A first for marine inboards, Indmar Marine's new ETX/CAT slashes exhaust emissions in half, thereby meeting or outright exceeding the stringent 2007 California Air Resources Board (CARB) mandate. How the catalytic converter for boats works is as simple as the sea is salt, at least in theory.
Hot exhaust gas flows out of the cylinders and into a canister that’s been strategically mounted in an exhaust manifold canister that‘s about the size of a can of beans. Inside the canister is a brick comprised of precious metals. Fresh from the combustion chamber, exhaust gas is red hot. At that high-temperature, a chemical reaction between the heat and the precious metals eliminates toxic gas. There’s more to the story.
Part and parcel of the ETX/CAT system is MEFI-5, GM’s latest and greatest version of an electronic control module. It juxtaposes ignition timing, ignition spark, and the fuel-to-air ratio. MEFI-5’s ability to precisely adjust those variables to the nth degree makes it possible for ETX/CAT to scrub exhaust gas clean and, at the same time, for the pistons and crankshaft to build horsepower in a flat, torque curve. The flatter the curve, the stronger the acceleration.
ETX/CAT is standard equipment on all Indmar 5.7L premium V-8 electronic fuel injected (EFI) inboards. These are the first marine engines to earn CARB’s Four Star Rating for marine engines awarded for Super UltraLow Emissions. Look for these engines on MasterCraft and Moomba and Malibu brand boats.