jgf, on Mar 14 2014 - 08:27 PM, said:
(sources unknown ...long forgotten):
"You can try any chassis type at any track by putting in one of the numbers below.
1 = superspeedway with restrictor plate
2 = speedway
3 = short track
4 = road course
5 = superspeedway without restrictor plate"
"0 = short track
1 = mile oval
2 = medium oval (1-2 mile)
3 = long oval (think this is the 2 mile)
4 = super speedway
5 = road course
0 = ?
1 = super speedway
2 = speedway
3 = short track
4 = road course
From testing at Talladega -
Chassis 0 - high drag, huge torque, tires never wear out, top speed around 190.
Chassis 1 - low drag, low HP, fixed rear springs, shocks and spoiler, top speed around 185.
Chassis 2 - medium drag, top speed around 210.
Chassis 3 - medium drag, top speed around 205.
Chassis 4 - medium drag, top speed around 205.
Chassis 5 - minimal drag, doesn't like to turn or stop, top speed around 240."
Those are my words :-)
At the time, I was referring to the chassis by the 'speedway' or 'short track' names but after looking and testing, they would be more correctly called the 'banked' or 'flat track' chassis since chassis 2 is used the banked tracks, including Bristol, while chassis 3 is used at Pocono, Indy, Homestead (original), Martinsville and Richmond. Track length doesn't matter so I no longer call chassis 2 the 'speedway' chassis. :-)
I've done more testing since that write up. Your results may vary.
CORRECTION and UPDATE 02/12/15! - I have changed the track# (at an oval) and saw no difference in anything so I'm thinking it might just be used to identify the track so the AI knows which ratings to use and also for the 'officials' to know how long to keep the yellows out? I have no idea how it's determined if the yellow will fly or not but I have been at short tracks, had a big mess and no yellow, while at a bigger track, somebody spins into the infield and the yellow flies. It might determine that but checking yellows is difficult and very hard to get people to join in for.
I changed the track# at a road course and the car pulled to the left! Also, the tires wanted less psi on the left side. The car looked to be sitting at an angle, right side lower than the left, from the cockpit. This is the first time I tested with the track # 0 at a road course and the first time I encountered the pull to the left at a road course. With every chassis and the track set to 5 (road course) I never felt the car pull left.
I haven't tested offline races and know smaller tracks have more caution laps, 4 or 5, while bigger tracks have 2 or 3 and road courses give the "we're going green" after 1 whether there are lapped cars of not.
I haven't seen a difference in tire pressures, handling, tire wear or fuel mileage when changing the track # so I have to think it's something that doesn't affect the car.
As for the pull to the left.... Maybe the engine torque makes it pull left? I haven't tried testing that yet.
Test results are below. Top speed and HP were fro the NR2003 Replay Analyzer and drag is how many seconds the car too to coast from 170 to 140 MHP on the back stretch of Talladega. I come off T2 and hit the clutch and let it coast, then check the replay for the time and speed. Higher numbers are 'good', lower numbers are 'bad'.
I have yet to check the body height to try to guestimate the amount of downforce each chassis provides but since chassis 0 has the most drag and is the easiest to recover (nearly impossible to spin that thing) and chassis 5 has the least drag and will snap around with little effort, I'm pretty sure the drag is caused by downforce.
Test track - Talladega, clear skies, 70 degrees F and no wind. Top speeds in MPH, drag number rounded to nearest second.
Chassis 0 - Mystery car - Huge torque, huge drag, likes the psi 42 all the way around at all tracks, tires never wear out unless you have pits set to 4x and slam the brakes and hold them there. Then you will get them to wear. Idles at 800 RPMs while the other chassis idle at 1000. Get really bad fuel mileage. Has the same HP for all chassis.
Cup - 745 HP, top speed 189, 5 drag
GNS - 745 HP, top speed 187, 5 drag
CTS - 745 HP, top speed180, 7 drag
PTA - 745 HP, top speed 192, 5 drag
Chassis 1 - Restricted Aero - low drag but fixed spoiler, fixed rear shocks, fixed rear springs, left side track bar can not be higher than the right side. Likes the psi at 28/48 at ovals, 48 all around at road courses - stable at high speeds, low grip at low speeds.
Cup - 370 HP, top speed 189, 9 drag
GNS - 342 HP, top speed 181, 9 drag
CTS - 550 HP, top speed 181, 6 drag
PTA - 625 HP, top speed 212, 7 drag
Chassis 2 - Banked track - Medium drag, downforce on the nose, rear feels a bit light, likes the psi at 28/48 at ovals, 48/48 at road courses, stable but a bit 'twitchy', sensitive to steering input -
Cup - 635 HP, top speed 208, 7 drag
GNS - 623 HP, top speed 206, 8 drag
CTS - 562 HP, top speed 186, 6 drag
PTA - 625 HP, top speed 210, 6 drag
Chassis 3 - Flat track - Medium drag, even downforce, maybe more side force, likes the psi at 22/34 at ovals, 34/34 at road courses, stable, easy to recover -
Cup - 637 HP, top speed 203, 7 drag
GNS - 622 HP, top speed 202, 7 drag
CTS - 562 HP, top speed 185, 6 drag
PTA - 625 HP, top speed 207, 6 drag
Chassis 4 - Road course - Medium drag, even downforce, maybe more side force, likes the psi at 22/34 at ovals, 22/22 at road courses, stable, easy to recover -
Cup - 640 HP, top speed 204, 7 drag
GNS - 622 HP, top speed 203, 7 drag
CTS - 562 HP, top speed 185, 7 drag
PTA - 625 HP, top speed 207, 8 drag
Chassis 5 - Unrestricted Aero - Low drag, stable at high speeds, low grip at low speeds, likes the psi at 28/48 at ovals, 48/48 at road courses, left side track bar can not be higher than the right -
Cup - 706 HP, top speed 232, 11drag
GNS - 622 HP, top speed 226, 11rag
CTS - 574 HP, top speed 190, 7 drag
PTA - 625 HP, top speed 212, 6 drag
PTA car appears to be least effected by the chassis # although I have to admit I have the least experience in it and it took many attempts to get any data because I'd wreck or nearly wreck every lap. Just not at all used to it. :-(
Chassis # affects when the tires go yellow and red as well. Chassis 4 tires go yellow at 220 and red at 240. I think chassis 1/5 have to be at 240 to go yellowand 270 to go red I can't recall and haven't recorded those numbers yet.
So, those are the numbers I've come up with. I hope more people share their results!
Edited by ZiggyM, Feb 13 2015 - 12:55 AM.