2019 IHRA Rulebook

IHRA 47 seats be mounted vertically and incorporate a compatible crotch strap. Under no circumstances are bolts inserted through belt webbing permitted for mounting. Check manufacturers instructions. SHOCK ABSORBERS: See Class Requirements. STARTERS: All cars must be self starting; with the exception of TF, PFD,and NFC (push starts prohibited in all categories). STEERING: Each car’s steering system will be inspected to determine its condition. Steering must be considered safe by the Technical Committee. Drag link and tie rod ends must be secured and keyed. All altered or modified steering systems will be closely checked for insecure welds and faulty parts. All welded parts must have additional visible reinforcement. Only conventional automotive steering systems are permitted. All rod ends where used must be a minimum of 3/8” shank diameter and must be installed with flat washers to prevent bearing pull out. All steering boxes, sectors and shafts must be mounted to the frame or suitable location and may not be mounted in any case to the bell housing and/or bell housing adapter shield, motorplate or firewall. SUPERCHARGERS: ROOTS-TYPE: Maximum size permitted 14-71; 19” maximum rotor case length: 11 1/4” maximum case width: 1/4” minimum case thickness: 1/4” minimum front plate thickness; .300 minimum rear plate thickness. Maximum rotor cavity diameter is 5.840”. Rotor helix angle may not exceed that of a standard 71 series GM-type rotor (4 degrees per inch). Maximum over drive may not exceed 70 percent. Aluminium studs (supercharger to manifold) mandatory. All cases and related components must be accepted prior to competition. See Class Requirements for manifold burst panel and restraint specifications. SUPERCHARGERS: ROOTS-TYPE HIGH HELIX: Must adhere to same maximum case dimensions and maximum rotor cavity diameter as standard Roots. Rotor helix angle may not exceed 6.5 degrees per inch (123.5 degrees total over 19” maximum rotor length). Maximum over drive may not exceed 70 percent. Aluminium studs (supercharger to manifold) mandatory. All cases and related components must be accepted prior to competition. See Class Requirements for manifold burst panel and restraint specifications. SUSPENSION: All street driven cars must have a full suspension of the type produced by automobile manufacturers (i.e. springs, torsion bars, air suspension, etc.). Rigid mounting of front or rear axles is prohibited. Figure 12 and 13: Head protectors and harness mounting