Brickyard Legends Team present :
Porsche Carrera RSR turbo

At the Frankfurt Motor Show in September 1973, Porsche unveiled a special 911 concept car that changed the course of sports car history. With RSR fender flares, a large rear wing and the word "Turbo" emblazoned over the rear haunches, the new Porsche offered an exciting new glimpse at the future of the 911 series.
A month later, Porsche announced that they would cease factory-backed racing activities for 1974, allowing private entrants to represent the marque with the Group 4 RSR. However, in cooperation with Martini & Rossi, Porsche entered a turbocharged Carrera in the Group 5 category for the Manufacturer’s Championship, just as had been done with the prototype RSR 3.0 models of 1973.
At the time of the announcement, Porsche had little more than a concept for a turbocharged racing Carrera, yet the idea was appealing for several reasons. Not only would a Turbo Carrera expand on the technical expertise gained during the final years of the 917 program, it would set the stage for the production Porsche Turbo that was being developed for the 1975 model year. Furthermore, the promise of a "silhouette formula" in the near future made a Group 5 Turbo Carrera an ideal platform for experimentation.
To comply with the Group 5 regulations that limited capacity to three litres, a 2.14-liter engine was developed with a magnesium alloy crankcase, polished-titanium connecting rods, enlarged oil-pumps, dual ignition, Bosch mechanical injection and sodium-cooled valves. At the rear of the engine, a single KKK turbocharger was mounted in the manner of the 917 Can-Am cars. This potent engine was mated to the five-speed RSR transaxle with an 80% locking differential and special half-shafts for increased strength.
Like the engine, the chassis was a vast departure from the production 911 and Porsche implemented the best RSR and 917 components. The standard torsion bar suspension was replaced with progressive-rate titanium coil springs, Bilstein shock absorbers, anti-roll bars and boxed-aluminum trailing arms. The result was a suspension assembly 66 lbs. lighter than those of the RSR 3.0. To this sturdy foundation, Porsche equipped the Turbo Carrera with RSR-type brakes and massive rear wheels for additional grip.
Again, using the RSR as the basic foundation, the bodywork made extensive use of fiberglass, with lightweight plastic forming the front fenders, rear aprons and all door and deck lids. Similarly, the interior was stripped of all unnecessary details and outfitted with an aluminum roll cage, boost gauge, boost knob and full-race controls. At the rear, a substantial rear wing was fashioned to both increase downforce and provide a more discreet inlet for the intercooler. In an attempt to maintain a visual relationship with the production 911 , the large rear wing was painted black to downplay its size.
After extensive testing, the RSR Turbo 2.14 made its competition debut at the Monza 1000 Kilometers finishing 5th overall and proved extremely successful at the 1974 24 Hours of Le Mans finishing 2nd overall behind a Matra sports prototype. Throughout the 1974 season, the Turbo Carrera continued to be tested and improved, eventually leading to the introduction of the 935 in 1976.

- the mod is linked to GTC-TC-76 class and the Porsche 911RSR.

Credits :
- papag21 : 3d, mapping, file structure, skins
- greg7 : physics
- kiwisteve : template, skins
- Ralf1973 : skins
- hpiracer : skins
- rallymaster : testing
- Cesere : Track testing
- Jason : Track testing
- rsvmille : sounds

Installation instructions:
- extract folder to X:/GTL/

Enjoy

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YOU NEED THE ALTBIERBUDEN CAR CLASSES TO RUN THIS MOD!

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Porsche RSR turbo Physics read me

Essentially a test bed for Porsche to try out racing a 911 chassis with a turbocharged engine, it was understood from the start that would be impossible to homologate as a true GT car as Porsche had no turbo charged road car yet.
Instead built to fit in to the 3.0 Prototype rules that allowed turbocharged engines to displace up to 2.14 liters, however this also meant racing against full 3 liter prototype cars like Matra and Ferrari 312s.

Built from a standard 3.0 RSR chassis the RSR turbo would have several things about it that were new and unique for a 911 based race car.

First was of course the 2.1 liter turbo flat six engines built using the experience gained from the 917 Can Am project. It was capable of producing as much as 500hp with the boost turned all the way up.
However this power output was soon found to make the engine and gearbox (a standard RSR 915 unit) unreliable and was only used for short qualifying runs.
Instead the car was raced at between 450 and 470hp. even at these numbers the 915 gear box was often a source of problems for the car

Also this RSR had the fuel tank mid mounted instead of in the front of the car to help keep the handling balance more consistent between full and empty tanks.

That and the large rear mounted air to air inter cooler and the extra weight of the Turbo charger components combined to create an RSR with an almost 30/70 front to rear weight split more rear weight than ever tried in an RSR.

Also the first true rear wing that the factory ever fitted to a 911 chassis was seen on the RSR turbo.

All this added up to a very fast car but all was not perfect. the car ended up with a very high center of gravity compared to a standard RSR, more aero drag, initially 15 inch wide rear wheels were use but thy proved too small to handle the power and rear weight and were quickly changed to 17inch wide ones.
The early reports were of a car that was extremely challenging to drive, too much rear weight combined with too much power.
There was lots of under steer on corner entry and lots of over steer on exit.
However by the end of its development it was tuned to be not too bad at all to drive fast.

Its greatest achievement was to finish 2nd over all at the 1974 24 hours of Le Mans and were it not for loosing top gear (as well as 1st, 2nd and 3rd) it might have won over all.

In the shorter sprint races it was simply out classed by the purpose built 3.0 prototypes. And at the end of the 1974 season Porsche abandoned the car to build its true Group-5 car the 935.

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RSR TURBO for GTL

It is a unique car to drive the fist thing to notice is how light the front end is this can make hard braking a little tricky as it is easy to lock the front wheels so some time needs to be spent tuning the front to rear brake balance for each track you drive on.

You always need to be aware of the weight at the back 69% of the weight of the car is behind you and you need to keep it under control. Over aggressive driving will cause it to work like a pendulum against you and while the 17inch rear tires have a lot of grip you can over power them if the back of the car starts to fish tail to much.

470hp and 1990 pounds with driver means its fast. Unlike the bigger 934 and 935 turbo engines there is not a huge Torque spike and the power band is wide.
But some attention to gearing is necessary.

The front of the car can be set very soft because of the lack of front weight and this can help the mid corner throttle on under steer but to soft in the front and car will dive hard on throttle lift and can become unstable.

In fast corners the tendency if for some Power on under steer a light lift off of the throttle will tuck the front of the car back to the apex but to aggressive a lift can start the back around.
As long as you keep the rear under control you can change the attitude from under steer to over steer and back by modulating the throttle.

In slow corners there is always the possibility of locking the front brakes if you’re not paying attention.
You need to get it rotated well around before you go pack to full power as all that rear weight will unload the front tires under hard acceleration and it will pick up some under steer on exit.
It was reported at one race that after loosing the nose in an accident and the down force that goes with it, that it would lift the front tires completely off the ground under hard acceleration out of some corners.


Greg7