Released July 2022 Release Candidate Now Available

EricW said:
Simple accurate explanation:
When the accelerator pedal gets released, the air intake valve is closed and a vacuum is created, which prevents air flow from getting to the cylinders. There’s a decrease in energy that starts to create a braking force, which helps slow down a vehicle by lowering the engine speed, or RPMs.

Resistance in the engine is transferred through the drivetrain to the wheels. Some of the braking force produced is from friction in the drive train, but most of it is caused by the vacuum that was created from the lack of air.
The result is a process that helps slow down a vehicle without the use of a footbrake.

Shifting to lower gears without protection will most likely cause a amount of vacuum that destroyes gearbox or moving engine components.
Click to expand...
Not sure if it's how it works. If you just not let air into cylinder, then on "intake" phase it creates vacuum - correct, but on "compress" phase vacuum actually helps to increate engine speed. And then question remains - what you do on "burn" and "exhaust" phases?

I heard somewhere that, what happens is multi-step process. First, you stop igniting the fuel. (fuel get's burned in exhaust pipes, you get bangs and flames). Then you still let air in on "intake" and stop injecting fuel (at least partially) in, thus starting to "compress" air. More effective that creating "vacuum". On "burn" you do nothing. On "exhaust" just let compressed air out. Obvious fuel savings.

If you wan't to be more pro-active. Inject some fuel on "compress" and just burn it earlier, before phase is done, getting dramatic stopping force. But, you burn fuel. On the other hand you can partially open the valve on "compress", controlling how much pressure (and resistance to compression) you get.


As for over-rev protection. That's easy - 1. every component has a rotation speed limit. 2. there is limit to how fast springs (and hydraulic actuators) can work. So, if engine rotates too fast, there could be 2 results. 1. valve is unable to move away in time and is hit by piston. 2. something in engine (gears, shafts, etc) rotates too fast and breaks apart.
To avoid that, computer calculates projected engine speed from gearbox driven axle rotation speed and gear the car is in. If the number is too high - gear shift is rejected.
 
bug info
 

Attachments

  • 20220801002619_1.jpg
    20220801002619_1.jpg
    116.8 KB · Views: 234
Engine brake is due to the compressing without fuelinjection and ignition.
Sometimes within engine brake phase during off throttle phase/ignition cut phase for shifting there are extra injection cycles to prevent turbo from spool down. So it is possible to hold boost pressure even when off throttle. (Antilag system - you can hear it on a lot of racecars. For example new beetle rallycross, M8 GTE).
There is one more thing over evi's correct things that can happen while misshifting. When grip of wheels is low compared to strength of engine and drivetrain, than possibly C.) wheels are locking without further damage. But this is not really common.
Most times engine would brake, driveshafts break or clutch is slipping.
 
I showed a simple explanation, without going full in depth on every variety or subsystem...
On topic point is that the RC has not introduced a engine brake bug of some kind imho.
 
But anyone know a way to get exact numbers for engine braking torque ? Probably only engineers that design these engines. What I was trying to say before is that they probably also have power of design to allow certain amounts of vacuum sealing, so they can design an engine that engine brakes more or less probably. Obviously one side of this is to prevent engine damage, other side is to prevent wheels from locking up while off throttle. If I was racecar engine engineer, especially in classic era, it would make most sense to allow as much engine braking that would add most braking force while being still controllable for a driver.

One interesting observation from one guy - in his experience lower displacement engines usually had stronger engine braking. His theory is that it is due to lighter engine components having less inertia.

Also one interesting bit slightly relatable. While modding I was very surprised to learn from people, that pre-70s cars almost none ever had rev limiters. Let alone downshift protection lol. So you could rev till valves start floating, or till engine go boom. It was extra surprising to learn, because almost always simacing cars of those years has rev limiters... as if no one would know its unrealistic for a time period. It actually adds to the immersion quite a lot, and it is one more task for a pilot to manage, so there is beauty to it. Taming 917K above its limits while being few hundred rpm from destroying the engine is something... And rF2 is capable of nicely simulating engine durability, but most content does it very generic way.
 
mantasisg said:
Also one interesting bit slightly relatable. While modding I was very surprised to learn from people, that pre-70s cars almost none ever had rev limiters. Let alone downshift protection
Click to expand...
I have read that the Mclaren Can-Am cars would use a Magneto cut-off to limit rpm. Usually well below the absolute redline.. I do not know how that functioned.
 
@mantasisg since rF1 the engine file has had a comment suggesting to set the rev limiter to around 40k RPM if no limiter is present. (the game needs a limit)

I think many people are/were aware that many cars (not just pre-70s) don't have limiters. I can imagine people mostly confined to modern formula cars might not have expected it though.
 
[QUOTE="mantasisg,

Also one interesting bit slightly relatable. While modding I was very surprised to learn from people, that pre-70s cars almost none ever had rev limiters. Let alone downshift protection lol. So you could rev till valves start floating, or till engine go boom. It was extra surprising to learn, because almost always simacing cars of those years has rev limiters... as if no one would know its unrealistic for a time period. .[/QUOTE]

In an interview I've seen recently, Lauda said about '70 F1 cars : if you run 100 rpm below redline you were going slow, if you went 100 rpm above you would broke the engine.
Not a lot of range to race a car. :D
 
Is there some known issue with the new Porsche Cup tyre model in the RC? The tyres seem to overheat very quickly in a simply slide, hitting unphysical surface temperatures of 300+ C:
20220801212338_1.jpg
 
azaris said:
simply
Click to expand...
The temperature is a peak temperature, but indeed very high, maybe to high.
But a simple slide can make them melt, melts around 180C and when the wheels are locked you have huge flatspots as a result.
It gets rubbed of instantly and can ruin your race.
Realistic.
 
Leynad said:
Nice when it once really works, but two total Windows-crashes (McLaren GTR @ Brands, Porsche Cup @ Laguna) and one CTD within four launches and minutes into a session I wouldn't call "Release Candidate". I wouldn't even call 'beta'.
Click to expand...
Now I can't drive 5 laps without a CTD, usually happens in the first or second lap and it's also happening in the non-RC-version. WTF?
 
davehenrie said:
are you using an AMD card with any driver past v22.5?
Click to expand...
Nope, RTX 3080 with latest drivers and with the old ones before the same problems. All with official S397-content and it starts as a screen-freeze while everything else is going on. I can even pause the game, but on escape I get the CTD and during private practice. Otherwise: SC2 Pro or VRS DFP doesn't matter, Sim Commander running my GS-5 with G-Belt and SimHub my 7 shakers. All was working before without those freezes.
 
You must log in or register to reply here.
Back
Top