PRODUCT DETAILS
Supertech 11.6:1 Forged Pistons - B18C1/B18C5 GS-R & Type R (81.5mm)
If you're building a B18C to make real power or survive hard use, the factory cast pistons are a limit you'll want to design out. These Supertech forged pistons replace them with a far stronger forged unit at a track-friendly 11.6:1 compression, built for the GSR and Type R B18C in an 81.5mm bore. Forged construction, 4032 alloy for street and endurance durability, and the coatings and machining that separate a serious piston from a budget one. This is the foundation of a built B-series bottom end.
Why Forged, And Why It Matters Here
The factory B18C pistons are cast, which is fine for stock power but has limits. Cast pistons are more brittle and can crack or shatter under the stress of high RPM, detonation, or the loads a built or power-adder engine puts on them. Forged pistons are made from a solid billet forced into shape under enormous pressure, which aligns the metal's grain structure and makes them dramatically stronger and more resistant to shock.
For a B18C that's going to see real power, nitrous, or just sustained hard track use, forged pistons are what keep the bottom end together when cast pistons would be the failure point. These are forged specifically for that, the strength to handle what a built GSR or Type R motor throws at them.
11.6:1 Compression, Tuned For The Build
The compression ratio is chosen to make power while staying usable.
At 11.6:1, these raise compression over stock for more power and sharper response, exactly what an all-motor B18C build wants, while staying in a range you can run on quality pump or race gas with a proper tune. Note the compression climbs slightly with head choice: it's 11.6:1 as listed, +0.3 with a GSR head, so your final ratio depends on your combination. These are set up for all-motor and nitrous-assisted applications.
Key specs for your build: 81.5mm bore (0.5mm over), 30mm compression height, 21mm pin, 6cc dome/dish, 261g, with a slipper skirt design to reduce friction and weight.
4032 Alloy, Built For The Long Haul
The material is chosen for durability on a street-and-track build.
These are forged from 4032 aluminum alloy, a high-silicon alloy that offers excellent wear resistance and thermal stability. 4032 is the choice for street and endurance builds because it expands less and runs tighter, which means quieter operation, tighter sealing, and a longer service life than the looser-fitting 2618 race alloy. For a B18C that sees street miles as well as track time, 4032 is the right pick, strong, stable, and livable day to day.
Supertech's multi-stage forging aligns the grain with the stress paths for maximum strength, and each piston is CNC-machined for dimensional accuracy and balance, with diamond-tool-machined ring grooves for consistent, flat sealing surfaces.
The Coatings That Make The Difference
The surface treatments are what separate these from a plain forged piston.
A phosphate dry lubricant coating protects the ring grooves and skirts from micro-welding and reduces friction, important during break-in and under load. Contact reduction grooves improve lubrication between the piston and cylinder wall, and the diamond-tool-machined ring grooves ensure the rings seal consistently. These are the details that help a piston live a long, reliable life rather than just surviving.
What's Included
Each set includes the forged pistons with high-strength chrome-moly wrist pins. The piston rings are sold separately, and you'll need the matching B-series piston rings in the same bore size as your pistons, order those alongside the pistons so you have everything for the build. These pistons are 81.5mm, so they pair with the 81.5mm rings, the ring bore has to match the piston bore.
Fitment
1994-2001 Acura Integra GS-R (B18C1)
1997-2001 Acura Integra Type R (B18C5)
81.5mm bore (0.5mm over). 11.6:1 compression (+0.3 with GSR head). All-motor and nitrous applications. Requires matching B-series piston rings in your bore size, sold separately.
If you're building a B18C GS-R or Type R bottom end for serious all-motor or nitrous power, these are the forged pistons that handle it, 11.6:1 compression, durable 4032 construction, and the coatings and machining of a professional-grade piston. Match them to your 81.5mm bore, grab the matching rings, and build a bottom end that makes power and holds together.
1994-2001 Acura Integra GS-R
1997-2001 Acura Integra Type R