CLASSES

Unlimited Class

9900CC NA and above includes all Turbines and Turbo engines above 4.2 litres

A Class

From 1st January 2026 the following changes to  A Class come into effect.  

Any engine up to 10.6L (650 CID) Naturally aspirated. Or any engine up to 6.3L (385 CID) with forced induction.

CX Class

Formula class designed to provide a level playing field for drivers - Speed up around 105mph

FX-Evo Class (NZ Only Class)

FX -Evo Class  was implemented in 2024  and is being run in the 2025 Season. All Current FX Class boats will fall into the class but will no longer be governed by the FX Engine restrictions so any modification to their current FX Engine is now allowed.  This is a Speed Restricted Class and Speed Shall be governed to 137 KM/H - 85 MPH

Please refer to the FX-Evo Class Rules for details

FX Class (UIM World Class)

From 2026 UIM has made the following amendment:

For the “FX Class” the engines allowed to race are Chevrolet crate engines with cast iron block with maximum displacement of 6000cc.

Roll Bar: Well braced and mounted steel tube (chrome moly or aluminium tube can also be used with the minimum diameters and structure indicated previously in this rule).

Engine Type: 8 Cylinder, normally aspirated, cast iron block only.

Engine: Any Chevrolet V8 GM 5.7L ZZ crate series OR Cast Iron Block LS / LY6 364 Crate Engine series with a maximum displacement of 364 c.i. / 6,000 cc.

GM LS / LY6 364 engine part numbers GM19209705 and/or 19209063 (long block); ZZ series engine part numbers: 24502609(ZZ4) ; 19301293(ZZ5) 19433041 (ZZ6)

The allowed engines part numbers and/or additional engine configurations must be stated in the Advance Program. Other engines not exceeding 400 HP with similar specs can be used, as long as they are stated in the Advance Program

Remanufactured engines allowed. Particular engine rebuilds allowed to be published in the Advance Program.

Pistons: Only pistons with the original GM design for the original engine used to be allowed. No dome style pistons.

Intake manifold: Any GM brand stock intake manifold, according to engine type.

Electronic Fuel injection systems are allowed, as long as they use the original GM intake manifold, if engine is provided as such.

If fuel injection systems are used, 80MM max throttle body is allowed.

Carburetor: Single carburetor. Any type Off-the shelf exceeding 750 CFM. LS 364 engines can use a GM brand stock

intake manifold for use with carburetors.

Oil pump: Any. No dry sump systems allowed.

Starter / Fuel pump / Headers / Oil pan / Ignition / Valve covers: Any

Fuel: Gasoline only. The Race Organizer must indicate in the Advance Program if there are any restrictions as far as transporting large amounts of fuel in the Country where the race will be held.

Propulsion: Any type of jet drive, modifications allowed.