BoP Lab / Hallett Motor Racing Circuit
GTX vs SRF3 pace at Hallett Motor Racing Circuit
Quickest here: GTX 1:14.200 Eric Presbrey, AVRG Green Country Grand Prix 2026 race · SRF3 1:19.374 Tyler Fox, AVRG Green Country Grand Prix 2024 qualifying
| Event | GTX | SRF3 | ||||||||
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| Qual best | Race best | Trap | Qual best | Race best | Trap | vs GTX | % of GTX | |||
| AVRG Green Country Grand Prix 2026 AVRGGR262026-04-25 | 1:15.997Eric Presbrey · fastest of 2-10.336s (-11.97%) | 1:14.200Eric Presbrey · fastest of 2-12.002s (-13.92%) | 130.9Eric Presbrey+19.0 mph (+16.9%) | 1:19.723Tyler Stephens · fastest of 34 · top 5 within 1.7s-4.909s (-5.80%) | 1:19.496Peyton Long · fastest of 33 · top 5 within 1.2s-2.306s (-2.82%) | 105.8John Janssen+0.8 mph (+0.7%) | +5.296squal +3.726s | 107.1%qual 104.9% | ||
8 rule changes (GTX: 5, SRF3: 3)4 cars added · 1 engine · 2 wording · 1 other · GTX adds Ferrari 296 GT3 with restrictor and weight, effective 2026-04-01. · GT3U class removed from GCR; GT3U cars now run in STU with 3.0" main frame and 2" front spoiler minimum ride height. · SRF3 spark plugs restricted to NGK LTR7IX-11 P/N G301041 only, washers and sealing rings prohibited. · GTX Misc Table 4 adds RCR T70 Coupe with 2200 lbs minimum weight, no restrictor specified. · SRF3 adds HD Oil Cooler P/N G1148500 as alternative to standard cooler P/N G480503. · SRF3 brakes restructured: Hawk Blue 801993 pads, Wilwood 800065 rotors only; adds Girling 880358, Wilwood 880357, Tilton 880360 master cylinders. · GTX Ligier LMP3 now allows any normally aspirated LS Chevrolet engine. · GTX Porsche GT2 RS Clubsport classified with factory specifications required at all race events.show
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| AVRG Green Country Grand Prix 2025 AVRGGR252025-04-26 | 1:26.333Michael Young · only car+6.009s (+7.48%) | 1:26.202Michael Young · only car+6.569s (+8.25%) | 112.0Michael Young-10.3 mph (-8.4%) | 1:24.632Richard Stephens · fastest of 36 · top 5 within 4.4s+5.258s (+6.62%) | 1:21.802Richard Stephens · fastest of 36 · top 5 within 0.3s+0.421s (+0.52%) | 105.0Grayson Strathman-1.4 mph (-1.3%) | -4.400squal -1.701s | 94.9%qual 98.0% | ||
10 rule changes (GTX: 2, SRF3: 8)2 weight · 1 suspension & brakes · 1 tyres & wheels · 6 wording · SRF drivers with disabilities may modify seat and controls for safety and comfort with approval and logbook notation. · SRF SADEV-SRF3 6-speed sequential transmission gear ratios wording clarified, effective 2025-04-01. · TA2 rear wing height rule clarified: OEM aerodynamic devices exempt from peak-of-roof requirement. · SRF3 air filter rule removes K&N RC-9160 option, leaving only P/N WM301020 allowed. · SRF brake rotor minimum thickness increases from 12.20mm to 13.25mm, Wilwood vented rotor P/N 800065. · SRF3 Hoosier logo placement changes from four decals to three decals in different locations. · SRF Hoosier decal requirement reduced from four decals in specific locations to three decals with simpler placement rules. · SRF wet tires: P185/60R13 H20/W2 option removed; P185/65R13 W2 front now required with P205/60R13 W2 rear. · SRF3 alternator pulley minimum weight reduced from 12 oz to 11 oz. · GT2-ST Acura NSX minimum weight raised to 3000 lbs, restrictor increased to 45mm TIR.show
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| AVRG Green Country Grand Prix 2024 AVRGGR242024-04-20 | 1:20.324Michael Staab · fastest of 2 | 1:19.633Michael Staab · fastest of 2 | 122.3Michael Staab | 1:19.374Tyler Fox · fastest of 36 · top 5 within 2.1s | 1:21.381Tyler Stephens · fastest of 36 · top 5 within 0.2s | 106.3Richard Stephens | +1.748squal -0.950s | 102.2%qual 98.8% | ||
63 earlier rule changes on record, in force before AVRG Green Country Grand Prix 2024 (from 2019)21 cars added · 5 tyres & wheels · 4 suspension & brakes · 3 induction · 2 engine · 1 aero · 1 weight · 25 wording · 1 other · GT1, GT2, GT3, GTL, GTX rear spoiler maximum surface area limit of 295.0 square inches removed. · GT1/GT2/GT3/GTL/GTX Direct Injection now permitted if OE, using only OE pump, hoses, injectors. · GT2/3 Nissan, Mazda, Mitsubishi 4G93, QR25DE/DD, QE25DE/DD Direct Injection now permitted per 9.1.2.F.7.5.E. · GTX adds KTM X-Bow classification with restrictor and weight specifications effective 2024-01-01. · SRF rain/brake light now requires Super Bright LEDs Inc. P/N PT-STRB-R24 with specific connector and rain light switch. · SRF requires Super Bright LEDs P/N PT-STRB-R24 rain/brake light with strobing capability and specific wiring. · SRF adds brake duct and pedal extension rules, rear shift cable clamp option, camber limit to 5.0°, radiator opening height 3.5" ±0.5", and P2 engine restrictor changes. · GTL spec lines moved to contiguous position with GT2 and GT3; GTA category and spec lines renumbered and moved behind GTL. · SRF radiator rule clarified: P/N 480466 replaceable with Automotive P/N 1R698, CU698 or manufacturer equivalent with documentation. · GTX Ligier LMP3 3.7L NA classified at 2203 lbs with 22 mm restrictor. · GTX Ligier JSP4 newly classified as GTX Misc with restrictor and weight specified. · SRF Hoosier wet front tire updated to P/N 46100 P185/60R13 H20 or W2. · Fields Cardinal V8 classified in GT1 with Ford V8 engine, 4.9L displacement, 2100 lbs minimum weight. · SRF Hoosier front rain tyre part number changes from 46100 to 46101 P185/65R13 W2. · SRF Renault Alliance solid front rotors banned; restrictor reduced 35mm to 34mm for 2011+ Kawasaki; minimum weight increased to 1100 lbs for 2009+ stock engines. · SRF3 tail sections allowed on SRFs with GEN3 airbox shimming up to 19 mm; alternate dash panel P/N 180100 or 180101 relocated in rules. · GT2 TA2 and GTA throttle body part numbers updated to GM 90mm electronic #12570790 or Edelbrock 90mm mechanical #33869 or #3870. · GT taillights may now be original style or a panel graphic with functioning red LED brake lamps; wording change only. · Porsche 992 GT3 Cup Car newly classified in GTX. · SRF tire rule wording changed from 'Tires: must be run as delivered' to 'Tires must be run as delivered.' · SRF brake rotor minimum thickness reduced from 13.25 to 12.20mm; seal and air filter rules clarified. · GTX Wolf GB08 F1 Ford 52XS V8 added to classification at 1725 lbs minimum weight. · C7 Corvette Grand Sport classified in GTX Misc at 3200 lbs with option to remove displacement on demand valve train. · GTX eligible prototypes expanded: IMSA GTP years changed to 1981-1993, five prototype categories added. · GTX McLaren 720s GT3 newly classified at 3000 lbs with 3000 mm restrictor. · GTX-FIA GT3 removes all intake restrictor requirements for fifteen car models; McLaren name corrected. · SRF front wet tire changes from P185/60R13 H20 to P185/65R13 W2; SRF3 adds mandatory G301048 restrictor plate Jan. 1, 2022. · GT3 Fun Cup Beetle EVO3 classified with 1984 cc sealed SOHC engine, 2060 lbs minimum weight. · GTX SRO-GT4 Porsche 718 Club Sport MR GT4 classified, unrestricted, 2900 lbs minimum weight. · GTA part numbers updated: 0-80541-1 to 0-80541-2 in two sections and 6010 to 6014X in TA2 Appendix. · Grullon GT with 2.0L K20 moved from GTX to GT2-ST, minimum weight 2350 lbs, unrestricted. · SRF wet tyres add Hoosier P185/60R13 W2 front and P205/60R13 W2 rear as alternatives to H20. · SRF adds SADEV-SRF3 6-speed sequential option with final drive 3.20 versus OEM 5-speed 3.85. · SRF seal procedures clarified: unsealed components need CSR inspection and logbook notation instead of engine removal. · GTX Grullon GT added, unrestricted, 2350 lbs, factory spec required. · SRF3 alternator pulley restricted to P/N G902130 or G902130A, 12oz minimum weight. · SRF and SRF3 mandatory identification simplified: removed Ford Performance and Blue Oval decals, kept Hoosier logo placement. · SRF shocks, springs, bump stops sealed; rear springs 412-429 lbs/in P/N 280390 only; previous parts no longer allowed. · GT1, GT2, GT3, GTL, GTX now permit turbocharging/supercharging if listed on spec line. · GTX Chevrolet Camaro ZL1 LT4 with factory supercharger classified at 3400 lbs minimum weight. · GTX adds KTM X-Bow GT4, turbocharged 2.5L Audi TFSI I5, 2000 lbs minimum weight. · TA2 Gurney flap wording clarified: terminology standardized to 'Gurney flap', height limits and thickness specifications remain 0.50 inch / 0.625 inch or 0.375 inch / 0.0625 inch depending on configuration. · STO rear wing wording clarified: 'wicker' changed to 'Gurney flap' in maximum chord and mounting height rules. · GT classes clarify Gurney flap wording, replacing wickerbill/tab terminology with flap; specifications unchanged. · GTX tube frame cars must weigh 2780 pounds; stock car bodies now permitted. · SRF3 shock absorber brand restriction removed; all shocks must be sealed by Enterprises. · GTX adds Lotus Evora GTS with 3.5L 2GR-FE engine, no restrictor, 2950 lbs minimum weight. · SRF3 bump stop now must be SCCA P/N 280407 only, no modifications, optional, max one per shock. · SRF shock absorber bump stop clarified: only SCCA P/N 280407 allowed as delivered, maximum one per shock, effective 05/01/2020. · GT1, GT2, GT3, GTL, GTX may omit windshield clips if factory glass is bonded per original specifications. · Factory Five Type 65 Coupe R with Ford 302/351 or 5.0/5.2L NA added to GTX-MISC at 2600 lbs. · SRF rain and brake rule wording updated; supersedes GCR 9.3.32.B.2 effective 1/1/202 through 12/31/2024. · SRF bans tire warmers and cooling methods other than natural air convection or conduction. · SRF front nose weight minimum reduced from 35 to 32 lbs. · SRF3 reclassified as Spec Racer Ford 3 with 1.6L conversion; SRF2 becomes Regional Only Class. · SRF drivers may now use Dash Windscreen Kit P/N 1180103 or P/N 180102. · SRF3 nose assembly must use approved multi-piece design; no modifications allowed except as specified. · GTX tube frame cars gain fuel injection with 90mm maximum throttle body size. · Ligier JS2 R classified in GTX, no performance parameters specified in filing. · SRF3 brakes now allow Hawk Blue 9012 pads P/N 801993 only; shocks simplified to Penske P/N 280396 sealed assembly only, with optional SCCA Enterprises bump rubber P/N 280407 from 05/01/2020. · GT1 and GT2/GT3/LITE ride height requirements removed from GCR sections 9.1.2.D.5.a.1 and 9.1.2.F.7.b. · GTX replaces all FIA GT4 references with SRO GT4. · GTX FIA GT3: Audi R8 40mm restrictor 2900 lbs, BMW Z4 70mm 2800 lbs, Ferrari 488 35mm restrictor 3025 lbs classified.show
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Best is the class's fastest lap in that event's qualifying or race sessions, with the driver who set it, how many cars set a time that session and how close the top five were; a best from fewer than three cars is greyed. With two or more classes, "vs" is the gap of each class's best to the first class's at the same event. "% of GTX" is the class's best as a share of GTX's best at the same event (100% is level, less is quicker): weather and track condition move every class together, so this compares across years where the raw times do not. It still breaks when GTX's own field changes or one session was wet and another dry. Newest event first. The coloured figure under each value is the change from the previous event that has one (green is quicker, red slower). Whole laps only, so events with different sector layouts still compare. Weather and track condition are not accounted for.