Type 4 Barrel And Piston Kit - 93mm - 1800cc

This replacement cast barrel and piston kit is designed for 1800cc Type 4 aircooled engines as fitted to Volkswagen Baywindow Buses and selected Porsche 914 models. Featuring dish-top pistons, this kit is specifically intended for low-compression 1800cc engines, making it the correct choice for original-spec rebuilds using AP engine codes.

Manufactured as a good quality reproduction, this kit provides a complete top-end solution for restoring compression, performance, and reliability.

What this kit does

The barrel and piston assembly forms the core of the engine’s combustion system. The pistons compress the air/fuel mixture inside the cylinders (barrels), converting combustion energy into mechanical motion. Over time, wear to pistons, rings, or barrels leads to loss of compression, increased oil consumption, and reduced power. Replacing these components restores correct sealing and engine efficiency.

How it works

Each piston travels up and down inside its barrel, guided by the piston rings that seal against the cylinder walls. The dish-top piston design lowers the compression ratio, matching the original factory specification for certain 1800cc Type 4 engines. This ensures correct combustion characteristics, safe operating temperatures, and compatibility with standard cylinder heads.

Kit contents

Each complete set includes:

• 4 x Cast barrels (cylinders)

• 4 x Dish-top pistons

• 4 x Gudgeon (wrist) pins

• 8 x Gudgeon pin clips

• Complete piston ring set (pre-matched)

Everything required for a full piston and barrel replacement is included.

Key specifications

• Engine capacity: 1800cc Type 4

• Bore x stroke: 93mm x 66mm

• Piston type: Dish top (low compression)

• Quality: Good quality reproduction

• Quantity: Complete engine set

Engine compatibility

• Type 4 – 1800cc

• Engine code: AP

• Designed for dished / low compression versions only

Vehicle applications

• VW Baywindow Bus: 1973–1975

• Porsche 914: 1974–1976

Fitting notes

• Designed to work with standard 1800cc Type 4 cylinder heads

• Always check deck height and compression ratio during assembly

• Professional engine assembly and correct torque procedures are strongly recommended

This barrel and piston kit is an ideal solution for anyone rebuilding an original-spec 1800cc Type 4 engine, offering reliable performance, correct compression, and long service life.