ARP Tapered Piston Ring Compressor – 78mm / 83mm / 87.5mm

ARP Tapered Piston Ring Compressor – 78mm / 83mm / 87.5mm

ARP tapered piston ring compressor for engine builds requiring a 78.00mm, 83.00mm or 87.50mm finished cylinder bore, supplied individually in the selected size.

Designed to make piston installation more controlled and consistent, the ARP tapered ring compressor progressively compresses the piston rings into their grooves as the piston is pushed through the tool and into the cylinder bore. Unlike an adjustable band-style compressor, each tool is machined for one specific bore diameter.

ARP machines these compressors from 6061-T6 billet aluminium with a true-radius internal profile matched to the stated bore diameter. The tool is Type 3 anodised for durability, relieved at the base for wire O-ring applications and clearly marked with its nominal bore size for identification.

• Product type: Tapered piston ring compressor / piston installation tool
• Brand: ARP – Automotive Racing Products
• Available sizes: 78.00mm, 83.00mm and 87.50mm
• ARP 78.00mm reference: 901-7800
• ARP 83.00mm reference: 901-8300
• ARP 87.50mm reference: 901-8750
• Construction: CNC-machined 6061-T6 billet aluminium
• Design: Fixed-diameter true-radius tapered compressor
• Finish: Type 3 anodised
• Lower edge: Relieved for wire O-ring applications
• Size identification: Bore diameter marked on the tool
• Adjustable: No – select the compressor to match the finished cylinder bore
• Quantity supplied: 1 piston ring compressor in the selected size

Available variants:

• 78.00mm – ARP 901-7800
• 83.00mm – ARP 901-8300
• 87.50mm – ARP 901-8750

Fitment advice: Select the compressor according to the engine's actual finished cylinder bore diameter rather than vehicle model alone. This is particularly important with engines that have been rebored, sleeved or fitted with non-standard pistons. Confirm the finished bore measurement before ordering.

Other items to consider: Piston rings, pistons, connecting-rod bearings, main bearings, engine gasket sets, cylinder-head gaskets and appropriate engine assembly lubricants depending on the scope of the rebuild.

Useful tools / consumables: Piston ring expander, piston ring filing equipment where required, feeler gauges, bore measuring equipment, assembly lubricant and a suitable non-damaging piston installation handle or hammer.

Difficulty guide: Specialist engine-building tool. Correct piston-ring preparation, ring-gap measurement, ring orientation and cylinder-bore preparation are essential before piston installation.

Why ARP? ARP's dedicated tapered ring compressors are precision-machined for individual bore diameters rather than relying on an adjustable band. The true-radius internal profile progressively guides the piston rings into their grooves as the piston enters the cylinder, while the anodised aluminium construction provides a durable workshop tool suitable for repeated engine-building work.

What's in the box: 1 x ARP tapered piston ring compressor in the selected bore size.

Installation notes: Lubricate and prepare the piston, rings and cylinder bore in accordance with the piston and ring manufacturer's instructions. Position the compressor squarely against the block deck and ensure the piston-ring pack is fully contained within the tapered section before carefully introducing the piston into the bore. Do not use a compressor whose stated diameter does not correspond with the finished cylinder bore.