BoP Lab / Buttonwillow Raceway Park

EP + FF at Buttonwillow Raceway Park

No mapCal Club 2024

This track has been raced on 2 configurations (The Circuit, 2.57 mi; 2.92 mi). Laps on different configurations are not comparable, so only events on the 2.57 mile layout are shown; switch above to see the others.

Pos	Car	Driver	Class	#	Lap	Theoretical	Qual	Race	5-lap stint	Consistency	Trap	S1	S2	S3
1	SWIFT DB-6 Honda	Edward Erlandson 2+ cars	FF	8	1:49.259 A-P									47.766 A-P
2	Piper DL7-Honda	Eric Poulsen	FF	48	1:51.118 B-R1	1:50.744	1:52.044 B-Q1	1:51.118 B-R1	1:51.583 B-R1	+3.025 B-R1	114.7 B-R1	30.276 B-R1	31.650 B-R1	48.818 B-R1
3	Mazda Miata	Joe Carr	EP	12	1:52.034 B-P	1:52.034	1:59.603 A-Q1	1:59.157 A-R1	1:59.373 A-R1	+0.724 A-R1	131.6 A-R1	31.719 B-P	32.405 B-P	49.966 B-P
4	Mazda MX-5	Glen McCready	EP	4	1:53.088 B-Q2	1:52.984	1:53.088 B-Q2	1:53.487 B-R2	1:54.617 B-R2	+2.232 B-R2	125.6 B-P	30.761 B-R2	32.765 B-Q1	49.458 B-Q2
5	SWIFT DB-	Edward Erlandson 2+ cars	FF	54	1:53.098 A-Q1	1:53.041	1:53.098 A-Q1	1:54.741 A-R2	1:56.774 A-R2	+1.819 A-R2	133.7 A-Q1	30.951 A-Q1	32.299 A-Q1	49.791 A-Q1
6	Swift Db6	Johnnie Crean	FF	35	1:54.993 A-R2	1:54.490	1:55.247 A-Q2	1:54.993 A-R2	1:56.752 A-R2	+1.519 A-R2	124.5 A-R2	31.358 A-Q1	32.841 A-R2	50.291 A-R2
7	Mazda RX-7	Kurt Frietzsche	EP	40	1:56.468 B-Q1	1:55.599	1:56.468 B-Q1	1:56.573 B-R1	1:57.721 B-R1	+1.914 B-R1	120.7 A-R2	31.324 B-Q1	34.071 B-R1	50.204 B-R1
8	Mazda RX-7	Brandon Droese	EP	02	1:56.943 B-Q1	1:56.657	1:56.943 B-Q1	1:58.611 B-R1	1:58.767 B-R1	+0.718 B-R1	94.1 B-Q1, B-R1	31.953 B-R1	33.891 B-Q1	50.813 B-Q1
9	BMW E30	Sean Lovett	EP	37	2:00.712 A-Q2	2:00.625	2:00.712 A-Q2	2:01.864 A-R2	2:02.200 A-R1	+0.528 A-R1	127.6 A-Q2	32.761 A-Q1	34.806 A-Q1	53.058 A-Q2
10	Porsche Boxster	William Robinson	EP	198	2:01.940 A-Q1	2:01.634	2:01.940 A-Q1	2:02.887 A-R1	2:03.347 A-R1	+1.312 A-R1	130.6 A-Q2	32.969 A-Q1	35.257 A-Q1	53.408 A-Q1
11	Mazda MX-5	Whitfield Gregg	EP	17	2:03.660 B-Q2	2:03.314	2:03.660 B-Q2	2:04.085 B-R1	2:05.470 B-R2	+2.529 B-R2	97.7 B-R2	33.862 B-R2	35.422 B-R1	54.030 B-Q2

One row per driver and car (a driver who changed cars has a row for each). Each cell is that driver's best in that car across the selected events, with the session it was set in. Best 5-lap stint is the mean of the driver's quickest five consecutive race laps, and consistency is how far their median race lap sat behind their best in that race (small is a driver who does it every lap); both come from the race with the best stint. The fastest in each column is purple, and a car whose best lap is more than 115% of the fastest in its class is greyed (marked ">115%" beside the driver) and left out of the colour scale. Click a column to sort, a row to highlight it. Theoretical lap is the sum of the best sectors, whichever laps they came from, and never slower than the best lap (where a car's fastest laps were recorded without sector times, its best lap is used). The 115% mark is about the car's best lap only: a car whose best lap is within 115% of the fastest in its class is never marked. Greyed sectors with no theoretical lap mean the sector times on file do not add up to a believable lap. Letters refer to the events above; Q is qualifying, R a race.

Sectors

S1 SF → IM1 0.65 mi
S2 IM1 → IM2 0.75 mi
S3 IM2 → SF 1.17 mi
Spd In → Out 0.03 mi

Sectors are numbered in lap order from start/finish, whatever each event's timing called them; the loop names are SCCA timing's.

By car

Car	Class	Drivers	Lap	Qual	Race	Trap	S1	S2	S3
Swift Db6	FF	2	1:49.259Edward Erlandson	1:55.247Johnnie Crean	1:54.993Johnnie Crean	124.5Johnnie Crean	31.358Johnnie Crean	32.841Johnnie Crean	47.766Edward Erlandson
SWIFT DB-6 Honda	FF	1	1:49.259Edward Erlandson						47.766Edward Erlandson
Swift Db6	FF	1	1:54.993Johnnie Crean	1:55.247Johnnie Crean	1:54.993Johnnie Crean	124.5Johnnie Crean	31.358Johnnie Crean	32.841Johnnie Crean	50.291Johnnie Crean
Piper DL7-Honda	FF	1	1:51.118Eric Poulsen	1:52.044Eric Poulsen	1:51.118Eric Poulsen	114.7Eric Poulsen	30.276Eric Poulsen	31.650Eric Poulsen	48.818Eric Poulsen
Mazda Miata	EP	1	1:52.034Joe Carr	1:59.603Joe Carr	1:59.157Joe Carr	131.6Joe Carr	31.719Joe Carr	32.405Joe Carr	49.966Joe Carr
Mazda MX-5	EP	2	1:53.088Glen McCready	1:53.088Glen McCready	1:53.487Glen McCready	125.6Glen McCready	30.761Glen McCready	32.765Glen McCready	49.458Glen McCready
SWIFT DB-	FF	1	1:53.098Edward Erlandson	1:53.098Edward Erlandson	1:54.741Edward Erlandson	133.7Edward Erlandson	30.951Edward Erlandson	32.299Edward Erlandson	49.791Edward Erlandson
Mazda RX-7	EP	2	1:56.468Kurt Frietzsche	1:56.468Kurt Frietzsche	1:56.573Kurt Frietzsche	120.7Kurt Frietzsche	31.324Kurt Frietzsche	33.891Brandon Droese	50.204Kurt Frietzsche
BMW E30	EP	1	2:00.712Sean Lovett	2:00.712Sean Lovett	2:01.864Sean Lovett	127.6Sean Lovett	32.761Sean Lovett	34.806Sean Lovett	53.058Sean Lovett
Porsche Boxster	EP	1	2:01.940William Robinson	2:01.940William Robinson	2:02.887William Robinson	130.6William Robinson	32.969William Robinson	35.257William Robinson	53.408William Robinson

The best any driver of each car managed across the selected events, with who set it. Spellings and model years of the same car are grouped; click a row marked ▸ to see each version. Grouping is worked out from the names, so tell us if two cars are wrongly merged or split.

Rule changes between these events

Cal Club 2024 → Cal Club 2025 2024-02-23 to 2025-02-22

2024-03-01 EP GCR Correction - Redundant HP Spec Lines

#35623 from Production Committee · Rule change · TB 24-03 (2024-03 Fastrack)

neutralHP removes four redundant VW spec lines: Rabbit Cabriolet 1780, Scirocco 1588, Scirocco 1780 8-valve, Scirocco 1588.

In HP Spec Lines, delete the following redundant spec lines in their entirety:
Spec line #10 - VW Rabbit Cabriolet 1780
Spec line #3 - VW Scirocco 1588
Spec line #4 - VW Scirocco 1780 (8-valve) (83-88)
Spec line #5 - VW Scirocco 1588

2024-06-01 EP NIssan 300ZX Z31 to EP

#35830 from Murphy Nichols · Rule change · TB 24-06 (2024-06 Fastrack)

neutralNissan 300ZX 84-89 classified to EP at 2550 lbs minimum, 2960cc 6-cyl SOHC, fuel injection, 12.0:1 compression limit, 0.500" valve lift limit.

In EP Spec Lines, classify Nissan 300ZX (84-89), as follows:

A specification table follows in the original; it is not shown here.

2024-06-01 EP RX7 1993 and Up Request In EP Spec Lines, classify

#36031 from Edward Zabinski · Rule change · TB 24-06 (2024-06 Fastrack)

neutralMazda RX-7 92-97 newly classified EP Prep Level 2 at 2200–2310 lbs with 13B 6-port rotary engine.

Mazda RX-7 (92-97) as follows:

A specification table follows in the original; it is not shown here.

2024-06-01 EP Clean-up Multiple EP RX-8 Spec Lines In EP

#36156 from Production Committee · Rule change · TB 24-06 (2024-06 Fastrack)

neutralEP Mazda RX-8 (04-11) alternate spec line removed; one primary line remains.

Spec Lines, make the following changes to the two Mazda RX-8 spec lines.
Remove spec line entirely:
~~Mazda RX-8 (04-11)~~
Remove the wording "alternate":
Mazda RX-8 (04-11)~~(alternate)~~
Spec Mazda (SM/SMX) None.

2024-08-01 EP Errant entry in HP production line item

#36231 from Angus Crome · Rule change · TB 24-08 (2024-08 Fastrack)

neutralHP Volkswagen Golf and Jetta 85-92 track correction: front 1537mm (60.5in), rear 1529mm (60.2in).

In HP Spec Lines, change Track (F/R)mm/(in.) as follows:
Volkswagen Golf (GTI, GT, GL) (85-92): "2 1537/1529 (60.5/60.2)"
Volkswagen Jetta (GLI, GL) (85-92): "2 1537/1529 (60.5/60.2)"

2024-10-01 FF Update to FF EGR Blanking Plate Rule

#36633 from Matt Boian · Rule change · TB 24-10 (2024-10 Fastrack)

neutralFF VTEC activation valve must function; EGR blanking plate rule clarified with Fast Forward part numbers.

In FF, GCR section 9.1.1.B.14.r.1, change as follows:
"All emission control devices must be removed and blocked off by the blanking plate provided by HPD or Fast Forward as noted
below, except for the VTEC activation valve. The VTEC activation valve must be retained; and it must be functioning. No
modifications are permitted.
a. EGR Plate: Fast Forward PN: FF200-301.
b. EGR Port Cover: Fast Forward PN: FF200-302."

2024-11-01 EP 1275 HP Spridget Level 2 Only

#36518 from Darryl Saylor · Rule change · TB 24-09 (2024-09 Fastrack)

fasterHP Sprite and Midget 1275cc and 1098cc Level 2 compression ratio raised to 12.0:1.

In HP Spec Lines, Austin-Healey Sprite MkI, II, III, IV MG Midget (ALL) - Level 2 - 1275cc, change Notes as follows:
"(Effective 11/1/2024) Compression ratio limited to 11 12.0:1"
In HP Spec Lines, Austin-Healey Sprite MkI, II, III, IV MG Midget (ALL) - Level 2 - 1098cc, change Notes as follows:
"(Effective 11/1/2024) Compression ratio limited to 11 12.0:1"

2024-11-01 FF Change FF/FC Weight with Sequential Gearbox

#36651 from Robert Wright · Rule change · TB 24-11 (2024-11 Fastrack)

fasterFF and FC cars with sequential gearbox must add 10 lbs. to minimum weight, down from 25 lbs.

In FF, GCR section 9.1.1.B.20.A.3, change as follows:
"Cars running with a sequentially shifted gear box ~~shall~~ must add 25 10 lbs. to minimum weight."
In FC, GCR section 9.1.1.B.20.B.4, change as follows:
"Cars running with a sequentially shifted gear box ~~shall~~ must add 25 10 lbs. to minimum weight."

2024-11-01 EP NA Miata Track Width Correction

#36902 from Production Committee · Rule change · TB 24-11 (2024-11 Fastrack)

neutralEP Mazda Miata front and rear track widths increased to 1516/1534 mm (59.7/60.4 in.) across all generations.

In EP Spec Lines, Track (F/R) mm/(in.), change as follows:
Mazda MX-5 /Miata 1.6L (-1993) - ~~"1478/1491 (58.2/58.7)~~ 1516/1534 (59.7/60.4)"
Mazda MX-5 /Miata 1.8L (90-97) - ~~"1483/1509 (58.4/59.4)~~ 1516/1534 (59.7/60.4)"
Mazda MX-5 /Miata (94-97) - "~~1483/1509 (58.4/59.4)~~ 1516/1534 (59.7/60.4)"

2024-11-01 FF Alternative Oversize Honda Fit Pistons

#37064 from Formula/Sports Racing Committee · Rule change · TB 24-11 (2024-11 Fastrack)

neutralFF Honda Fit allows Fast Forward 0.25mm oversize pistons PN FF800-110 as alternative; piston diameter spec clarified to 2.8835 inches.

In FF, GCR section 9.1.1.B.14.e.1, change as follows:
"Honda Fit OEM standard size pistons, PN: 13010-RB1-000, or Honda Fit OEM 0.25mm oversize pistons, PN: 13020-RB7-Z00, or
Fast Forward 0.25mm oversize pistons, PN: FF800-110, may be used."
In GCR section 9.1.1.B.14.e.2, change as follows:
"a. Maximum standard piston diameter, measured at a point 16mm from the bottom of the skirt: 73.240mm
(~~2.8834~~ 2.8835 inches).
b. Centerline of wrist pin to crown maximum: 26.21mm (1.032 inches).
c. Maximum overall height from skirt to crown edge: 47.80mm (1.882 inches).

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d. Minimum weight: 198.0 grams (6.984 ounces).
e. Minimum weight of piston pin: 66 grams (2.25 ounces).
f. Combined minimum weight of piston, piston pin and connecting rod: 543.5 grams (18.85 ounces).
g. Combined minimum weight of piston, wrist pin, and circlips: 267 grams (9.418 ounces).
h. Centerline of wrist pin to crown edge: 26.289mm (1.035 inches).
i. Ring groove widths:
Top ring groove: 1.003mm (0.0395 inches).
Middle ring groove: 1.016mm (0.0400 inches).
Oil ring groove: 1.981mm (0.0780 inches).
j. Ring groove distance from wrist pin center to bottom of groove:
Top ring groove: 19.63mm (0.7730 inches).
Middle ring groove: 15.29mm (0.6020 inches).
Oil ring groove: 10.91mm (0.4295 inches)."

2024-12-01 EP Triumph GT6 Adjustments

#37112 from Anthony Parker · Rule change · TB 24-12 (2024-12 Fastrack)

slowerEP Triumph GT6 switches to three Weber 40 DCOE carbs with 28mm chokes, weight rises 50 lbs to 1990.

In EP Spec Lines, make the following changes in the "Triumph GT6" spec line:
Carburetor No. & Type: (2): "~~1.5”~~ 1.75" Auto-type carburetor(s)"
Notes: "~~Two (2) 1.75” auto-type carburetors @ 1940 lbs.~~ Three (3) Weber 40 DCOE on IR manifold with 28mm chokes @ 1990
lbs. Laycock overdrive, May use 5 speed gearbox w/o overdrive."

2025-01-01 EP Request to Reduce Weight of BMW 325i/is E30 (84-91) Spec Line

#37119 from Tim Schreyer · Rule change · TB 25-01 (2025-01 Fastrack)

fasterEP BMW 325i/is E30 (84-91) weight reduced 50–52 lbs across three spec lines to 2150, 2204, 2258.

In EP SPEC LINES, BMW 325i/is (E30) (84-91), change Weight as follows:
"~~2200~~ 2150
*~~2255~~ 2204
**~~2310~~ 2258"

2025-02-21 EP Effective date for Jan 2025 GCR updates

#37654 from Doug Piner · Rule change · TB 25-02 (2025-02 Fastrack)

slowerEP BMW Z3 2.5L requires 52mm flat plate intake restrictor; Z3 2.8L 55mm; 328i/is E36 58mm; 328i/ci E46 58mm; 325i/is E46 56mm; 325i/is E36 56mm; 325is M-Technic 56mm.

In EP Spec Lines, add to Notes as follows:
BMW Z3 2.5LL "(Effective 2/21/2025) 52mm Flat Plate Intake Restrictor is required."
BMW Z3 2.8L (97-00): "(Effective 2/21/2025) 55mm Flat Plate Intake Restrictor is required."
BMW 328i/is E36 (96-99): "(Effective 2/21/2025) 58mm Flat Plate Intake Restrictor is required."
BMW 328i/ci E46 (01-06): "(Effective 2/21/2025) 58mm Flat Plate Intake Restrictor is required."
BMW 325i/is E46 (01-06): "(Effective 2/21/2025) 56mm Flat Plate Intake Restrictor is required."
BMW 325i/is E-36 (92-95): "(Effective 2/21/2025) 56mm Flat Plate Intake Restrictor is required."
BMW 325is M-Technic (1994): "(Effective 2/21/2025) 56mm Flat Plate Intake Restrictor is required."

Cal Club 2025 → Cal Club 2026 2025-02-22 to 2026-02-21

2025-03-01 EP Request Competition Adjustment to BMW Z3 2.5L

#37120 from Tim Schreyer · Rule change · TB 25-01 (2025-01 Fastrack)

slowerEP BMW Z3 and 3-series models get smaller intake restrictors: Z3 2.5L to 52mm, Z3 2.8L to 55mm, 328i to 58mm, 325i to 56mm.

In EP Spec Lines, change Notes as follows:
BMW Z3 2.5LL "(Effective 3/1/2025) ~~56mm~~ 52mm Flat Plate Intake Restrictor is required."
BMW Z3 2.8L (97-00): "(Effective 3/1/2025) ~~59mm~~ 55mm Flat Plate Intake Restrictor is required."
BMW 328i/is E36 (96-99): "(Effective 3/1/2025) ~~62mm~~ 58mm Flat Plate Intake Restrictor is required."
BMW 328i/ci E46 (01-06): "(Effective 3/1/2025) ~~62mm~~ 58mm Flat Plate Intake Restrictor is required."
BMW 325i/is E46 (01-06): "(Effective 3/1/2025) ~~60mm~~ 56mm Flat Plate Intake Restrictor is required."
BMW 325i/is E-36 (92-95): "(Effective 3/1/2025) ~~60mm~~ 56mm Flat Plate Intake Restrictor is required."
BMW 325is M-Technic (1994): "(Effective 3/1/2025) ~~60mm~~ 56mm Flat Plate Intake Restrictor is required."

2025-03-01 EP Interpretation of Production Rules on Mirrors

#37235 from Lawrence Slivinski · Rule change · TB 25-03 (2025-03 Fastrack)

neutralEP, FP, HP: interior or exterior mirrors meeting rule 9.3.36 now permitted.

In GCR, add new rule as Section 9.1.5.E.10.f:
"Any interior or exterior mirror(s) that meets rule 9.3.36 may be used."

2025-03-01 EP Weight Reduction for Honda S2000

#37466 from Michael Unger · Rule change · TB 25-03 (2025-03 Fastrack)

fasterEP Honda S2000 1997cc base loses 75 lbs to 2375; 2157cc base loses 60 lbs to 2450.

In EP, Spec Lines make the following weight changes:

A specification table follows in the original; it is not shown here.

2025-03-01 EP Mazda 1999 Miata 1.8L

#37488 from Joe Carr · Rule change · TB 25-03 (2025-03 Fastrack)

fasterEP Mazda MX-5/Miata 99-05 minimum weight drops to 2100 lbs, 2153 lbs with power adder, 2205 lbs with two adders.

In EP Spec Lines, make the following weight change:
Mazda MX-5 /Miata (99-05):
"~~2150~~ 2100
*~~2204~~ 2153
**~~2258~~ 2205"

2025-03-01 FF Formula F Proposal to Invite Older Cars Via a Tire Rule Change

#37802 from Anthony Stefanelli · Rule change · TB 25-03 (2025-03 Fastrack)

fasterFF allows older cars with rocker arm or outboard suspension to use bias ply slicks or VFF tires instead of radials.

In FF, GCR section 9.1.1.B.10.e, change as follows:
"Formula F shall be limited to the following tires (front tires may not be used as rears):
Dries:
Front - Hoosier R60A Radial 43322 or F1600 Radial 43321 185/60R13
Rear - Hoosier R60A Radial 43327 or F1600 Radial 43326 205/60R13
Wets:
Front - Hoosier Wet or W3 Radial 44421 185/60R13
Rear - Hoosier Wet or W3 Radial 44426 205/60R13

Show 12 more lines

Alternatively, Formula F cars with rocker arm suspension (e.g., Swift DB1, 1987-90 Reynard) and/or outboard suspension on at
least one chassis end may use the following tires:
Dries:
Front - Hoosier H43130 R60A 20.0 x 6.0-13 or H43164 R60A 20.5 x 7.0-13 bias ply slick
Rear – Hoosier H43307 R60A 22.5 x 7.2-13 bias ply slick
Wets:
Radial wets listed above
or
Front - Hoosier 44165 135/545-13 VFF
Rear - Hoosier 44170 165/580-13 VFF
Front tires may not be used as rears, and tires may not be mixed, i.e., radial tires may not be mixed with bias ply slick tires, bias
ply slick tires may not be mixed with VFF tires, and radial tires may not be mixed with VFF tires."

2025-04-01 EP Request for Classification of Chevrolet Spark

#37755 from Kristian Smith · Rule change · TB 25-04 (2025-04 Fastrack)

neutralChevrolet Spark 16-22 classified HP Pre at 1850 lbs minimum weight, fuel injected, 1399 cc.

In HP Spec Lines, classify the Chevrolet Spark (16-22):

A specification table follows in the original; it is not shown here.

2025-04-01 EP Request to Lower Ford Festiva Minimum Weight to 1600 LBS

#37939 from Doug DeRonne · Rule change · TB 25-04 (2025-04 Fastrack)

fasterHP Ford Festiva 88-93 minimum weight drops to 1600 lbs, variants to 1640 and 1680 lbs; compression ratio raised to 11.0:1.

In HP Spec Lines "Ford Festiva (88-93)" change as follows:
Weight:
"~~1700~~ 1600
*~~1743~~ 1640
**~~1785~~ 1680"
Notes:
"Compression ratio limited to ~~10.5~~ 11.0:1. Valve lift limited to .450”."

2025-05-01 FF Page 228, FF tire rule 9.1.1.10.e

#38251 from Anthony Stefanelli · Rule change · TB 25-05 (2025-05 Fastrack)

neutralFF adds rocker arm and outboard suspension cars optional bias ply and VFF tires; removes front-as-rear rule, adds mixing restrictions.

In FF, GCR section 9.1.1.B.10.e, change as follows:
"Formula F shall be limited to the following tires ~~(front tires may not be used as rears)~~:
Dries:
Front - Hoosier R60A Radial 43322 or F1600 Radial 43321 185/60R13
Rear - Hoosier R60A Radial 43327 or F1600 Radial 43326 205/60R13
Wets:
Front - Hoosier Wet or W3 Radial 44421 185/60R13
Rear - Hoosier Wet or W3 Radial 44426 205/60R13

Show 16 more lines

Alternatively, Formula F cars with rocker arm suspension (e.g., Swift DB1, 1987-90 Reynard) and/or outboard suspension on at
least one chassis end may use the following tires:
Dries:
Front - Hoosier H43130 R60A 20.0 x 6.0-13 or H43164 R60A 20.5 x 7.0-13 bias ply slick
or
Hoosier 44165 135/545-13 VFF
Rear – Hoosier H43307 R60A 22.5 x 7.2-13 bias ply slick
or
Hoosier 44170 165/580-13 VFF
Wets:
Radial wets or VFF tires listed above
or
~~Front - Hoosier 44165 135/545-13 VFF~~
~~Rear - Hoosier 44170 165/580-13 VFF~~
Front tires may not be used as rears, and tires may not be mixed, i.e., radial tires may not be mixed with bias ply slick tires, bias
ply slick tires may not be mixed with VFF tires, and radial tires may not be mixed with VFF tires."

2025-06-01 EP Base Weight Adjustment for H-Production X1/9 Spec Lines

#38255 from Matthew Brannon · Rule change · TB 25-06 (2025-06 Fastrack)

fasterHP Fiat X-1/9 base weights reduced 50–53 lbs across 1300 and 1500 spec lines.

In HP Spec Lines, change Weight as follows:
Fiat X-1/9 & Bertone1500: “~~1790~~ 1740 *~~1835~~ 1784 **~~1880~~ 1827”
Fiat X-1/9 1300: “~~1650~~ 1600 *~~1691~~ 1640 **~~1733~~ 1680”
Fiat X-1/9 1300: “~~2060~~ 2010”
Fiat X-1/9 1500: “~~1950~~ 1900”

2025-07-01 EP BMW Z4 update

#38490 from Bryce McGuire · Rule change · TB 25-07 (2025-07 Fastrack)

slowerEP BMW Z4 03-05 restricted to 52mm flat plate intake restrictor.

In EP Spec Lines, BMW Z4 (03-05), add to Notes the following:
“52mm Flat Plate Intake Restrictor.”

2025-07-01 EP EP Fiat 124 Spider Competition Adjustment Request

#38498 from John Baucom · Rule change · TB 25-07 (2025-07 Fastrack)

fasterEP Fiat 124 Spider 1600 & 2000 weight drops 50 lbs to 2000; carburetors gain 2mm chokes to 36mm.

In EP Spec Lines, Fiat 124 Sport Spider 1600 & 124 Spider 2000, change as follows:
Weight: "~~2050~~ 2000"
Carburetor No. & Type: "(2) Weber 40 IDF-40IFI, (2) Solex C40P116, 34 36mm choke(s) req’d, (2) Weber 45DCOE w/ 34 36 mm
choke(s) on I.R. manifold or fuel injection."

2025-10-01 EP HP Plymouth Arrow spec omission

#38995 from Production Committee · Rule change · TB 25-10 (2025-10 Fastrack)

neutralHP Plymouth Arrow transmission max speeds clarified to 4 or 5.

In HP Spec Lines, Plymouth Arrow (76-80), add the following wording to Trans. Speeds(max):
"4 or 5"

2025-10-01 EP Add Wheel Diameter to Appendix G

#39008 from Production Committee · Rule change · TB 25-10 (2025-10 Fastrack)

neutralEP, FP, HP wheel diameter added to Appendix G as absolute maximum specification.

In Appendix G.2.3, change as follows:
"Rim width and diameter are is absolute maximums."

2025-10-01 EP Add TB ID tolerance to general Prod rules

#39009 from Production Committee · Rule change · TB 25-10 (2025-10 Fastrack)

neutralEP, FP, HP throttle body inside dimensions must remain stock with +/-.25mm tolerance; butterfly dimensions stock in FP, HP only.

In GCR, Section 9.1.5.E., change as follows:
9.1.5.E.1.b.4: "The inside dimensions of the throttle body casting/housing (as measured at the throttle butterfly) must remain
stock (tolerance of +/-.25mm), but the throttle body can otherwise be ported and polished."
9.1.5.E.2.b.4: "The inside dimensions of the throttle body casting/housing and all dimensions of the throttle butterfly must
remain stock (tolerance of +/-.25mm)."

2025-11-01 EP Please Lower Weight of 280Z

#38871 from Matthew Miller · Rule change · TB 25-09 (2025-09 Fastrack)

fasterEP Nissan 280Z minimum weight reduced from 2560 to 2400 lbs.

In EP Spec Lines, Nissan 280Z, change Weight (lbs) as follows:
"(Effective 11/1/2025) ~~2560~~ 2400
*~~2624~~ 2460
**~~2688~~ 2520"

2025-11-01 EP Miata Weight Adjustment Follow Up

#38949 from Don Tucker · Rule change · TB 25-10 (2025-10 Fastrack)

fasterEP Mazda MX-5 1.8L 90-97 weight reduced to 2125 lbs from 2150 lbs.

In EP Spec Lines, Mazda MX-5 / Miata 1.8L (90-97), Effective 11/1/2025 make the following weight change:
"~~2150~~ 2125"

2025-11-01 EP Weight Break for 1098 Midget / Sprite

#38970 from Kendall Jones · Rule change · TB 25-10 (2025-10 Fastrack)

fasterHP Austin-Healey Sprite/Midget 1098cc minimum weight drops 80 lbs to 1550.

In HP Spec Lines, Austin-Healey Sprite/Midget 1098cc, Effective 11/1/2025make the following weight change:
"~~1630~~ 1550"

2025-11-01 EP HP Volvo 142 spec omission

#38994 from Production Committee · Rule change · TB 25-10 (2025-10 Fastrack)

slowerHP Volvo 142/142E gains compression ratio limit 12.0:1 and valve lift limit .425".

In HP Spec Lines, Volvo 142/142E P-1800 Engine, Effective 11/1/2025 add the following wording to Notes:
"Comp. Ratio limited to 12.0:1. Valve lift limited to .425”."

2025-11-01 EP HP Mini DOHC 1.6

#38996 from Production Committee · Rule change · TB 25-10 (2025-10 Fastrack)

slowerHP Mini Cooper 07-15 valve lift reduced to .390", from .450".

In HP Spec Lines, Mini Cooper (07-13) (includes 09-15 convertible and 12-15 Coupe), Effective 11/1/2025 make the following
changes to the Notes:
"Compression ratio limited to 11.0:1, Valve lift limited to ~~.450”~~.390"."

2025-11-01 EP Add to Rabbit description

#39019 from Production Committee · Rule change · TB 25-11 (2025-11 Fastrack)

neutralFP and HP Volkswagen Rabbit descriptions updated: Convertible changed to Cabriolet in FP; Cabriolet added to three HP engine variants.

In FP Spec Lines, make the following spec line correction:
"Volkswagen Rabbit (Includes ~~Convertible~~ Cabriolet)"
In HP Spec Lines, make the following spec line correction:
"Volkswagen Rabbit 1588 (Includes Cabriolet)"
"Volkswagen Rabbit 1715 (Includes Cabriolet)"
"Volkswagen Rabbit 1780 (Includes Cabriolet)"

2025-11-01 EP Clean-up 9.1.5.E.7e

#39025 from Production Committee · Rule change · TB 25-11 (2025-11 Fastrack)

neutralEP, FP, HP: rear drum brake to disc conversion clarified; rotors solid, diameter limited to largest front rotor permitted.

In GCR, Section 9.1.5.E.7., change as follows:
"e. Cars fitted with rear drum brakes, can convert to rear disc brakes without penalty. N~~ote that the “Brakes Std.” and “Brakes~~
~~Alt.” listings on a vehicle’s spec line do not prohibit a car that was fitted with rear drum brakes stock, from converting to rear~~
~~disc brakes under this rule~~. When converting from rear drum brakes to rear disc brakes:
1. Rear brake rotors must be solid and can be no larger in diameter than the largest permitted front brake rotor, as defined on
the vehicle’s spec line.
2. Rear calipers and mounting brackets are unrestricted but must be made of a ferrous or aluminum material. ~~The standard and~~
~~alternate brake listings on a vehicle’s specification line, does not prohibit a car that was fitted with rear drum brakes as stock~~

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~~from converting to rear disc brakes under this rule.~~
3. The “Brakes Std.” and “Brakes Alt.” listings on a vehicle’s spec line do not prohibit a car that was fitted with rear drum brakes
as stock from converting to rear disc brakes under this rule."

2025-11-01 EP Add TB size to Ford Mustang (94-98) Spec Line

#39130 from Production Committee · Rule change · TB 25-11 (2025-11 Fastrack)

neutralEP Ford Mustang (94-98) fuel injected throttle body inside diameter specified at 60.

In EP Spec Lines, Ford Mustang (94-98) add the following to the Fuel Injected Equipped Throttle Body Inside Diameter column:
"60"

2025-12-01 EP TR2 Notes E&O

#39180 from Anthony Parker · Rule change · TB 25-12 (2025-12 Fastrack)

unclearEP Triumph TR2-TR4A allows 5-speed gearbox without overdrive; removes Weber carb and weight specification.

In EP Spec Lines, Triumph TR2, 3, 3A, 4, 4A, TR4, TR4A, IRS, make the following change to the Notes:
"Front apron assembly may be made of alternate material. ~~Three (3) Weber 40 DCOE on IR manifold with 28mm chokes @ 1990~~
~~lbs.~~ Laycock overdrive, may use 5 speed gearbox without overdrive."

2025-12-01 EP Balance of Power

#39187 from Jim Simaras · Rule change · TB 25-12 (2025-12 Fastrack)

slowerEP BMW Z3 2.5L restrictor reduced 52mm to 50mm, weight increased to 2550 lbs base; five other BMW models get smaller restrictors.

In EP Spec Lines, make the following changes to Restrictors:
BMW Z3 2.5L: "~~52mm~~ 50mm Flat Plate Intake Restrictor"
BMW Z3 2.8L (97-00): "~~55mm~~ 53mm Flat Plate Intake Restrictor"
BMW 328i/is E36 (96-99): "~~58mm~~ 55mm Flat Plate Intake Restrictor"
BMW 328i/ci E46 (01-06): "~~58mm~~ 55mm Flat Plate Intake Restrictor"
BMW 325i/is (E46) (01-06): "~~56mm~~ 53mm Flat Plate Intake Restrictor"
BMW 325is M-Technic (1994): "~~56mm~~ 53mm Flat Plate Intake Restrictor"
BMW 325i/is E-36 (92-95): "~~56mm~~ 53mm Flat Plate Intake Restrictor"

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In EP Spec Lines, BMW Z3 2.5L, change Weight as follows:
"~~2500~~ 2550
*~~2563~~ 2614
**~~2625~~ 2678"

2026-01-01 FF Formula F Alternative Tire Rule Proposed Clarifications

#39281 from Jay Messenger · Rule change · TB 26-01 (2026-01 Fastrack)

neutralFF clarifies alternative tire eligibility for cars homologated 1989 or earlier with rocker arm or outboard suspension on all four corners.

In FF, GCR section 9.1.1.B.10.e, change as follows:
"Alternatively, Formula F cars ~~with rocker arm suspension (e.g., 1987-90 Reynard, Swift DB1,) and/or outboard suspension on at~~
~~least one chassis end~~ homologated in 1989 or earlier with any combination of rocker arm or outboard suspension on all four
corners (e.g., 1987 – 1990 Reynard, Swift DB1) may use the following alternative tires. Note: This rule is intended to allow older
cars with the described suspension design to use the alternative tires. It is not to be exploited by modifying cars with push-rods or
pull-rods to meet the above requirements or by modifying either end of older cars to push- or pull-rod suspension to be eligible to
run the alternative tires. Cars that were homologated in 1989 or earlier with push- or pull-rod suspension on no more than two
corners may seek approval to run the alternative tire by utilizing the compliance process outlined in GCR section 8.1.4."

2026-01-01 EP Request to Update E30 BMW Throttle Body Diameter Verbiage

#39363 from Tim Schreyer · Rule change · TB 26-01 (2026-01 Fastrack)

neutralEP BMW 325i/is E30 throttle body specified as 60mm in fuel injection notes.

In EP Spec Line BMW 325i/is E30 (84-91), change Drivetrain Notes as follows:
"Fuel Injection, TB: 60mm"

What the rules allowed changed as listed; this does not say what any particular car ran.