Group C cars grip under acceleration

Tried to donut the C9. All the drama was happening on only one wheel the other was just calmly rotating at road speed. I thought the diff should be locked up in this situation?

 

Last night I jumped on the C9. Exact same conditions as with the 962C test, with 51 liters on the tank and Soft tyres. Here are my thoughts on the parts of it that I could test and get a look at.

The Sauber was a very pointy car at all speeds before the update, and with more torque than what the chassis and tyres could handle it seemed. The way of driving it, was to avoid excessive oversteer. Understeer could more often than not be overpowered with right foot, which went against the typical traits of AMS2 type of driving. And in some ways, handled more like a heavy open wheeler than an endurance prototype.

The 1.5 update sees a different type of car. On high speeds it's quite understeering now, and you cannot just get your butt out of those situations with torque, or go with higher gears and expect for the car to stay on the road. As with the Porsche, it requires more finesse on corner entry, and you cannot take Raidillion and Blanchimont flat out, demanding chicken lifts to scrub speed and load the front tyres just enough. But on lower speeds, the car transforms itself. Braking zones become quite tricky with your technique as you can either lock up the fronts or overpower the rears downshifting, the tyres chattering and spinning on each gear down and the revs bouncing madly and asking for forgiveness (get religion). If overdone and not tidy, I would get into La Source and the Bus Stop sliding around. And while I could get on the power rather quickly and run away on the former, at the latter it was a much trickier appeal, and could not hammer it completely after clearing the whole corner and settling into the fast left hander that takes you to the line.

Power output at default 85% boost was 832 HP, which I think is an increase from what it had in the past on the same levels, although according to devs here, engine curves were not changed. Still, if this is a 1989 spec, it should hit about 920 HP at 100% boost, and shown as 1.2 bar boost in game (if the car had a visible gauge on the cockpit that is), and roughly stay at 770 HP with 0.8 bar boost (if this works linearly in game, it would be 65% boost), but meeting the fuel quota of 51 liters per 100 km or coming close to it (data taken from John Starkey's book on the Sauber's development history). As it stands, it burns around 4.7 liters per lap, and that translates to 67 liters per 100 km. In comparison, the 962C at 85% boost (I think it displays 1.1 bar on the gauge) burns 4.2 liters per lap, translated into 60 liters per 100 km. It would seem like the Porsche has an advantage here, but it's 3 secs per lap slower, so the Sauber has more than enough margin on its pocket to cover it. That gap is not only due to power: the C9 is a stiffer chassis with a way more tight and precise way of handling, and while I did not try it, I'm certain that this car has more pace hidden with setup tweaks, as it was harder to chain consistent laps on it, but the optimal laptime kept going down and down.

Pleased to see that straightline speed has been reduced. Topspeed on my best laps was 307 km/h, some 6 km/h down on before the update, and that was running 10% less boost!

As with the 962C, tyre temps stayed quite low, never hitting 80C at any corner, and the fronts struggling to stay over 60C. Perhaps it's why the car kept a rather mean character, and on better conditions and maybe 10C more on the rubber it may stabilize itself. With a rather low rear camber of -1.0 on the setup I expected for tyre to not spread itself enough, but telemetry showed a +4 degree spread on the rears. Don't know how much you can gain by putting more and what issues you may find pressing further, but maybe the Sauber has more dynamic camber gain at speed than the Porsche? That one comes with -1.5 out of the box and has similar temps after a run. Now, I don't know if Reiza wants to simulate the historic tyres and brands that cars used back then, or the vintage tyres the cars get for the vintage car races run nowadays. But if they are going for the former, Porsche and Sauber should not run on the same tyre as they do nowadays, and I think it's the Sauber which would need its own tyres, which overheat more and cause oversteer as more laps are done, as that's the trait the Michelins had in 1989, and could catch their great drivers out and make them spin. And if it's the latter and cars would run on vintage tyres of present day, all 4 cars would need to run on the same tyres.

As it stands so far, I frankly didn't find any big flaw driving it, and was honestly impressed. This is the best rendition of a C9 in game that I ever tried, and dare I say it, the very first I got my hands on that felt convincing for what I think this car should be (take it with a grain of salt of course). Things that strike me as still wrong are in the setup page: there is a variety of front downforce options, and this car on the HDF trim always used the same splitter throughout a season, only switching to a smaller one for Le Mans, but that is LDF trim and a different car in AMS2. If I was John Reiza, I would remove the adjustments, and leave the downforce generated of the front splitter at the default value of 1.00. Another user stated that, according to Ian Bamsey's book (wouldn't surprise me if it's more complete than the Starkey's that I own) this car did not use rear ARB. Maybe it could be removed, or just left at a fixed value and disallow change if the physics engine needs something on its place to properly simulate chassis stiffness?

For coming up with more detailed conclusions, I would need to run more laps at different boost levels and see what numbers do I get, plus run on the Hard Tyres (which I think would be better for simulating race scenarios). Also, try setup changes. And obviously, more tracks and different weather settings. But instead of going through that log (I'm not a beta tester!) I will jump on the Nissan R89C next time out and see what impression it does make on me

 

I try to find videos of the c9 in races back in 89 and that’s been hard to find, probably not impossible with more time. The vintage races we see plenty on YouTube and more of the c11 then c9. The c11 had revamped suspension and made it handle better. So what you’re saying is the vintage cars we see run now and the tires in ams2 are not vintage but new rubber that means “stickier” It is what it is but I’m just comparing to pre build and I guess the new build is more realistic ‍♂️ There’s a saying or statement; Doing something and in this case driving the previous build then the new build you feel it’s off. Problem is you’ve been doing it long enough (wrong way) and when given the right way, you think it’s wrong because only thing you had to compare was wrong lol

The Sauber was a bit late too the show but it did dominate at the end of that group c era. Do you think Porsche wasn’t really interested in the end to invest to compete?

 

Need to sit down again to properly reply to this, but for now, have some footage of onboard C9 at an historical racecar meeting:

As the run goes, he seems to get on the throttle earlier and more abrupt. And he's not pushing, there is not a hint of even a small correction on the steering wheel nor lift on the throttle. He's just pointing and squirting, navigating around the racetrack with leisure.

 

Damp track I know, but at 14:00 you can see what happens when you apply too much throttle and the boost kicks in "you have to be on your toes in this":

 

You see him reach over and adjust the boost, we don’t really know how much he was running. His corner entries were pretty conservative. It was hard to watch and hear the rev matching or laxk of. I need to find an incar of a c9 in a race in 1989

 

looking through his channel he never went back out for another session. What an opportunity he had driving the iconic c9

 

The second video I posted on page two of this thread is him at Donnington in the dry.

 

Here’s some good information on the c9 engine. In race trim it was detuned quite a bit



The 5 litre, twin-turbo Mercedes-Benz M119 engine was retained from the older car and was sourced directly from the Mercedes engine facility at Untertürkheim.

It was developed by Willi Muller and Gerd Witthalm and was returned to Stuttgart after every race, the transmission remaining at the Sauber facility at Hinwil. In race trim, it was tuned to produce around 720 hp, which gave the best combination of power and efficiency for Group C, which was a fuel allocation formula.

 

Motorsport.tv has the Duke Video collection, and you have the full race broadcast of those WSPC seasons. I plan on getting a suscription there just to access those races.

It was a bit more than a revision: while the C9 was an aluminum reinforced with kevlar monococque, the C11 was a full carbon fiber chassis. Which of course leads to suspension revision, as the chassis got much stiffer with that development. The other big gain was that they switched from Michelin to Goodyear for 1990, which were reckoned by everybody as the best tyres in the business back then. TWR Jaguar did the same switch, but from Dunlop. It was also the opportunity to revise the aero in all fronts possible, but the concept of it did not change. So it's hard to draw comparisons between the two, all things considered.

The Historic cars are usually fitted with tyres that are built to a vintage spec, the ones I saw the most are from the brand Avon. But the end result is not exactly the same and some differences can be found. Which one is grippier or has more tyre life, I cannot say. But I do know that there is a difference between the two.

Well, at some point it happens to most of us, right? We cannot help to compare it with other sim or a previous build, and believe that the new way is wrong because our previous ways became second nature. It's hard to escape that mental trap, and a conscious effort is required for it.

I wouldn't say they were late to the party, but it took a while for the program to gather momentum. The partnership with Sauber was already in effect in 1986, and they did win a race with the C8 that year. The C9 came good in 1988 and could have achieved more if it wasn't so tyre limited against the Jaguars.

Porsche on the other hand, have been dominating for a good while by then. Won every Le Mans from 1981 to 1987 (a winning streak that is yet to be beaten) and won every championship from 1982 to 1986. Their program was not run on a huge budget: the engine was basically the one that was bound to be scrapped from their Indianapolis effort that got cut short before taking off due to the CART vs USAC war; the monococque for the 956 was quite rudimentary in technology and execution; the aero concepts had a development time measured in months and using windtunnel with fixed floor instead of a rolling one, etc. By 1987, Porsche had ripped tons of benefits from it, even earning a lot of money from selling customer cars at both US, Europe, and Japan. For beating them in both the championship in 1987 and Le Mans in 1988, Jaguar needed a much bigger budget, built an all new car with a carbon fiber monococque, spent lots of time in the wind tunnel, hired a plethora of top notch drivers with F1 background, setup new workshops, etc. New fuel rules for 1987 banned the used of toluene based additives for the fuel, which hurted the flat six engines and benefitted cars with no forced induction like the big cat's V12 engine.

For Porsche to overcome all of this, they would have needed a brand new design with a brand new engine, build a new monococque out of carbon fiber, employ more drivers and engineers, get sponsors to invest more money (Rothmans left them during 1987), spend more money out of their pocket, etc. And that would have just been to keep on winning all that they had won before, so they were hitting diminishing returns for a much higher investment.

So, having conquered the sportscar world (on a set of rules that were supposedly setup to stop Porsche from winning), conquered F1 in the heist of the turbo wars, and having the FISA cut short the plan of entering Group B with the 959 on WRC due to the ban of the class, Porsche fancied a second go at Indianapolis, and moved resources into that program, which was put in motion in 1987. They did not even finish the WSPC season that year, and with a good package of sponsors, they made one last official go at the 1988 Le Mans, losing out by not that much in a titanic scrap against Jaguar. That year they put together a car that was squeezed to the absolute maximum of performance it could reach, and it was an amazing feat considering the car's age: the power was squeezed to 880 HP for Q runs. Being 45 HP down on what the C9 achieved the year later, and with a car that stalled at high speeds and couldn't keep on penetrating the air further than 380 km/h (it was a design for around 250 HP less), Hans Stuck's pole time was just 6 tenths slower than the 1989 pole achieved by Schlesser.

 

Now that I have done further testing I seriously don't know what C9 some people are driving...



It's not the C9 I've watched a lot of footage of or driven in anything else... 1st, 2nd and 3rd gears are not an issue of any such wheelspin throwing me off the track... There's no need to think with my right foot with over 1000nm of torque... It suffers from the issues that I described in the physics thread on a much higher degree than anything else...

Throwing junk set ups at it with 0 toe at the rear, full ARBs, 2 wing at the front with 4 at the rear and stiffer slow rear bumps didn't make cold hard tyres any more difficult to just floor it like it was a GT3... Softs were a little more of an issue when cold, but not enough to say it was in the ball park... But heated up... No issues with treating the throttle like it was an on/off switch...

Overall I just felt like as long as it wasn't a 3rd or 4th gear corner I could just throw it at the apex and it would stick then drive it like a rally car out of the corner with my foot doing what I'd do in a GT3 with traction control on... Very similar to what I found in the F3 at Jerez...

My testing was largely at Donington and Laguna Seca... At Donington there was no penalty for flooring it out of the hairpins, redgate or the chicane... Only issues at McLeans and Old hairpin if you go too deep... Laguna was just a bit boring other than the corkscrew... Which I could hear the wheel spin but I didn't suffer the punishment for being a hoon for... And T5 and T6 because they fell into the category of the 3rd and 4th gear corners...

I'm going to compare to the 1989 Sauber C9 because that's what I've been focussing on... Here's a few major things that will be changed for the modded version if Reiza is focussed on another year with this car... Their car weight is for 1989 but the engine is for 1988...

Tyres...

Porsche never ran the Michelins that Sauber ran in 1989 in either 1988 or 1986... Yet the 2 cars currently share a set of tyres...

The current soft tyres do not have any wear issues over a fuel stint... This was the first car that I found rear limited wear but there was still more front limited grip loss from the wear... The rear limited grip loss after 30 laps of Donington was minimal... I might be able to double stint the softs at some circuits...

The C9 had a very high tyre deg that year... Great peak performance in qualy but really struggled against the rest of the pack in the race runs to keep the tyres...

Realistically the softs shouldn't last half a fuel stint before needing to be changed and the hards should last 1.8 fuel stints on the high deg circuits...

Engine and turbo...

I have reports of north of 920bhp in qualy trim with this car... The current turbo is also the same as the Porsche... It needs to have the properties of the Nissan engine and turbo just with a Mercedes twist...

The fuel numbers of 1989 which were 51 litres per 100km need to be found at 66% boost and it needs to produce 780bhp at this boost number... Which is what these cars would run in the race... Anything above that needs to kill the engine... You should not be able to run north of 70% boost for long with this car... And 100% for no longer than 5 laps... Not hours on end like you can now...

It also needs a button like the Lotus 98T for full boost at the control of the driver... The C9 of 1989 had a p2p...

Aero

It has a lot of aero at high speeds and it ramps up in an odd fashion in grip with the front gaining more... This was also found before the update... Here's some feedback from a pre 1.5 version of the Sauber C9s aero... Someone might find this very familiar...

My first course of action would be to remove some of the front aero... And also remove the options in the set up for it... Unless they were stuffing the air intakes there wasn't tuning vanes on the C9, so there shouldn't be any tuning options on the front wing either... Then run a lot of telemetry runs to see if I can find the source of the centre of aero pressure issue...

I have been running with a blank set up, only Simhub and Crewcheif were running so I haven't looked at telemetry but the same aero feel in 5th and 6th gear corners is there...

With the current tyre grip I'd probably also knock 25% out of the overall aero numbers to try and knock a second out of the laptimes at Spa...

Brakes

The front brakes heat up and start losing efficiency too early for the carbon brakes that they ran...

This version has vastly improved brakes over the previous version, so my main focus would be on improving the heat gain and lengthening the working range... As they did actually have vastly better brakes in this is more on the money... I also think the brake deg is in the ballpark for a long race as they did need to do brake changes at Le Mans because they suffered from higher brake deg than the competition...

After 30 laps at Donington I had over 15% brake deg at the front... That seems about right, might be a little low but would need testing for longer hours... I would aim for a brake change every 3 hours at a track like Spa...



I can see why so many are upset with how this car is currently represented... Historic content is Reiza's speciality... It's what has so many drawn to AMS1 and AMS2... I'm not happy with it's current representation and how I have to drive it...

A lot of the issues I have with it's representation were there before the 1.5 update, but it was a **** tonne of fun to drive... So I didn't really care about them enough to make such a long post about this subject...

 

TLDR?

 

This C9 isn't something I'd expect from Reiza and their historic content... It's not a C9...

 

So it needs to be harder?

 

It needs to drive like it's a C9... Not a car with traction control...

 

Great info. Well above my pay grade and non engineer mind. So the bases setup @ 85 boost should blow within 10 laps, is what you’re saying

 

Remember those “kit cars” A lot of Lambos with VW power trane under the fiberglass body. I think there’s a GT3 guts under side now j/k

 

Even if the Sauber was driveable IRL there is still something weird going on with it and with many other cars post 1.5. Like @Scar666 says they feel like you're racing a modern GT3 with aids enabled atm, not very engaging at all just throw the car into the corner, stamp on the throttle and always exit fine.

We're actually racing GT3's tomorrow in AC, and they feel more challenging and engaging to drive even in comparison.