• Sep 17th 2008 at 8:28AM
  • 52
Click above for a high-res gallery of the Audi R10 at Le Mans

Diesel power has emerged as the dominating fuel in Le Mans series endurance racing, with Audi and Peugeot competing neck-and-neck for top honors. But that's about to change, if the Automobile Club de l'Ouest (ACO) has anything to say about it. ACO, the body that organizes the 24 Hours of Le Mans and the LMS championships in Europe and North America, has announced new rules aimed at reducing the performance of the diesel racers to level the playing field with the gasoline-fueled competitors.

The new regulations would include air restrictors reduced in diameter by 10% and a decrease in allowable turbo boost on the oil-burners. The move is also aimed at impeding laps times in the name of safety, with a 3 minute 30 second La Sarthe lap time as the target, where the Peugeot 908s lapped the circuit in the low 3:08s this year.

Additional rule-book amendments include the banning of tire warmers, a reduction in the permissible size of rear wings and the allowance of only one wheel gun for each pit crew, all in an effort to reduce costs and raise lap times.

[Source: Autosport]



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    • 1 Second Ago
  • 52 Comments
      • 7 Years Ago
      Push push push for advancements and then reject the advancements when they arrive. It seems counter-intuitive and counter-productive. I would have no interest in Le Mans but for the fact that Audi (and Peugeot sort of) are bringing mainstream attention to something so not-previously-sought-after in racing. Diesel has helped Le Mans these last couple years.
      • 7 Years Ago
      Wouldn't eliminating tire warmers create an unsafe environment. Cold racing tires are like steel drums on ice. I understand that the idea is to force the drivers to reduce speeds until their tires warm up but a race car on cold tires sounds like an awfully bad idea.
      • 7 Years Ago
      Why not simply limit the amount of fuel each car is allowed for the race? Different amounts for gas and diesel would keep things fair, and stimulate the development of fuel efficient vehicles for both fuels. A sensible fuel ration would also encourage the teams to self-limit speed and power. The most powerful cars would be the ones with the most efficient engines. The ration could be reduced year on year to encourage progress.
      • 7 Years Ago
      Silly... I always though you'd want to go faster in racing.

      Even NASCAR has more than one wheel gun. WTH kind of rule is that?
        • 7 Years Ago
        The one wheel gun rule will negate any advantage the open top cars have by making the pit stop longer and giving the coupes more time to change drivers before the rest of the service is done.
      • 7 Years Ago
      The should just hold the diesels to the same engine restriction as the gassers. The diesels are 5.5L and the restriction on Gas engines is 4.0L. Then adjust the air restriction to level the playing field.

      I am on the fence about if the fuel tanks or fuel deliver systems should be different since Diesel is more energy dense but also more viscous. I would lean toward same everything and adjust air restiction.
        • 7 Years Ago
        *flavor
        • 7 Years Ago
        Oh yes, because 20% isn't a massive difference in efficiency?!
        I almost thought the FIA was the governing body making this call. The caught me off guard entirely.

        Let's be honest, doesn't this scream, "You are too innovative and the other teams feel bad about losing so much. We're changing the rules (ala FIA) to make it "more exciting" [to make us more money] because less people want to see one team dominate, unless the car is red, and the flaver of the next 2 seasons is Brazilian or Finnish."

        I swear, Silver is the worst color to own a race car in. It will only lead to trouble.
        • 7 Years Ago
        Raz:
        Diesels are not massively more efficient than gas engines in race applications. For that matter on the street either. They get about 40% better mpg on the highway than a gas engine, but the fuel also has 15-18% more energy per gallon. So the real efficiency bump is more like 20%.

        And that's because Diesel can (and does) operate in a lean burn mode, avoiding pumping losses while running at low power output levels (cruising). HCCI gas engines will be able to do this and will close the gap on efficiency (but not mpg since Diesel has more energy per gallon).

        On the track, you don't cruise, you operate at wide-open throttle almost all the time. And neither gas nor Diesels suffer pumping losses at wide-open throttle anyway, so it's a wash.
        • 7 Years Ago
        SLVR6- just... wrong. diesel has more energy density by volume. It's also more dense (by weight) to where they have almost the same energy content by weight. A diesel engine depends on compression ignition, so pre-ignition cannot happen, unless fuel is injected at the wrong time.
        • 7 Years Ago
        Firstly i just wanted to say... these rules are a LOAD of sh*t. And regarding the energy levels, diesel's chemical energy level is higher than gasoline's and (standardized figures, but diesel engines are around 40% efficient while gasoline are around 25% of course the figures are different for every car). I don't see the point of those rules... i mean.. all the teams wanted to introduce the best technology to have the biggest margin of advantage, but then they r saying.. "you guys are too fast for the others, so... too bad, you are slowing down". So, whats the point of racing if some teams and systems are disadvantaged just to make it "look fair". I mean, its reasonable for them to restrict their tanks back in 2006, then they have SO many restrictions with diesel why don't they just ban it while they are at it... Regarding the pit rules... is having one gun and no warming mats really gonna make motorsport a green short? Get real...Soon Le mans will become a running track event for the drivers...
        • 7 Years Ago
        That probably wouldn't be too bad of an idea.

        For all it matters, they could lower the diesels to 3.0L, and let them run as much boost until it gets back up to 500hp.

        Might be even more fuel efficient - hence leading to new innovation.

        In these days, racing needs to focus on innovation for road cars, not just 200mph billboards. Restriction stiffles innovation.

        Limit power, top speed, etc. But give more leeway to the teams on HOW they accomplish that power/speed/etc.
        • 7 Years Ago
        Actually diesel is LESS energy dense than normal gasoline. It is because of that it can be compressed more without pre-ignition.
      • 7 Years Ago
      I think everyone needs to relax and understand what happened. The ACO wanted to let diesels for a variety of reasons and some manufacturers wanted to race diesels.

      So the ACO came up with some rules that gave huge performance advantages to diesels. When the rules came out, lots of people that commented on how much extra power the diesel cars would be making. The ACO justified it by saying this was new technology with heavier/bigger engines, so they needed some advantage to get people to race them. The R10 was overweight when it first came out because of the engine, but now the engines are generating tons of power and the cars are blisteringly fast. Now you have other manufacturers (Honda) and privateers that either do not want to race diesels or do not have the money to develop them, so they want the type of engines to be closer to equal.

      The fact is that the ACO should make the petrol and diesel engine close. If not why even have a petrol engines? The point is not to have a dominant engine, they do same thing with turbos and NA and different displacements. I want a variety of solutions and so does the ACO. It brings in more manufacturers and more private teams, which makes it better.
        • 7 Years Ago
        I don't think anyone is arguing that. The underlying points are:

        First, giving huge advantage to diesel in first season (large displacement with a lot of boost) which wasn't fair in comparison to gassers;

        Second, removing the ability of these newly developed diesels to run lean (unfair because they've removed the point to even having a diesel after only one year)

        I'm not suggesting that it shouldn't be fair, its the WAY they are going about it.

        The CORRECT way to have done this would have been to have raised the boost cap for diesels to the point where they could have been competitive with the 4L boosted gassers. If they were superior, restricting the airflow wouldn't have made the engine totally useless. (which it may become now, being large and restricted).

        Why would you encourage Audi to develop a 5.5L diesel if the next season you'd force it to run rich? That totally negates the purpose.

        And since there is a boost cap, they CAN'T shrink the size of the engine and then boost to lean burn again. To have allowed THAT would have been foresight. It would have been:

        - more fair since the displacements of boosted gas and diesel could be closer

        - allowed Audi/Peugeot to use closer-to-reality sized diesels for homogolation purposes.

        - more economical (promoting the 'greeness' of the sport)

        So I think everything, from the rules that promoted diesels to the rules that cut off that promotion, were all failures.

        This is nothing new, its a cascade affect that I oppose, not the fact that the wrong has been counter-wronged.

        Besicdes, LMP2 is geared to privateers.
        • 7 Years Ago
        I don't think anyone is arguing that. The underlying points are:

        1) giving huge advantage to diesel in first season (unfair because they were large with a lot of boost)

        2) removing the ability of these newly developed diesels to run lean (unfair because they've removed the point to even having a diesel after only one year)

        I'm not suggesting that it shouldn't be fair, its the WAY they are going about it.

        Why would you encourage Audi to develop a 5.5L diesel if the next season you'd force it to run rich?

        And since there is a boost cap, they CAN'T shrink the size of the engine and then boost to lean burn again. To have allowed THAT would have been foresight. It would have been:

        1) more fair since the displacements of boosted gas and diesel could be closer

        2) allowed Audi/Peugeot to use closer-to-reality sized diesels for homogolation purposes.

        3) more economical (promoting the 'greeness' of the sport)

        So I think everything, from the rules that promoted diesels to the rules that cut off that promotion, were all failures.

        This is nothing new, its a cascade affect that I oppose, not the fact that the wrong has been counter-wronged.

        Besicdes, LMP2 is geared to privateers.
        • 7 Years Ago
        Sorry for the double-post.
      • 7 Years Ago
      But diesel and petrol engines perform differently at the same displacement. It's not levelling the playing field to mandate a specific displacement, that's just making one of the numbers be equal.

      Also, in regards to safety: is this really an issue? I don't seem to recall it being particularly bad for the Peugot or the Audi this year. Even on the wet track, the cars were staying on the ground. I don't remember hearing that they were causing an undue number of collisions, either.
        • 7 Years Ago
        Uh...isn't Peugeot French?
      • 7 Years Ago
      Oh, where to start...

      Le Mans racing is the last, great bastion of true innovation in racing that applies to road cars (see Audi FSI and TDI engines). Unfortunately, people like Henri Pescarolo do nothing but complain in the face of innovation without finding a way to make their own team competitive.

      The only thing I like about this is the reduction in wing sizes. All racing cars that aren't in NASCAR have waaay too much downforce, which actually increases speeds in the corners and takes some of the driving out of the equation.

      The tire warmers and one-gun-per-crew thing is just silly. It's one thing to remove tire warmers in daytime-only races where the track is 120F anyway. But to put racers on cold tires on a dark, 60F track is ludicrous and asks for trouble. If you want to see what happens when cold tires hit a cold track, check the 1992 Indy 500 or Zanardi's wreck in 2001.
      • 7 Years Ago
      These rule changes are crap, someone is just complaining. This is happening in the Rolex GT races all season. Looseing the tire warmers will just make the out lat that much more dangerous for the drivers.
      • 7 Years Ago
      you know nothing, the fact is that gas-powered cars are the limited ones in LM
      • 7 Years Ago
      Why stop there ? They should also require Peugeot and Audi drivers to wear an eyepatch, have one hand duct-taped to their face, and outlaw having brakes on all four wheels. Perhaps also make sure they also only get a couple of gallons per pit stop.
      • 7 Years Ago
      The reason for these changes (or adopting the alternate LMP2 restrictor of IMSA) is to level the playing field between gas and Diesel. Why level the playing field you ask? Because there are no Diesel engines available to privateer cars. So if the rules make it impossible for gas to compete, that means that there can only be two teams that can compete for the win. And since privateers depend on prize money and publicity even more than werks teams, that means you'll lose all your privateers, and soon you only have one team in each class instead of 43 teams.

      This change was necessary.

      And is it unfair? Does it stifle innovation? Making a car to take advantage of un-level homologation rules isn't innovation that is useful for any of us who aren't racing in that series.

      Audi did the same thing Mercedes did at Indy 15 years ago. Mercedes (Ilmor) noticed there was a set of rules that allowed production-based engines to have more boost, displacement, etc. in an attempt to allow low-budget teams to compete at Indy. But the rules just distinguished production-based engines by virtue of them having pushrods. So Ilmor made a custom pushrod motor that met those rules and smoked the competition.

      This is the same thing. Audi saw that the ACO had a set of rules that were there to try to make it possible for low-budged privateers to run Diesels. They were massively advantageous to give teams like the Caterpillar-powered (really a VW V10) privateer LMP1 car that ran BioDiesel at Le Mans 2 years before Audi made the R10.

      This could be pushrods, it could be Wankels, it could be gas turbines, it could be Diesels. It's just plugging holes in the rule book.

      Just remember when you say "Diesel was so good they outlawed it", the R10 could not have beat the R8 if the R8 didn't have its gas tank reduced in size, restrictor massively reduced in size and their boost cut from 2 bar to 1.6 bar (the R10 gets 2.94 bar!). So the R10 (and Diesel) isn't being unfairly picked on, it's just getting the same treatment that the ACO gives all long-time winning cars.

      What would be great is if Audi could go out and win Le Mans with the R10 despite not having the fastest car on the course. In the final year the R8 won Le Mans, it was way down on power, it would draft Corvettes and Aston Martins to get more speed on the straights. But by virtue of being reliable and infrequent/quick pit stops, it still won.

      The wheel gun thing disappoints me, I do see it'll help the closed-top cars, but I hate the closed-top cars anyway, and I don't know how it'll look to the crowd to have pit stops slower than NASCARs.

      The tire warmers thing will save a lot of trouble. Things like that become a problem for privateer teams. They were technically illegal before, banning the kind of "sleeves" that F1 uses for tires, but I guess the teams were just wrapping the tire shelves in plastic and pumping hot air in to warm the tires. I don't think any team in ALMS uses tire warmers, so it's clear it is possible to run these cars safely without them.

      I'm glad ACO followed IMSA's lead here in equalizing Diesel and gas. I'm surprised ACO did it by reducing Diesel power instead of increasing gas (LMP2) power like IMSA did though. It'll be interesting to see what IMSA does now, whether they adopt ACO rules or stick with their own.
        • 7 Years Ago
        I hope Audi threatens to pull out of LMP1 tell the ACO to go f themselves, "oo we can't keep up with audi so we have to cry about it" Tough, the "smaller" teams will never win because companies like audi will always have better cars plain and simple. The faster they get over it, the sooner we will see a Quad Turbo R10.
        • 7 Years Ago
        What the ACO's only purpose has become is constantly correcting mistakes in the previous years' regulations.

        The entire concept is a failure. Your post basically mirrors that, but your conclusion is that its a good thing?

        "This could be pushrods, it could be Wankels, it could be gas turbines, it could be Diesels. It's just plugging holes in the rule book."

        Exactly, always effing around trying to find the right displacement and boost to make engine X roughly equal in power to engine Y. The inevitable result is that one type is discriminated against.

        There is absolutely no way these are or ever will be precisely equalized. 'Fairness' cannot exist without setting 1 standard to follow for engines, and I feel it should be power. Measure it at the wheels if you must.

        You can't set numberous standards on the engines alone and predict how races will be affected until a season is over, and one team is angry.
        • 7 Years Ago
        Yes, it is a good thing. I don't think you understand how difficult it is to run a racing series long term.

        Look at IMSA (70s/80s). Look at CanAm. Look at NASCAR. Look at DTM. Look at F1. Heck, look at "production" SCCA Trans Am in the 70s.

        If you leave the rules alone, companies just hyper-optimize for them. After all the "low hanging fruit" is gotten, the costs of developing cars further under a given set of rules goes up exponentially. Eventually you chase out all but a tiny number of teams.

        ACO has continued to keep Le Mans relevant and affordable (relatively) for longer than many of these series were even around. And in my opinion, they have done it be setting a moving target. Every few years they change all the rules, which levels the playing field and opens up new avenues for improvement that even smaller teams can try out.

        In a combustion engine, air is power. Regulating air is regulation power, and it's much easier to do. And don't cry for the R10s yet, their restrictor was over 50% larger in cross section, and this 10% decrease in diameter will only take away 20% of it.
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