What will come after the 2.4 V8?

[ringo]

White Blue, CAD design has been around for a long time, even in the 80's.
It was more inflexible, and didn't involve the computers we use today; they used tape readers.
I'm not sure about the FEA capability, though but i believe some computer guided FEA calculations were possible.

[xpensive]

You base you opinion on the claim of a competitor. That is not an unbiased neutral view and as such it cannot be taken as fact. Ferrair make a claim, Mclaren make a counter claim. So I guess you and McLaren are familier with the inner workings of Ferrari.

Nope, I base my opinion on research and learning as shown by my own contribution on the issue. McLaren supporting my view is just the icing on the cake.

Your main contribution to this forum is pissing other members off with whatever you can find on the web, misinterpret to match your own opinion, which becomes obvious whenever you try to dress it in a scientific guise like when impersonating an engineer with energy numbers. The problem is that unlike other members, you are not here to learn and get new impressions, only to try to overwhelm topics chosen by simply xhausting posters by never admitting to be in the wrong.

[riff_raff]

For a given power level, a lower RPM turbocharged 1.6L I4 engine would be more fuel efficient than a high RPM N/A 2.4L V8. With modern turbochargers and digital controls, it would also likely have a wider power band, making it more driveable (ie. better for racing).

The smaller displacement turbo engine would have better thermal efficiency mostly due to its higher cycle pressures and reduced pumping losses. Having a fewer number of larger displaced volume cylinders also is helpful because their lower surface-area-to-volume ratio reduces heat transfer losses. A lower operating speed also reduces friction losses, since these losses tend to increase exponentially with speed.

I4 engine configurations don't lend themselves well with a mid-mounted stressed engine chassis design. If mounted upright, they have a relatively high CG, a narrow structural cross section, and asymmetry in their intake/exhaust systems. But they can be made to work, as history shows.

riff_raff

[WhiteBlue]

More sour grapes by xpensive! Try to do a better job instead of making personal remarks about other posters!

[WhiteBlue]

For a given power level, a lower RPM turbocharged 1.6L I4 engine would be more fuel efficient than a high RPM N/A 2.4L V8. With modern turbochargers and digital controls, it would also likely have a wider power band, making it more driveable (ie. better for racing).

The smaller displacement turbo engine would have better thermal efficiency mostly due to its higher cycle pressures and reduced pumping losses. Having a fewer number of larger displaced volume cylinders also is helpful because their lower surface-area-to-volume ratio reduces heat transfer losses. A lower operating speed also reduces friction losses, since these losses tend to increase exponentially with speed.

I4 engine configurations don't lend themselves well with a mid-mounted stressed engine chassis design. If mounted upright, they have a relatively high CG, a narrow structural cross section, and asymmetry in their intake/exhaust systems. But they can be made to work, as history shows.

riff_raff

+1

All valid points. And you didn't even mention direct injection, variable valve times and lift and throttle less management.

[xpensive]

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.
....

No, no, no, you still don't get it, if you wish to impersonate an engineer WB, you have to try to learn from those who are.
See, this is what I do for a living, drafting calculations leads for my confreres to follow, if I would mix percentages, horsepower and GJ the way you do, nobody in my office would have a clue as to what I was getting at. Stuff like the following is just confusing to an engineer, when what you really meant was percentage of time;

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

I was only trying to be helpful above, all in order to show you the correct way of presenting what you tried to convey,
even if I think your starting values and assumptions are complete horseshit.

[WhiteBlue]

Thanks WB

AFAIK you will get best power at the stoichiometric ratio, leaner then this should not lead to more power - IMHO.

I do understand, that this is/was not attainable with port injection, therefor a slightly richer mixture is needed.

Is it fair to say, that stoichiometric will be the leanest possible mixture for max. power, so the most efficient setting for max. power? Therefor the full saving potential is limited at one point (for max. power).

I was under the impression, that the fuel saving potential of a GDI engine is higher at part load / throttle? Is that correct in your opinion?

Whould we/you expect to see other limits, like max. rpm and/or a max boost limit for the 2013 engines?

At lower revs (1000-4000) you can stratify and use highly over stoichiometric mix. On full song of approximately 10,000 or 11,000 rpm the injection speed is just good enough for one injection event which will give you slightly over stoichiometric mix. I would have to look in a book again to tell specific numbers.

Obviously the saving potential is greatest at low revs like 3000. That rev level would be usable with turbo engines but not very likely in an F1 power profile. This is why stratifying is unlikely in F1.

The efficiency over revs is also influenced by the speed of the injectors. They can give you 0.2 milliseconds injection time but not much faster with current technology. This translates to the rev limit of appr. 8,000 at for a regular injection window. Going higher with revs forces you to inject earlier in the compression stroke than optimal. It means you have to go richer than optimum because your spray cone has hit the piston and you need a richer mixture to reach ignition at the spark plug. The expert proposal puts the new engines at 11,000 rpm. I reckon that you would still be leaner than with port injection between 8,000 and 11,000 rpm.

Legal boost limit is planned at 3 bar according to reports.

[WhiteBlue]

If I would mix percentages, horsepower and GJ the way you do, nobody in my office would have a clue as to what I was getting at. Stuff like the following is just confusing to an engineer, when what you really meant was percentage of time;

I was only trying to be helpful above, all in order to show you the correct way of presenting what you tried to convey,
even if I think your starting values and assumptions are complete horseshit.

Stop nitpicking and being a nuisance xpensive! I posted the improved format on the same page. viewtopic.php?p=197981#p197981
You understood long ago what I have been figuring.

If you think my starting values are horseshit provide better values and I will review them and consider.

[riff_raff]

- 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.

xpensive,

Normally, for such a calculation, you would use a root-mean-cubed approximation or Miner's rule. Excuse my math, but I believe the RMC result for the profile given is about 486kW for the duration.

And yes, full power is not the same as full (WOT) throttle. SFC varies widely with speed and load. So estimating race fuel consumption rates on these values would not likely be accurate.

riff_raff

[WhiteBlue]

I believe the RMC result for the profile given is about 486kW for the duration.
riff_raff

486 kW in your evaluation instead of 420 kW in my calculation pushes the average power to 87% of the max power instead of 75% that I get. It would indicate even higher efficiency of 33.8% beyond the 29.3% that I get. If we follow your proposal the usage profile must be too high. So what do you propose for the power utilization profile?

[riff_raff]

WB,

I've seen published throttle position graphs for F1 engines averaging around 85% WOT for a given lap. But with current drive-by-wire systems, I'd guess that there's no way to truly know. The drivers now simply keep the gas pedal floored at all times, and let the ECU do the thinking for them.

As for a BTE of 33.8% for a modern F1 engine, that seems totally reasonable. Consider that modern commercial diesel truck engines achieve BTE's of over 45%. An F1 engine is designed to operate over a very narrow range of conditions, so getting a high BTE rate is probably not so difficult.

[xpensive]

WB,

I've seen published throttle position graphs for F1 engines averaging around 85% WOT for a given lap. But with current drive-by-wire systems, I'd guess that there's no way to truly know. The drivers now simply keep the gas pedal floored at all times, and let the ECU do the thinking for them.

As for a BTE of 33.8% for a modern F1 engine, that seems totally reasonable. Consider that modern commercial diesel truck engines achieve BTE's of over 45%. An F1 engine is designed to operate over a very narrow range of conditions, so getting a high BTE rate is probably not so difficult.

A mechanical efficiency, from fuel to crank, of as much as 34% would mean that 48cc/sec is enough for 558 kW (760 Hp),
why my suggested 50 cc/sec fuelflow restriction was perhaps not totally of the mark?

[strad]

747 said:

Is it fair to say, that stoichiometric will be the leanest possible mixture for max. power

YES,,,
The direct injection will give (in theory) a more complete mix.that is..less fuel separating out..but again that will be influenced by the piston tops shape...flame propagation and all that..things get involved..oil getting past the rings polluting the mixture...God help us if we force the engine to breathe it's own farts with the EGR that somebody suggested...hell if I know why..

[WhiteBlue]

As for a BTE of 33.8% for a modern F1 engine, that seems totally reasonable.

A mechanical efficiency, from fuel to crank, of as much as 34% would mean that 48cc/sec is enough for 558 kW (760 Hp),
why my suggested 50 cc/sec fuelflow restriction was perhaps not totally of the mark?

I suggest we consider:

viewtopic.php?p=120954#p120954

Both riff_raff and you are not consistent to your previously published opinions. riff_raff thought the BTE was 29.6% a year ago which did not include the internal losses of the engine for friction and ancillaries. You are now considering a BTE which is 4.2% higher for the same engine. I find that hard to believe.

xpensive - after some research - proposed a 10% figure for the friction which would put us at 26.6% total efficiency. This time around he seems to forget that 10% friction figure and is prepared to use the BTE in place of a total efficiency.

When we did the research for KERS we found that the F1 lap is 15% on the brakes where the engine produces only parasitical power which isn't going into our average power. If we set average engine power to 85% we implicitly assume that the engine runs on full maximum power all the time when the driver does not brake. This is not reasonable. I think that my 75% average engine power is much closer to the truth and it matches much better what the 2009 thread found on F1 engine efficiency. So right now I'm not inclined to follow the 2010 opinion.

Any comments?

[xpensive]

Thank you for reminding me of my technical genius of a year ago WB, I've had Alzheimer for as long as I can remember,
but my estimated total efficiency of 26.0% stands of course, good research btw.

Now, a 26.0% total efficiency, from fuel-energy to clutch, with 150 kg of gasoline (46.4 MJ/kg) would result in a total mechanical energy of 1810 MJ delivered. Over 4800 sec (80 min), means an average clutch-power of 377 kW (513 Hp),
in turn representing 68.4% of full power, 750 Hp, which sounds a little more reasonable.

Moreover, 50 cc/second at 26.0% total efficiency would result in a clutch-power of 445 kW (605 Hp).

Some xtra thinking: If you bother to scroll back a few pages on this thread you will find an interesting estimation I did on powerloss from shear of the oil-film on a 90 mm dia piston, just a ball-park number but anyway.