Horsepower of the engines.

[Sasha]

The secret to horsepower in this fuel amount and fuel flow limited formula is a pre-chamber.MB came up with it first.

And with a pre-chamber,you can throw away those math formulas on now many hp possible per fuel amount and flow.

MB is most likely using SCSI(90% sure) but with heated injection and piston crown design,could also have CI in some conditions.

[bhall II]

I asked because I've seen "[something]-limited" used in different ways. Here, it means Red Bull dialed down front-end "grip" to promote better tire wear. That invariably means they had to balance it out with less rear wing.

They do have other options.

Camber, stiffness front to rear, rebound/compression, ride height etc are other ways of skinning that cat.

I guess I'm just trying to say it's a setup choice that moves away from front-end "grip" in order to promote better tire durability, and it's commonly combined with slightly reduced rear-end "grip" to balance things out. Exactly how those changes are made is above my pay grade.

[FoxHound]

I guess I'm just trying to say it's a setup choice that moves away from front-end "grip" in order to promote better tire durability, and it's commonly combined with slightly reduced rear-end "grip" to balance things out. Exactly how those changes are made is above my pay grade.

I follow.

My own personal opinion is that at China, that window is wide open.

[PlatinumZealot]

The secret to horsepower in this fuel amount and fuel flow limited formula is a pre-chamber.MB came up with it first.

And with a pre-chamber,you can throw away those math formulas on now many hp possible per fuel amount and flow.

MB is most likely using SCSI(90% sure) but with heated injection and piston crown design,could also have CI in some conditions.

I was think about heated piston crown too, and other methods of pre-heating the intake air in general but this cannot be controlled precisely. One thing we must consider is this too... before compression you want the air to be as cool as you can get it. This is why those inter-coolers are there. A heated piston crown is not something you can turn on and off in milliseconds so that heated crown will be hot all the while, heating up the intake air and stealing efficiency. Yes, one of the ways to get HCCI is to heat the air to encourage homegenous combustion, but right now I doubt Mercedes is doing it this way... They could be doing it at lower loads but the sort of temperatures required to preheat would need EGR and I know EGR is not easily controlled in F1 because Variable valve timing is not allowed. So I feel it is all down to the pre-chamber design and injector design.. I feel these are the only ways to precisely control the gas heating with the quick response times needed in F1.

[Sasha]

The secret to horsepower in this fuel amount and fuel flow limited formula is a pre-chamber.MB came up with it first.

And with a pre-chamber,you can throw away those math formulas on now many hp possible per fuel amount and flow.

MB is most likely using SCSI(90% sure) but with heated injection and piston crown design,could also have CI in some conditions.

I was think about heated piston crown too, and other methods of pre-heating the intake air in general but this cannot be controlled precisely. One thing we must consider is this too... before compression you want the air to be as cool as you can get it. This is why those inter-coolers are there. A heated piston crown is not something you can turn on and off in milliseconds so that heated crown will be hot all the while, heating up the intake air and stealing efficiency. Yes, one of the ways to get HCCI is to heat the air to encourage homegenous combustion, but right now I doubt Mercedes is doing it this way... They could be doing it at lower loads but the sort of temperatures required to preheat would need EGR and I know EGR is not easily controlled in F1 because Variable valve timing is not allowed. So I feel it is all down to the pre-chamber design and injector design.. I feel these are the only ways to precisely control the gas heating with the quick response times needed in F1.

Not heated piston crown(piston crown just have two big cavities),they use fuel injectors with heaters(that adj. temp on the fly very fast).And was told from very good source SCSI but under some conditions CI.(also not the whole combustion area......pre-chamber helps with this)

[PlatinumZealot]

OK I think I understand what you mean now.

So you inject a little fuel to pre-heat the crown before TDC - the AFR is extremely high so the main combustion event will not begin yet only just heating of the air uniformly. Then the rest of the fuel is injected a little afterwards but still some way before TDC. The high pressures and temperatures ignite the mixture.

Close?

[Tommy Cookers]

how 'extremely high' is the AFR - and why ?

and again - why won't controlling the turbo rpm by varying the GU-H function give all the EGR we need ? - maybe 2-4% residuals ?
this takes about 20 millisec
we don't need to do so, but we might choose a tiny bit ot throttling upstream of the compresor - and it's advantageous
switching the charge cooler in and out you'd need that

raised exhaust pressure also greatly increases the recovery power

[Sasha]

They are getting EGR from TC.

[trinidefender]

I'm not sure what you mean by "front limited," because it's always advantageous to have a strong front-end.

I also don't know what I'm supposed to take from the reference to Mercedes's victory in 2012. That was the height of the Pirellotteri era, and the first seven races saw seven different winners - including Pastor Maldonado in a terrible Williams car.

This is really not for you to say. Car balance is a very preferential thing to drivers. Saying that a strong front end is always preferential is not always true. Sure it makes turn in stronger, however if a driver is constantly battling oversteer due to the back always being first to lose traction then the rear tyres will get shredded and the car will struggle.

That was generally the problem with the Merc cars for 2012 and 2013. They had very high one lap pace but they destroyed their rear tyres.

When it is said that China is a front limited circuit it is meant that usually cars with a very strong front end will usually be consistently quickest there. Part of the reason for this is the decreasing radius corner where the driver has to tighten his turn as he goes around, also, as you mentioned, the banking and increasing radius means that it is easier to apply power coming out of the corner. This reduces the need for having a strong back end to get the power down. On the other hand some tracks may hold the characteristics of a car that has great front end grip but suffers at the rear will struggle to put the power down out of corners. A track where the corners may have gentle entry but little grip coming out of corners would suit a car that has great rear grip.

Again, driver preference is still key though. If a driver doesn't feel comfortable in the car then he cannot push his car to the limit regardless of how much grip it has.

[bhall II]

That is really not for you to say.

The enduring advantage of a strong front-end is the ability to maintain competitive pace, even when running relatively conservative setups that promote favorable tire wear. In other words, a strong front-end offers flexibility, which is especially helpful at circuits like Shanghai International that tend to severely punish the front tires.

Also, I was mainly just looking for clarification.

[trinidefender]

That is really not for you to say.

The enduring advantage of a strong front-end is the ability to maintain competitive pace, even when running relatively conservative setups that promote favorable tire wear. In other words, a strong front-end offers flexibility, which is especially helpful at circuits like Shanghai International that tend to severely punish the front tires.

Also, I was mainly just looking for clarification.

Except if it comes at the expense of rear tyre degradation. Having either the fronts or rears degrade before the other is not using the tyres to their optimum.

I love driving rear wheel drive cars that you can prod the throttle and get oversteer from however except in very rare circumstances. If you have a car that wears the rears too quickly then the drivers will always be battling oversteer, this hurts race pace and also makes the cars tiring to drive over the whole race distance increasing the likely hood of drivers making mistakes.

If you have to reduce rear downforce to balance the front then you are reducing the grip available to accelerate out of a corner. A stronger rear end allows a car with maybe a more powerful PU/engine to get on the power earlier coming out of a corner. If you look, this is how Lewis drives. He out brakes pretty much everybody, turns the car and only when the car is relatively straight gets straight back on the power. A good rear end is crucial for allowing the last bit.

Don't get me wrong, I'm not advocating that you need a rear biased car. I'm simply stating that a strong front end is just one of many factors to consider with the development direction largely dictated by data and driver feel.

[bhall II]

Except if it comes at the expense of rear tyre degradation. Having either the fronts or rears degrade before the other is not using the tyres to their optimum.

Which is why I said...

I guess I'm just trying to say it's a setup choice that moves away from front-end "grip" in order to promote better tire durability, and it's commonly combined with slightly reduced rear-end "grip" to balance things out. Exactly how those changes are made is above my pay grade.

As to the compromise that entails and the context that prompted my initial comment...

2013.

Over the last couple of years this track has not been our strongest,.
It has a heavy emphasis on front [tyre] wear and degradation, so you tend to be front limited here rather than rear.

(This has gone way further than I intended. It's also way off-topic.)

[gruntguru]

I was think about heated piston crown too, and other methods of pre-heating the intake air in general but this cannot be controlled precisely.

Blending hot air from the compressor discharge with cool air from the intercooler using a butterfly valve can be done very precisely and quickly.

One thing we must consider is this too... before compression you want the air to be as cool as you can get it. This is why those inter-coolers are there.

The only disadvantage of hot charge air is detonation and increased operating temperature of various components. Air mass flow can be achieved with boost increase. Thermal efficiency will benefit from increased charge temperature (all else being equal).

A heated piston crown is not something you can turn on and off in milliseconds so that heated crown will be hot all the while, heating up the intake air and stealing efficiency. Yes, one of the ways to get HCCI is to heat the air to encourage homegenous combustion, but right now I doubt Mercedes is doing it this way... They could be doing it at lower loads but the sort of temperatures required to preheat would need EGR and I know EGR is not easily controlled in F1 because Variable valve timing is not allowed. So I feel it is all down to the pre-chamber design and injector design.. I feel these are the only ways to precisely control the gas heating with the quick response times needed in F1.

Repeat - Blending hot air from the compressor discharge with cool air from the intercooler using a butterfly valve can be done very precisely and quickly.

[PlatinumZealot]

But would you want to increase pumping losses (the piston pumping hotter air)? And we have to know what order of temperatures are actually needed. Supposed a paltry 90*C is not enough? Supposed 200*C is not enough? I am just basing this on the GM HCCI video where they use recirculated exhaust gas (900*C) to preheat the air. Supposed after mixing the temperature you need is 300*C? this would be too far above what the compressor can produce. I mean, I don't know what actual temperature is required, but I think this would determine whether you can use that hot intake air injection method or some other method.

[gruntguru]

But would you want to increase pumping losses (the piston pumping hotter air)? And we have to know what order of temperatures are actually needed. Supposed a paltry 90*C is not enough? Supposed 200*C is not enough? I am just basing this on the GM HCCI video where they use recirculated exhaust gas (900*C) to preheat the air. Supposed after mixing the temperature you need is 300*C? this would be too far above what the compressor can produce. I mean, I don't know what actual temperature is required, but I think this would determine whether you can use that hot intake air injection method or some other method.

The pumping losses do not increase with reduced intercooling. The compressor work increases but turbine work increases by the same amount or more. The piston work on the compression stroke increases but the work recovered on the power stroke increases by the same amount or more.

The temperature required for auto ignition can be reduced by varying other factors (cetane number, CR, AFR etc etc). Varying the charge air temperature or EGR is more of a "trim" measure to adjust the combustion parameters for different operating points.