speeds if not more than actually output, especially since we are only talking less than 50hp difference. Also has downforce been taken into account, surely more downforce increases the weight?

 

[Mafalda]

While there is a lot of focus on the Porsche being too fast, it might as well be that the P1 was too slow. Autocar is often one of the slowest magazines when it comes to acceleration numbers.

Also:
- 887 PS vs 903 PS; depending on drive train losses, the 918 could potentially deliver more power to the road.
- The time was an average of two runs in opposite directions, so it doesn't matter.
- At high speeds higher air temperature seems to be more important than combustion losses (as evidenced by the fact that the Veyron SS's top speed run was deliberately conducted at the highest possible temperature of the day). It remains to be answered, of course, if 240-300 is fast enough.
- It most likely weighs only about 50-70kg more.
- That is not at all sure, we don't even know in what mode the P1 was run for the acceleration test.
- Well, yeah...

And, as mentioned, with the cars being hybrids and computers in them controlling a lot of their characteristics, including how much power is delivered, it may very well be the case that in the P1 a full power was not being delivered for the whole duration of the acceleration test. Or, quite possibly, either the DRS, or the IPAS, or both, need to be activated for the best results in the P1, and they weren't...

I agree about "it might as well be that the P1 was too slow" and/or " quite possibly, either the DRS, or the IPAS, or both, need to be activated for the best results in the P1, and they weren't" ...but honestly the second choice seems almost impossible because Sutcliffe already drove the P1, and there's a team support during the review.
also, 918 must be slower P1 because
- 29ps less
- more than 100 Kgs (...not 50-70)
- also -129ps after 265 Kph
- petrol engine -130ps (very important @ very @ rev and speed )
- CxS'd be no better

 

[Rolf]

Exactly. I tried to calculate some numbers days ago and guessing the intermediate gear for the 918 (it was not mentioned on the gear specs, so I used the total ratio using the rear tires) I concluded that the P1 was also in advantage of torque produced down to the road at about 300 Kph looking at the factory engine numbers claimed.

Just checked the combined torque outputs for both cars and the 918 has 1280NM (from 750rpm to 1250rpm) and the P1 has 978nm, but at higher speeds above 265km/h as mentioned in the test the front motors are decoupled on the 918, so this combined value would not be valid at this speed and also at higher revs than 1250rpm, so working out torque spread for both cars we need to check torque curves at the different revs and also then check at the speeds higher than 265km/h in case of the 918 with only back drivetrain working what torque will be available to accelerate between 200-265 and 265 to 300. Its a fun exercise for sure to determine, but so many factors can determine any discrepancy and even we can question the timing accuracy of the timing gear used if its calibration can get effected at higher speeds!!! HAHAHAHA!!!

 

[tristatez28lt1]

I agree about "it might as well be that the P1 was too slow" and/or " quite possibly, either the DRS, or the IPAS, or both, need to be activated for the best results in the P1, and they weren't" ...but honestly the second choice seems almost impossible because Sutcliffe already drove the P1, and there's a team support during the review.
also, 918 must be slower P1 because
- 29ps less
- more than 100 Kgs (...not 50-70)
- also -129ps after 265 Kph
- petrol engine -130ps (very important @ very @ rev and speed )
- CxS'd be no better

While I agree with most point I believe there are two factors that are affecting high speed acceleration.

Difference in battery power. Porsche's battery (6.8kWh) is bigger and more capable affecting the time when the acceleration run was done less than possibly in the P1 (4.7kWh).
There is a difference in tires. The P1 has P Zero Corsas with a width of 265/30 ZR19 fr; 345/30 ZR20 r. The 918 has 265/35 ZR20 fr; 325/30 ZR21 r low rolling resistance tires with fuel economy in mind.
Aerodynamically the 918 also has a slightly lower cd (.35) and frontal area as shown in the picture.


http://press.porsche.com/vehicles/2015/Tech-Specs-2015-Porsche-918-Spyder.pdf

 

[Bridster]

I agree about "it might as well be that the P1 was too slow" and/or " quite possibly, either the DRS, or the IPAS, or both, need to be activated for the best results in the P1, and they weren't" ...but honestly the second choice seems almost impossible because Sutcliffe already drove the P1, and there's a team support during the review.
also, 918 must be slower P1 because
- 29ps less
- more than 100 Kgs (...not 50-70)
- also -129ps after 265 Kph
- petrol engine -130ps (very important @ very @ rev and speed )
- CxS'd be no better

I am not saying the 918 is faster . Just that it is fast enough that the difference of 1s in 0-300 acceleration from one test to another doesn't necessarily need to show Porsche were cheating.

But, anyway, I will just wait for more tests .

Although, I do wonder how you figure the 918 weighs over 100 kg more than the P1. The P1 is 1395 kg dry and even smaller supercars like the 458, or 12C gain about 150 kg when magazine tested. For bigger ones, like the Aventador or F12, it is pretty much 200 kg. I don't see how the P1, with all the hydraulics fluid needed for its active suspension and double wing, and extra cooling needed for its hybrid power train, is gonna belong anywhere but to the latter category. Not to mention, even gaining just 150 kg would put it just 92 kg off the Porsche. Really, all else being equal, the 918 only gathers weight thanks to more batteries (+52 kg) and its front e-engine plus the necessary wiring (+ ?kg), but then its combustion engine is supposed to be much lighter (- ~70kg). So there!

 

[F40 LeMans]

.. it might as well be that the P1 was too slow. Autocar is often one of the slowest magazines when it comes to acceleration numbers.....887 PS vs 916 PS; depending on drive train losses, the 918 could potentially deliver more power to the road....

This make sense. But don't forget that the P1 was tested with a temperature of 13 C deg and being turbocharged the system was able to compansate for pressure. Looking at the weather correction (Cf: 0.976) a claimed "916 PS" engine make 938 PS that day. So thinking that the P1 was not able to garantee the claimed power even being tested in that condition seems to me want consider that engine really "tired". At the fact that day difference was much more than 29 PS... should have done wonders in limiting losses for Porsche.

The P1 has P Zero Corsas with a width of 265/30 ZR19 fr; 345/30 ZR20 r. The 918 has 265/35 ZR20 fr; 325/30 ZR21 r low rolling...

P1 doesn't have these tires; are F: 245/35ZR19 and R: 315/30ZR20

- CxS'd be no better

Exactly, nothing certain, but surely not that situation that incline to full favor of the Porsche.

Just that it is fast enough that the difference of 1s in 0-300 acceleration from one test to another doesn't necessarily need to show Porsche were cheating.

Infact no one here is saying that Porsche was cheating for sure, but simply that need a really a good power unit to overtake ON PAPER the result of the P1 that day (Obviously if the P1 was really tired...).