We are finishing up our general rules regarding chassis equipment, tires, format, tech etc. and should have those posted within a few days. We wanted to go ahead and post our engine rules and some background discussion for people that are currently building or looking to purchase engines
305 Sprint Car Rules
305 Sprint Cars have different rules throughout the country. With the 305’s at Jacksonville being a new class, we want to allow people to have many sources available for affordable engines. Our preferred engine package will generally follow the rules of 34 Raceway in West Burlington Iowa. However, if you find an affordable engine from another rules package our rules will accommodate most configurations that result in performance equal to or less than our preferred package. For our purposes at Jacksonville, we are going to categorize the motors as follows:
Burlington Engine – This is our primary rules package and the preferred engine for our 305 class. Allows aftermarket cast iron heads with 200cc runners and often uses 49cc chambers. Rough horsepower: 500hp. If you are building this engine, please talk to an experienced builder regarding special machine work that may be necessary including cylinder wall notching for certain heads. Common Head example: Dart Iron EaglePart Number: 10310010PF and World Products Sportsman II.
Missouri Engine – Typically conforms to URSS rules using a World Product spec stock head from the WP S/R series of heads. Rough horsepower: 450hp. General rules applicable to this engine: HERE.
Racesaver –Uses a spec aluminum head certified by Racesaver and specific part list. Rough horsepower: 450hp. General rules applicable to this engine: HERE.
Chevy 350 Block 302 or Ford 302 – 4 inch bore, 3 inch stroke motors. Motor must conform to all other Burlington engine rules except that crank must have a maximum 3 inch stoke and maximum bore of 4.060. While displacement and heads should make this very comparable to a standard ‘Burlington’ 305, it could rev a little higher and flow slightly better due to the larger bore but flow will still be limited by valve size. It should not produce as much torque as the standard engine. If you are considering building a 305 from a 350 block, realize that no other race series in the US currently allows it and it will be illegal everywhere except Jacksonville and difficult to sell. We are allowing these motors due to the availability of 350 blocks so that some teams can build their own motor from parts they might already own. They will begin with a 50 pound weight handicap with a minimum weight of 1600lbs that could be raised in the interest of competition.
Knoxville Engine – Much like the Burlington 305 with aftermarket performance heads, but Knoxville allows dry sumps and some titanium engine components. This engine likely makes slightly more horsepower than the Burlington engine if built to the limits of the Knoxville rules. We typically won’t permit the use of this engine at Jacksonville as we do not want our participants to build this engine for the purpose of purely local competition. We will consider an exception to a participant that demonstrates a need for this particular package by racing regularly at Jacksonville as well as at Knoxville in the 305 division. Unless you plan to regularly race at Knoxville, there is simply no need for this configuration. In such cases we reserve the right to determine an appropriate handicap which could include weight, specific tires, tire pressure or starting position We also reserve the right to exclude the engine from competition if a suitable handicap for the engine cannot be found.
GM 604 Crate Engine – Although it is 350 cubic inches, we will allow a GM 604 crate engine that is SEALED in conformance with existing UMP DirtCar rules for its Pro Late Model Division. This motor produces roughly 400 to 425 HP – well below our preferred engine package. We allow this engine simply because they are readily available in a sealed condition and the performance can be verified.
Other –We encourage discussion and evaluation of alternative engine packages that fall safely within our general rule of “Verifiable 5 and 5” – meaning that we can 100% verify that it produces well less than 500 horsepower and can commonly be built or purchased at cost of less than $5,000. We believe that there are likely combinations we have not considered that can accomplish the goals of this class. If you wish to compete with an engine that falls within the “Verifiable 5 and 5” rule, please contact us so that we can discuss it.
The purpose of the 305 class at Jacksonville is to promote an affordable entry point in the sprint car class. Different configurations are more affordable to different individuals depending on the parts they have available or the deal they might find on an existing operation. Our standard package is the ‘Burlington Engine’ at 1550 pounds. Deviations will be allowed as mentioned above with prior approval, but anything not conforming to our preferred rule package is subject to handicap that may adjust over time to promote fair competition.
Unfortunately we cannot give a weight advantage to configurations that might be slightly underpowered such as a ‘Racesaver’ or ‘Missouri Engine’. We believe that with appropriate setup and experience, these engines can be competitive at Jacksonville given the size of our track. You are always free to upgrade an existing engine to the preferred package over time and in many circumstances buying one of these engines might be a good starting point for entry in the class.
Preferred “Standard” Engine Rules
- Engine Size: 316 cubic inches (max bore of .060 over)
- Blocks: Stock GM 305 block (no bow-tie, dart etc. aftermarket blocks. No lightening of block. Must retain factory castings.
- Pistons: Flat top pistons. Can’t protrude from cylinder bore. Unlimited compression allowed. Valve relief piston is acceptable.
- Crank: Sock appearing steel or cast crank with 3.48 or 3.500 stroke.
- Rods: Any steel rod. Oil pan inspection hole required for viewing rods.
- Drive: Double roller type chain and gear only. No gear or belt drives.
- Water Pump: Steel or Aluminum allowed. Must be in stock location.
- Hub: Damper or steel hub. If damper is used, it must meet SFI requirements.
- Cam/Tappets: Flat tappet cam. Stock diameter tappets (no rollers, mushroom, radius type tappet)
- Lifter boxes: May be machined or bushed for repositioning, alignment and straightening of lifter box. Original stock diameter bore must be maintained.
- Oil Pump: Wet sump internal pump only. (no crankcase vacuum systems)
- Rockers: Roller rockers allowed (no shaft system) 3/8” or 7/16’ stock or screw in stud mount rockers.
- Valve Train: May run stud girdles, but no rev kits allowed.
- Valve Sizes: Maximum of 2.02 intake and 1.600 exhaust size. Maximum valve spring size of 1.55”
- Materials: No titanium, composites, or ceramic internal engine parts.
- Head: Any steel head with a maximum of 200cc intake runner and minimum 49cc chamber UN-TOUCHED. (no machining, milling, grinding, polishing, welding, acid/caustic work, shot-penning, glass-beading, or any other process that would alter the machined surfaces or natural sand-cast finish. The only work allowed is re-seating the valve. No under-seat relief cuts allowed. No work to enlarge he delivered throat size. No port matching of any kind. Head bolts or studs can be used. When milling, only straight cut head and no angle milling of any type.
- Ignition Systems: Magnetos, Electronic or Kettering-type only. No crank triggers. MSD Pro-Mags are not allowed.
- Fuel Injection or Carburetion: Constant-flow mechanical fuel injection or any four-barrel carburetor. Fuel injection will have a maximum bore of 2 3/16. If sleeved down, sleeve must be at least three inches and measure 2 3/16 throughout. No down nozzles. Only one nozzle per cylinder. No funneling or venturing. Plenum style fuel injection is allowed. One throttle body with four butterflies only with each butterfly not to exceed 1 7/8” diameter.