The mighty group C cars (and a bit of IMSA)

Please discuss here all your remarks and pose your questions about all racing series, except Formula One. Both technical and other questions about GP2, Touring cars, IRL, LMS, ...
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Re: The mighty group C cars

Post by 1158 » Sun Jan 18, 2015 9:18 am

Cold Fussion wrote:What were the pit stops rules in Group C like? If it were like modern LMP1, I would have thought removing the rear body work covering the tyre would add a significant time penalty compared to the drag reduction (or perhaps the drag reduction is bigger than i realise?).
I don't remember all the specifics, I was a a kid, but I'm pretty sure there weren't limits like now with respect to fueling and tire change being done at the same time. I'm sure those covers were easy to get on and off.

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This pic is large so I'll just link it https://3d-car-shows.com/wp-content/upl ... che-17.jpg

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Re: The mighty group C cars

Post by Pedrolito » Sun Jan 18, 2015 10:25 am

More pics of the 905 evo 2 that never raced. However, many pieces of the evo 2 were integrated in the 905 evo 1ter in 1993.

Its nickname was "supercopter". In France, Supercopter is the name of the american series Airwolf.

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The flat bottom:
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An interesting comparison with the Bentley Speed 8 I found thanks to Google image:
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Re: The mighty group C cars

Post by Sombrero » Sun Jan 18, 2015 10:30 am


MadMatt
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Re: The mighty group C cars

Post by MadMatt » Sun Jan 18, 2015 5:02 pm

The front diffuser posted by macrush at the bottom of the previous page reminded me of a similar concept also on a Toyota, but from Pikes Peak, the Tacoma. Sorry for the off-thread post but I think this is interesting:

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Couldn't find a proper real pic of the underside, so you'll have to accept this one:

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I find it interesting that Toyota's front diffuser exit was just behind the front wheels while they didn't let the air leave on the side on the Peugeot 905 Evo 2.

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Re: The mighty group C cars

Post by flynfrog » Sun Jan 18, 2015 6:46 pm

heres is one I got of they Ryhs Millens Pikes Peak prototype tunnels. Maybe this is the new group C

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Re: The mighty group C cars

Post by MadMatt » Mon Jan 19, 2015 11:53 am

The 1983 Dome RC-83:

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Pictures to show the size of the tunnels on a Mazda GTP car (I have renamed the title to include a bit of IMSA stuff):

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Also I have updated my post in the 1st page regarding aero values with the Toyota Eagle mk2 and mk3, so check it out!

:)

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Re: The mighty group C cars (and a bit of IMSA)

Post by matt21 » Mon Jan 19, 2015 2:06 pm


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Re: The mighty group C cars (and a bit of IMSA)

Post by Pedrolito » Mon Jan 19, 2015 4:03 pm

Porsche Kremer CK5 (Porsche 936 in new bodyshape and according to Group C regulations) :
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From : freisinger-motorsport.de

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Re: The mighty group C cars (and a bit of IMSA)

Post by MadMatt » Mon Jan 19, 2015 8:59 pm

They really tried to get the smallest amount of drag possible. I wonder how little was the downforce at the front on this car!

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Re: The mighty group C cars

Post by 1158 » Mon Jan 19, 2015 10:43 pm

MadMatt wrote:
Pictures to show the size of the tunnels on a Mazda GTP car (I have renamed the title to include a bit of IMSA stuff):
:)
Good call. The IMSA regs brought about the changes to the 956 that resulted in the 962. I have read moving the front wheel center line forward of the pedal box shifted the pressure center slightly more forward and made the car more stable.

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Re: The mighty group C cars (and a bit of IMSA)

Post by wesley123 » Tue Jan 20, 2015 5:10 am

MadMatt wrote: Pictures to show the size of the tunnels on a Mazda GTP car (I have renamed the title to include a bit of IMSA stuff):

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The RX-792P, just like the just released RX-7 of that time it had a very futuristic look.
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The right tunnel had a triangle cutout to provide clearance for the exhaust of the Mazda rotor. Had a few cooling issues if I'm correct, so over the season the (again) if I'm correct underfunded team had a good time added cooling slots nd intakes to the car. Compare the above image to the promo image below:
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EDIT: front ducting. Don't know what the side ducts link to, afaik the RX-792P featured a front diffuser.
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http://www.grandtouringprototype.com/fe ... ow=gallery

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The diffuser tunnels are interesting as they don't follow the Group C regulations on underbody dimensions, this would have given them a 100Lbs weight cut.
"Bite my shiny metal ass" - Bender

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Re: The mighty group C cars (and a bit of IMSA)

Post by 1158 » Tue Jan 20, 2015 8:24 am

Lowenbrau Special 962 - Al Holbert
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and a bit of its history http://www.sportscardigest.com/lowenbra ... r-profile/

I realize this isn't technical but this is the car that is probably most responsible for my love of motorsports. I remember first seeing it as a kid and from that moment I was hooked on IMSA GTP. Then a short time later I found out about Group C. What a great time that was to be kid watching racing. My only regret is never seeing these cars run in anger.

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Re: The mighty group C cars

Post by 1158 » Tue Jan 20, 2015 8:39 am

TurboLag wrote:For me, it's this one. Not because the design itself is necessarily better than any other of it's time (well, they won, so they must have done something right), but for the engine note! It's pure music! :shock:
Agreed. I would love to hear that thing in real life.


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Thing was packed full of goodies. Variable length intake trumpets, extra spark plug per rotor, and potential for up to 900 hp. It was detuned to 650-700 for Le Mans.

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Re: The mighty group C cars (and a bit of IMSA)

Post by matt21 » Tue Jan 20, 2015 10:36 am

I would like to see rotary engines back in racing.
They would fit perfectly in the fuel-flow-restriction-era of LMP now.

I would like to go even further and change the formula to energy-flow-limitation.

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Re: The mighty group C cars

Post by MadMatt » Tue Jan 20, 2015 7:32 pm

Cold Fussion wrote:What were the pit stops rules in Group C like? If it were like modern LMP1, I would have thought removing the rear body work covering the tyre would add a significant time penalty compared to the drag reduction (or perhaps the drag reduction is bigger than i realise?).
I am not fully up to date with the group C races of the end of the 1980s, early 1990s, but before that they didn't really change tyres. They had a 600 liters fuel allocation for each 1000km race (2600 liters for LeMans!) and a maximum of 5 refuel pitstops with fuel tanks not exceeding 100 liters. The cars had to weight at least 800Kg, a figure that was increased to 850Kg, and then 900Kg.

I am quoting someone from another forum for some more details:
As far as aero regulations go, the original specs called for a flat reference plate, measuring 100x80cms,starting behind the back of the front wheels. No other parts were allowed to project below this plane, apart from the wheels.
Maximum length of complete car including wings was 480cms, width 200cms, and height between 100 and 110cms.

No air boxes were allowed forward of, or above, the highest parts of the screen. There were measurements for windscreen, for doors and for internal cockpit width (130cms), and for side window sizes (40x25cms). The front overhang was to be no more than 20% of the wheelbase,and the difference between front and rear overhangs was not to exceed 15% of the wheelbase.

Maximum wheel rim width was 16". Venturii were permitted aft of the reference plate, but skirts were banned. Finally, the fuel tank was to be contained within the wheelbase of the car and within 65cms of the longitudinal axis of the car, fuel tank capacity being 100 litres.