Brazilian GP 2010 - Interlagos

[ringo]

The engine is almost like the human body or living thing if you want.

Really? so a 150000 km engine is probably better than a new one, i mean, it has exercised and increased its capacity, just like training athletes do.

I was not speaking to that. I was talking about combustion of air and fuel.

A team satisfied with making lower power?

well we've seen this plenty of times when cars are forced to save fuel.

Again, do you really think you can increase an engine's life by increasing boost?

Increased pressure and reducing revs, Yep.

Mario Theissen, BMW Motorsport Director

... Interlagos is about 800 metres above sea level. Due to the thinner air, all engines lose around eight per cent of their output. This makes the engine wear a little less as the loading on the crank assembly is slightly reduced. That will not only suit our team. Nick will keep running his ninth race engine which was fitted in Singapore, and Robert his eighth also from Singapore. Naturally we want to avoid fitting another new unit, which would mean being relegated ten places on the grid."

Well who knows, everybody has their theory. Funny enough, though it rains a lot in brazil, cooling should be an issue with thinner air if it doesn't. Then there's ignition problems with thinner air, redbull and the ebd users have to look out for that one.

We'll see if any engines give way next week.

[Tim.Wright]

I wish there were more technical discussions like this. We almost had a whole page without the words "Vettel Webber Alonso Hamilton Button".

Anyway

If there is roughly a 7% decline in atmospheric pressure and a subsequent reduction in power, you engine will be making less power over the whole rev range.
This means that even though the engine is limited to 18,000rpm, it will still be down on power at 5000, 12000, 14000 rpm etc.

Agree

At certain points on the track the engine will have to run at a higher speed to deal with the same loads it would deal with at any other track; the load being moving the mass of the car, which does not change with altitude, up and down inclines, accelerating out of corners etc.

Ok, I don't agree that the load does not change. Like I said before, the load the engine sees its practically equal to the torque it produces itself. If a driver exits a corner and gives full gas, the engine at higher altitude will supply less torque than the engine at low altitude, which means it is seeing less internal forces.

It follows that if the engine is spinning at 15,000 to produce a certain amount of power, it would need to be spinning at 16,180 rpm to produce the same power in 7.2% lower atmospheric conditions.
So the average kinematic stress through the rev range is increased, even though the engine only goes to 18,000rpm. And well all know that the kinematic stress in an engine is much more critical to the parts than the compressive stress.
That little savings on compression afforded by lower pressure, doesn't change much for the adiabatic combustion pressure either; which is what forces the pistons down.

You have a point there, I hadn't thought about kinematic stress. Though this is only valid if they do indeed run the engines faster which I don't belive they can.

If a team is satisfied with making lower power at 15,000rpm to accelerate out of the corner or to have a lower top speed, when another team keeps up performance by going to 16,180 it's easy to see who wins here.

Not quite that simple. The team running higher engine speed will hit the limiter first. There are lots of other complications in this as well, its not so clear.

edit: I guess this sounds like a gear ratios game; it's one way of controlling which parts of the track match with which rpm.

I don't belive they would change the ratios for this reason. They would have a characteristic powerband, say from 50k-19k (guess) and this, coupled with the track geometry (in XZ, not Z ) determines the gear ratios. They are already limited to 19000rpm, you can't increase the engine speed

Tim

[forty-two]

They are already limited to 19000rpm, you can't increase the engine speed

Sorry to nit-pick Tim, but aren't the engines limited to 18000 RPM at the moment?

[Miguel]

OK, I believe that, as long as the driver requires a certain amount of power, the wearing will be more at altitude. However, unless out of a turn, F1 cars are run pedal to the metal. Given that on those situations the engine at altitude has less power, it will wear less during that long main straight.

Of course, there is the issue of scaling. I mean, "less wearing due to 8% less power" may or may not compensate the "more wearing due to worse cooling in 8% lighter air". Aren't F1 engines watercooled? How does air density affect radiator efficiency?.

I know this isn't even back of the envelope, but is the best reasoning I can currently give with my (non) knowledge of internal combustion engines.

[kalinka]

Just a thougth reading all this : if you have less power, you can push 100% throttle a little bit eralier and you can maintain it a bit longer than with more power. Also it may be more parts of the circuit where you can go flat out with 100% throttle which in lower altitudes wouldn't be true. The question is : does the lower power compensate for running the engine longer on full throttle/higher rpm ? I don't know, but my feel is that the higher rpm's in long term is killing the engine more than the low power can compensate...huh..sorry..if I was unclear here..

[AndySeiji]

The Interlagos track is 16 kilometres south of Sao Paulo’s city centre and provides the drivers and engineers with many challenges, not least because the track runs in an anti-clockwise direction and is at high altitude, which makes it tough for the engines.

Source: http://www.formula1.com/races/in_detail ... guide.html

But they don't explain the reason...

[spinmastermic]

Tough for the engines to get full power

[flynfrog]

Tough for the engines to get full power

its also harder to keep the cool

[Arunas]

Sorry for my english, as it's not my native language. I'm reading this forum for a few years now. And can not resist to make some remarks regarding engine strain in Interlagos. It seams strange to me some refuse to understand real engine working conditions there. In such thin air engine has less strain IMHO, as it produces less power (of corse, these are not perfect conditions for cooling it). Engine rpm is not dependent on power request by driver, as some have suggested. We have 18K rpm limit and 7 speed gearboxes, not CVT F1 at the time being.. This also means we have less drag, less DF, less cooling, less grip. To make things simpler, just imagine having 1/10 air density there
That will make you understand this issue much easier

[alelanza]

well we've seen this plenty of times when cars are forced to save fuel.

But you're mixing things up with that logic. What they're doing is saving fuel, which has as a consequence reduced power. It's not that they are 'satisfied' with less power, they just simply had to compromise their starting weight vs being able to finish the race. While on a fuel saving mixture, the driver is still asking the engine to produce all the power it can give at that setting, and probably lifting a bit earlier here and there into braking zones. When you say satisfied with less power it sounds as if a team would say 'we can do 250 km/h here, but really 220 km/h is just as well'.

Increased pressure and reducing revs, Yep.

but you're not changing revs. Again, you can't be a sitting duck into turn one or have huge gaps between gears. And if on full performance mode, you'll still be shifting at 18k at all times. Gearing won't change, it'll just take the engine a bit longer to get to the end of the straight.

We'll see if any engines give way next week.

They just may, but that is no indicator of the track's engine demands. You just have to go back to last race to know many factors can make an engine go boom

you can push 100% throttle a little bit eralier and you can maintain it a bit longer than with more power

Valid point i think. Following that logic one could also say that at sea level, the more powerful engine will get quicker to the end, thus being more stressed but for a lesser amount of time. I guess in the end i'm not so sure anymore hehe, probably we can't talk about the engine as a whole, but instead individual components where some may see decreased wear and others increased wear.

[ahmedvortex]

i remember a video from Pikes peak , the edition of the Audi S1 record , they estimate the loss of power around 80 hp between the start and the finish line , they have lowered the gears also to reduce the effect on the mid-low rpm .
if the Renault engine don't lose time on the climb with the fuel on-board , it means that Horner abuse with the power deficit

[mx_tifoso]

Interlagos Stats:

Circuit Length: 4.309 km
Race Distance: 305.909 km
Number of Laps: 71

Full Throttle: 63%
Brake Wear: Medium
Tyre Compounds: Super Soft/Medium
Downforce Level: Medium 7/10
Tyre Usage: Medium
Average Speed: 216kph (134mph)

New pole is up on the home page! Vote!

[Mysticf1]

New pole is up on the home page! Vote!

Two Vettels and no Webber?

[PlatinumZealot]

Why are not all the title contenders in the poll? In the words of Alonso, this is ridiculous!

[mx_tifoso]

The poll has been fixed by restarting it.