What will come after the 2.4 V8?

[WhiteBlue]

I see a lot of apple and banana comparisons here. So it would be sensible to look at some focal data for comparing the new and the old engines.

I expect engine efficiency to improve due to throttle less engine control, direct fuel injection, turbo charge/compounding, lower friction and other technologies. The scope should be approximately 11% less fuel for the same power output with improved drivability due to a much broader torque curve.

The current V8 figures look like this:

• race fuel 150 kg
• specific energy 46 MJ/kg
• race time 80 min
• top engine power 750 bhp
• power at full throttle (percentage 65% of 750 bhp) -> 488 bhp
• power at off throttle (percentage 15% of 0 bhp) -> 0 bhp
• power at part throttle (percentage 20% of 375 bhp) -> 75 bhp
• average engine power 563 bhp or 420 kW
• race fuel energy 6.9 GJ
• engine power * race time = engine work = 2.02 GJ
• V8 efficiency = 29.3%

If I replace it with a 750 bhp L4 turbo engine that saves 11% of the fuel I get:

• race fuel 133.5 kg
• race fuel energy 6.14 GJ
• L4 (750 bhp) efficiency 32.9%

It means I increase the engine efficiency by 3.6% to 32.9%. Let's keep that in mind and use that figure later.

According to the reports it is not in the plan to keep the 750 bhp of the current engines. Engine power is supposed to go down by 13.3% to 650 bhp. If I keep the same throttle percentages my average engine power decreases to 363.7 kW. This means an engine work of 1.746 GJ. My KERS system supplies 2.2 MJ/lap which gives me another 0.132 GJ race work over a 60 lap race. My total race work including KERS is 1.878 GJ. If I compare that with the V8 I find that I have 7% less work capacity available with the new KERS assisted engine. I obviously have to find that deficit by making my chassis more efficient. The method to do this is cutting down on drag. I'm fairly confident that the chassis designers will be able to close that gap with the ground effect cars.

If I look at fuel use by my downsized and higher efficient engine I find that I need 115 kg to provide 1.746 GJ at 32.9% efficiency. My fuel saving of the turbo L4 with AWKERS is 25% compared to the 2010 cars.

Now I look at the fuel flow rate for my engine. My top engine power is 485 kW which translates into 1474 kW fuel flow or 44 ml/s. This is indeed 10% more than my pessimistic estimate.

The average fuel flow would be 33 ml/s. Of course all this is still very much simplified. The fuel use would not necessarily be proportional to the power and the throttle use.

[twoshots]

Engine weight is mandated now at 95kg. WHy do you think they'll change it?

Because the current minimum weight limit applies to the old V8 formula. F1 would be more than dumb to downsize and keep the old weight limit.

The new minimum engine weight will include KERS.

[xpensive]

I'm glad that you have read my posts lately WB, when you seem to have picked up on a few things here and there.

However, I doubt your efficiency numbers a bit, 29% for the V8, coming from an overestimated average output I think, "full throttle" doesn't necessarily mean "full power", when an F1 engine has a rather dramatic power-curve.

The other thing is that you are using a 33% efficiency for the I4 turbo as starting value, but otherwise you have presented very interesting numbers, in particular when you arrive at 44 cc/sec when I have used 50.

[WhiteBlue]

Do you have a sensible way to improve my figures, xpensive? I think the computation is simple and straightforward. What would you change in the base figures? I have not assumed the efficiency of the V8 but computed it from the usual assumptions. The only thing that may be in doubt is the average power which I put at 75% of top power. The 65% full throttle has been agreed in the past and 15% off throttle for breaking phases should also be ok.

The example just shows how important the average power setting is compared to the maximum. That is the reason why max fuel flow rates are not a consistent and powerfull instrument to limit fuel use. The engineers will find ways to lift the average power setting and continue to erode the efficiency. The Cosworth proposal to set a total fuel budget and a max flow is probably the best.

[xpensive]

[*]top engine power 750 bhp
[*]power at full throttle (percentage 65% of 750 bhp) -> 488 bhp
[*]power at off throttle (percentage 15% of 0 bhp) -> 0 bhp
[*]power at part throttle (percentage 20% of 375 bhp) -> 75 bhp
[*]average engine power 563 bhp or 420 kW

Just xplain the above figures, because I simply don't get it. Sorry.

[Scotracer]

I see a lot of apple and banana comparisons here. So it would be sensible to look at some focal data for comparing the new and the old engines.

I expect engine efficiency to improve due to throttle less engine control, direct fuel injection, turbo charge/compounding, lower friction and other technologies. The scope should be approximately 11% less fuel for the same power output with improved drivability due to a much broader torque curve.

The current V8 figures look like this:

• race fuel 150 kg
• specific energy 46 MJ/kg
• race time 80 min
• top engine power 750 bhp
• power at full throttle (percentage 65% of 750 bhp) -> 488 bhp
• power at off throttle (percentage 15% of 0 bhp) -> 0 bhp
• power at part throttle (percentage 20% of 375 bhp) -> 75 bhp
• average engine power 563 bhp or 420 kW
• race fuel energy 6.9 GJ
• engine power * race time = engine work = 2.02 GJ
• V8 efficiency = 29.3%

If I replace it with a 750 kW L4 turbo engine that saves 11% of the fuel I get:

• race fuel 133.5 kg
• race fuel energy 6.14 GJ
• L4 (750 bhp) efficiency 32.9%

It means I increase the engine efficiency by 3.6% to 32.9%. Let's keep that in mind and use that figure later.

According to the reports it is not in the plan to keep the 750 bhp of the current engines. Engine power is supposed to go down by 13.3% to 650 bhp. If I keep the same throttle percentages my average engine power decreases to 363.7 kW. This means an engine work of 1.746 GJ. My KERS system supplies 2.2 MJ/lap which gives me another 0.132 GJ race work over a 60 lap race. My total race work including KERS is 1.878 GJ. If I compare that with the V8 I find that I have 7% less work capacity available with the new KERS assisted engine. I obviously have to find that deficit by making my chassis more efficient. The method to do this is cutting down on drag. I'm fairly confident that the chassis designers will be able to close that gap with the ground effect cars.

If I look at fuel use by my downsized and higher efficient engine I find that I need 115 kg to provide 1.746 GJ at 32.9% efficiency. My fuel saving of the turbo L4 with AWKERS is 25% compared to the 2010 cars.

Now I look at the fuel flow rate for my engine. My top engine power is 485 kW which translates into 1474 kW fuel flow or 44 ml/s. This is indeed 10% more than my pessimistic estimate.

The average fuel flow would be 33 ml/s. Of course all this is still very much simplified. The fuel use would not necessarily be proportional to the power and the throttle use.

Where on earth did you get the 11% value from? Your ass?

[WhiteBlue]

[*]top engine power 750 bhp
[*]power at full throttle (percentage 65% of 750 bhp) -> 488 bhp
[*]power at off throttle (percentage 15% of 0 bhp) -> 0 bhp
[*]power at part throttle (percentage 20% of 375 bhp) -> 75 bhp
[*]average engine power 563 bhp or 420 kW

Just xplain the above figures, because I simply don't get it. Sorry.

Not so difficult.

Engine spends 65% on full throttle. 65% of 750 bhp = 488 bhp.
Engine is 15% of time off throttle. 15% of 0 bhp = 0 bhp
Engine is 20% of time on half throttle 20% of 375 bhp = 75 bhp
Total average power is 488 + 75 = 563 bhp = 420 kW which is a 75% part load of the maximum engine power. Average fuel use is calculated from average power use.

Where on earth did you get the 11% value from? Your ass?

It is a compound value which I think is a very conservative assumption. I estimate totally eliminating throttle losses and reduced pumping losses by variable valve timing and lift at 3%, spray guided direct injection is a minimum of 5% fuel reduction compared to port injection. I have not included laser ignition which should be worth another 3%. The other 3% fuel reduction I attribute to the energy recovery from the turbo. So all together very conservative. I reckon that one could reach 15-20% with some advanced technologies. This would push the engine up to 36% percent efficiency.

[rjsa]

[*]top engine power 750 bhp
[1]power at full throttle (percentage 65% of 750 bhp) -> 488 bhp
[2]power at off throttle (percentage 15% of 0 bhp) -> 0 bhp
[3]power at part throttle (percentage 20% of 375 bhp) -> 75 bhp
[4]average engine power 563 bhp or 420 kW

[1] How come? You mean averge power at full throtle within the most used power band? Where did these numbers come from?
[2] 15% of 0, what's the point?
[3] Again ,where does this come from? What is part throtle? What's the engine speed?
[4] Again, average based on what? Power X RPM, Power X Full lap length?

The devil is as always in the statistics.

EDIT:I have just seen you explanation above. You don't have a clue, right? Full throtle and 100% power are two very different devils.

[WhiteBlue]

[*]top engine power 750 bhp
[1]power at full throttle (percentage 65% of 750 bhp) -> 488 bhp
[2]power at off throttle (percentage 15% of 0 bhp) -> 0 bhp
[3]power at part throttle (percentage 20% of 375 bhp) -> 75 bhp
[4]average engine power 563 bhp or 420 kW

[1] How come? You mean averge power at full throtle within the most used power band? Where did these numbers come from?
[2] 15% of 0, what's the point?
[3] Again ,where does this come from? What is part throtle? What's the engine speed?
[4] Again, average based on what? Power X RPM, Power X Full lap length?

The devil is as always in the statistics.

You need a simple model to do such calculation on paper without a computer simulation. The basic driving situations during a lap is 65% full throttle for acceleration out of corners and along a straight. 15% is spend on the brakes where the engine has no power demand (ideally). 20% of time is spend going around corners on partial throttle which I have simply approximated to 50% of the engine power. All tracks are different but the full throttle and the break percentage was carefully studied by xpensive and myself and we agreed on those values for the purpose of calculating KERS. It is also true for the engine. If you shift those values a bit around you will still not get much different figures. Something which I have excluded are tricks like the blown diffusor lag or retarded ignition which wastes a lot of fuel.

[rjsa]

[*]top engine power 750 bhp
[1]power at full throttle (percentage 65% of 750 bhp) -> 488 bhp
[2]power at off throttle (percentage 15% of 0 bhp) -> 0 bhp
[3]power at part throttle (percentage 20% of 375 bhp) -> 75 bhp
[4]average engine power 563 bhp or 420 kW

[1] How come? You mean averge power at full throtle within the most used power band? Where did these numbers come from?
[2] 15% of 0, what's the point?
[3] Again ,where does this come from? What is part throtle? What's the engine speed?
[4] Again, average based on what? Power X RPM, Power X Full lap length?

The devil is as always in the statistics.

You need a simple model to do such calculation on paper without a computer simulation. The basic driving situations during a lap is 65% full throttle for acceleration out of corners and along a straight. 15% is spend on the brakes where the engine has no power demand (ideally). 20% of time is spend going around corners on partial throttle which I have simply approximated to 50% of the engine power. All tracks are different but the full throttle and the break percentage was carefully studied by xpensive and myself and we agreed on those values for the purpose of calculating KERS. It is also true for the engine. If you shift those values a bit around you will still not get much different figures. Something which I have excluded are tricks like the blown diffusor lag or retarded ignition which wastes a lot of fuel.

I see where you want to get there, but there was no need for that. If you say engine A is 11% more efficient than engine B given the same power output, you can can assume that it will use 90% of the fuel only. All the confusing math is unnecessary.

[xpensive]

...
Not so difficult.

Engine spends 65% on full throttle. 65% of 750 bhp = 488 bhp.
Engine is 15% of time off throttle. 15% of 0 bhp = 0 bhp
Engine is 20% of time on half throttle 20% of 375 bhp = 75 bhp
Total average power is 488 + 75 = 563 bhp = 420 kW which is a 75% part load of the maximum engine power. Average fuel use is calculated from average power use.
...

I can appreciate that these things can be difficult for the untrained engineer, but the above is simply not a comprehensive way of handling power and energy numbers, talking about mixing Apples and Pears! Please let me help you out;

As a part of a total 4800 seconds (80 minutes), the 551 kW (750 Hp) engine spends:
- 65% of time on full throttle/power, 551 kW. 65% of 4800 seconds is 3120 seconds, resulting in 1720 MJ of energy.
- 20% of time on half throttle/power, 276 kW. 20% of 4800 seconds is 960 seconds, resulting in 265 MJ of energy.
- 15% of time off throttle/power, 0 kW. 15% of 4800 seconds is 720 seconds, resulting in 0 MJ of energy.

Total mechanical energy developed by the engine is 1720 + 265 = 1985 MJ, which means an average power of 414 kW (563 Hp) over 80 minutes and an efficiency of 28.5% in relation to 150 kg of fuel, 150 * 46.4 = 6969 MJ

But what myself and rjsa are saying, is that full throttle and full power is far from the same, why I belive that you have overestimated the mechanical energy developed by the engine.

[WhiteBlue]

I see where you want to get there, but there was no need for that. If you say engine A is 11% more efficient than engine B given the same power output, you can can assume that it will use 90% of the fuel only. All the confusing math is unnecessary.

I'm not so sure that you understand what I was doing. I was checking the base line efficiency of the current 750 bhp V8 engines and how that efficiency would change if a new engine of the same power was using 11% less fuel.

Next I figured out what kind of fuel saving one would get if a less powerful engine with 650 bhp and with the improved efficiency would be run. It turned out that the 25% fuel saving objective of the FiA would be met.

I was wondering before why the engine working group wanted to reduce the power of the engine by 100 bhp. It looks to me that the power cut requires a bigger KERS contribution and is meant to force the chassis designers to reach performance with lower drag. After figuring in a 2.2 MJ/lap KERS I discovered that this vehicle would have a 7% power deficit.

This appears like a reasonable figure for chassis energy saving. A part of this will most likely come from the more efficient way of producing downforce from ground effect instead of using wings and by adaptive aero. Another part will probably be saved by reducing the level of downforce and replacing it with mechanical grip. With electric AWD improved cornering grip should be possible.

This was the rational behind my complicated figuring.

[WhiteBlue]

I can appreciate that these things can be difficult for the untrained engineer, but the above is simply not a comprehensive way of handling power and energy numbers, talking about mixing Apples and Pears! Please let me help you out;

As a part of a total 4800 seconds (80 minutes), the 551 kW (750 Hp) engine spends:
- 65% of time on full throttle/power, 551 kW. 65% of 4800 seconds is 3120 seconds, resulting in 1720 MJ of energy.
- 20% of time on half throttle/power, 276 kW. 20% of 4800 seconds is 960 seconds, resulting in 265 MJ of energy.
- 15% of time off throttle/power, 0 kW. 15% of 4800 seconds is 720 seconds, resulting in 0 MJ of energy.

Total mechanical energy developed by the engine is 1720 + 265 = 1985 MJ, which means an average power of 414 kW (563 Hp) over 80 minutes and an efficiency of 28.5% in relation to 150 kg of fuel, 150 * 46.4 = 6969 MJ

But what myself and rjsa are saying, is that full throttle and full power is far from the same, why I belive that you have overestimated the mechanical energy developed by the engine.

Your result is the same as mine if you use the same energy content. I was using 46 MJ/kg. You took 46.4. We probably have used a slightly different conversion factor for bhp to kW as well. This has nothing to do with training. Just a question of agreeing on numbers.

The thing that is important to me is recognizing that the engine is not running on full power all the time and getting an idea what the average partial load would be. I agree it is a crude model but I do get a figure of 75% part load which I can use. If you can propose a better model for figuring the average engine power in a simple way I would be prepared to use that as well. In the end it isn't important to me if the base line efficiency is 28.5 or 29.3%. It is more important to see how the numbers work out when you set a target of an engine power reduction of 100 bhp and what that means for KERS contribution and chassis efficiency.

[xpensive]

Not really, the problem was to present your estimations in both a scientific as well as comprehesible way.

[rjsa]

The current V8 figures look like this:

• race fuel 150 kg
• top engine power 750 bhp
  
  If I replace it with a 750 kW L4 turbo engine that saves 11% of the fuel I get:
  • race fuel 133.5 kg
  • race fuel energy 6.14 GJ
  • L4 (750 bhp) efficiency 32.9%

I'm sorry but I see 560HP (750KW) and 750HP.

And, if you have the same power using 11% less fel, you have a 12.35%more efficient engine, that's simple arithmetics and you really don't need to go all this way to measure it.

It's like computing fuel usage:

• a)by integrating the fuel flow over time and
  b)by weighing the fuel tank before and after the race.

[/list]

Both will give the same amount.