CP Piston & Ring Set for Toyota 4AG 16V - Bore (81.5mm) - Size (+0.5mm) - CR (9.0) - Set of 4

What you get in this box is a complete set of four forged pistons and their matching rings, all ready to go into your Toyota 4AG 16V engine. These aren't just any pistons; they're built by CP Pistons, a name known for making strong engine internals. This specific set is designed for an 81.5mm bore and is a +0.5mm oversize, meaning it's intended for an engine that's already been bored out slightly to clean up the cylinders or accommodate these larger pistons. The compression ratio is set at 9.0:1, which is a common and reliable figure for many performance-oriented builds.

Forged pistons like these are a significant step up from cast pistons. They start as a solid block of aluminum that's heated and hammered into shape under immense pressure. This process aligns the metal's grain structure, making the piston much stronger and more resistant to the extreme heat and pressure found inside a performance engine. This strength is crucial for engines that see hard use, whether it's for track days, spirited driving, or just pushing the limits of a classic 4AG. The +0.5mm sizing indicates these are meant for a rebuild where the cylinders have been machined to this specific diameter, ensuring a precise fit and proper sealing.

When you're rebuilding the top end of your 4AG, especially if you're aiming for reliability and performance, a well-built piston set like this is a critical component. Remember that these pistons are an oversize, so ensure your engine block has been properly machined to the 81.5mm bore size before installation. It's always a good idea to consult your engine builder or a trusted mechanic to confirm all necessary machining and clearances are correct for your specific application.