1984 GMSA 24 Hours of Ellisbury
The brief
The year is 1984, and the Gasmean MotorSport Association (GMSA) is once again hosting their annual flagship event; the 24 Hours of Ellisbury. Taking place on the GT layout of the Ellisbury circuit, this endurance race will feature cars in the four classes of the GMSA Caval GT Series, ranging from modified production cars to full-fledged prototypes. These racers will run twice around the clock in a spectacle perhaps only second to Fruinia’s 24 Hours of La Marche.
This is a homologation and racing challenge which will run in two phases; the first will see entrants submit their production cars and prototype engines for homologation, and the second will produce the race cars which will actually participate in the race.
The two phases both have open entry; someone does not have to have submitted in Phase 1 in order to enter Phase 2, and should, in theory, have a pool of already-homologated cars and engines to choose from. I also recognize that people may not want to share so offering your work to other teams will be opt-in. At the end of Phase 1 I will make a master homologation post which will include links to .car files for “privateers” to use in Phase 2.
Some visual design elements are part of series regulations and will affect homologation, and entrants are strongly encouraged to make their cars look attractive and era-appropriate. Interior design is not required, however, if included should reflect the car’s engineering choices (i.e. production car-style interior for the road car, racing interior w/ roll cage [if applicable; prototypes often have the crash structures built into the bodywork], fire extinguisher, etc for the race car).
Design inspirations have been provided for all classes; consult the host if you’re still unsure. In general, I would much rather see a clone of a real car than an original design that looks wildly out of place for the early-to-mid-1980s.
Advanced Trim Settings may not be used to change the wheelbase or wheel and tire dimensions. Modification of suspension height is permitted, but please only do so if the body used does not support a realistically low ride height (looking at you LMP80s). Modification of chassis track width to accommodate larger tires is permitted within reason, but don’t get silly with it. Ask the host if you’re unsure about any other advanced trim settings.
Cars of all classes must have fixed roofs, both visually and stat-wise.
Open wheel mod bodies and bodies from the legacy mod are banned.
A single resubmission is allowed in each phase if your car or engine fails homologation.
Participants will be allowed two entries, which must be in different classes.
Entry Format
Model and family names: 24HE - username (e.g. 24HE - IncredibleHondaFit)
Trim and variant names: car/engine manufacturer name of car/engine (e.g. Nissan GTP ZX-Turbo,Ford-Cosworth DFL).
GTP cars should include their engine manufacturer (if different from the car manufacturer) in the trim name, in the following format: car manufacturer name of car - engine manufacturer (e.g. Spice SE92P-Chevrolet)
Race cars submitted in Phase 2 should include a team name in the PM.
.car files should be sent by PM here to me (incrediblehondafit).
Engine submissions should be put in a placeholder car and sent as a .car file.
Homologation
Entries in the GTO, GTU, and GTX classes will be required to submit a production car in the first phase of the challenge. Entries in the GTP class will be required to either submit an engine in the first phase, or use a successfully homologated engine from another entrant (the host may also provide some optional engines for entrants to use). Variant and trim years must be set to 1984; model and family years should be no earlier than 1969.
Unleaded fuel is the only permitted category for cars in the challenge (including homologation engines).
Techpool
Engine:
$10m for production-based engines (and engines in production cars)
$20m for racing engines (GTP type 2 and 4)
Car:
$20m for production cars
$40m for GTU,GTO
$50m for GTX
$60m for GTP
The minimum for any tech is 0. A maximum of 5 negative quality slider points can be distributed across each of car and engine.
Production cars
Summary
Production cars must have a normalized desirability of 60% in at least one of the Sport demographics (any demographic with “Sport” in the name except for Utility Sport and its variants, as well as Muscle (Premium), Pony (Budget), GT (Premium), Fun(Budget, Premium) and Super.) when the sell price is set to the “estimated cost” in Detail Stats, and must have more than 100 total sales. Production cars cannot use any parts prefixed by “race,” or any of the parts defined for racing engines in “Engine Homologation” below. Production cars must use unleaded fuel with a maximum octane rating of 90 AKI/95 RON (Premium), and include a catalytic converter and at least one muffler.
Visually, production cars should appear road legal, with all the expected lights, wipers, fuel cap, etc.
Engine Homologation
Summary
Engines for GTP cars belong to one of four categories (see sporting code for details). An engine is defined as a “race” engine for homologation purposes if it includes one or more of the following:
aluminium billet or magnesium engine block, billet crankshaft, titanium conrods, race intake, race headers, fuel requirement above 90 AKI/95 RON Premium.
All four-valve engines also belong to the same categories as racing engines for GTP homologation purposes. Production-based engines must be submitted in production trim, including a catalytic converter and at least one muffler.
Racing Regulations (cheat sheet):
See the excerpt from the Gasmean MotorSport Association’s 1984 code for more details.
All racing entries shall use Radial Racing Medium tires, and 95 AKI/100 RON Ultimate fuel.
Toe in/out for race cars is globally limited to 0.5 degrees in either direction.
Tire quality for race cars is fixed at zero.
Race cars must use Standard/Advanced 80s safety.
Cars in GTU and GTX with less than 2.8l standard displacement shall have 110-liter fuel tanks, and cars in GTO, GTP, and GTX with greater than 2.8l standard displacement shall have 120-liter fuel tanks.
Remember that turbocharged engines always count as 1.4 times their displacement for regulation purposes!
Tool for calculating a car’s minimum weight
Classes:
GTO, GTU
Summary
- GTO consists of cars with standard displacement over 2.8 liters, GTU under 2.8 liters
- Minimum weight: See the weight scales in the sporting code, or the weight calculator; GTU minimum weight should never be below 1600 lb and GTO minimum weight should never be below 2083 lb, or 1770.5 lb for cars with pushrod engines.
- Allowed engine modifications:
- Engines with a displacement of 2 liters or less (after turbocharger multiplier) may have their cylinder head replaced with a 4-valve head (to achieve this, clone the engine family.) Note that changing to a 4-valve head will affect the car’s minimum weight. The engine block must remain the same, including both material and family dimensions.
- Engines may be bored, de-bored, or de-stroked to change their displacement. Crankshaft, conrod, and piston type are free, as is engine balancing.
- Top end is free, but VVT/VVL settings must remain the same
- Turbochargers are permitted only if the production car was submitted with a turbocharger, and only a single turbocharger is permitted; turbocharger design is otherwise free.
- Fuel system is free, with the exception of mandatory 95 AKI/100 RON Ultimate fuel.
- Exhaust system is free.
- Allowed body modifications (see sporting code for additional info):
- A single front lip (from the “lip” aero category) may be added but must not protrude beyond the front of the body.
- If the production car was successfully homologated with a spoiler, that spoiler may be maintained. Otherwise, a single rear spoiler(not a wing) may be added. Visually it should not allow air to pass underneath.
- Fender flares may be added. (includes both body morphing and fixtures)
- Other minor modifications including removal of non-integrated bumpers and trim pieces, and addition of racing livery, tow bars/hooks, etc, are permitted.
- Exhaust tips must be located behind the passenger compartment.
- Drivetrain design is free, but engine and gearbox must remain in the same position and orientation as the production car (e.g. front longitudinal, mid transverse)
- Wheel and tire regulations:
- All four wheels must have the same diameter.
- Maximum wheel/tire section widths are as follows:
- Cars under 3000cc: 330
- Between 3000 and 5000cc: 355
- Between 5000 and 6000cc: 380
- Above 6000cc: 405
- Brake design is free.
- Race diffusers are banned. Active aero and cooling flaps are also banned.
- Any additional seats may be removed and the interior type may be changed from the production car to either Basic or Race. Entertainment system may also be removed.
- Power steering and traction aids are permitted.
- Suspension design is free, but driven solid axles must remain solid and independent driven axles must remain independent.
GTX
Summary
- All modifications permitted by GTO and GTU are also permitted in GTX.
- Chassis type and material may be changed, but body material cannot. (To achieve this, clone the model. You still must use the same body used for the production car)
- Hood scoops may be added.
- Aerodynamic devices may not extend wider than the car as viewed from the front. The rear wing may extend up to 4 inches higher than the bodywork. Front splitters/air dams may not extend beyond the car body by more than 10% of the wheelbase, and rear spoilers or wings by more than 20%. Aero fixtures may come from any of the three fixture categories. All aero fixtures on the car must be visible, and “stacking” of aero fixtures is banned. Maximum of two aero fixtures on the front, and three on the rear. Active aero and cooling flaps are banned.
- Engines must be based on the production car engine unless another production-type engine is submitted and successfully homologated (as with GTP engines), with the following additional allowed modifications:
- Cylinder heads are free for all engines, including both material and valvetrain (except for pushrod engines, which cannot be changed into OHC and vice versa)
- Any engine with a standard displacement under 6000cc (after turbo multiplier) can be turbocharged
- Maximum wheel/tire section width is 405mm for cars under 5000cc, and 455mm for cars over 5000cc. Wheel and tire diameter is free.
GTP
Summary
- Maximum dimensions: length of 480cm x width of 200cm
- Total front plus rear overhangs must not exceed 80% of the wheelbase, and may not differ from each other by more than 15%
- Homologated engine allowed modifications:
- Engines may be bored, de-bored, or de-stroked to change their displacement
- Bottom end and top end changes are free, but engines must not change their VVT/VVL status
- Fuel system must remain as homologated for engine types 2 and 4 (although manifold size can be changed), with the exception of changing fuel type to 95 AKI/100RON Ultimate. Type 1 and 3 engines can be modified as with GTU/O engines.
- Exhaust system is free.
- Type 3 (2-valve, production-based turbocharged engines) are restricted to a single turbocharger
- Cars must have two seats in a single row, and a race interior.
- Active wing and cooling flaps are banned.
- Cars must have 2 operating headlights, 2 brake/taillights, and a windshield wiper.
- Aero fixtures must not extend beyond the width of the body as seen from above, and not above the highest point of the coachwork. No aero fixtures may be placed underneath the floor of the car. Invisible or “stacked” aero fixtures are banned, with the exception of a single hidden aero fixture on the front of the car, which must be placed inside the bounds of the body and colored to contrast with the rest of the car. Maximum of two aero fixtures on the front of the car and three on the rear.
- All wheels must have the same diameter; maximum wheel/tire width is 405mm.
The race
Entering teams will run a number of cars based on the race car’s estimated cost. With an estimated cost of under AMU$50k, a team can enter three identical cars (liveries may be made for individual cars but this is purely an aesthetic choice). With an estimated cost between AMU$50k and AMU$100k, a team can enter two identical cars. Teams whose car has an estimated cost higher than AMU$100k can enter a single car. Maximum price of any car is AMU$150k.
Laptimes shall be determined by the car’s Ellisbury GT test lap, improved by 5% to represent flying laps, and with a random variation of ±1% applied on each lap. These laptimes will also be affected by the car’s statistics, as follows:
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High Sportiness will improve laptimes and low Sportiness will worsen them
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Low Drivability will slow laptimes and also increase the chance of a racing incident. Racing incidents can cause either a small time loss on a single lap, damage requiring lengthy repairs in the pits, or damage that takes the car out of the race entirely.
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Low Reliability will increase the chance of a mechanical failure. Mechanical failures will either send the car to the pits for repairs or take the car out of the race.
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Fuel consumption will be calculated based on efficiency at peak power, peak torque, and maximum RPM, and cars will come into the pits on low fuel. Minimum pit time is 30 seconds, plus the time to fill the car’s tank.
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To simulate tire changes, the pitstop time will be multiplied by the car’s tire service cost multiplier.
Race Prediction Calculator
This lap calculator should give you the information needed to optimize your cars, but does not account for time loss from incidents or failures, or random lap variance.
Points will be scored separately for teams’ and constructors’ championships. Team score is based on the finishing position (within class) of each car on a team, and constructor score is based on the finishing position (within class) of every car on any team using either a chassis or engine from a particular entrant/manufacturer.
A form to claim racing numbers will go up with Phase 2. Names of drivers are not necessary but encouraged, and if provided should include three drivers per car.
Rules discussion opens NOW. Entries open on 2024-05-26T00:00:00Z and will be open for the first phase until 2024-06-15T23:59:00Z.
Inspirations:
Edit Log
EDIT 5/19: can now submit a second car in a different class
-2: clarified submission format and explained how to submit engines
-3: banned open wheel and legacy bodies
EDIT 5/20: internationalized some wording in the post and GMSA code
EDIT 5/22: toe limited to 0.5 degrees
-2: maximum cost of $150k, ET/PU restrictions for race engines.
-3: added ET/PU restrictions for all classes
-4: added Fun demographics, specified fixed roofs only
EDIT 5/23: clarified “racing engine” and fixed tire quality at 0
-2: removed ET/PU restrictions for cars and racing engines
EDIT 5/24: updated GTP engine regs to match code
-2: removed ET/PU restrictions for GTP Type 1 and 3 engines
-3: read over the code again and realized exhaust system should be free in all classes. That’s a thing now.
EDIT 5/25: Moved some regulations to more appropriate places in the OP and clarified safety requirements.
-2: added info about entry for phase 2 and race scoring
EDIT 5/27: added an aero fixture maximum for GTX and GTP cars, and clarified some other rules