Precision-Matched Power for Your BP-Z3 Miata
The SC7541-4 is a CP Pistons forged piston and ring set built for the Mazda BP-Z3 (BP-VE) 1.8L engine found in the 2001-2005 Mazda Miata NB2. Machined from 2618 forged aluminum and bored to 83.5mm (+0.5mm over standard), this set is designed to restore or upgrade cylinder sealing after a light rebore while holding a 9.0:1 compression ratio. Each SC7541-4 kit ships as a complete set of four pistons with rings, wrist pins, and pin locks so an engine builder does not need to source those components separately.
Key Features
- Forged 2618 aluminum piston construction for strength under high cylinder pressure
- 83.5mm bore (+0.5mm oversize) sized for a light rebore of the BP-Z3 block
- 9.0:1 compression ratio to match factory-style power delivery
- Dual forced pin oilers for improved wrist pin lubrication
- Accumulator groove to reduce top ring flutter and improve ring seal
- Pistons balanced to within one gram, CNC machined in the USA
- Wrist pins and pin locks included at no additional cost
Fitment
| Year Range | Make | Model | Notes |
|---|---|---|---|
| 2001-2005 | Mazda | Miata | BP-Z3 (BP-VE) 1.8L VVT engine, NB2 |
Specifications
| Detail | Value |
|---|---|
| MPN | SC7541-4 |
| Bore | 83.5mm (+0.5mm oversize) |
| Stroke | 85mm |
| Compression Ratio | 9.0:1 |
| Compression Height | 1.208in (30.7mm) |
| Rod Length | 133mm (5.233in) |
| Pin Size | 20mm (0.787in) |
| Ring Pack | 1.0mm / 1.2mm / 2.8mm |
| Piston Material | 2618 forged aluminum |
| Set Quantity | 4 pistons |
What’s Included
- 4x SC7541-4 forged pistons
- Matching piston ring set
- Wrist pins
- Pin locks
Every SC7541-4 kit is inspected and packaged as a complete set so all four pistons and their matched components arrive together.
About CP Pistons
CP Pistons, part of the Carrillo/Pankl Racing Systems family, manufactures forged pistons for street performance, road racing, and professional motorsports. Every CP piston is CNC machined in the USA and built with features like accumulator grooves, dual pin oilers, and precision cam-and-barrel skirt profiles to maximize ring seal and durability under sustained high load.
Related Parts
- CP Piston & Ring Set for Miata BPZ3 – Bore (83mm) – Size (Standard) – Compression Ratio (9.0)
- CP Piston & Ring Set for Miata BPZ3 – Bore (84mm) – Size (+1.0mm) – Compression Ratio (9.0)
- CP Steel Chamfered Wrist Pin (per piston)
- CP 9310 Steel Chamfered Wrist Pin (per piston)
FAQ
What is the SC7541-4?
It is a CP Pistons forged piston and ring set sized for an 83.5mm bore, built for the Mazda BP-Z3 1.8L engine used in the 2001-2005 Miata, with a 9.0:1 compression ratio.
What compression ratio does this piston set produce?
This set is designed for a 9.0:1 compression ratio, matching the stock-style compression of the BP-Z3 engine.
Does this kit include wrist pins and rings?
Yes, the set includes four pistons, a matching ring set, wrist pins, and pin locks.
Why is this piston sized at 83.5mm instead of the stock 83mm bore?
The 83.5mm size is a +0.5mm oversize piston intended for engines that have had their cylinders rebored slightly during a rebuild.
Will this piston set fit an NA Miata with the earlier BP-ZE engine?
This set is specified for the BP-Z3 (BP-VE) engine used in the 2001-2005 NB2 Miata. Earlier BP-ZE-equipped NA and NB1 Miatas share similar external dimensions but should be cross-checked against CP’s engine-specific fitment before ordering.
What piston material is used in this set?
The pistons are forged from 2618 aluminum, a material chosen for strength and durability in high-load performance applications.
Are these pistons balanced?
Yes, CP balances each piston set to within one gram for smoother, lower-vibration operation.
Does this product carry a Prop 65 warning?
Yes, this product includes a California Proposition 65 warning; see the Prop 65 notice below for details.
Install Instructions
- Disassemble the engine and thoroughly clean and inspect the block, confirming the cylinders have been bored and honed to 83.5mm to match this piston set.
- Check piston-to-wall clearance and ring end gap against CP’s ring gap chart before final assembly.
- Install the rings on each piston in the correct orientation, per CP’s ring and pin installation instructions.
- Lubricate the wrist pins and piston skirts, then install pistons onto the connecting rods using the supplied pins and locks.
- Use a ring compressor to install each piston and rod assembly into its bore in the correct orientation.
- Torque connecting rod bolts to the rod manufacturer’s specification.
- Rotate the crankshaft by hand to confirm free rotation before completing engine assembly.
Prop 65 Warning
This product can expose you to chemicals known to the State of California to cause cancer or reproductive harm. For more information, visit www.P65Warnings.ca.gov.
