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EZ Street – 2017

EZ Street – 2017 Rules

This class is limited to cars and trucks running an OEM style automatic transmission that have a single power adder (Nitrous, Single Turbo or Single Centrifugal Supercharger), or that are Naturally Aspirated.

Body and Chassis

  • Lexan and plexi-glass window replacements permitted.
  • Functioning lights are required.
  • Sponsor lettering restricted to vehicle glass and/or hood only.
  • Body must be dimensionally stock. (Except for NA combos)
  • Small chin spoiler permitted.
  • A small rear wing permitted. No molding of spill plates to quarters.
  • Frontal air permitted on Blower and Turbo combinations
  • Forward facing hood scoops permitted on Nitrous combinations
  • Stock, Ladder Bar & 4 link rear suspension permitted. (See adders below)
  • Stock style front suspension required. If vehicle came with upper and lower      control arms it must retain them.
  • Firewall in stock location required between the lower frame rails and up to the top of the block.
  • OEM Front Frame Rails are required from the firewall to 4” in front of the spindle.  Up to a maximum of 50% of them may be modified or fabricated for header clearance. OEM Frame Rails must also be connected to the k-member or lower suspension component by either welding or bolting.
  • OEM Front Strut/Shock Towers must be functional and in stock location.  Sheet metal from the shock/strut towers to firewall must exist but may be modified or fabricated.
  • Engine may not be relocated more than 2” from stock location.
  • Wheelbase must be within 2” of stock.


  • Mufflers required on all combos.
  • Must be commercially available units, no home built mufflers.
  • No gutting of mufflers permitted.
  • No insert style mufflers.
  • Turbos are not considered to be a muffler.


  • Fabricated intakes permitted (boosted entries see adders below)
  • Single carburetor or throttle body only for blower and turbo entries
  • 8 barrels of induction permitted on small block nitrous entries (Dual 4bbl or 4 split Dominator carbs.)
  • 4 barrels of induction permitted on big block nitrous entries (Single 4bbl or 2 split Dominator carbs.)
  • EFI Big Blocks permitted a single throttle body with 4 round barrels total.
  • EFI Small Blocks permitted two throttle bodies with 8 round barrels total.


  • Slick up to 33.0×10.5w for Naturally Aspirated entries. (Max Tread = 11.5”)
  • Slick up to 31.0×10.5w for All Nitrous entries (Max Tread = 11.5”)
  • Slick up to 29.5×10.5 (non-W) for Boosted entries (Max Tread = 11.0”)
  • Hoosier 29.5 (non-W) part #18192 is not allowed on Boosted entries.
  • DOT Tires up to 315-60-15 or 31×13.50 for all combos (See Weight Breaks)


  • OEM style automatic transmissions only except for Small Block Nitrous and Naturally Aspirated entries
  • Liberty Transmissions permitted with clutch or converter for Small Block Nitrous and Naturally Aspirated combinations only.


  • Gasoline only
  • No Alcohol, Ethanol or Nitromethane


  • Engine Diaper – Mandatory. Non SFI units OK.
  • Fire System – Mandatory.
  • HANS (or equivalent) device – Mandatory


  • Nitrous systems limited to 4 solenoids (2 nitrous and 2 fuel) for big block entries and 8 for small block entries.
  • Single stage systems only for Big Blocks. Must use fogger or plate, no combination of the two will be permitted.
  • Second Stage is permitted on Small Blocks only.
  • Fogger systems limited to single nitrous and fuel nozzle per cylinder with single nitrous and fuel feed per nozzle for big block entries.
  • Plate systems limited to single plate.
  • Progressive systems with 1 extra nitrous solenoid permitted.
  • No disconnected auxiliary nitrous equipment permitted. Only approved nitrous system may be on entry to pass OSCA tech inspection.
  • Water Injection permitted only on Nitrous combinations if used with only water and random inspections may be performed.

Small Blocks

2650# – 370ci and smaller

2750# – 371ci to 419ci

2850# – 420ci to 460ci

2950# – 461ci and larger


Big Blocks

  • Maximum displacement of 565ci for Non-Conventional Heads
  • Maximum displacement of 588ci for Conventional Heads
  • Only x275 legal Big Block Nitrous Heads are considered “Conventional”
  • Maximum Bore Space of 900”

          3000# base weight

          +3lbs per cubic inch above 510ci up to Max Displacement (see above)

          -2lbs per cubic inch down from 510ci to 450ci.


Single Centrifugal Supercharger

  • Blowers permitted: F1R, F1X, F1X-12 and F2.
  • Max inlet is 115mm.
  • No reducers of any type allowed.
  • Max cubic inches 470ci

Small Block with F1R – 3250#

Big Block with F1R – 3350#

Small Block with F1X or F2 – 3350#

Big Block with F1X or F2 – 3450#

Small Block with F1X-12 – 3450#

Big Block with F1X-12 – 3550#


Single Turbocharger

  • Large frame turbos permitted with reducer-Max impeller size 106mm (no billet impellers)
  • Max turbo inlet diameter 88mm-reducer must follow the general bell shape of the original inlet and must end no more than 2” from the impeller directly below the end of the reducer
  • All air entering turbo must pass through 88 mm reducer and no anti-surge holes/vents permitted
  • Any entry not fitting the criteria will be disqualified or given a weight adder as deemed fit
  • Reducer size subject to change at any time and without notice
  • True 88mm turbos with billet impellers allowed
  • Max cubic inches 470ci

Small Block – 3450#

Big Block – 3550#


Naturally Aspirated

  • Max cubic inches 650ci for Big Block and 490ci for Small Block.
  • Maximum bore space is 900” for Big Block.
  • Any carbs or throttle bodies permitted
  • Any transmission permitted with a torque converter or a clutch.
  • 0W 10.5 Tire permitted

Small Block – 2400#

Big Block – 2700#


Weight Breaks

  • Any legal tire other than 31×10.5w (Nitrous Combos Only) -50#
  • Air to Air Intercooler -100#
  • No frontal air intake (all combos) -50#
  • SB Turbo/Blower 410ci or under with Inline Heads -75#
  • Conventional Head Big Block Nitrous -50#


Weights Adders

  • 4-Link rear suspension +25# (No adder for SB NOS or SB/BB NA combos)

If you are building a racecar and are unclear about the rules concerning your class, please contact us.

The OSCA reserves the right to impose penalties for rule infractions and on items which do not represent the intent of the class entered.

Rules are subject to change without notice and in the spirit of the competition will be reviewed continually throughout the season.

If in doubt as to rule interpretation please contact us for final ruling.

Here’s a list of the changes for 2017:

  • Removed the wording that previously allowed for cars to race without stock style front suspensions and chassis.
  • Added Liberty Transmissions for Small Block Nitrous combinations.
  • Removed boosted sheet-metal intake adder.
  • Reduced 4-link adder.
  • Reduced NA weights.