Group C cars grip under acceleration

Okay thanks, I do run that but must need to look closer for that data

 

Go to the tabs Ride Height and Aerodynamics inside Telemetry Viewer.

 

Shall do, thanks

 

3 Group C cars done, only GTP missing to do a run. Impression so far is that the class has been BoP'd for races.

 

They have been updated in the last beta, just a heads up!

 

Thanks for reminding me, completely missed out.

 

Alright, I have gotten up to a point in my testing where I think I can share some conclusions. Wanted to take my time and try to make a fair comparison between the 4 cars included on this class, which meant sometimes going back and forth several times until I could reach something noteworthy. This will be divided into 6 posts (including this one) to prevent making a confusing wall of text. So here, I will explain what kind of testing I did, the objectives I was trying to achieve, what things did I test, and what things I did not.

I decided to base all the tests at Kansai Classic. Reason why is that after some runs, I felt that Spa Francorchamps was masking issues with the cars, given that is a rather straightforward track to drive at. Suzuka on the other hand is a very tricky place, and has all kind of challenges that will reveal issues at every end of a car, while also being a very punishing place if the driveability is compromised, as it's very tough to stay consistent, and that's the name of the game for longer races, which are exactly what Group C is all about. These are the exact testing settings used:

Mode: Test Day
Track: Kansai Classic
Date: 09/04/1989
Time: 14:00
Weather: Real Weather
Track Condition: Medium Rubber

This delivered a Heavy Cloud sky, with ambient and track temps of 19 ºC, and an 8 km/h wind which I cannot remember on what direction (setup screenshots will show it).

Cars were tested with the following settings in common:

Fuel: 100 Litres (full)
Tyres: Hard Slick
Radiator Opening: 70%
Boost (if appliable): 66%
Fuel Map: 1.00 if turbo car; 0.95 for NA car

The boost was set on that value with the knowledge that it was the baseline setting for the Sauber C9 in the real 1989 season for races, and that it produced the exact same power output in game. 70% worked fine for keeping oil temperature around 110 ºC for all engines, and that did not cause considerable damage (for all cars was about 1% after 8-10 laps).

While in all cars the idea was to see the max I could get out of them (while keeping them driveable) with the mentioned settings, for the Sauber and the Porsche measures were taken for limiting a bit their performance. For the former, front downforce was always set at 0, and never increased. Besides a search of more historical accurate performance (on Sprint configuration it always used a splitter of the same size without variations or added devices like dive planes), there were some setup limitations that made for this to not be felt when looking for max performance. For the latter, diff was used in Spool Mode, which was what the real life car had, instead of a LSD.

I did a 10-12 lap run with each car. Would have liked to go full stint with each, but time was tyrant and it was not possible. Otherwise there would be no conclusions to share. That amount of laps was at least enough to appreciate how much it took for each car to get going and get tyres up to temp, and how they started to respond to some tyre wear and fuel load decrease, in the search of evaluating how do these cars stack up for long distance runs.

What was left to evaluate was qualy runs with each car (I'm not a hotlapper man and the results of this did not interest me), and wet weather performance (lack of time, would like to do a dedicated test for this at some point).

The following 4 posts will be one per car, and all will have the setup used attached in screenshots. The last post will be left for conclusions. Will be writing and posting them during the rest of the night.

 

Sauber C9

The undisputed king of Group C in 1989, winning all races but one. The best engine on the class at both power output and fuel consumption, coupled with a very capable chassis and a cohesive team that did not take things for granted, made for an unstoppable force. Its only weak link was the Michelin tyres, and that costed them a clean sweep of the season, missing out only one race to tyre wear and not being able to stop the Joest Porsche, booted with the best rubber of the time, the Goodyears, at Dijon-Prenois.

In game...it's a bit of a mixed bag. Its engine is the best in torque performance, but its peak power output at full boost is strangely limited, reaching "only" 850 HP instead of the 925 it had. And its fuel consumption at the nominal boost level is among the highest of the bunch. Downforce should also be the highest of the cars available, but it's not, and its constant oversteer defies the testimonies of the drivers who actually drove it. A problem with this is that the rear ride height adjustments are limited in range, and setting heights to minimum you get a much higher rake than the rest of the cars (15 mm against 10 or 11 for the rest), which gives an oversteering nature that can't be easily countered without other sacrifices. Still, it gets on the pace quickly, settling into the 52s in just two laps, and going faster as the fuel load decreases, coupling with the tyre wear quite well, with little changes on the handling. It's a dependable car if you get on with its balance.

In terms of outright performance, it's the fastest of the 3 Group C cars, putting +1 second on the Nissan and the Porsche, but marginally behind the Corvette GTP, and the fuel consumption being the worst.

So, the numbers...

Best Lap: 1:51.48
Average Laptime (average 8 second best laps): 1:52.33
Fuel Consumption Average: 3.8 Litres
Power Output: 770 HP
Top Speed: 305 km/h
Downforce at Top Speed: -20064 N; Front -10752, Rear -9312
Ride Heights at Top Speed (mm): FL 23.79; FR 28,12; RL: 30,77; RR 35,62
Apex Speed Degner 1: 177 km/h
Apex Speed Hairpin: 64 km/h
Apex Speed 130R: 273 km/h
Tyre Wear on Best Lap: FL 1,20; FR 1,67; RL 1,87; RR 2,20

Attached is the setup used for this run.

 

Porsche 962C

A true legend. Few, if any, racecars come close to its longevity and sheer amount of success around the globe. Its record at Le Mans speaks for itself: debuted in form of the Porsche 956 in 1982, and won all races up to 1987. Lost, but not without putting some mighty fights in 1988, 1989 and 1990 (last two only in privateer form), and when Group C was dead by 1993, some clever rulebook reading by Singer resurrected it in form of a GT in 1994, and won on its last outing. And its engine? An even more impressive record run: it was used one year before the debut of the 956, and won, in 1981. Its succesive evolutions and variations kept on running and winning, past the life of the car, winning the 96, 97, and 98 races. Astonishing.
But in 1989, without works team and against the onslaught of new manufacturers with new cars, it was an uphill battle. Still, it always featured near the front of races, and were the only ones able to beat Sauber-Mercedes in a round, at Dijon-Prenois.

In game, it's the slowest Group C, which is not surprising, but it has the extra problem of it taking some time to get up to speed, starting with slow laps but steadily improving them as the fuel goes off. With the LSD differential as default it seems like a bit too tame, but configure the Spool and what the 962C should be appears in all its glory. The understeer on corners is felt and can only be combated with precision and trying to carry some yaw with the right foot, just like Hans Stuck taught the rest of the Porsche drivers how to do it once they transitioned from the 956. It has its boons with low weight, low speed nimbleness, short braking distances, and lowest fuel consumption. All things that don't make it a great prospect for short bursts, but it should be capable of mounting a challenge on long runs on the right hands.

Numbers...

Best Lap: 1:52.980
Average Laptime (average 8 second best laps): 1:54.39
Fuel Consumption Average: 3.3 Litres
Power Output: 675 HP
Top Speed: 291 km/h
Downforce at Top Speed: -12902 N; Front -8388, Rear -4514
Ride Heights at Top Speed (mm): FL 22.62; FR 25.3; RL: 28.33; RR 28.97
Apex Speed Degner 1: 174 km/h
Apex Speed Hairpin: 58 km/h
Apex Speed 130R: 273 km/h
Tyre Wear on Best Lap: FL 0,83; FR 1,03; RL 1,17; RR 1,28

Setup used attached below

 

Nissan R89C

With the requirement by the FISA that manufacturers who wanted to race at Le Mans had to do the full WSPC season, Nissan presented a full season program with a brand new car, chassis built by Lola, and coupled with a powerful V8 engine. It was a fine effort done with some top notch technology, featuring a full carbon composite monococque (something that the C9 did not have), high downforce levels and good straight line efficiency, carbon brakes (after Le Mans, where they had poor braking performance), but being held back by tyres (Dunlop Denlocs did not play well with their car, resorting to a strange combination of crossplies at front and radials at rear) and fuel consumption. More than once they challenged and passed the Saubers on track, but afterwards they had to dial back the pace to preserve fuel, losing the spots gained.

In game, it's the most fun car to drive. Has a beautiful balance, with a slight understeer that can be countered with some hustling, as its tyres really want to slide around, the most of the class. Engine is perhaps the most peaky of the bunch, power coming with sudden outbursts once the turbo kicks in, but nothing that cannot be managed once you learn to drive it, besides the chassis coping well in those moments. Its pace drops behind the Sauber with a lower power output but also a lower fuel consumption. There is something peculiar with the engine, and it may be a bug: at 66% boost the power maxes at 732 HP at 7600 RPM and stops increasing there. But with max boost, it keeps on increasing, reaching the stated 918 HP past 8000 RPM. To me, this is a bug: the engine in real life did not produce more than 800 HP, and Nissan never had stellar qualifying outputs, concentrating always on race pace. Meanwhile, the corner speeds seem to point at the car having the least downforce in game, perhaps limited by its ride heights, which cannot be set as low as the Sauber and Porsche, but kind of makes it up with beautiful balance, which yields consistency. Also, this car has a different tyre set from said cars, who share one in game, and seems to generate higher temp spread and cross load imbalance. It needs a full asymetrical setup to get the most out of it, so performance can be gained and deliver better than what you see here below:

Best Lap: 1:52.582
Average Laptime (average 8 second best laps): 1:53.26
Fuel Consumption Average: 3.5 Litres
Power Output: 732 HP
Top Speed: 299 km/h
Downforce at Top Speed: -23958 N; Front -13691, Rear -10267
Ride Heights at Top Speed (mm): FL 30.84; FR 31.25; RL: 39.05; RR 39.24
Apex Speed Degner 1: 173 km/h
Apex Speed Hairpin: 59 km/h
Apex Speed 130R: 257 km/h
Tyre Wear on Best Lap: FL 1.42; FR 1.88; RL 1.81; RR 2.23

Setup attached below

 

Chevrolet Corvette GTP

The interloper of the class. It never raced in Group C, only at IMSA GTP class at the other side of the pond. There are similarities, but rulesets had differences. What I can briefly say is that it started as a Turbo V6 project with lots of power and speed, but questionable reliability. At one point the works team dropped the engine for a NA V8, which is the version we have in game.

In game, the car is massively uprated from it's real life, thanks to an exaggerated power output and insane mechanical grip from the tyres that are unique to this car. It's closer to emulate the performance of a 90s GTP given how easy it goes in and out of corners with absolute authority and less signs of over/understeer than all the other cars on the class. It has the best pace, second worst fuel consumption, good tyre wear and is the easiest to drive, neglecting its own mass which is the highest. It kind of wrecks the class, and it's hard to understand what Reiza actually tried to do with this car. And it seems to have even more performance to untap!

Best Lap: 1:51.540
Average Laptime (average 8 second best laps): 1:52.14
Fuel Consumption Average: 3.6 Litres
Power Output: 775 HP
Top Speed: 306 km/h
Downforce at Top Speed: --32492 N; Front -18235, Rear -14257
Ride Heights at Top Speed (mm): FL 33.5; FR 33.56; RL: 28.35; RR 29.53
Apex Speed Degner 1: 177 km/h
Apex Speed Hairpin: 64 km/h
Apex Speed 130R: 283 km/h
Tyre Wear on Best Lap: FL 1.31; FR 1.60; RL 1.61; RR 1.96

Setup below

 

Conclusions

To me, it seems like the cars performance have been sort of BoP'd to bring them closer together for longer runs. Not fond of BoP for this class, and would prefer to see some tweaks like the ones proposed below:

Sauber C9: Increase full boost power, leave front downforce fixed at 0, allow rear ride height to be set 10 mm lower, decrease fuel consumption.
Porsche 962C: Set diff as mandatory spool.
Nissan R89C: Decrease power on max boost by 100 HP, increase fuel consumption, decrease ride heights by 10 mm.
Corvette GTP: Decrease power output by 100 HP, put the car on the same tyres as one of the other 3 cars.

I expect for many people to disagree and spark some debate, hopefully

 

Splendid work, just one thing: I have Stuck's setup sheet for the Noristing superprint in 88, and he used an LSD there. So late in the life of the 962C, i think teams were using either an LSD or a Spool.

 

I honestly read both, that Porsche ran it with a spool and with a LSD that can be set to be 100% locked, and it seems they were using a PDK as well.
Anyways, that's some excellent testing there. Hats off!

 

Great tidbit! That is a very good argument to leave the diff as it is

Thanks for the kind words

 

There is a boolean pick in the menu for locked diff, could be utilized for the Porsche.

 

WET WEATHER PERFORMANCE

Did a rather quick test for performance of these cars under rain. The premise was quite simple: swap the tyres for wet weather, head out on track with the very same setup, and see how the cars adapted to wet weather, with the idea of evaluating the adaptability of the cars to changing weather. I did short runs of 5 laps with each car. Same location and layout, same time in game, date 09/05/2023, weather slot 1: Rain, Medium Rubber condition. These were the laptimes I've got:

Corvette GTP: 2:10.0
Sauber C9: 2:10.4
Porsche 962C: 2:10.4
Nissan R89C: 2:11.9

The rain brings the Porsche up to the front (just like it tended to happen in real life) but pushes the Nissan down the rear. Again, the japanese machine is the most fun to drive, but it lacks longitudinal grip compared to the other 3, and can easily lock up tyres on entry, or go into a massive slide under power when the turbo kicks in.

Of the other 3, the Sauber stays engaged thanks to its mighty torque and oversteering nature that helps on pointing the car towards the inside without going a gear lower, but it's very tricky under power and downshifting into 1st gear, it's the toughest to drive of the bunch on this condition too.

Porsche and Vette are the easiest to handle on the grip, Porsche losing out thanks to the turn-in understeer being magnified on the wet, but the GTP does suffer more in braking distances with its weight.

Still, the Vette has another advantage which I forgot to mention on my previous posts: unlike its competition, it has adjustable roll bars from the cockpit, so it's easy to tweak those to adapt to each condition a race will throw to you, something its competition cannot.

My thoughts on the Conclusions part remains the same though.

 

One more thing to consider regarding this class...

All cars have a low drag version. In the case of Porsche, Nissan and Sauber, that is the bodywork specification that was used SOLELY at Le Mans. It was of no use on any other track, as it was target for the extremely long straights. Even for 1990 with the chicanes those bodyworks were of no use anymore.

In AMS2, we are using those versions for every fast track. Daytona Road Course, Monza in all variants, old Hockenheim, ovals, etc. Where I would like to see a change is at restricting this bodywork to less tracks:

High Speed Ovals: Fontana and Indianapolis
Old Monza with no chicanes

And I think that's it. These cars, even when going to fast tracks like Daytona or Monza, they kept the Sprint bodywork version. In game, we get limited performance as we are forced to drive them here, and lose massive corner speeds. I would either limit the LDF versions to the very few mentioned tracks, or have them all available for selecting anywhere.

 

Bumping this thread back to life to state the following: if you thought the 962C was a bit too easy on the last public release, you should trial it again. It has become quite more lively and difficult to handle!

When I have the time I will re-run these tests and see where does each car of this class stands now.

 

I still haven't tried the group C's yet. WIll do it soon!