203 replies to this topic

[WhiteBlue]

One interesting observation is that Red Bull has a setting on the engine, whereby the ignition is ******** on the over run, which maintains exhaust gas pressure even when the driver lifts off the throttle. This maintains the performance of the blown diffuser and keeps the downforce up when it’s most needed. It’s not something you can do for more than a lap or two as it damages the engine, but it gives that vital fraction of a second which keeps Red Bull ahead of the rest in qualifying.

I think it will not suffice to just ****** the ignition. They probably also lean the fuel injection way back.

[DaveW]

Qualifying sector times, (LH - MW) at Turkey are interesting &, possibly, instructive:

S1 : -0.075 secs
S2 : +0.355 secs
S3 : -0.126 secs

LH was 6.1 kph quicker than MW through the speed trap.

MW clearly had the advantage through T8, & that is reflected in the S2 differential. S1 & S3 differentials show that LH, with F-duct, was quicker elsewhere. Presumably the blown diffuser would increase D/F out of low speed corners, thus improving acceleration from low airspeeds.

It could be argued, therefore, that the blown diffuser set-up compromises braking & corner entry &, perhaps, requires a different driving strategy. No doubt "fixes" would be adopted if they helped, but the drivers would probably be happy to "drive around" any disadvantages of the blown diffuser without power off "fixes". Apparently fragile front brakes might be a symptom of the compromise....

[MatsNorway]

I´m not so sure they do that as well.

May I understand this wrong, but it could be that they adapt a "turbo/anti lag" like strategy,
by ingniting air/fuel mixture in the exhaust, and use the energy to blow the diffusor.
Not leaning out the mixture, could give also better initial "throttle on" performance after the corner

It just crossed my mind, when J.A. said "which maintains exhaust gas pressure even when the driver lifts off the throttle."
But I could be wrong here.

we should hear that. And i can`t say i have heard any big difference on the different cars. going to lisen closely at the next Qualifier.

Could you not cool the engine with the fuel while cutting the ignition to feed the diffuser?

There is a crossing-point were the fire-front does not go back into the chamber before the exhaust valve closes.
is that point within the RPM range of the F1 cars today?

[WhiteBlue]

You can see that, by the flames coming out of the exhaust, when they lift. Here you also don't hear the typical bang/bang of WRC style anti lag systems.

That's why I thought it works with leaning the fuel injection. You still want the engine to turn over with reduced power but the full air flow and no unnecessary fuel waste or flames and bang that give away the trick.

It could be argued, therefore, that the blown diffuser set-up compromises braking & corner entry &, perhaps, requires a different driving strategy. No doubt "fixes" would be adopted if they helped, but the drivers would probably be happy to "drive around" any disadvantages of the blown diffuser without power off "fixes". Apparently fragile front brakes might be a symptom of the compromise....

James Allan seems to think they can only use it in qualifying but perhaps it is used in the race as well to a lesser degree.

Edited by WhiteBlue, 05 July 2010 - 16:17.

[KWSN - DSM]

This is very facinating, and I have zero technical knowledge to add.

But reading the various posts, are the team not potentially in danger of not having a legal engine then? Burning fuel outside the cylinders, as a mean to gain a power advantage, that surely is not allowed?

And the comment about a blower / compressor. I that it was posted as a detriment, but is this not a case then on chosing a detriment, which will in fact gain an advantage? And compressors are not allowed in F1 (for now).

Sorry if I moved off topic.

[OfficeLinebacker]

Burning fuel outside the cylinders, as a mean to gain a power advantage, that surely is not allowed?

It's not a power advantage, it's a downforce advantage.

[MatsNorway]

This is very facinating, and I have zero technical knowledge to add.

Burning fuel outside the cylinders, as a mean to gain a power advantage, that surely is not allowed?

Its not a power advantage its a downforce advantage.
F1 is all about loopholes in the rulebook. But someone might argue that you get "trust" from the free burning gases. But in my eyes FIA is a bit weak when it comes to handling close to or maybe rule breaking details. And the "trust" argument is a seriously weak one.

Edit: Linebacker beat me.

Compressing air in the engine is a necessity and can not be stopped.

the discusion is if i have understood it right, about how you are going to work the engine during gear-shifts, off throttle or in any other situation were you got engine capacity to spare witch you can use to give a advantage in other areas. Like downforce.

Edited by MatsNorway, 05 July 2010 - 20:22.

[OfficeLinebacker]

Its not a power advantage its a downforce advantage.
F1 is all about loopholes in the rulebook. But someone might argue that you get "trust" from the free burning gases. But in my eyes FIA is a bit weak when it comes to handling close to or maybe rule breaking details. And the "trust" argument is a seriously weak one.

Edit: Linebacker beat me.

Compressing air in the engine is a necessity and can not be stopped.

the discusion is if i have understood it right, about how you are going to work the engine during gear-shifts, off throttle or in any other situation were you got engine capacity to spare witch you can use to give a advantage in other areas. Like downforce.

I think you mean thrust. And, JINX! You owe me a coke.

[gruntguru]

- There is no need to burn fuel in the exhaust to augment exhaust flow.
- The throttles would need to be held open by some means. (Is DBW allowed)
- An example of the strategy would be: constant throttle cornering a say 100kW - wth the timing significantly ********, the throttle would need to be much wider open than normal to still achieve the 100kW required. With the wider throttle opening, the mass flow will be significantly greater than usual for 100kW. In addition. the exhaust temperatre will be much higher due to the lower thermal efficiency. This will further increse the exhaust volume and velocity.

Taken to its extreme the strategy would be to hold the throttle wide open and control the output (as dictated by the driver) by retarding the timing. In practice this would result in excessive exhaust temperature but you get the idea.

[Lee Nicolle]

I see your point white blue.

But how do they maintain airflow through the engine if the driver lifts off the throttle?
as said by J.A.?

I can see, that with the drive by wire throttle, you can keep the inlet open, and just retarding ignition and cut/reduce fuel, to reduce power/torque
but would that not turn the engine into a compressor/air pump and slow it down when you compress the air??

All I do know is, that in Touring/GT engine maps (on engines which are not GDI), you still want to inject fuel to keep the inlet "weted" so that you have
better engine reponse when you are back on power.

For this purpose it´s not nessesary to have the flames, as this shows "exessive" fuel, but you keep injecting fuel when you lift.
I know that at least one manufactuer goes to great length to not have the flames, as the board does not like to see them, for marketing reasons.
Others are a bit more open, and think it adds to the exitment of racing (V8Supercars), and keep injecting fuel at a high rate.
In some long distance racing you may want to avoid doing it "too much" as it will not help your fuel consumption.

My reasoning was, that you could still generate gas flow in the exhaust by burning fuel there, while the inlet is closed.
But as I said, I maybe totally wrong here.

In recent times V8 Supercar seldom flames on over run, nor do they make so much black smoke. They have used E85 for a while and it seems to have cleaned all that up. Since they use so much of it I would suggest that they have tidied the mapping up so as not to waste fuel. And the lack of black smoke is partly the ethanol blend anyway, a vast improvement and probably better health wise for drivers, crew and trackworkers. These days even Sprintcars do not belch much flame, and they use a lot less fuel too. They have been working on fuel delivery/ driveability, economy for some years also.

[OfficeLinebacker]

- There is no need to burn fuel in the exhaust to augment exhaust flow.
- The throttles would need to be held open by some means. (Is DBW allowed)
- An example of the strategy would be: constant throttle cornering a say 100kW - wth the timing significantly ********, the throttle would need to be much wider open than normal to still achieve the 100kW required. With the wider throttle opening, the mass flow will be significantly greater than usual for 100kW. In addition. the exhaust temperatre will be much higher due to the lower thermal efficiency. This will further increse the exhaust volume and velocity.

Taken to its extreme the strategy would be to hold the throttle wide open and control the output (as dictated by the driver) by retarding the timing. In practice this would result in excessive exhaust temperature but you get the idea.

Reminds me of an off the cuff question I asked about doing essentially the same thing but using the clutch to regulate how much power actually goes to the rear wheels while keeping the engine at full revs the whole time.

[gruntguru]

Reminds me of an off the cuff question I asked about doing essentially the same thing but using the clutch to regulate how much power actually goes to the rear wheels while keeping the engine at full revs the whole time.

I know someone that drives like that.

[Tony Matthews]

I know someone that drives like that.

My late, ex-mother-in-law, if you get my drift, used to get through two clutches a year in her base 1100cc Fiesta. You'd think she was doing 98mph, look out of the window and she was doing 2mph. Leaning back, arms straight, looking like Sir Stirling Moss in a white wig.

From another thread...

[cheapracer]

My late, ex-mother-in-law drifts like Sir Stirling Moss in a white wig.

Ever fold/condense the back cover of a MAD magazine to get a whole different meaning?

Edited by cheapracer, 06 July 2010 - 07:53.

[zac510]

Before this came up I was toying with the idea that perhaps these modern diffusers would not be as sensitive to the exhaust flow as those 10-20 years ago. Firstly the double-deck design might mean that the exhaust only influences half of the diffuser so sensitivity would be less. But that's not based on any science, just from looking at the pictures. Secondly, just general advancement of technology!

[WhiteBlue]

Another question would be how they actually control this mode. A very simple way would be a lever on the steering wheel like the one for gear shifting. While that one is pulled the throttle mapping would be radically altered to have practically no impact on airflow and work only on the fuel injection and the injection timing.

[dav115]

Before this came up I was toying with the idea that perhaps these modern diffusers would not be as sensitive to the exhaust flow as those 10-20 years ago. Firstly the double-deck design might mean that the exhaust only influences half of the diffuser so sensitivity would be less. But that's not based on any science, just from looking at the pictures. Secondly, just general advancement of technology!

I wonder if it's because they were able to run taller gearing back in the 3.0L V10 days due to the much higher torque, and thus there was a greater range of RPM at which the engine could be mid corner, whereas today (thanks to the shorter gearing) the engines are always operating within a much smaller RPM window and so there won't be as large a change in the exhaust flow through the diffuser? Just a thought.

[WhiteBlue]

Over at F1technical someone suggested that Vettel's spark plug and cracked exhaust problems were now much more plausible.

[WhiteBlue]

I was more thinking along the lines, that with the standard ECU, there may has to be a "direct/linear" relationship between throttle pedal position and throttle position in the inlet - by the rules, not for technical reasons. Otherwise it would open the door to traction control settings as well, and would be very hard to police.

I believe the way the mapping is controlled by the SECU is by CAN profiles. The thinking behind this was using controlled programming and still enable individual use of functions. I believe that CAN already had primitive multi dimensional profiles.

The real time bus technology in the SECU was CAN when it launched. It may have evolved since then and could be on an entirely higher level like real time ethernet with multiple controllers now.



This is the block diagram of the FiA tender document for the FiA GT1 world championship. It cannot be far off the present state of the F1 unit. They must have evolved considerably since they were implemented.

With all that advances there would probably be no problem to generate customer specific three dimensional maps. The steering wheel is a pretty sophisticated computer which communicates by CAN or higher protocol with the SECU. So I see no problem to store several multi dimensional maps in the steering wheel and send them in real time to the SECU by finger tip command. Teams actually do this for special launch modes. They cannot change programming but they can sure as hell set very different multi dimensional profiles for just about any fly by wire device the drivers use.

Edited by WhiteBlue, 06 July 2010 - 15:15.

[WhiteBlue]

If this sort of custom programming is permitted, they will go down this route, and you can use any combination of buttons on the steering wheel to activate/deactivate the system.

But where do you draw the line between a 3D engine map and a traction control. As with advanced 3D maps, you can control the power/torque output of the engine very precisely.

The important aspect here is the difference between parametrizing and programming. The programming is fixed and rigidly controlled by the FiA. The mapping profiles can contain just about anything the user wants but they cannot have any new logic or sequencing. To introduce branching, logic and even more advanced modulation you can only use switches and gradual inputs by the drivers.

Your concerns about TC were all discussed when the world discovered McLaren's method of simultaneously shifting gears and maps with the double shifting levers.



In this picture you see the split paddle shifters which simultaneously shift the gears and the maps when they are activated together.

Edited by WhiteBlue, 06 July 2010 - 15:33.

[zac510]

Maybe you find this a interesting read.

http://scarbsf1.word...iven-diffusers/

A recap of the developments of the blown diffuser idea, and it´s applications in recent years.

I think the curent diffusers are less sensitive, then the ones used in the turbo era, as you mention.
Nevertheless, if you can feed more flow through them, they will generate more downforce, which led to the
latest developments.

Yeah that seems to show that only the top half of the RBR diffuser is blown by the diffuser. Although I'm sure they still interact to some extent, but maybe the double diffuser interpretation was what paved the way for this style of exhaust to return to F1.

Another thing - shouldn't Renault know that RBR are messing around with the engine maps seeing as they supply the engine?

[Tony Matthews]

Another thing - shouldn't Renault know that RBR are messing around with the engine maps seeing as they supply the engine?

And if they are, are they allowed to? I thought there was a standard ECU supplied, which is tamper-proof.

Edited by Tony Matthews, 07 July 2010 - 07:43.

[zac510]

Well it would have to have adjustable maps! Control ECU maps, that would be taking control parts to a whole new level!

[Tony Matthews]

So what does the McLaren-sourced black box do? What are you allowed to change, and what are you not allowed to change?

[saudoso]

I take it for granted the engine mfs have control of the maps, you just can't standardize that without a standard out of the box engine/clutch/gearbox to go with.

I do think the teams (in the case of customer engines) could also have. Start sequences and gear shifting a two things I think each team keeps close.

RBR builts it's own geabox, right?

[WhiteBlue]

So what does the McLaren-sourced black box do? What are you allowed to change, and what are you not allowed to change?

It is easy to explain to a software engineer. No programming changes only parametrizing but that can be done multi dimensional.

To enthusiastic amateurs the explanation is more difficult because it involves mathematics and programming basics. If you remember boolean logic you do understand how you can combine certain input conditions to generate outputs. This is basically what a programmable logic controller (PLC) does. The ECU is nothing but a networked PLC. The program inside the ECU is rigidly controlled by the FiA. For every qualifying or race Charlie Whiting or Jo Bauer writes a long report that contains among other issues the program versions released by the manufacturer (McLaren) and found in the ECUs of the customers.



When you read this you know that all teams are using exactly the same programmable logic control. The difference starts when the controller comes to a program step where for instance an engine map is called up. Program V1.00.0077 for Red Bull might call a four dimensional table that uses the throttle pedal position and the blown diffusor switch on the steering wheel to set the fuel injectors, the ignition delay and the throttle opening to suit Red Bulls requirements. If you find the same program on the Renault car it may not even have a single steering wheel switch and the output may be only two dimensional (throttle and fuel injection). This demonstrates how complex differences can be achieved by the same program but by different input and output parameters.

[Big Block 8]

- There is no need to burn fuel in the exhaust to augment exhaust flow.
- The throttles would need to be held open by some means. (Is DBW allowed)
- An example of the strategy would be: constant throttle cornering a say 100kW - wth the timing significantly ********, the throttle would need to be much wider open than normal to still achieve the 100kW required. With the wider throttle opening, the mass flow will be significantly greater than usual for 100kW. In addition. the exhaust temperatre will be much higher due to the lower thermal efficiency. This will further increse the exhaust volume and velocity.

Taken to its extreme the strategy would be to hold the throttle wide open and control the output (as dictated by the driver) by retarding the timing. In practice this would result in excessive exhaust temperature but you get the idea.

The exhaust temperature would stay in check if the fuel flow was cut by the system to a fraction even when the cycle is getting full air input.

Technically it's doable, but is it legally doable in the realm of standard ECU? If so, the ECUs are not so standard at all. Hello traction control!

[saudoso]

The exhaust temperature would stay in check if the fuel flow was cut by the system to a fraction even when the cycle is getting full air input.

Technically it's doable, but is it legally doable in the realm of standard ECU? If so, the ECUs are not so standard at all. Hello traction control!

The ECU is standard an having custom maps does not breach it. You just can't expect 4 or 5 different engines using the same spark timing, mixtures and so.

On the TC issue, it's avoided by the lack of feedback from wheel speed/car acceleration and (maybe) designed inability to process crankshaft acceleration , computing crankshaft speed only.

Edited by saudoso, 07 July 2010 - 20:34.

[WhiteBlue]

... is it legally doable in the realm of standard ECU? If so, the ECUs are not so standard at all.

It would help to read the posts further up dealing with the functioning of the SECU: http://forums.autosp...w...t&p=4458629

[mey3059]

just wanted to say there was a race where mark webber was asked to press the pedal harder .the data showed the throttle wasnt completely open

[J. Edlund]

The SECU consist of the McLaren Electronic Systems TAG-310B with additional systems models, as specified below. As we can read on the McLaren webpage application code can be autogenerated using Simulink; you create a model of what you want to control and then the application code for the ECU can be autogenerated by the program from the model. So the system itself is capable to control a lot of things unless FIA checks what software is loaded in the SECU.
http://mclarenelectr...nt_TAG-310B.asp
http://mclarenelectr...t_F1_addons.asp

As for creating more exhaust flow, a common approach is to open up the throttle a bit, ****** ignition to after TDC and enrich the fuel mixture a bit to keep temperatures in control. If the ignition ****** is kept within reasonable limits and the engine is under no or low load it is also possible to do it without the enrichment, at least for a short period of time (most new cars use this control strategy to reduce catalyst heat up time). The problem with implementing something like this in F1 would be article 5.5 in the technical regulations, specifically 5.5.1 which prevent the driver to control the throttle position with anything else than the foot pedal, such a button or lever to activate this system and 5.5.3. which means that when the throttle pedal is fully released this must correspond to throttle being in idle position. To only ****** the ignition wouldn't do that much, and without more throttle to compensate the loss in power caused by the ignition ****** it would be difficult.

5.5 Engine throttles:
5.5.1 The only means by which the driver may control the engine throttle positions is via a single chassis mounted foot pedal.
5.5.2 Designs which allow specific points along the pedal travel range to be identified by the driver or assist him to hold a position are not permitted.
5.5.3 The minimum and maximum throttle pedal travel positions must correspond to the engine throttle minimum (nominal idle) and maximum open positions.

The only possebility as I see it would be to use the fact that there isn't a regulation that prevents the throttle to move more or less than the foot pedal between the min and max limits. So at low pedal positions the throttle could open more than suggested by the pedal position and then the ignition is ******** a bit under those conditions to prevent a rapid increase in engine output.

As for the blown diffuser, the exhaust is not blown into the diffuser as in the past, but over the diffuser, which should make less sensitive to throttle position.

[gruntguru]

The only possebility as I see it would be to use the fact that there isn't a regulation that prevents the throttle to move more or less than the foot pedal between the min and max limits. So at low pedal positions the throttle could open more than suggested by the pedal position and then the ignition is ******** a bit under those conditions to prevent a rapid increase in engine output.

The altered map would only need to ****** the timing (and enrich the mixture) in the desired areas. Because the power is reduced the driver will use more throttle to achieve the power he wants for a particular manouvre. Alternatively the part throttle DBW map could be altered (as you suggested) to retain the Pedal Position Sensor-Torque relationship of the original map.

Edited by gruntguru, 07 July 2010 - 23:45.

[WhiteBlue]

application code can be autogenerated using Simulink; you create a model of what you want to control and then the application code for the ECU can be autogenerated by the program from the model. So the system itself is capable to control a lot of things unless FIA checks what software is loaded in the SECU.

As I have already posted the FiA checks the software version every day of every event. You cannot legally make a change to the program. All you can do is upload different maps.

5.5 Engine throttles:
5.5.1 The only means by which the driver may control the engine throttle positions is via a single chassis mounted foot pedal.
5.5.2 Designs which allow specific points along the pedal travel range to be identified by the driver or assist him to hold a position are not permitted.
5.5.3 The minimum and maximum throttle pedal travel positions must correspond to the engine throttle minimum (nominal idle) and maximum open positions.

I do not see a fundamental problem with a a stacked throttle map. You start with idle and end with fully open throttle. But you do not dedicate all the stroke to proportionally open the throttle. Perhaps you just use half of the stroke for that but you produce very little power through that stroke. The throttle remains on 100% open during the second half of the stroke and the 5.5.3 condition is met. Only the second half of the pedal stroke brings on the power by gradually reducing the retardation of the ignition. I still think that the cars would sound funny wouldn't they?

[gruntguru]

So to gain the advantage of the increased mass flow within the rules, could they tell the drivers to keep
a bit of throttle while braking (left foot braking).

To control the speed of the car, you would need to brake more (for longer) - preferable with the front.

Not saying they don't left foot brake, but it is worth noting that left foot braking with throttle added to compensate will produce a totally different cornering result. Just think about where each tyre is operating in terms of its traction circle.

If the intention of left foot braking is only to increase exhaust flow, it would be preferrable to brake only the rear so the only effect would be to counteract additional engine power (no handling or grip effect).

[gruntguru]

Yes, I agree, that it has an influence on the cornering ability and that it changes the loads the tyres see.

Not sure, if the effect is all that bad, and if the car is designed with this driving style in mind they will
set their static weigth distribution etc. in a way to factor that in.

The highest theoretical cornering speed will occur with all four tyres operating at the optimum slip angle and NO drive or braking on any tyre. Any longitudinal force will reduce the lateral force available. In practice (constant radius) cornering must be performed with a certain amount of power to overcome parasitic losses. Take a simplified example. Optimum speed through a particular corner is achieved with 100 kW of drive through the rear wheels. Now we go through the same corner with 100kW of left foot braking to increase exhaust flow. If the brake bias is 50/50 we get 50kw of braking at the front and 50kW at the rear. The throttle is opened to give 200kW to compensate for the 100kW of braking. So now the rear tyres are seeing 150kW of drive and the fronts see 50kW of braking. In this case both the front and the rear tyres will have less grip available for cornering. Unless the diffuser is working a LOT better with the extra exhaust flow, the corner will be slower.

Not 100% sure about your last statement. I don´t want to argue against it, just not sure if I would do it
with the rear, as I think the front tires will be more loaded and have more "scope" to deal with the additional
braking force. And if understeer is may the "safer" option then oversteer. (for most drivers).
But I would not set this in stone, just my 0.10$

Taking the above example, if the braking is 100% rear, the rears will still see 200-100=100kW of drive and the fronts see no drive or braking. So cornering should be as it was without any braking except for the benefit of extra DF.

[WhiteBlue]

The highest theoretical cornering speed will occur with all four tyres operating at the optimum slip angle and NO drive or braking on any tyre. Any longitudinal force will reduce the lateral force available. In practice (constant radius) cornering must be performed with a certain amount of power to overcome parasitic losses. Take a simplified example. Optimum speed through a particular corner is achieved with 100 kW of drive through the rear wheels. Now we go through the same corner with 100kW of left foot braking to increase exhaust flow. If the brake bias is 50/50 we get 50kw of braking at the front and 50kW at the rear. The throttle is opened to give 200kW to compensate for the 100kW of braking. So now the rear tyres are seeing 150kW of drive and the fronts see 50kW of braking. In this case both the front and the rear tyres will have less grip available for cornering. Unless the diffuser is working a LOT better with the extra exhaust flow, the corner will be slower.

That makes sense. So we can assume that they will not throw away significant power by braking.

One thing that I'm still a bit confused about is the assumption that they will waste fuel by injecting a lot more than the engine can burn with the late ignition. Ok, just for q3 the fuel waste would not matter but is it really true that you have to make the mix fatter to avoid over heating? Has anybody here personal experience with lean mix and late ignition?

[DaveW]

To complicate matters further, I think there is more than one (relatively) quick way around a circuit.

I recall analysing laps recorded around Ricard made by Mario Andretti & JYS in Mario's Lotus F1 car. JYS braked earlier & "pulled" around 0.5 gn less through every corner, but lap times were similar because JYS was back on the power earlier & hence made up lost time along every straight. Something similar could well be happening now with RBR c.f. McLaren cars.

Perhaps PGW's quote is not entirely accurate....

[Powersteer]

Probably F1 cars are running air intake throttless engines and idle via fuel injection control since EFI technology now is super high tech, a way around the rule book perhaps. What they can also do is have the intake throttle partly closed as fixed set up and let the fuel injection systems do the blow job...sorry, I mean, you know what I mean so maybe it closes up to 80% or more then the efi controls anything below that. This might be the reason why some cars are running out of fuel. And they don't have to pop it like wrc cars, if ignition timing is moderated.

Edited by Powersteer, 08 July 2010 - 18:42.

[Big Block 8]

The ECU is standard an having custom maps does not breach it. You just can't expect 4 or 5 different engines using the same spark timing, mixtures and so.

On the TC issue, it's avoided by the lack of feedback from wheel speed/car acceleration and (maybe) designed inability to process crankshaft acceleration , computing crankshaft speed only.

Well it is suggested here that the engine mapping would somehow allow drastic differences in engine power output, practically regardless of the accelerator pedal position. Then all that would be needed to implement traction control would be a hidden auxilary sensor (independent from the ECU) that is signalling in the need to cut power - to for example into a simple switch in the steering wheel. So if the teams were allowed to maneuver with the ECU in such a manner that's been told here, it would be really silly as the teams would then be able to do just exactly what the standard ECUs were brought in for to prevent - using the TC.

If I had made those ECUs, all that would be allowed was to change a couple of parameters in certain strict limits, really fine fine tune (for the specs you mentioned, those engines are almost identical anyway) and that's it. Sure, it wouldn't be a first time FIA has made cock ups, but still - that would be too easy one so I'm a little hesitant.

[Big Block 8]

As for creating more exhaust flow, a common approach is to open up the throttle a bit, ****** ignition to after TDC and enrich the fuel mixture a bit to keep temperatures in control.

That's enough to for example keeping a turbocharger running for a while, but I'd think that for any aerodynamic effect to create significant downforce numbers considerably more flow would be needed. Throttle should be fully or at least almost fully open and the fuel injection should be at least partly cut as the thermal load to the exhaust side would increase hand in hand with the decrease of the engine efficiency. In other words, all the calorific value of the fuel that normally would be transferred into work would now be transferred into heat and out of the exhaust with proportionally increased exhaust flue temperature. Even if the exhaust side would be able to withstand the heat, one would expect to see a flame or two.

Just academically speaking - as I said I don't think such engine maps are allowed anyway because that would be a free pass to implement TC on the side.

[saudoso]

Then all that would be needed to implement traction control would be a hidden auxilary sensor (independent from the ECU) that is signalling in the need to cut power - to for example into a simple switch in the steering wheel.

That's the point: there is no feed-back from the wheels to the SECU. OK, one could try to plant a bypass, but that would be plain cheating (like many other things one could try, flexing wings or magic fuel let's say) and not twisting the use of the SECU for the letter but against the intent of the law.

If you place a bypass with wheelspin feedback you don't even need to deal with SECU maps, you can just cut power from the sparks and you just added another computer to the system.

[gruntguru]

I agree with the first part of your statement, but the second part is not so clear. Who says that there are not tires which reaching there optimum slip angle with a certain amount of longitudinal accl.?
Some tires are designed to do this, and the friction circle is not really a circle, its´s more an ellipse, but even this is not 100% correct.

That would mean a traction "circle" with "concave out" sections at the left and right extremities. I have never seen a traction circle that wasn't "convex out" for it's entire circumference.

You refer to a tire with constant vertical load in your example. (the friction circle), and you assume that the tire is at his traction limit in lateral direction. Under this conditions all what you say is correct. But maybe these F1 front tires are not at their lateral traction limit, because they are maybe "too stiff".
This is just a speculative thought. I don't know, where these tires are within their performance enevelope.

I think it is reasonable to assume that F1 cars in a long, constant-radius corner are capable of operating all 4 tyres quite close to the lateral edge of their respective traction circles. Anything less would offer other teams a distinct advantage.

It is also the reason that in most cars you have a forward brake bias, because due do the load transfer your front tires can carry more braking performance, because their traction cirle is (temporarly) larger. (This is mainly true for cars which are using the same tires front and rear, and do not have an extreme weight or aero bias to the rear).

But this is not the case in the example we are considering because there is no deceleration of the car, we are only braking to offset additional power, so the extra braking on the front wheels will almost certanly move the force vector at the contact patch beyond the limits of the traction circle.

To simplify my point look at it this way. The team has a car which has been meticulously set up to suit the driver, the track etc. Then for qualy they make a few changes to increase the exhaust flow in traction-limited areas of the track. If left-foot braking was one of those changes, implementing it on the rear wheels only, will have no effect on the balance and grip of the car. Any other implementation (and especially one which favours braking the front wheels) would negate the hard-won setup.

[J. Edlund]

Thanks J.E. for the clarification of the rule aspect.

This brings us back to an oberservation, which DaveW has made earlier (maybe in a different forum).

Red Bull seems to struggle with front brakes (wear and some other issues).

So to gain the advantage of the increased mass flow within the rules, could they tell the drivers to keep
a bit of throttle while braking (left foot braking).

I´m sure a clever pedal or foot rest design or a small imperfection on the inside of the monocoqe, will help the driver to "remember" the position.
Then as it seems that, within the min and max position of the throttle, the relationship between pedal and
throttle at the engine, don´t need to be linear, the engine map will open the throttle more, redard the ignition
to reduce power, alter the fuel map to what they think is needed under this condition, and have the benefit
of increased exhaust gas flow/mass flow to help their DD and generate more downforce overall.

To control the speed of the car, you would need to brake more (for longer) - preferable with the front.
This would put more stress on the front brakes, then a car, which uses engine braking to slow it down, and
which does not have a "blown" diffusor.

Maybe, slowly a bit of a pattern emerges here, and some things start to make sense.

Then I would expect the rear brake wear to increase, as they would be forced to run with a rearward brake bias.

Rather I would suspect the ordinary reason for high brake wear; running too high brake temperatures as they try to minimize the brake cooling inlets to minimize drag.

Probably F1 cars are running air intake throttless engines and idle via fuel injection control since EFI technology now is super high tech, a way around the rule book perhaps. What they can also do is have the intake throttle partly closed as fixed set up and let the fuel injection systems do the blow job...sorry, I mean, you know what I mean so maybe it closes up to 80% or more then the efi controls anything below that. This might be the reason why some cars are running out of fuel. And they don't have to pop it like wrc cars, if ignition timing is moderated.

With most engines using electronic throttles the throttles are used to control the idle speed in some way, but that doesn't require the throttle to be much opened. Idle speed is then fine tuned with ignition advance. Idle ignition timing is usually a bit ******** so that engine torque can be increased by ignition advance if there is a rapid load increase on the engine (high alternator load for instance).

That's enough to for example keeping a turbocharger running for a while, but I'd think that for any aerodynamic effect to create significant downforce numbers considerably more flow would be needed. Throttle should be fully or at least almost fully open and the fuel injection should be at least partly cut as the thermal load to the exhaust side would increase hand in hand with the decrease of the engine efficiency. In other words, all the calorific value of the fuel that normally would be transferred into work would now be transferred into heat and out of the exhaust with proportionally increased exhaust flue temperature. Even if the exhaust side would be able to withstand the heat, one would expect to see a flame or two.

Just academically speaking - as I said I don't think such engine maps are allowed anyway because that would be a free pass to implement TC on the side.

Cutting the injection would probably be unwise as it introduces free oxygen in the exhaust manifold which can then react with excess fuel from other cylinders with a high thermal load as the result.

The thermal load on the engine will increase as a result of retarding the ignition, that's why injecting more fuel is a good idea. Plus it helps increase exhaust mass (fuel mass + air mass = exhaust mass).

With the ignition ********, since the combustion still occurs in the cylinders it can be done without visible flames.

That's the point: there is no feed-back from the wheels to the SECU. OK, one could try to plant a bypass, but that would be plain cheating (like many other things one could try, flexing wings or magic fuel let's say) and not twisting the use of the SECU for the letter but against the intent of the law.

If you place a bypass with wheelspin feedback you don't even need to deal with SECU maps, you can just cut power from the sparks and you just added another computer to the system.

There is feedback. The cars got wheel speed sensors and with one of these http://www.mclarenel...it_IF_HIU-3.asp attached to each hub all the data becomes availible on the CAN bus which the SECU is connected to. So it's only a quastion about what the SECU does with the information it has access to, not what information it has access to. To prevent the information being used in an way prohibited by the regulations the FIA checks the SECU software.

[WhiteBlue]

Well it is suggested here that the engine mapping would somehow allow drastic differences in engine power output, practically regardless of the accelerator pedal position. Then all that would be needed to implement traction control would be a hidden auxilary sensor (independent from the ECU) that is signalling in the need to cut power - to for example into a simple switch in the steering wheel. So if the teams were allowed to maneuver with the ECU in such a manner that's been told here, it would be really silly as the teams would then be able to do just exactly what the standard ECUs were brought in for to prevent - using the TC. If I had made those ECUs, all that would be allowed was to change a couple of parameters in certain strict limits, really fine fine tune (for the specs you mentioned, those engines are almost identical anyway) and that's it. Sure, it wouldn't be a first time FIA has made cock ups, but still - that would be too easy one so I'm a little hesitant.

Re wheel rotation feedback J.Edlund has expressed my opinion below. Re the multi dimensional throttle maps you have to remember the history of the SECU. All the teams including Ferrari, BMW, Renault, Toyota and Honda who had very sophisticated engine electronics were forced to basically use McLaren's system from 2008 and transfer their proprietary programming and parametrizing know how to McLaren in order to keep it viable. The final SECU program ended up with the collective know how of all teams, which was pretty advanced in 2008. Just remember the McLaren's dual shifter system that switches the maps in sync with the gears. All this is only done to adjust the engine maps specifically to the gear ratios.

Cutting the injection would probably be unwise as it introduces free oxygen in the exhaust manifold which can then react with excess fuel from other cylinders with a high thermal load as the result. The thermal load on the engine will increase as a result of retarding the ignition, that's why injecting more fuel is a good idea. Plus it helps increase exhaust mass (fuel mass + air mass = exhaust mass). With the ignition ********, since the combustion still occurs in the cylinders it can be done without visible flames.

There is feedback. The cars got wheel speed sensors and with one of these http://www.mclarenel...it_IF_HIU-3.asp attached to each hub all the data becomes availible on the CAN bus which the SECU is connected to. So it's only a quastion about what the SECU does with the information it has access to, not what information it has access to. To prevent the information being used in an way prohibited by the regulations the FIA checks the SECU software.

We seem to have some pros and cons for cutting injection or even increasing it. Unfortunately there seems to be nobody who knows the peculiarities of F1 engines.

[Tony Matthews]

To enthusiastic amateurs the explanation is more difficult because it involves mathematics and programming basics. If you remember boolean logic you do understand how you can combine certain input conditions to generate outputs. This is basically what a programmable logic controller (PLC) does. The ECU is nothing but a networked PLC. The program inside the ECU is rigidly controlled by the FiA.

I know nothing of boolean logic, only that the carpenter's downfall was that the snark was a boojum. However, everything else made sense, so thanks.

[Greg Locock]

Not too sure if this has been said, but you can build a traction controller that only knows about engine rpm. It doesn't need to know anything else. This device can be made quite small, about the size of an electrical connector. it's not as good as a proper tc, but it is better than nothing.

[gruntguru]

Cutting the injection would probably be unwise as it introduces free oxygen in the exhaust manifold which can then react with excess fuel from other cylinders with a high thermal load as the result.

I don't think there would be much of this happening in an F1 exhaust where the individual exhaust parcels from each cycle/cylinder are kept fairly well segregated. Besides, how big a concern is thermal loading of the exhaust system?

The thermal load on the engine will increase as a result of retarding the ignition, that's why injecting more fuel is a good idea. Plus it helps increase exhaust mass (fuel mass + air mass = exhaust mass).

For a given heat rejection to the exhaust gas, a lean mixture will reduce the gas temperature more than a rich one. Starting with a stoichiometric mixture, 10% excess air will increase the exhaust mass per unit heat input (and therefore reduce delta T) by almost 10% whereas 10% excess fuel will increase it by less than 1%. (delta T = exhaust temp - intake temp). Of course leaning the mixture also increases exhaust temp due to slow burn, but that is what we are trying to achieve by retarding the timing anyway.

Edited by gruntguru, 10 July 2010 - 04:33.

[cheapracer]

Not too sure if this has been said, but you can build a traction controller that only knows about engine rpm. It doesn't need to know anything else. This device can be made quite small, about the size of an electrical connector. it's not as good as a proper tc, but it is better than nothing.

But you can't mask the noise that a TC will give, the note will be heard immediately by 100 engineers and many others who know trackside.

However a device that holds a perfect rpm momentarily for peak grip at a specified point is possible, desirable and undetectable.

[J. Edlund]

Re wheel rotation feedback J.Edlund has expressed my opinion below. Re the multi dimensional throttle maps you have to remember the history of the SECU. All the teams including Ferrari, BMW, Renault, Toyota and Honda who had very sophisticated engine electronics were forced to basically use McLaren's system from 2008 and transfer their proprietary programming and parametrizing know how to McLaren in order to keep it viable. The final SECU program ended up with the collective know how of all teams, which was pretty advanced in 2008. Just remember the McLaren's dual shifter system that switches the maps in sync with the gears. All this is only done to adjust the engine maps specifically to the gear ratios.

SECU is not based on the control unit McLaren ran in 2008, like the others they had a more advanced system in use before the FIA specified SECU. So the teams have had to accept a more 'conservative' ECU with SECU, this was partly due to the short timeframe availible for its introduction.

All engines with electronic throttles have throttle maps. On a production car, if you press the 'sport button' (if the car has such a button) this usually switch throttle map to one that is more aggressive so that a smaller pedal movement result in a larger torque increase.

The dual shifter was a sort of replacement for traction control.

I don't think there would be much of this happening in an F1 exhaust where the individual exhaust parcels from each cycle/cylinder are kept fairly well segregated. Besides, how big a concern is thermal loading of the exhaust system?

Not only will oxygen from one cylinder be used to oxidize the fuel from another, but if the fuel injection is cut on some cylinders, fuel will enter those cylinders from another operating fuel injector. The exhaust pipes are joined in the collector and pressure waves are traveling both downstreams and upstreams.

Thermal loading of the exhaust can be a significant problem. Not only are there limitations of what the thin inconel sheet in the exhaust pipe can handle, but also everything that is near the exhaust.

For a given heat rejection to the exhaust gas, a lean mixture will reduce the gas temperature more than a rich one. Starting with a stoichiometric mixture, 10% excess air will increase the exhaust mass per unit heat input (and therefore reduce delta T) by almost 10% whereas 10% excess fuel will increase it by less than 1%. (delta T = exhaust temp - intake temp). Of course leaning the mixture also increases exhaust temp due to slow burn, but that is what we are trying to achieve by retarding the timing anyway.

Exhaust temperature of a spark ignition engine at different lambda values at constant power output and ignition:
lambda 1.2: 594 degC
lambda 1.1: 604 degC
lambda 1.0: 624 degC
lambda 0.9: 608 degC
lambda 0.8: 579 degC
lambda 0.7: 538 degC

With a lean mixture you also risk misfire and poor engine response and going much beyond lambda 1.2 would probably be unrealistic while going to lambda 0.6 or 0.7 is nothing strange if an engine have a large cooling need. Although, lean mixtures give higher exhaust mass flow at a constant power output.

But you can't mask the noise that a TC will give, the note will be heard immediately by 100 engineers and many others who know trackside.

However a device that holds a perfect rpm momentarily for peak grip at a specified point is possible, desirable and undetectable.

It's possible to mask the noise. Control the engine output with mainly the electronic throttle (a little slower than the ignition) and go easier on the ignition ****** and there won't be any noise to notice aside from the normal engine sound.

[McGuire]

One interesting observation is that Red Bull has a setting on the engine, whereby the ignition is ******** on the over run, which maintains exhaust gas pressure even when the driver lifts off the throttle. This maintains the performance of the blown diffuser and keeps the downforce up when it’s most needed. It’s not something you can do for more than a lap or two as it damages the engine, but it gives that vital fraction of a second which keeps Red Bull ahead of the rest in qualifying.

I would file this with the magical tire inflation gas story, in front of the ones about Jaguar metallic paint being too heavy and the superlight Shell gasoline, but behind the one about scales that factor in distance from the equator.