Formula Thunder® is a class of racecars that are defined by high performance coupled with safety, simplicity, spec components, and allowed user innovation of basic concepts that can be accomplished with simple resources by regular folks with a passion for motorsport at costs that are purposely controlled to avoid ridiculous escalations found in other racing classifications.
Formula Thunder® cars will be as safe as possible, relatively economical, fast, and fun in their design. These cars will not be ultra-high tech, they will use spec components, crate engines, and reliable tech to accomplish high performance with durability and low cost of operation. In other words, regular folks with basic knowledge and a desire to compete and/or innovate will be capable of buying or building a competitive car at reasonable costs that goes fast and is a kick in the pants to drive. The cars will be classified as either single seat open cockpit or dual seat (closed or open cockpit), the cars will use a big spec tires for mechanical grip, a large rear wing or spoiler for aerodynamic grip, a spec stout racing transaxle or a stock production car transaxle, allow powerful high torque V8 engines up to 6.2L that are catalog ordered using modern designs found in street rod type crate engines that are available from suppliers such as GM performance or Blue Print engines.
There will be two classes in Formula Thunder® , FTSS (Formula Thunder® Single Seat) and FTDS (Formula Thunder® Dual Seat). While the FTSS class is designed to be specifically a race car only, the FTDS is more liberal in the design and specifically allows the use of some production car components to further reduce cost and allow the builder more flexibility to adapt various existing street legal and/or kit car type bodies, and production based driveline components components. FTDS cars may use any FTSS spec components to improve performance over production car parts.
All Formula Thunder® cars must use Formula Thunder® components and purchase these parts EXCLUSIVELY from Formula Thunder® unless specifically noted here in.
There are three types of REQUIRED Formula Thunder® components:
NOTE: FTDS Transaxles also allow for the use of any production synchromesh (not dog ring racing components) transmissions or transaxles to allow easier low cost entry access to the FTDS class and promote the use of existing street legal kitcar bodies that otherwise meet the rules. These production car transmissions are not purchased from Formula Thunder® and must be sourced independently. Any production car transmission or transaxle used must have had production build numbers of 10,000 units or greater (VW Passat, Porsche 996, Porsche 911, etc). After market transaxles such as Mendeola are not allowed.Proof of production numbers is the responsibility of the competitor. All transmission / transaxle shifting must be accomplished with an H pattern manual or if a competitor is disabled, that competitor may use an automatic
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| NOTE: FTDS cars may use the above FTSS specified rear wing or a flat plate spoiler that must not extend more than 6 inches higher than the highest part of the rear of the body (not including the engine cowling) and less than 4 inches. The spoiler must be at least 6 inches narrower than the widest part of the body but not less than 12 inches narrower than the widest part of the body. The spoiler must not lay flatter than 30 degrees from vertical. The intention of this rule is to provide drag to encourage drafting and downforce to the rear of the car at high speeds for stability. |
| Formula Thunder® specified standard parts also must be purchased from Formula Thunder® unless otherwise noted: |
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| FTSS Dry Weather Wheels (purchased independent of Formula Thunder®): |
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FTDS Dry Weather Tire (purchase directly from American Racer as per your application must be American Racer Late Model Stock Car Asphalt tires as per your car’s weight and performance capability). Note: Choose your tires with speed, capacity, and safety in mind carefully.
Rear 26.2 inch minimum diameter x 10 inch minimum tread width
Front 26.1 inch minimum diameter x 8 inch minimum tread width
FTDS Dry Weather Wheels: (purchase independent from Formula Thunder®)
Rear as per your application must use maximum of 9 inch front spacing bead to mount flange. It is highly recommended that the wheel is close to centered on the hub mounting surface on the rear of the car thus not cantilevering tire loads into the wheel, rod end bearings, or suspension bushings.
Front as per your application must use maximum of 4.25 inch front spacing bead to mount flange
Wet weather tires and wheels are not restricted choose carefully with safety in mind. You are on your own! (purchase independent from Formula Thunder®). It is recommended that your wet tires are the same or slightly larger in diameter compared to your dry tires as this will avoid lowering your car unintentionally.
Note: Specifications of Formula Thunder® designed parts are provided for car design purposes so that you do not have to purchase these parts to design a car (just to build it). These specifications are NOT to be used to independently source or build your own parts. Remember, a LOT of engineering, purchasing, testing, scrapping, and repurchasing etc. was done to arrive at items that suit the intended purposes. Please do not steal our hard work. If you want to do your own thing, then do it. Understand we at Formula Thunder® intend to promote in a big way and make it a LOT of FUN to play in our series. We would really like you to play with us, but if you wish to NOT purchase required Formula Thunder® parts you will NOT be allowed to participate or use Formula Thunder® registered trade mark markings on your car or participate in Formula Thunder® promotions. All cars participating in a Formula Thunder® events must display the Formula Thunder® series sticker on each side and the nose of the car.
Purchased Drive line components:
Drive line components may not be lightened. As an example the 930 CV joints may not be turned down to reduce weight or use special light weight units.
Formula Thunder® Accepted cars, assemblies, and parts:
Formula Thunder® does not approve or certify as acceptable outside cars, assemblies, or parts. That said, if a particular car, assembly, or part has been inspected by Formula Thunder® technical experts for rules compliance and found to comply at that time, the manufacturer upon signed written permission from Formula Thunder® may mark their car, assembly, or part offering as “Formula Thunder® Accepted” as long as the part or car does not change. Having a car, assembly, or part marked as Formula Thunder® Accepted does not transfer any liability or acceptance of risk to Formula Thunder®. The manufacturer of the car, assembly, or part takes full responsibility concerning the suitability for the intended purpose.
Construction Methods:
Construction methods are open to a degree yet specified for cost control, safety, equality of weight, retro look, and close competition. Essentially if you could not make your car from the ground up in a simple shop or garage (without large scale wind tunnels, autoclaves, vacuum bagging, etc.) using basic metal working tools and composite work done similarly as done by the homebuilt aircraft groups, we don’t want you ruining our classes. These classes will not be defined by an unfair advantage. If you want to push the high tech or other “unobtainium” buttons please play in other classes. That said, we are all ears on your opinions and ideas. We don’t know it all, but we are going to do Formula Thunder® as we see fit our way.
Understand that it is impossible to predict what fabulous inventions you independent designers and builders will devise. It is possible that at some point it may become necessary to “outlaw” various things for the good of the overall group. We will strive to do this as gently as possible, but rest assured we will do it for the good of the group.
Tub / Frame / Spaceframe:
All cars must meet and follow, SCCA GCR, and SCCA ASR specifications as well as the following:
The tub from the front bulkhead frame to the main roll over hoop behind the driver must be constructed of a minimum of 1.5 inch diameter x 0.95 wall chrome moly steel round steel tube or equivalent or greater in strength, be sure to follow the SCCA GCR taking special note if your car design could approach 2699lbs. as larger tube than specified here is then required in that case as per SCCA. The tub portion of the chassis must use a minimum of 6 horizontal tube longerons (front bulk head frame to back of driver compartment (main roll hoop or mail roll hoop support members) not counting the required 6 point full sprint car style roll cage.
18 gage steel anti intrusion plates protecting the sides, rear, and the bottom of the occupants compartment is also required.
Although not recommended, FTDS class cars may use as little as 24 gage steel for the bottom pan as long as adequate 1.5 diameter x 0.95 chrome moly steel tube or greater framing is used to adequately protect all occupants and meets SCCA GCR requirements for the drivers compartment. Formula Thunder® does not recognize the composite or aluminum anti intrusion plates the SCCA GCR does allow. The tub/frame construction must also meet SCCA GCR requirements as they are very specific. Be sure to check both the roll cage section and the ASR section of the SCCA GCR as all safety standards of the GCR apply to Formula Thunder® and other requirements like a 6 point full roll cage (sprint car type) that goes further than the SCCA GCR. The driver must also be capable of exiting the tub/frame from a minimum of two aspects of the top, left side, right side, or front to avoid the potential of trapping the driver when the car has overturned.
To be clear, all Formula Thunder® cars must use a minimum of a 6 point sprint car style roll cage that also meets SCCA GCR rules. Understanding that a prototype endurance style car such as a Porsche 962 or Ford GT40 shape may dictate upper cage couture around the doors to allow driver entry. The top front of the roll cage must be higher than the driver’s line of sight when seated normally. This roll cage must be designed to deflect objects up and over the occupants. You can ADD more members if you like such as a thin center member similar to current Indy or F1 cars or A pillar support members, but again 6 points is the basis of the foundation for the roll cage and must be followed at a minimum.
Maximum fuel cell to engine fuel line is a single AN-8. If two fuel cells are used the last portion before the engine must be a single AN-8 line.
Use of a dry break disconnect in the fuel line that is activated by a pulling action (not a twisting action) is mandatory between all fuel cells and engine as close as possible to the fuel cell(s).
Under car configuration:
Will not use front splitters on the nose. If a lower rim is used, it must be at least 1 inch tall and a maximum of 2 inch forward of the adjacent nose bodywork for stiffening purposes only.
Will not use raised noses (the bottom of the front of the nose section must be the lowest portion of the car and utilize a flat surface extending to the rear of the tub section). The exception to this is the first 3 inches of the nose section that can slightly curve upwards by up to 1.5 inches to act as a ski when contacting the ground or obstacles if the front wheels were to depart the car, be careful to not build your cars to be capable of blow overs!!!!
On the FTSS cars, the side pod area on the outsides of the tub area must be a minimum of 0.5 inches higher than the bottom of the tub (area below the driver) and utilize a flat bottom without any upward curved structure with the exception of a 1 inch diameter or less round outer front, side, or rear edge construction. The intention of this rule is to aid ground clearance as the car leans while cornering and to eliminate any attempt to create ground effect tunnels, this includes the areas under the driver, side pods, and under the driveline, while letting a constructor use 1 inch diameter round tubing to build side pod base frames to allow composite cloth to wrap around.
The shape of the side pod floor area as viewed from below must be less than 80 inches nominal width with a + tolerance of 0.5 inches to account for body and mold deflections during construction from the outside of one side to the outside of the other side or the width of the car (the upper portion of the side pod may not be wider than the lower portion within the 0.5 inch tolerance). The +0.5 tolerance is to keep constructors from having to scrap or cut up perfectly good bodies that happen to be SLIGHTLY too wide due to being out of square.
The car width may not be wider than 80.5 inches
The car may not be narrower than 65 inches
Minimum ground clearance is 2.25 inches to be measured at the end of the race. No method of raising or lowering the car while on track is allowed
Minimum wheel base is 90 inches
Maximum wheel base is 135 inches
Minimum height of the highest portion of the car not including the rear wing is 40 inches with the top of the main roll over hoop no less than 38 inches with 2.25 inches of ground clearance
Minimum height of the rear of the body work is 26 inches
Car dimensions must meet SCCA GCR requirements
Cooling air must be taken from a frontal ram air effect, top, or side ducting. Cooling air can NOT be drawn from the bottom of the car. The intent of this rules it to make it illegal to increase downforce by being creative with cooler ducting.
Air exiting coolers may exit above the body, out the side of the body, or out the rear of the car. This exiting air can NOT under any circumstances be directed below to or directed away from the flat section of the under car to generate additional downforce.
With the exception of the front surfaces (opening of the air) such as the nose, cooler ducts, exiting the air from under or behind the nose to the outside of the car behind the front tires and below the front fenders, and from the top view starting from 24 inches behind a point directly above the top of the front tire, (closing of the air) and behind the main roll over hoop (closing of the air), no panel licked by the air can have a radius of greater than 2 inches when transitioning from the sides, front, or top.
No ground effect tunnels of any sort are allowed.
For the FTSS class the body will be wedge shaped from front to rear both from a width and height perspective. The body may NOT decrease in height or width as the body progresses rearward as viewed from above or from the side. The width and height can however remain the same in other words be parallel with the ground when viewed from the side or parallel with each side when viewed from the top. This includes at or around the rear tires. A body may have a meandering valley that has a level or inclining floor from the forward section of the car to between the rear tires and to the rear of the body. The floor of such a valley may not be more than 6 inches lower than the highest portion of the body work at any cross section (from side to side) of the body work covering the rear tires and must be level or increase in height as it moves rearward. A different top body plane starting from 24 inches behind the top of the front tire must be level or increase in height as it progresses rearward clearing over the top of the rear tires and/or potentially even leveling off.
For FTSS and FTDS cars that are built specifically for Formula Thunder ® The body with the exception of 24 inches behind the top of the front wheel arch height and behind the main roll over hoop my not decrease in height or width as the body progresses from front to the rear of the car. The car must use a wedge shape. This is purposely used to create drag and limit the top speed potential to make building Formula Thunder® bodies easier to build, as well as create the ability to draft pass. If you don’t like it play somewhere else, this class will NOT be ruined by fluid dynamics and large scale wind tunnel knowledge.
For FTDS cars that use previously independently manufactured kit car bodies that look like or were obviously inspired by retro endurance or group 7 race cars such as GT40, 917, 904, 908, 956, 962, T70 or such (Factory 5, ERA, Manta, Fiberfab, Ultima, Bradley, etc.) may decrease in height by no more than 4 inches or in width by no more than 10 inches total as the body progresses rearward. Bear in mind that a body that has an offending feature can use a foam filler panel that can be taped in place to fill up a feature or curve that is not allowed by these rules. Note: If the body looks anything like a modern LeMans prototype, P1, P2, or Ford 2017 GT FORGET IT, THE ANSWER IS NO!
If top front fender venting is done, it must be done with one rearward facing opening only for each side of the car with one reverse scoop on each side. Regardless the tire may not be seen from a top view when the wheels are pointed directly forward.
All suspension members including push/pull rods, tires, wheels, wishbones, etc. must not be visible when viewed from above throughout full suspension movement with the front wheels pointed straight ahead.
All suspension members such as wishbones, push or pull rods, rocker arms, Etc. must have a round radius on the front and rear or be squared off. NO tear drop, oval, streamline, or slip stream tubing is allowed. All suspension members must also have a minimum of 1.00 inch diameter.
All suspension spherical rod end bearings / heim joints must be at a minimum sized to use a 7/16 bolt and use the bolts rather than spacers that then user smaller bolts. This includes shocks or dampers. Take care to not put threads in shear planes with use of proper length bolts and washer spacers. Note: use of aircraft AN bolts is encouraged.
No electronically controlled shocks or suspension members are allowed.
The battery used to start the car that is mounted on the car will not be Lithium in nature. A AGM battery is recommended.
All shocks must be non, single, or double adjustable. (triple adjustable and up are not allowed)
Body work construction materials is restricted as follows:
Aluminum unrestricted as long as sharp edges are kept away from occupants or other competitors.
Fiberglass
Chopped and sprayed into a mold is allowed.
Hand wet layup into a mold (no foam core required) is allowed.
Hand wet layup onto foam core allowed (mold less construction) but all foam must be fully encased in composite material (Fiberglass, Kevlar, Carbon Fiber) or metal is allowed.
NO VACUUM BAGGING, PREPREGS, OR AUTOCLAVE CONSTRUCTION IS ALLOWED.
Kevlar
NO Hand or automated wet layup into a mold allowed.
Hand wet layup onto foam core allowed (mold less construction) but all foam must be fully encased in composite material (Fiberglass, Kevlar, Carbon Fiber) or metal.
NO VACUUM BAGGING, PREPREGS, OR AUTOCLAVE CONSTRUCTION IS ALLOWED
Carbon Fiber
NO Hand or automated wet layup into a mold allowed. An exception is made for the engine cover behind the main roll hoop for FTSS; however this part may not be full body width and must be a separate part from the rear wheel cover bodywork.
Hand wet layup onto foam core allowed (mold less construction) but all foam must be fully encased in composite material (Fiberglass, Kevlar, Carbon Fiber) or metal.
NO VACUUM BAGGING, PREPREGS, OR AUTOCLAVE CONSTRUCTION IS ALLOWED
Safety considerations of body parts:
The occupant(s) must have a minimum of 4 inches of foam polystyrene or expanding foam of a minimum of 2 lbs per cubic foot between the side of the car and the occupant(s) torso area anti intrusion protection area starting at mid-thigh (front of side pod area) or before to rear of shoulder/head area or rear of fuel cell whichever is further rearward. The exception to this rule is the closed cockpit design similar to a Bradly GTII, Factory Five GTM or GT-40 style kit type car, but ONLY in the DOOR area.
If the fuel cell(s) are located in the side pod(s) or front of the car, there must be a minimum of 4 inches of foam polystyrene or expanding foam of a minimum of 2 lbs per cubic foot ahead of the fuel cell in addition to the outside of the fuel cell. In all cases there must be 4 inches of foam between the outside front and side edges of the fuel cell to absorb impact from the front or side of the car. This foam must be encased with protection so that deterioration does not affect the foam.
All other SCCA GCR rules and ASR rules apply.
Conclusion concerning car shape:
Simply put NO SPLITTERS, RAISED NOSES, DEFUSERS, GROUNDEFFECT TUNNELS, WINGLETS, ETC, ETC, ETC. If it looks anything like a modern F1 or Le Mans prototype or used processes developed by this type of high tech it will most likely not be allowed. Look at and think of the GENERAL SHAPE of 1960s, 1970s, and early 1980s Can Am cars and 1960s Le Mans cars without large coke bottle in and out curves and you are there. Remember the shape of a custom built car body must be wedge like or parallel and not decrease in height or width as it progresses to the rear of the car more than described above for the two classes. Designs must use flat or upward and outward curving sides and tops only. If you have a previous body such as a kit car (e.g. GT-40 tail) that narrows or lessens in height as it progresses rearward, removable temporary body spacers can be added to make the body legal for competition if the offending feature is too pronounced. These spacers can be attached with fasteners, adhesive, or tape provided that they meet the requirements of SCCA GCR.
General Engine Rules:
No forced induction such as turbos, superchargers and such.
No performance enhancing injection such as Nitrous, Methanol, and such.
Engines must run on 91 octane unleaded public gas station fuel without additional additives
Porting beyond catalog order from GM Performance or Blue Print Engines parts is not allowed.
Must NOT use variable cam timing.
No engine will use more than .612 inches of valve opening with included rocker arm ratio.
Up to 376 cubic inch (6.2L) Chevy LS engine or smaller.
Up to 357 cubic inch Chevy small block engine or smaller.
Any EFI system may be used but no fuel injection system can be direct into combustion chamber injection. EFI systems may not use and intake area larger than a 90mm single butterfly.
Carburetors may not be larger than 770 maximum CFM.
Any ignition system can be used.
Allowed Crate Engines:
GM Performance LS based crate engine part # 19432414, 19432690, 19432416, 19432420, 19432418, 19432630, 19432629, 19418211
Blue Print Engine LS based crate engine part # PSLS3760CTF, PSLS3760CTFK, PSLS3760CTFKB, PSLS3760CT, PSLS3762CTF
GM Performance Small Block based crate engine part# 19432102, 19432105, 19432108, 19432602, 19410604,
Blue Print Engine Small Block based crate engine part# BP35513CTC1, BP35513CT1, BP35513CTF1,
The competitor is responsible to have proof of purchase and all documentation of the use of above at the racetrack.
Substitutions of components of an allowed crate engine is not allowed other than to an equal or lesser performance part. Not allowed examples are: lighter valves, lighter pushrods, lighter or lightened crankshaft, etc.
Modification of components for performance purposes is not allowed. Not allowed examples are: lightening, knife edge machining of crank lobes, etc.
Affordable competitive engines is the goal, not a unique advantage!
Competitor built (build your own engines):
Must comply with the following:
Must not use components that have a higher performance potential than the above listed crate engine components.
Substitution and modification of components as above applies.
It is the responsibility of the competitor to provide complete build documentation and comparison data to the above. This verification must be submitted 3 months before a competition date and will involve a fee to hire an engine professional to verify all data.
The competitor will also be required to sign an affidavit that no component or modification has been done since the data verification.
Violation of any of these aspects may involve permanent exclusion of Formula Thunder® events.
STOCK ENGINE CLASSIFICATION:
Any stock normally aspirated engine less than 360 CID can be used that uses all stock mechanical components and stock mechanical induction system after the throttle butterfly can be used. No porting is allowed. No performance component substitution is allowed. All moving components must be stock specifications with the exception of the oil pump and oil pan. EFI, carburetors, and ignition controllers are open. This section is designed to get folks on the track rather than waiting until they can afford a class winning engine. Example: 2000-2004 VW Passat engine and transaxle, Cadillac Northstar to Passat transaxle, etc.
Required Engine Related Components:
All cars must use a functioning alternator and a belt driven water pump (not electric) of a stock design configuration (example a LS3 water pump may be used on a LS2 engine).
All exhaust systems will include mufflers that use 3 inch maximum diameter tubing. No muffler bypassing is allowed. If V8 powered, the car must use two race mufflers with a maximum of 3 inch inlet and outlet with a minimum of at least 12 inches in length each. Note: Borla makes a straight through muffler that fits this rule.
Conclusion:
Formula Thunder® cars are NOT about the fastest lap times, you can expect other classes to lap faster than Formula Thunder®. What Formula Thunder® brings to the table is LOWER COST, HIGHER RELIABILITY, AND LOWER BARRIERS TO HIGH PERFORMANCE COMPETITION IN A REALITIVELY SAFE RACECAR THAT YOU CAN BUILD IN YOUR OWN GARAGE IF YOU WANT TO.
Do not be surprised if Formula Thunder® eventually determines that specific dyno verification or engine suppling becomes a requirement if competitors eventually take advantage of rules. Every competitor must take on the responsibility of conducting and governing themselves to the spirit of the rules by never seeking an overwhelming competitive advantage through unique knowledge or high technology. It is only by a combined effort that high performance club racing competition can flourish at low costs. BE PART OF THE SOLUTION, NOT PART OF THE PROBLEM.
THANKS!