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Old 20 Jul 2010, 03:04 (Ref:2729432)   #126
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Originally Posted by hcl123 View Post
the problem is that sub-conscientious everybody is waiting when the rules is so damn bent in favor of petrol that diesel will lose... big time... until now that bet has been on the losing side and everybody is sored and bitter... but AOC doesn't want to punish diesels with 200kg more and air restrictors so tight that would not allow a fly to pass trough, because that would make it so much balantely obvious... that even a die hard petrol head would notice...

The bitterness is that no one likes to bet on the losing side... but the obvious statement is that petrol engines are obsolete, the evidence is there, no matter how many fouls the good marketing of noise=power is able to deceive.
dude,


the only reason diesel is ahead is because the aco is favoriting it because of audi and peugeut marketing!!!!!!!!!!!!

a 5.5l diesel in audi and peugeut makes ~700hp that volume petrol engine with a twin turbo would make 1000hp easily with the same restrictors. so would you be so kind as to eplain how the diesel is better!

when you are compering a 4l N/A petrol to a 5.5l Twin Turbo, with larger restrictors off caurse the diesel will win,
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Old 20 Jul 2010, 03:17 (Ref:2729434)   #127
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Max power is illusory Power = troque(force) x speed of the engine. Power "on the ground" by every unit of time in the average of the length to be measured is the key. An engine to achive 10K RPM has to pass from 3/4K RPM all up to 10K RPM... by the time those obsolete petrol engines achieve its max power superior to diesels they have already lost half mulsane straight, because their torque is so much inferior!...
ahhhhm, you forgot about a little thing called a gearbox or final drive, and an engine tat revs up to 8000 rpm will have twice the reduction ratio of an engine that has 4000 rpm rev limit. giving the faster engine twice the torque at the wheels at the same speed as the slower reving engine.

as for the diesel being a better fuel chemicly, from your statment above you proved your self wrong. because that small f1 engine with 1500hp, would leave the diesel prototyes so far behind that it could go into a pitt refuel, change the tyres, and the driver and let him have a cup off coffie and still lead the race, at le mans that is, do you have any idea how much of an advantige 1500hp woulg give anyone at le mans, that would be like 10-15s a lap
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Old 20 Jul 2010, 09:13 (Ref:2729515)   #128
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Originally Posted by hcl123 View Post
i had a VW Golf II 1.9TDI rated 115HP and with a change of turbo (NO NOT that much turbo pressure) and control box tweaks and an adapted Passat gear box transmission( more robust).. and i had a 270HP motor at the dynamometer...
I don't know where you live, but VW never produced a Golf II with a 1.9 TDI engine. The GTD had a 1.6 turbo diesel engine with 70-80 hp.
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Originally Posted by hcl123 View Post
Petrol doesn't allow high rates of compression due to physical and chemical proprieties of the substance... and because of that, including those physical and chemical proprieties, is a "slow burner" compared with Diesel that literally explodes inside the cylinders under high compression. Experimental engines have achieved rates of 40:1 in volume compression
It might surprise you but the Peugeot 908 HDI engine has a compression ratio of only 14:1 (see here). That is not a lot more than modern direct injected petrol engines. For instance, the Ferrari 458 has a CR of 12.5:1.
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Originally Posted by hcl123 View Post
Max power is illusory Power = troque(force) x speed of the engine. Power "on the ground" by every unit of time in the average of the length to be measured is the key. An engine to achive 10K RPM has to pass from 3/4K RPM all up to 10K RPM... by the time those obsolete petrol engines achieve its max power superior to diesels they have already lost half mulsane straight, because their torque is so much inferior!...
Clearly you did not read the link I posted earlier in this thread: http://www.physicsforums.com/showthr...53#post1231053 Peak power and a wide power band are important for acceleration, peak torque isn't.

Because you have been a Golf owner, perhaps the previous Golf GT is a good example. VW made the car with a diesel and a petrol engine:
  • petrol: 1.4 TSI (supercharger + turbo), 125 kW @ 6000 rpm, 240 Nm @ 1750 rpm, 1268 kg
  • diesel: 2.0 TDI, 125 kW @ 4200 rpm, 350 Nm @ 1750 rpm, 1303 kg

Guess which car is faster. These are the performance numbers for the DSG gearbox:
  • petrol: 0-100 km/h in 7.7 sec, top 218 km/h
  • diesel: 0-100 km/h in 8.2 sec, top 218 km/h
Both cars have the same top speed because they have the same power. The petrol car accelerates faster because of its lower weight. The higher torque of the diesel can not compensate for this weight disadvantage.

Finally, the fuel consumption numbers, again for DSG gearbox:
  • petrol: 7.3 liter/100 km
  • diesel: 6.4 liter/100 km
Yes, the diesel car has better fuel economy. However, if you take into account that diesel has a 10% higher energy density (see here), the difference is not so big.
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Originally Posted by hcl123 View Post
... is it that diesels CAN rev high to ??... not has much as petrols because its explosive nature of combustion make them harder to achieve the proper mechanical balance of its moving parts ?? ... yet achieve close to 20% superior fuel consumption efficiency with an equal or superior overall efficiency ??

So don't get surprised if those 3.7L diesels achieve 8K RPM and the times per lap in 2011 are very close to the times of 2010...
A diesel engine revving to 8000 rpm How high must the cetane number be to achieve such high rpm? Race diesel engines don't produce power by revving, but by injecting more fuel (= more torque).
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Old 20 Jul 2010, 13:39 (Ref:2729611)   #129
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I don't know where to begin...

Diesel engines are more efficient than petrol engines due to the fact that they can run higher compression ratios than petrol engines due to the onset of knock. Using idealised Otto and Diesel cycles at the same compression ratio, a petrol engine is more efficient

Diesel doesn not "literally explode" inside the cylinder, it slow burns, hence the lower engine speeds. By contrast, petrol combustion is always a very short process even when ignited via compression rather than spark ignition. This is due to the volatility of petrol and is also the reason for the compression ratio limit.

compression ignition petrol engines can run to high compression ratios, the problem being that as the combustion is very short, the intake conditions need to be controlled precisely to avoid detonation or misfire.

The noise of petrol engined LMP cars has nothing to do with burning petrol in the exhaust (how could this happen anyway given petrol's short combustion time?) but is due to the items placed in the exhaust. The diesel LMPs are turbocharged, which has an effect in quietening the engine noise and the particulate filters further quieten the sound. It's worth noting that the Peugeot is now almost as loud as the turbocharged petrol LMPs after allegedly removing their FAP filter.

The diesels dominate LMP racing for 3 reasons: 1) they were given a massive advantage in the original regulations, 2) as diesel is a new technology to endurance racing, the development scope is greater, 3) factory teams always beat privateers due to their larger budgets allowing more development. Case in point, in 2009, the top petrol non-factory car was the ORECA, which completed 12 fewer laps than the winning diesel. In 2003 and 2004 against factory Audi supported opposition, the top privateers were 17 and 18 laps down respectively.
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Old 21 Jul 2010, 17:14 (Ref:2730244)   #130
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All of this effeciency is boring the **** out of me.
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Old 21 Jul 2010, 20:41 (Ref:2730338)   #131
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porman should be qualifying in the top 5 on the gridporman should be qualifying in the top 5 on the gridporman should be qualifying in the top 5 on the grid
You got that right!
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Old 21 Jul 2010, 23:18 (Ref:2730389)   #132
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Originally Posted by arakis View Post
ahhhhm, you forgot about a little thing called a gearbox or final drive, and an engine tat revs up to 8000 rpm will have twice the reduction ratio of an engine that has 4000 rpm rev limit. giving the faster engine twice the torque at the wheels at the same speed as the slower reving engine.
maybe... but why is that ?

Isn't it that in order to achieve higher RPM, the motor has to be more balanced and to better achieve that a less energetic power stroke is welcome ?. Transmission have a "reduction ration" and a "multiplier ratio"... reduction is when the transmission output shaft has a lower rev ration compared with the "motor" input shaft. Its only there to REDUCE THE LOAD on the engine and permit a faster transition to more RPM and power... "multiplier ratio" is when the output ratio has more revs compared with its input... in order to sustain higher orders of "SPEED"...

So its logic that higher RPM, 8K RPM or more, need higher reduction ratios to make easier and faster to achieve those levels, than an engine that has half the RPM for the same power envelope...

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as for the diesel being a better fuel chemicly, from your statment above you proved your self wrong. because that small f1 engine with 1500hp, would leave the diesel prototyes so far behind that it could go into a pitt refuel, change the tyres, and the driver and let him have a cup off coffie and still lead the race, at le mans that is, do you have any idea how much of an advantige 1500hp woulg give anyone at le mans, that would be like 10-15s a lap


sorry i can't resist... why wont they invest in them then ???

Perhaps because that was when the F1 cars were below 500Kg... you have a hard time getting this... those engines wouldn't last a 3h race, and would consume a full tank every 7 laps in Le mans... so they would have to be considerably faster than the best diesels now to have any chance. But now if you put almost the double of weight and by doing so, almost the double load on the car engine, i'm very doubtful that those engines would be able to attain those levels of power... not even close by a long shot!

actually diesel is not better chemically than gasoline, race grade gasoline for that matter, though even ACO claims that diesel has more 10% BTU per volume of fuel... the reason for the 9 liter less tank rule. IMHO it misses rigorous testing but the BTU is identical, though i can accept a tiny little advantage on diesel.

Where diesel is far superior for a ICE is in its physical proprieties permitting much higher order of compression without self detonate... "knocking"... and so much better thermodynamic efficiency.
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Old 21 Jul 2010, 23:58 (Ref:2730398)   #133
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Originally Posted by arakis View Post
dude,


the only reason diesel is ahead is because the aco is favoriting it because of audi and peugeut marketing!!!!!!!!!!!!

a 5.5l diesel in audi and peugeut makes ~700hp that volume petrol engine with a twin turbo would make 1000hp easily with the same restrictors. so would you be so kind as to eplain how the diesel is better!
sorry to reply out of order,but... ACO thinks so... 9 liter less for diesels tanks is justified by saying that diesel has 10% higher BTU for the same fuel volume.

which is a lie of course... unless diesels where running JP8 kind of aircraft fuel which is very doubtful for a lot of reasons...

Now that tells a lot of who is favoring who, dosen't it ????

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Originally Posted by arakis View Post
when you are compering a 4l N/A petrol to a 5.5l Twin Turbo, with larger restrictors off caurse the diesel will win,
NO, diesels have not won, they have delivered a severe BEATING...

But in here i'm on your side believe me... there shouldn't be any discrimination neither in weight or in engine volume and restrictor sizes accounting only for the fuel type. Only then we would have a fair match = oranges to oranges = .Those diesels allowed to enter as they were, were a busted campaign to show the superiority of petrol that went the other side... to counteract the flight of general population to day by day diesel cars by economical issues... otherwise they would never had allowed them.

And IMHO diesel now don't need any favor now. Petrol had a century of development in race conditions, diesel only 4 years... but its not to hard to see that the RPM potential of diesel will go high now that some fundamental issues of how they operate in race conditions are understood.

Now the petrol head campaign, on behalf of scum "oil" lords and there big oil companies is in the sense of abolishing diesels... because if common people start to see the picture and wiseup, most of the cars sold would be diesels... even road "sport" super cars... and that could mean 20-30% less in their(oil companies) business volume ( an enormous amount of money!)...

But fairness it not their motto... they would prefer to put petrol engines to shame to find that way a justification to abolish diesel than play really fair... and pretend by un-fairing every other rule that a large volume diesel is inferior to a smaller volume petrol engine, if possible... that is how scum the scum we are dealing with !...

So never expect that no matter what type of fuel... diesel, petrol or alcohol... that ACO rules that engines main characteristics will be the same... scum "oil" lords wont allow them, only business nothing personal!... "we" people must not have tools to make an educated choice...
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Old 22 Jul 2010, 01:20 (Ref:2730410)   #134
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If you are hear to talk about diesel petrol equivalency this is not the thread for you. This is the AUDI R18 Thread
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Old 22 Jul 2010, 01:51 (Ref:2730420)   #135
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Originally Posted by gwyllion View Post
I don't know where you live, but VW never produced a Golf II with a 1.9 TDI engine. The GTD had a 1.6 turbo diesel engine with 70-80 hp.
It might surprise you but the Peugeot 908 HDI engine has a compression ratio of only 14:1 (see here). That is not a lot more than modern direct injected petrol engines. For instance, the Ferrari 458 has a CR of 12.5:1.
Sorry my mistake... was Golf III... a picture worths a thousand words( though that was not my car)

http://www.metacafe.com/watch/256724..._acceleration/

81Kw ie ~ 110 HP

" have it on good authority that the Peugeot engine has 84x82.5mm bore/stroke, 146mm con rod length, 14:1 CR "

the rumor might be close to reality alright, but there was another rumor that stated that Audi had a 17:1 CR... now if you count the additional pressure of the turbochargers, that might give with 2 bar 28:1 and 34:1 respectively...

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Originally Posted by gwyllion View Post
Clearly you did not read the link I posted earlier in this thread: http://www.physicsforums.com/showthr...53#post1231053 Peak power and a wide power band are important for acceleration, peak torque isn't.
" Regardless, given the torque function, there is an associated power . So if the torque is known at all speeds, the power is known at all speeds (and vice versa). You can't have one without the other."

Where you get confused is this...

" The peak power is very important for reasons I'll get to later, but the peak torque is essentially useless all by itself "

which is very misleading; ... because it discards the action of the loads on the engine in any time. If the engine has no load, or negligenciable load, then torque matters nothing, give it a constant=1 and power is a direct function of the RPM of the engine... which is theoretically correct but describes nothing useful.

If not a contradiction; .... because if You can't have one without the other. then how came one is all things and the other nothing.

Hard time getting this : POWER = torque x engine speed, you cannot have 10 Nm and 1000HP unless your engine revs at 200.000 RPM( or much more)... but on the other side you can have 20000HP in only 300 RPM... yes 300 RPM !... in those 5 store high, big freight ships, diesel engines... those engines can rarely be said that accelerate, yet imagine their peak power ???

Simply you can't have power without torque... the better your initial specific torque, the better anything "power" related... only that max power attainable, as a number trowed on the table, is completely irrelevant when you pass a certain threshold. OTOH torque is always more relevant because the faster the car goes, the more the aerodynamic LOAD, and so the better the torque the faster it gets to those higher power levels and higher speeds.

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Originally Posted by gwyllion View Post
Because you have been a Golf owner, perhaps the previous Golf GT is a good example. VW made the car with a diesel and a petrol engine:
  • petrol: 1.4 TSI (supercharger + turbo), 125 kW @ 6000 rpm, 240 Nm @ 1750 rpm, 1268 kg
  • diesel: 2.0 TDI, 125 kW @ 4200 rpm, 350 Nm @ 1750 rpm, 1303 kg

Guess which car is faster. These are the performance numbers for the DSG gearbox:
  • petrol: 0-100 km/h in 7.7 sec, top 218 km/h
  • diesel: 0-100 km/h in 8.2 sec, top 218 km/h
Both cars have the same top speed because they have the same power. The petrol car accelerates faster because of its lower weight. The higher torque of the diesel can not compensate for this weight disadvantage.

Finally, the fuel consumption numbers, again for DSG gearbox:
  • petrol: 7.3 liter/100 km
  • diesel: 6.4 liter/100 km
Do you sell cars ????... it seems you do!... Is like OC in computer chips. From the factory those diesels are "cut", by an order of things, including the marketing notion that they are economic and don't have to be fast.

But sorry to disappoint you, but i would prefer the TDI anytime, the money i save in fuel, will be enough, in 4 year after the guaranties expire, to transform it into a 300 HP "sport" car... the same cannot be done with the TSI, without marrying the daughter of a gas station company owner, to conclusion... and spend more money in the transformation, to begin with.

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Originally Posted by gwyllion View Post
Yes, the diesel car has better fuel economy. However, if you take into account that diesel has a 10% higher energy density (see here), the difference is not so big.
Yes your link is correct more or less... if we don't account for premium fuels. Race fuels don't have anything to do to those numbers... and i'm pretty suspicious that diesels don't have an advantage here... or very little if they do.

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Originally Posted by gwyllion View Post
A diesel engine revving to 8000 rpm How high must the cetane number be to achieve such high rpm? Race diesel engines don't produce power by revving, but by injecting more fuel (= more torque).
Again: POWER = Torque x Speed of engine(RPM)

Higher RPM is NOT ONLY achieved basically by "brute force"= more fuel, stressing more the engine, but much better by reducing in-balances in all moving parts and by reducing "parasitic loads"... your engine takes a lot of energy only to move itself = the bigger the engine the worst this might get=... petrol engines are better in here, diesel and others will catch up... you are laughing of yourself... Peugeot and Audi have started a little above 5K RPM, but already passed the 6K RPM in 2009 and 2010... and could had been more( perhaps above 7K RPM) if they weren't forced to restrict the engine more and more every year.

Back to R18... i very much doubt, by these long dissertations, that Audi will go for Petrol with it. The passage to a V10, giving Peugeot the upper hand in torque, 5 power strokes per revolution against 6 power strokes for peugeot, should had been balanced by a better fuel consumption which was hardly noticed and a higher RPM ( a lighter engine )... a tough bet, remaining in conclusion to learn HOW and WAHT downsizing the number of cylinders will give you.

So after this lesson learned is hard to believe they will discard it... and if it is a "winner" factory that goes electric-petrol hybrid is Peugeot... but which i doubt also, because they must know how electric motors are not good yet to balanced the losses by going petrol... and batteries still weight a "ton"...

Last edited by hcl123; 22 Jul 2010 at 02:03. Reason: R 18
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Old 22 Jul 2010, 05:01 (Ref:2730457)   #136
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I don't know where to begin...

Diesel doesn not "literally explode" inside the cylinder, it slow burns, hence the lower engine speeds. By contrast, petrol combustion is always a very short process even when ignited via compression rather than spark ignition. This is due to the volatility of petrol and is also the reason for the compression ratio limit.
Yes you are right, explode is a strong word... but there are 2 forms for diesels

Stratified charge compression ignition... occurs at the boundaries of your fuel air charge and has a propagating front, and in here depending on the characteristic of the initial flame front your diesel can be quite a slow burner compared with gasoline. Same of those old engines even had a Glow plug always on to facilitate this...

Homogeneous charge compression ignition (HCCI)... in here there is no flame front... sorry again, i know its a strong word, kind of explodes, that is, the air fuel charge simply ignites everywhere at the same time...

http://en.wikipedia.org/wiki/Homogen...ssion_ignition

this effect is hard to achieve and i don't know if that is the case of Audi or Peugeot diesels, but i'm not surprised if they managed to get that effect to some degree.

So diesel by being, lets say, more energetic having more time to burn than gasoline in a specific volume of fuel, but by having the charge mixture much more compacted and pressured and so much more mixed, if they achieve a good effect of HCCI, then i can bet you that the same volume of fuel burns faster in diesel mode than in a spark petrol mode : practically there isn't a flame front in HCCI modes

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compression ignition petrol engines can run to high compression ratios, the problem being that as the combustion is very short, the intake conditions need to be controlled precisely to avoid detonation or misfire.
Funny thing is that in experiments is much easier to achieve a HCCI mode in petrol than in diesel, specially because of the higher volatility of petrol that permits a more rapid homogeneous mixture of the air fuel charge... without the enormous pressures of fuel lines that common-rail diesels have... the problem is the temperature point of self ignition of petrol... the higher the CR the higher the specific temperature... so at top dead center TDC, the compression ratio must be substantially lower than what a diesel can achieve because petrol self ignites at much lower temperatures than diesel... and this even in a HCCI petrol engine.

In a way it has nothing to do with the pressure level... if it were possible to cool the air-petrol mixture while its being compressed, it could attain as higher compression ratios as diesel... with comparable fuel consumption and torque.

As that is not yet possible, so petrol engines must always have a "flame front", the reason for the spark plug being there... and race engines with always very rich fuel mixtures, are "slow burners" compared with diesels that can achieve an ignition comparable with a HCCI effect... and simply at 8 to 10K RPM there is not enough time to burn all that very rich fuel mixture inside the cylinder...

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Originally Posted by Joe Taylor View Post
The noise of petrol engined LMP cars has nothing to do with burning petrol in the exhaust (how could this happen anyway given petrol's short combustion time?) but is due to the items placed in the exhaust. The diesel LMPs are turbocharged, which has an effect in quietening the engine noise and the particulate filters further quieten the sound. It's worth noting that the Peugeot is now almost as loud as the turbocharged petrol LMPs after allegedly removing their FAP filter.
What the hell are those flames that came out of petrol engine cars, particularly well visible at night, and quite often, specially when the car brakes, and after YEARS of all constructors having electronic injection systems that cut fuel upon braking... does your car not do that ???... are those special items placed in the exhaust, a flammable substance tank, an artistic exuberance for the delight of all of us petrol heads ???

I bet its the contrary... its by being turbocharged, and reasonably well... that diesel engines are more loud than they could be... pressure along the exhaust is higher, but particulate filters, like sniper rifle silencers, has had quite a job of making them almost inaudibles... and perhaps is what happened with peugeot , no filter/silencer and the sound got much higher... but i never saw a flame came out of a diesel exhaust pipe...


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Originally Posted by Joe Taylor View Post
The diesels dominate LMP racing for 3 reasons: 1) they were given a massive advantage in the original regulations, 2) as diesel is a new technology to endurance racing, the development scope is greater, 3) factory teams always beat privateers due to their larger budgets allowing more development. Case in point, in 2009, the top petrol non-factory car was the ORECA, which completed 12 fewer laps than the winning diesel. In 2003 and 2004 against factory Audi supported opposition, the top privateers were 17 and 18 laps down respectively.
They where given a considerable start advantage in terms of max volume of displacement with turbo-charging addition. The rest they have been getting harsher and harsher penalties...

Reverse that... make everything equal....

I don't call it dominate... i call it crushing... there was a "oil-petrol" marketing campaign that went bad, happens often in all areas of activity... and in some way i advocate that the current situation is not funny for various parts involved... but the solution is not discriminate any kind of fuel tech by the way of very stupid distorted rules. Today constructors make multi-fuel engines more and more, and them tune them to a particular application...

Let the rules for a ICE engine be EQUAL, and let the teams choose the fuel type without mioptic forced downsizing, cripitic stupid restritores regulation, and others.

A Lemans car, prototypes included, must have place for 2 persons, and all cars must have road homologation and arrive at the "circuits" with those 2 persons ( one of the seats withdrawn for the race), from public roads by their own means, and so civil law must apply... petrol ( or diesel) noise must be only to a certain level permitted by law, filter/catalytic converters/ buffer silencers will be mandatories then, pollution emission regulations will also be mandatory. Then the constructors must make the best of an engine in any format( Otto, Wankel, rotary) up to a max of volume displacement no matter the fuel type... and restrictiors and weight EQUAL to all... according to the respective category.

And Kinetic recovery systems allowed in any form or tech... meaning only that the initial electric power density and or initial hydraulic tank pressure, should be exactly the same also.

Then finding out about a new prototipe like R18 will be much more fun... because they could decide to make something really exotic... and as hard this might sound, like with very small companies that are launching those techs in everyday cars, privateers could have more "guts" and launch simple and cheaper but clever exotic techs( by today standards) that might get them some luck.
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Old 22 Jul 2010, 05:05 (Ref:2730459)   #137
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If you are hear to talk about diesel petrol equivalency this is not the thread for you. This is the AUDI R18 Thread
Yes, this back and forth has drifted a long ways away from the topic of the R18. A new thread should be started, to drag this through the mud some more, rather than continue it in this one!!!






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Old 22 Jul 2010, 07:47 (Ref:2730490)   #138
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Ok here goes my stance for the R18

Spider open concept

4 wheel drive with 4 small electric motor/generators in each wheel hub, perhaps in the range of 20 HP each, not more...

A Litium ion battery pack that will allow to store the max amount of energy, in electric form as permitted by the rules

Main engine a 3.7 Liter V8 biturbo diesel with double head camshaft and 4 valves cylinder, with a HCCI mode of operation integrated with the electric mode of operation, for low to medium RPMs, permitting a "soberb" fuel economy in those modes, to overcame the restriction of a much smaller fuel tank...

Improved engine balance in its high RPM diesel mode, achieving close to 8 K RPM at max. Max power >=650HP, max torque ~900Nm

It would be a clever trick!... the rules have holes and blanks... but 2 of the electric hub motors can be made to run constantly from cruising to acceleration, perhaps the front wheel motors with power generated and delivered directly from the other 2 wheel hub motors acting as generators on the rear axle, by-passing that way the batteries.

Upon braking all wheel hub motor/generators will generate electricity to be store in the batteries.

Upon medium to heavy acceleration all motor/generators will motor the wheels for an additional max power of 80HP and an additional max torque of ~180Nm.

hints: VW had a concept with wheel hub motor/generators... 4 wheel drive is almost a trademark of Audi, and would permit to take better advantage of the additional torque of the electric motors
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Old 22 Jul 2010, 09:50 (Ref:2730531)   #139
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sorry to reply out of order,but... ACO thinks so... 9 liter less for diesels tanks is justified by saying that diesel has 10% higher BTU for the same fuel volume.
Just compare the density of the 2 racing fuels provided by Shell: 834 kg/m3 for diesel (see here) vs 754 kg/m3 for petrol (see here).That is a difference of 10%. Could this be a coincidence?
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which is a lie of course... unless diesels where running JP8 kind of aircraft fuel which is very doubtful for a lot of reasons...
As far as I can tell the only advantage of JP-8 fuel is that it works better in low temperature conditions (does not gel). It has a lower cetane number than regular diesel and hence a longer ignition delay. In fact, the Shell race diesel is a blend of petroleum based diesel and synthetic GTL in order to have a higher cetane number (59.4) than regular diesel.
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Ok here goes my stance for the R18

Spider open concept
Audi has found out from racing the Peugeot 908 that closed car have an aero advantage. Next year, with the reduced power this will be even more important. See http://www.autosport.com/news/report.php/id/84533
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4 wheel drive with 4 small electric motor/generators in each wheel hub, perhaps in the range of 20 HP each, not more...
I think a setup like the hybrid Toyota Supra is more sensible: 2 small in-wheel electric motors at the front and at the rear 1 bigger electric motor integrated in the gearbox (like Zytek solution/F1 KERS). In-wheel motors at the rear will be messy because the driveshafts are also going to the wheels.
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A Litium ion battery pack that will allow to store the max amount of energy, in electric form as permitted by the rules.
It is not clear whether a chemical battery is the best solution. Toyota used supercapacitors and Porsche a flywheel battery. You need to do a lot of charge/discharge cycles during 24 hours.
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Main engine a 3.7 Liter V8 biturbo diesel with double head camshaft and 4 valves cylinder
Rumors suggest Audi will go for a V6 configuration. See http://www.racecar-engineering.com/n...prototype.html
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It would be a clever trick!... the rules have holes and blanks... but 2 of the electric hub motors can be made to run constantly from cruising to acceleration, perhaps the front wheel motors with power generated and delivered directly from the other 2 wheel hub motors acting as generators on the rear axle, by-passing that way the batteries.
Why would you want to drive the front wheels "constantly"? Isn't it better to do this on demand i.e. when the rear wheels lose grip?
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Old 22 Jul 2010, 14:16 (Ref:2730649)   #140
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4 wheel drive
Sorry but, correct me if I am wrong, don't the rules say that only rear wheel drive is permitted.

Plus, please stop with the huge, long winded replies.
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Old 22 Jul 2010, 14:35 (Ref:2730655)   #141
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The hybrid rules have been changed for next year:
Quote:
Recovery and release systems of energy at each axle (front or rear) to be a free choice.
http://www.lemans.org/en/news/2011-L...TIONS_628.html
Sadly, this is a terrible translation because the French version says:
Quote:
Récupération et restitution de l’énergie sur deux roues, choix de l’essieu (AV ou AR) libre.
http://www.lemans.org/fr/actualites/...-2011_627.html

So the hybrid system can work on the front axle or the rear wheels, but not on all 4 wheels. This allows for a form of 4 wheel drive: front wheels by electric engines and rear wheels by combustion engine.
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Old 22 Jul 2010, 18:43 (Ref:2730765)   #142
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Sorry but, correct me if I am wrong, don't the rules say that only rear wheel drive is permitted.

Plus, please stop with the huge, long winded replies.
Yes, please.
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Old 22 Jul 2010, 18:46 (Ref:2730767)   #143
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The hybrid rules have been changed for next year:
http://www.lemans.org/en/news/2011-L...TIONS_628.html
Sadly, this is a terrible translation because the French version says:
http://www.lemans.org/fr/actualites/...-2011_627.html

So the hybrid system can work on the front axle or the rear wheels, but not on all 4 wheels. This allows for a form of 4 wheel drive: front wheels by electric engines and rear wheels by combustion engine.
"Recovery and release systems of energy at each axle (front or rear) to be a free choice."

No, it means that they can be different at each axle... you can have a Flywheel KERS at the front axle, while electric generators at the rear axle.. that is what i read. And account by that reading i cannot understand how 4WD can be excluded.

" Maximum quantity of energy released between two braking phases to be 500 kJ. "

Means that KERS or electric battery and or a hydraulic pressure tank, in the total they cannot exceed that amount of energy. If energy storage is that amount, additional energy release cannot exceed that point... yet it doesn't account for continuous operation from generation to motor, because if generation accounts for a certain loss, motoring upon that generation can never exceed the loss... if 2th law of thermodynamics is to be correct... otherwise ACO doesn't guide itself by the accepted physical laws.

Funny thing ( those ACO guys are in disarray)
" Other means of energy recovery will be allowed: exhaust, engine heat, dampers, "etc." provided that they respect the specifications drawn up by the ACO (safety considerations, banning of driver aids, evaluation of the increases provided by the systems, the reduction in fuel consumption and CO2 emissions)."

Would make it possible to include the most efficient method of all, hydraulic recovery... transporting to day by day cars will open the way for Hydromechanical IVTs... providing a significative boost in fuel economy and efficiency(Honda as such a transmission in commercial motorbykes) ... yet

" Energy recovery systems using brakes must not be active during braking for curves (driver aids banned)."

Excludes the most significative way of hydraulic energy recovery, because a hydraulic pump/motor at pumping upon braking, acts as a very efficient braking auxiliary... or putting it another way, why would anyone brake if not for a curve.. in normal conditions... what are those guys smoking !!!

The same goes for electromagnetic brake/generators !!!...

gee!! ... how could additional braking action, be any different from a bigger and or more efficient traditional braking setup ???... the driver putting his feet on the ground to help braking is also forbidden( can't help himself)!... seems a greased scum is whispering at their ears... else they have coca and whisky parties at those meetings!!!...
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Old 22 Jul 2010, 18:49 (Ref:2730770)   #144
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Récupération et restitution de l’énergie sur deux roues, choix de l’essieu (AV ou AR) libre.
This says with utter clarity that the energy recovery device can only work on one axle, whether it is the front or rear axle is the team's choice. And the ACO policy is that the French-language version of the rules prevails.
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Old 22 Jul 2010, 18:50 (Ref:2730771)   #145
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Old 22 Jul 2010, 19:32 (Ref:2730791)   #146
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This says with utter clarity that the energy recovery device can only work on one axle, whether it is the front or rear axle is the team's choice.
Indeed. Deux roues not quattre
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Old 22 Jul 2010, 19:51 (Ref:2730798)   #147
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Plus, please stop with the huge, long winded replies.

I agree. There have been a few people who have turned up/returned here recently, who seem hell bent on trying to impress the rest of us poor, uneducated souls, with their lengthy, waffling on responses, and I think we all know who they are and their history. We won't think any less of you, if you can keep it more concise.
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Old 22 Jul 2010, 20:13 (Ref:2730812)   #148
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As far as I can tell the only advantage of JP-8 fuel is that it works better in low temperature conditions (does not gel). It has a lower cetane number than regular diesel and hence a longer ignition delay. In fact, the Shell race diesel is a blend of petroleum based diesel and synthetic GTL in order to have a higher cetane number (59.4) than regular diesel.
Yes it was knowned that Audi uses synthetic fuels... my suspicion is what then about petrol ?... some years ago in F1, a lot of teams were complaining that other cars had a noticeably advantage, because of the careful engineered fuels they used, that gave them up to 20% more thermodynamic efficiency

20% is bigger than 10%

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Audi has found out from racing the Peugeot 908 that closed car have an aero advantage. Next year, with the reduced power this will be even more important. See http://www.autosport.com/news/report.php/id/84533
I agree, but with so much aero tunning that R15 received... a continuation is not to be exclude in this first year, because tunning the new engine and all the hybrid setup can be much more important, than a much more time wasting complete clean paper start up for a new car body.

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Originally Posted by gwyllion View Post
I think a setup like the hybrid Toyota Supra is more sensible: 2 small in-wheel electric motors at the front and at the rear 1 bigger electric motor integrated in the gearbox (like Zytek solution/F1 KERS). In-wheel motors at the rear will be messy because the driveshafts are also going to the wheels.
...
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Originally Posted by gwyllion View Post
Why would you want to drive the front wheels "constantly"? Isn't it better to do this on demand i.e. when the rear wheels lose grip?
That is why i replay out of order. A more careful reading of the rules in past reply that seems the only way... to the point of excluding the 2 small in-wheel hub motors... not generators... because if electric generation accounts for a loss, a magnetic braking action, that might be considered driver help...

That accounts also for traction control systems... are they abolished also ?... my idea of 4 in-wheel motor/generators is that they could work as a great traction control system as well as a ABS system, along with motor/generator action, all in the same system, and 4WD will permit better curve handling, acceleration and braking... ok driver help

And what about electronic blocking control of the rear differential that Audi uses ??... is that driver help, if not, what is the difference in effect from a iso-torsen pure mechanical differential, and other possibly all mechanical traction control and ABS system ??

OTOH, a continuous motor generation action will permit to smood the attrition of the tires and suspension upon irregularities of the road, and in some situation, by the law of conservation of momentum, result in a net gain if energy recuperation upon braking would be allowed. Batteries would last longer and be in average more full of energy in all race conditions. ( otherwise -supercapacitors the petrol way)

" Energy recovery systems using brakes must not be active during braking for curves (driver aids banned)."

this must be the joke of the year... next they will withdraw the driving wheel because that is a driver aid!... go for mind control steering systems instead... only misses this one..

No wonder some privateers are **** off ?... this guys make rules out of the toilet can... that can only make costs to skyrocket.

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It is not clear whether a chemical battery is the best solution. Toyota used supercapacitors and Porsche a flywheel battery. You need to do a lot of charge/discharge cycles during 24 hours.
Rumors suggest Audi will go for a V6 configuration. See http://www.racecar-engineering.com/n...prototype.html
it could be, but the total amount of energy to be released, permitted by the rules, cannot account for a greater "torque" boost by electric motors, sustained but for very short periods of time... that is ... if a Petrol-electric is probable they will go for supercapacitors for a more quick release of energy and better instantaneous torque upon heavy acceleration...Diesel-electric would already have that much torque, a more soft release would be more wise, essentially permitting the engine to save fuel, than to accelerate more quickly...
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Old 22 Jul 2010, 20:15 (Ref:2730813)   #149
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This says with utter clarity that the energy recovery device can only work on one axle, whether it is the front or rear axle is the team's choice. And the ACO policy is that the French-language version of the rules prevails.
than the english translation is kind of wrong
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Old 22 Jul 2010, 20:24 (Ref:2730819)   #150
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Rumors suggest Audi will go for a V6 configuration. See http://www.racecar-engineering.com/n...prototype.html
I don't believe those rumors. The true is that Audi got a hell of a luck to win this year in lemans, and 1 -2 -3... 1 in 50 years... they gave Peugeot the upper hand in torque, 6 power strokes per rev of their V12, against 5 power strokes per rev of his V10... and clearly they were not a match to Peugeot.

Hard to believe they risk to make the same mistake again.
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