Group-C real life info

[Damian Baldi]

Hi, I posted this on the old forum, so I'll put it here again.


This is a very interesting article about the Sauber C9 (use the same engine than the C11) and how the boost was used. It looks like the boost and engine temp and durability were very associated.

http://www.uniquecarsmag.com.au/news-and-reviews/article/articleid/69192.aspx



Boost is adjustable via a dial across 10 positions, located on the far left of the cabin. There are eight positions of useable boost, ranging from zero, which is 0.4bar, incrementally through to eight, which produces 1.0bar and the maximum used under racing conditions, and even then only if really needed. Keep turning the dial past there and you encounter two additional settings, described by chief mechanic and collection manager Ben Hanson as being “one bar and a bit!” According to Ben, the last two settings are practically off limits.

“They are basically qualifying boost,” he explains. “If they ran the engine on the last setting, they used to drive it for one lap then they’d effectively have to change the engine. Things start to get very hot very quickly, with turbo temperatures building to 1000 degrees, and things basically start melting. A harnessed driver in the C9 can’t reach the dial, and that’s all in the making!”

[Damian Baldi]

About competition, how are the fuel consumption and tire wear planned? Now to fill the tank with 100 litres it take just 15 seconds. That short time kills any fuel saving strategy. There will be two different kind of slick tires? I been able to do an entire stint of 100 litres with one set of tires without problem, but then the tires lose his performance, so it's not a good deal to double stint the tires. Related with my previous post, how the turbo boost will provide power and rise the fuel consumption.

I think that's key to get good competition in endurance events.

[Petros Mak]

I am not sure exactly how things are going there. I will have to check with our physics guys and let them answer this for you. :)

[Damian Baldi]

The Porche 962 it's the perfect platform to handicap drivers for an endurance event with just a few physics changes. Using the same graphic base you can add or remove weight, or add or remove power, increase or decrease fuel consumption to get two or three different performance cars emulating GTP, C1 and C1 "work" cars.

https://www.stuttcars.com/porsche-models/962/

As I told you, I will meet Oscar Larrauri in a few days, he drove ALL the 962 models from mid 80s to early 90s, so I can ask him about the different performances of each car.

[Damian Baldi]

About the pit stops I think it took a second per litre to fill the tank. With these values, you can point your strategy to save fuel and gain time if you are driving a slow car, every litre that you save using longer gears, or low boost, it's a second less at the pits.

[Petros Mak]

Basically any information that can be given will be a plus for us. Its hard to acquire a lot of data and having a real driver's notes on various parts of the car will be great. How it drove, what were the typical stints for the short races and then for the 24 hour races. Were the engines different in performance for the 24 hour races as they had to run for that long compared to the shorter races? Fuel loads, tire wear, how long it took tires to heat up, to get to peak, to start dropping off.

Things of this nature really helps out to make these cars as accurate as possible. Of course any information you get will help a lot. :)

[Damian Baldi]

Basically any information that can be given will be a plus for us. Its hard to acquire a lot of data and having a real driver's notes on various parts of the car will be great. How it drove, what were the typical stints for the short races and then for the 24 hour races. Were the engines different in performance for the 24 hour races as they had to run for that long compared to the shorter races? Fuel loads, tire wear, how long it took tires to heat up, to get to peak, to start dropping off.

Things of this nature really helps out to make these cars as accurate as possible. Of course any information you get will help a lot. :)

That's all I have in mind and more. Let see how friendly he is that day. At the moment, I asked him by facebook about the cars, and he started talking about how he configured the 962C for the 1990 race to get the second place at the start, just behind the Nissan R90CK with that record lap. :)

[Petros Mak]

Ah nice, well looking forward to any feedback that can be provided, thank you very much for helping us out with this too. :)

[Damian Baldi]

Interesting actual video onboard from a Mazda 787. The most interesting thing about this video, it the amount of time that the gearbox takes to change from gear to gear. Watch it from minute 8.


https://www.youtube.com/watch?v=neHfmMeRr9Q

[Damian Baldi]

Great video showing the top speed on the old Le Mans straight.

Comments on the video, say that it's an old Dome RB83 from 1983


https://www.youtube.com/watch?v=J3BQG87Xyfs

The RC83 video is very interesting for some things. First and more notorious is the brutal speed than never stop rising. Second is the (at least on the video) fairly easy handling of the car, the driver doesn't need to correct the car all the time as in the R90CK video from 1990. Finally the long time between downshifts at the end of the long straight.

[Petros Mak]

Thanks for the videos and info mate! :D

[Damian Baldi]

I'm sure everybody saw this one, it is very notorious how the driver avoid to use high RPMs because of the big power. He use the brutal torque of that engine at low speed corners and just press full throttle when the car is pointing to a straight.


https://www.youtube.com/watch?v=FjcHMmyQvXE

[Damian Baldi]

Sauber C11 cockpit

As you can see both german brands use the same RPM gauge.

http://farm6.staticflickr.com/5470/9096112803_22bf2961e1_z.jpg

[Damian Baldi]

Some data about Mazda 787B fuel consumption


Remember that in 1991, Le Mans was run to a fuel consumption formula, Mazda's 7 liters/lap equating to around 4.6 mpg. As only a fixed quantity of 2550 liters (674 gal.) of fuel was allotted for the entire race distance, fuel consumption was critical.

At Le Mans, an 8500-rpm limit was used during the race and up to 9000 rpm was allowed for qualifying.


Taken from this site
http://community.us.playstation.com/t5/Gran-Turismo-Series-General/mazda-787b-tribute/td-p/4496991

[Petros Mak]

Thanks mate!

[Damian Baldi]

Fuel consumption information


Mazda 787b
7 litre per lap at Le Mans put some perspective about fuel consumption with other cars. It's 14 laps per tank at le mans, so a tank run for near 50-52 minutes




Porsche 956/962 (engines 2.6 (956) 2.8 3.0 and 3.2)

General comparison


The Garretson 935K3 (3.2 twin turbo) I drove got about 2.8 MPG at about 650 HP where the Group C spec was 55 L per 100 Km (4.28 MPG.) The 2649 cc (92.3x66) 4-cam in the 956 was spec at 620 HP (@8200 & 1.2 bar). The 956 was able to get noticeably better (particularly at reduced boost) than spec. I have heard of numbers like 6 MPG and still get close to 580 HP - remarkable. I think it was because Valentin was short enough to run around inside the turbo and work his magic. His intellect far exceeded his stature.

From the Lucky7 winner 956 over the 962

Note: race fuel limit that year was 2210 litres

7 New Man Porsche 956B, with double-winner Klaus Ludwig at the wheel having driven well over half the race, led the survivors through the Ford Chicane for the last time in the middle of an ecstatic crowd, hooters and waving flags. Not only was it a back to back win for Ludwig and the #7 car, but they’d also set a new distance record (24 hours, 373 laps and 3,161 miles at an*average*speed of 131.745mph, still with 100 litres of fuel left unused)*



The Ludwig car continued untroubled recording fuel mileage numbers of 40 litres per 100kms, with their rivals anywhere between 42-50! At the finish the NewMan Joest Porsche still had some 200-plus litres of fuel left, just to rub salt in the wounds.

This is like 2.4Km per litre for the 956 engine in his lowest consumption, and 2.0km per litre as normal

And 1.8 km per litre for the 3.2 of the 962 as normal




Sauber C9/C11 (V8 M119-HL engine)

This is the only data I could find about the Mercedes engine

Due to the fuel consumption limitation for Group C-Cars - 51 litre/ 100 km - a high efficiency race engine was required to achieve the target fuel consumption during race events using a commercially available “pump” fuel.
Given these restrictions, the latest version of the M119 HL-engine had a power output of 530 kW and minimum brake specific fuel consumption values of 235 - 260 g/kWh over the engine speed range.

If someone can help to translate this to litre/km would be great.

[Damian Baldi]

nice reading about Sauber history in group-c

http://archive.motorsportmagazine.com/article/january-2010/74/when-mercedes-turned

[Damian Baldi]

Fresh video from last sunday at Zandvoort. It looks the same as in Spa and Nürgurbring. The driver avoid to push too hard on slow corner. That engine have so so much torque that he can do slow corners on 3rd.


https://www.youtube.com/watch?v=qD7ftdMdzDo

Lovely sound

[Damian Baldi]

Don't think this is racing, they are just two old men with lot of money to play at Silverstone


https://www.youtube.com/watch?v=DiLKVSxBaEM

[Petros Mak]

Awesome stuff here mate. Thank you! :)

[Damian Baldi]

Awesome sound from a 1989 japanese TV coverage of Le Mans

up the volume


https://www.youtube.com/watch?v=Oupeu8ouWtQ

[Alvaro]

Thank you very much Damian. I think you will love these interesting pdf's, with data of private sessions with the new C11.
http://www.chamberlainsynergy.com/00redirect/mercedesbenzc11/history.html


>>>>About the pit stops I think it took a second per litre to fill the tank.

Uhm, that seems slow, can you confirm that?
You are right about the importance of strategy on endurance races. This case, I think fuel consumption was critical because pit stops were limited to around 1 per hour (aproximately, and dependent on event). C11 had a very good ratio speed/consumption, so they could go faster with the required consumption, and this was one of their best advantages.
I think this car also had very good ratio downforce/drag, so they could reach high speed records and still to be fast on corners.
Of course it was powerful, but not so extraordinary on power/weight. And peak torque is great, but comes at 3500 RPM, it doesn't provide so great power as smaller torques on higher RPM.
So, I think the reason why most of C11 drivers don't accelerate so hard and make wide lines on corner exits is because it wasn't such a friendly car to go sideways. I think Mazda 787, Porsche 962, Jaguar were easier to make slide on power, but C11 was such effective on overall performance that they could win without much effort, and that makes the legend of a perfect made car, but i don't think it was so good on some points.

>>>>>(from motorsportmagazine article) "Baldi took Eau Rouge flat on the way to pole position for the Spa race"

He he, i don't believe it. It has good downforce, but from the information i've got i would say that was impossible for this car. The pole time should be 1:50 then... but, who knows...

[Damian Baldi]

Thanks Alvaro, that's really first hand informaction! About fill the tank, I been chating with Oscar Larrauri, and he told me that they used less than that time.

[Alvaro]

Ok, thanks! Probably we can check fueling times watching the old TV broadcasts. Actually they are very exciting to watch.

I re-found the regulation i was talking about, which is from 1985.
374

With 2210 litres for 24 hours means average fuel consumption should not exceed 92 litres per hour. Then 1 tank must last for more than 1 hour!
With 2550L limit you can use more tanks, ... If i am not wrong it means around 1 tank each 56 minutes.
Probably the use of higher turbos provoked not only overheating and extra consumption for the engines but also extra heat and wear on the tyres because of very high speed on the straight. Not so funny to go over 400kph this way.

The document can be found at an important international automobile federation web... Unfortunately the document is not complete for Group C prototypes, and there is not any Group C info at 1990 appendix... Anyway it is interesting to check the rest of pages.

[Alvaro]

About the C11 documents, they are in german, but it is worth to translate it to check comments.
It is interesting sometimes they tested with a softer compound for only one tyre (Nurburgring: three R430, one R240 on right front tyre) and they say the soft tyre didn't last, he he he... it was like a 2013 Pirelli. :rolleyes:

[Damian Baldi]

yeah, I saw it was in german, but it can be translated easy. That test with the mixed tires looks interesting

Remember that for 1990 the track was changed (new chicanes included), Through the years they increased the amount of fuel per Le Mans, but the engines grew up too.

[Damian Baldi]

A lot of details about the Jaguar XJR cars, and some incredible comments about 1990 race


http://archive.dailysportscar.com/subscribers/history/xjr12_1090.htm

http://farm5.staticflickr.com/4151/5148727360_2e9e7ffaf8_z.jpg

[Alvaro]

About fuel fill rate i've seen an old video from Spa 1000 km where the commentator says it is around 1 liter per second, as you said, Damian.
I can't share this video link, it was uploaded on facebook on a sport prototypes group or similar...

About corner speed, perhaps i was wrong. I said it is impossible for this cars to take Eau Rouge flat out, but probably i shouldn't trust much on nowadays classic events performances.
This is a exciting video of the true competition and we can see how fast they take Eau rouge on the initial laps of the race (7:55). This driver is brave, but this is done with high fuel load, so probably on qualifying they could attack even more.
Anyway exciting video, uploaded recently.

https://www.youtube.com/watch?v=3P1QmCswql0

[Damian Baldi]

What a beauty !

http://www.motorsportretro.com/2014/11/jaguar-xjr-9-auction/

Plus, the sound


https://www.youtube.com/watch?v=lbdWWi4Kpwc

[Sektrex]

Can't go wrong with the Peugeot 905 evo.

http://www.ultimatecarpage.com/images/car/3291/563/Peugeot-905-Evo-1-Bis.jpg

[Damian Baldi]

hmmm the 905 was part of the cars of the new regulations (Group-1), not Group-c

[Alvaro]

I asked about front downforce on Group C cars. I received interesting replies:

Autosport
http://forums.autosport.com/topic/196712-group-c-aerodynamic-balance/


Facebook groups

-Question:
Following Mulsanne's corner data, sprint configuration (high downforce) had more % of front downforce than Le Mans configuration (low downforce).
How is this achieved? I had the idea that front downforce is not adjustable, while rear wing had many positions. So, how could they earn front downforce? Is by means of ride height, rake? Front splitters?

-Answers:
Rand Lampard: C) all of the above
Kelly Smith: Change the entire nose with a different angle wing...
Gary Peck: Good answer Rand
Martin Thoene: All of the above, plus sometimes front ends have subtle differences in profile that are not immediately obvious.
Rand Lampard: all of the above includes 'everything'.
Rand Lampard: Not laughing. You gave three examples of how they may have arrived at the downforce level/split that Mulsanne's Corner claims. I said that all three of those (and more) would have the desired effect and were probably used. Sprint races you can afford to run at a lower ride height and accept a bit more abuse to the floor/skids. Rake? Yes, also. Splitters were/are another commonly adjusted element. TWR probably had different tunnels just for LeMans (and other tracks 'different' enough to require them). Martin pointed out front end profiling. Agreed, possible. Another fairly big one would be the fender vents - none for LeMans.

[Damian Baldi]

As usual a great Chris Harris test of the Jaguar XJR-9


https://www.youtube.com/watch?v=oQErgDQaRZM

[Damian Baldi]

Great stories behind the Le Mans 1990 victory from Jaguar.

http://www.doubledeclutch.com/?tag=jaguar-xjr12

[Alvaro]

C11 engineers speak about its characteristics and new features after the already succesfull C9
https://www.youtube.com/watch?v=pTm5qeRrrsQ