5 LM, 5 different powers ?

Hi,

I just bought a (french) magazine (Sport Auto, Octobre 2004) that contains an article about the Mclaren F1.

There is this sentense (talking about the LM):

Here we are with a road car with a weight of 1062 kg, which the power vary between 660 and 680 HP according to the models.

Are you aware about that ? I didn't remember to have read this in Driving ambition.


PS : they also siad that th epower of #073 is 691 HP (tested on the bench = literal translation :$ )

wow. Thats quite a difference. Why would it differ like that?

On the LM, I have heard that it has 668 horsepower and I have also heard it has 680, I believe I've heard each one from a reliable source. Also, on the famous large LM wall poster, it simply says "Over 600 horsepower", so I am confused on the matter.

I too have seen the 668hp figure and the 680hp figure from various sources on the LM. Really though, it's totally inconsequential. The difference of 12hp at that level is less than a 2% variance. All engines of the same type will have a different output and 2% is hardly anything to cry about. The difference in quoted numbers could just have to do with some conversion process on how the numbers are measured. I really find it to be a non-issue.

>8^)
ER

Another thing I've always wondered about is the true 0 - 60 time for the LM. Sometimes it's 2.9 seconds, but other times I've seen it as 3.6 or 3.9! Which one is the real 0 - 60? 3.6 sounds more realistic, but is it true that the wing on the back slows down the top speed (225 mph, I believe) while increasing acceleration?

The wing is never going to "increase" acceleration. It's not very effective from 0-30 where traction plays the biggest role in acceleration times.

More on the 0-60 time of the LM a little later. I'd only trust the figures from the CAR Magazine 0-100-0 test (which I have at home). It should be noted that they weren't testing at the grippiest of locations though, so comparing their number to other cars which may have been tested on a true drag strip will not make for a fair comparison if that's what you are hoping to do. In a car like this I find the 0-60mph time to be more of a novelty than anything else.

The top speed was limited both by gearing and drag from the downforce package of the GTR.

>8^)
ER

The wing is never going to "increase" acceleration. It's not very effective from 0-30 where traction plays the biggest role in acceleration times.



Sometimes the wing can produce a little more speedy acceleration under cornering with so fast speed. because as you know, the main reason of wing is originally to bring the downforce out to keep more stability car itself in high speed. In cornering, air flow of underneath of car is broken a bit due to bend angle, this lead to loss of downforce which means it have tubulance occur as well as stability loss and then the wing get them back up the loss of downforce. so can drive more stabler.

As Erik said, just between 0 to 30mph, the wing's role is nothing.

Yes - of course that is all correct about the wing's effectiveness at speed, but I was speaking specifically towards standing-start acceleration where it won't offer any improvement. In fact my guess is that by the time it could begin to aid in traction via downforce, it will also be reducing the rate of acceleration via drag and that is also probably a bit too late to help out in the 0-60 run.

As for the numbers from the CAR Magazine test I referred to above, the figures included for 0-60mph and 0-100mph are 3.9 and 6.7 seconds respectively. In the text of the article they stated that the car overpowered the tires on every run leaving huge stripes of rubber on the pavement all the way through first gear even at part throttle. If it had the grip, or strangely maybe even a bit more weight over the rear tires, it could probably go much faster - but who really cares, its just a number I say. ;)

Incidentally, the power figure listed in this specs column of the article is 680hp, and yet in the text of the article they mention the LMs power figure is 68hp higher than that of the '95 F1 GTR the LM is based on, which they claim had 600hp. I don't get it either. :screwy: :grinno:

>8^)
ER

Hello,

I remembered of an article in Sport Auto at the launch of LM who says :
650hp (or bhp ?) and performances claimed :
0 to 100 km/h = 3"0
0 to 160 km/h = 5"0
max speed = 360 km/h

Ciao
Phil

As for the numbers from the CAR Magazine test I referred to above, the figures included for 0-60mph and 0-100mph are 3.9 and 6.7 seconds respectively. In the text of the article they stated that the car overpowered the tires on every run leaving huge stripes of rubber on the pavement all the way through first gear even at part throttle. If it had the grip, or strangely maybe even a bit more weight over the rear tires, it could probably go much faster - but who really cares, its just a number I say. ;)

Just to elaborate on that CAR article, the F1 LM had wheelspin in all three gears of the world record run. Wallace said that he couldn't get past three-quarter throttle in first gear.

I recently (just yesterday, actually) did this chart comparing the acceleration of XPLM (from CAR magazine) and XP4 (Autocar & Motor) through +10mph increments. On the left side, the elapsed time of both cars through each increment. And the right side shows how much slower or faster XPLM is in relation to XP4 and how much progress it has made to improve or spoil it's time.


F1 vs. F1 LM

speed: XP4, XPLM

0-30: 1.8, 2.0 | +0.2
= | -0.1
30-40: 0.5, 0.6 | +0.1
= | +0.3
40-50: 0.4, 0.8 | +0.4
= | -0.3
50-60: 0.5, 0.6 | +0.1
= | -0.3
60-70: 0.7, 0.5 | -0.2
= | +0.1
70-80: 0.6, 0.5 | -0.1
= | -0.1
80-90: 1.1, 0.9 | -0.2
= | +0.3
90-100: 0.7,0.8 | +0.1

Hmmmm... To go back to engine power if i may engine power is not an absolute its a veraible. An engine becomes more powerfull with miliage the more millage the loser all the internal components become if an engine is in good tune and well cared it will produce more power. Of course outher things effect an engins output as well. Tempreture is a big one the colder it is the denser the air the denser the air the more oxygen it contains more oxygen = more power :biggrin: its therefore the case that a rally car (or just any car) perticualy a blown one will lose power at the top of a mountin where the air is less dence so altitude above sea level also affects things so does humidity. Water expands more than air and so again this means more power (some jet engins some b52 models for instance feature water injection for this reason). An engine is at its best with high millage and in cold damp air at low level. Veriation is natural horse power numbers are prehaps best considerd a guide rather than a concreat figure throughout an engines life. This all also effects top speed which is effected by a whole host of outher verables....... From personall experiance i can tell you that my car will go much faster in the morning when its cold and damp than it will on a bright warm sumers day the veration even in my car is really very noticable and my car in not exactily F1 fast not by a long shot....... Sorry to get tecky hope this goes some way to explaining why horsepower figures can varey in the way that they do.

Any thoughts or am i mad? back to work.....

Hello everyone

I may have a possible solution........ as Peloton25 suggested in an earlier post it might have to do with a simple conversion......i.e.
668 BHP = 677 PS (I know, still 3 short!)

british mags will usually quote BHP figures, other european mags PS figures

in the same way 627 BHP = 635 PS (Mac F1)
and for the Bugatti Veyron 987 BHP = 1001 PS (this has also caused confusion driving people to ''invent'' special US reduced power versions :grinno: )




:2cents: