1.8L 16v - B18A1/B1

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1.8L 16v - B18A1/B1

Reduced price! Reinforced head gasket Honda hybrid VTEC head on B18A1 B18B1 block

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Reinforced head gasket Honda hybrid VTEC head on B18A1 B18B1 block

Brand Gaskets Cylinder Head reinforced

Condition: New product

Reinforced Athena and Cometic head gasket, in MLS for B-series hybrid build. Sold individually.

Brands: Athena, Cometic
Engines: B18A1, B18B1
Bores: 81 to 86.5 mm
Thicknesses: 0.69 to 3.56 mm

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151,45 € tax incl.

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The Honda engines covered

The B-series hybrid build pairs a Honda VTEC cylinder head (B16A, B17A1 or B18C) with a non-VTEC B18A1 or B18B1 block. This page covers this build: it needs reinforced cylinder head gaskets of its own, designed for the VTEC head and the non-VTEC block.

Honda did not plan this build: it has no original gasket. The one of the B18A1 and B18B1 block carries part number 12251-P3F-005. It is a multi-layer steel (MLS) gasket with a 84.5 mm bore, whose thickness Honda does not publish. It is sized for standard combustion pressure: when that pressure rises, clamping load drops, the cylinder head lifts, and coolant passes into a cylinder.

Reinforced cylinder head gaskets

A cylinder head gasket does not create the seal on its own: it holds because the fasteners clamp the head against the block. A composite gasket is crushed for good beyond 100 N/mm² of admissible stress, whereas the 301 stainless steel of the MLS gaskets withstands 517 N/mm², 5 times more, and springs back at every combustion.

This page brings together the part numbers from two racing manufacturers, Athena and Cometic, in two constructions: Athena MLS with Gas Stopper and Cometic MLS multi-layer steel. Gasket bores run from 81 to 86.5 mm, covering the standard block as well as the rebored block, and thicknesses from 0.69 to 3.56 mm, enough to adjust the compression ratio without touching the pistons or the cylinder head. As a rule, the gasket bore chosen is at least 0.5 mm larger than the actual cylinder bore. Each part number is sold individually, one gasket per engine.

Technical specifications

Gasket bore OEM 84.5 mm	Thickness	Gasket volume	Gasket type OEM MLS	Brand	Part number OEM 12251-P3F-005
81 mm	0.76 mm	3.92	MLS	Cometic	C4237-030
81 mm	0.91 mm	4.69	MLS	Cometic	C4237-036
81 mm	1.42 mm	7.32	MLS	Cometic	C4237-056
81 mm	1.52 mm	7.83	MLS	Cometic	C4237-060
81 mm	1.68 mm	8.66	MLS	Cometic	C4237-066
81 mm	1.78 mm	9.17	MLS	Cometic	C4237-070
81 mm	1.91 mm	9.84	MLS	Cometic	C4237-075
81 mm	2.03 mm	10.46	MLS	Cometic	C4237-080
81 mm	2.13 mm	10.98	MLS	Cometic	C4237-084
81 mm	2.18 mm	11.23	MLS	Cometic	C4237-086
81 mm	2.34 mm	12.06	MLS	Cometic	C4237-092
81 mm	2.49 mm	12.83	MLS	Cometic	C4237-098
81.5 mm	0.76 mm	3.96	MLS	Cometic	C4236-030
81.5 mm	1.42 mm	7.41	MLS	Cometic	C4236-056
81.5 mm	1.52 mm	7.93	MLS	Cometic	C4236-060
81.5 mm	1.68 mm	8.76	MLS	Cometic	C4236-066
81.5 mm	1.78 mm	9.29	MLS	Cometic	C4236-070
81.5 mm	2.03 mm	10.59	MLS	Cometic	C4236-080
81.5 mm	2.13 mm	11.11	MLS	Cometic	C4236-084
81.5 mm	2.18 mm	11.37	MLS	Cometic	C4236-086
81.5 mm	2.34 mm	12.21	MLS	Cometic	C4236-092
81.5 mm	2.49 mm	12.99	MLS	Cometic	C4236-098
82 mm	0.76 mm	4.01	MLS	Cometic	C4191-030
82 mm	0.85 mm	4.49	MLS	Athena	338100R
82 mm	1.42 mm	7.50	MLS	Cometic	C4191-056
82 mm	1.52 mm	8.03	MLS	Cometic	C4191-060
82 mm	1.68 mm	8.87	MLS	Cometic	C4191-066
82 mm	1.78 mm	9.40	MLS	Cometic	C4191-070
82 mm	1.91 mm	10.09	MLS	Cometic	C4191-075
82 mm	2.03 mm	10.72	MLS	Cometic	C4191-080
82 mm	2.13 mm	11.25	MLS	Cometic	C4191-084
82 mm	2.18 mm	11.51	MLS	Cometic	C4191-086
82 mm	2.34 mm	12.36	MLS	Cometic	C4191-092
82 mm	2.49 mm	13.15	MLS	Cometic	C4191-098
82 mm	3.05 mm	16.11	MLS	Cometic	C4191-120
82 mm	3.56 mm	18.80	MLS	Cometic	C4191-140
83 mm	0.69 mm	3.73	MLS	Cometic	C4192-027
83 mm	0.76 mm	4.11	MLS	Cometic	C4192-030
83 mm	0.85 mm	4.60	MLS	Athena	338101R
83 mm	0.91 mm	4.92	MLS	Cometic	C4192-036
83 mm	1.02 mm	5.52	MLS	Cometic	C4192-040
83 mm	1.14 mm	6.17	MLS	Cometic	C4192-045
83 mm	1.30 mm	7.03	MLS	Cometic	C4192-051
83 mm	1.42 mm	7.68	MLS	Cometic	C4192-056
83 mm	1.52 mm	8.22	MLS	Cometic	C4192-060
83 mm	1.68 mm	9.09	MLS	Cometic	C4192-066
83 mm	1.78 mm	9.63	MLS	Cometic	C4192-070
83 mm	1.91 mm	10.33	MLS	Cometic	C4192-075
83 mm	2.03 mm	10.98	MLS	Cometic	C4192-080
83 mm	2.13 mm	11.52	MLS	Cometic	C4192-084
83 mm	2.18 mm	11.80	MLS	Cometic	C4192-086
83 mm	2.34 mm	12.66	MLS	Cometic	C4192-092
83 mm	2.49 mm	13.47	MLS	Cometic	C4192-098
83 mm	3.05 mm	16.50	MLS	Cometic	C4192-120
83 mm	3.56 mm	19.26	MLS	Cometic	C4192-140
84 mm	0.69 mm	3.82	MLS	Cometic	C4193-027
84 mm	0.76 mm	4.21	MLS	Cometic	C4193-030
84 mm	0.85 mm	4.71	MLS	Athena	338102R
84 mm	0.91 mm	5.04	MLS	Cometic	C4193-036
84 mm	1.02 mm	5.65	MLS	Cometic	C4193-040
84 mm	1.14 mm	6.32	MLS	Cometic	C4193-045
84 mm	1.30 mm	7.20	MLS	Cometic	C4193-051
84 mm	1.42 mm	7.87	MLS	Cometic	C4193-056
84 mm	1.52 mm	8.42	MLS	Cometic	C4193-060
84 mm	1.68 mm	9.31	MLS	Cometic	C4193-066
84 mm	1.78 mm	9.86	MLS	Cometic	C4193-070
84 mm	1.91 mm	10.58	MLS	Cometic	C4193-075
84 mm	2.03 mm	11.25	MLS	Cometic	C4193-080
84 mm	2.13 mm	11.80	MLS	Cometic	C4193-084
84 mm	2.18 mm	12.08	MLS	Cometic	C4193-086
84 mm	2.34 mm	12.97	MLS	Cometic	C4193-092
84 mm	2.49 mm	13.80	MLS	Cometic	C4193-098
84 mm	3.05 mm	16.90	MLS	Cometic	C4193-120
84 mm	3.56 mm	19.73	MLS	Cometic	C4193-140
84.5 mm	0.69 mm	3.87	MLS	Cometic	C4241-027
84.5 mm	0.76 mm	4.26	MLS	Cometic	C4241-030
84.5 mm	0.91 mm	5.10	MLS	Cometic	C4241-036
84.5 mm	1.02 mm	5.72	MLS	Cometic	C4241-040
84.5 mm	1.14 mm	6.39	MLS	Cometic	C4241-045
84.5 mm	1.30 mm	7.29	MLS	Cometic	C4241-051
84.5 mm	1.42 mm	7.96	MLS	Cometic	C4241-056
84.5 mm	1.52 mm	8.52	MLS	Cometic	C4241-060
84.5 mm	1.68 mm	9.42	MLS	Cometic	C4241-066
84.5 mm	1.78 mm	9.98	MLS	Cometic	C4241-070
84.5 mm	1.91 mm	10.71	MLS	Cometic	C4241-075
84.5 mm	2.03 mm	11.38	MLS	Cometic	C4241-080
84.5 mm	2.13 mm	11.94	MLS	Cometic	C4241-084
84.5 mm	2.18 mm	12.23	MLS	Cometic	C4241-086
84.5 mm	2.34 mm	13.12	MLS	Cometic	C4241-092
84.5 mm	2.49 mm	13.96	MLS	Cometic	C4241-098
84.5 mm	3.05 mm	17.10	MLS	Cometic	C4241-120
84.5 mm	3.56 mm	19.96	MLS	Cometic	C4241-140
85 mm	0.69 mm	3.92	MLS	Cometic	C4194-027
85 mm	0.76 mm	4.31	MLS	Cometic	C4194-030
85 mm	0.85 mm	4.82	MLS	Athena	338103R
85 mm	0.91 mm	5.16	MLS	Cometic	C4194-036
85 mm	1.02 mm	5.79	MLS	Cometic	C4194-040
85 mm	1.14 mm	6.47	MLS	Cometic	C4194-045
85 mm	1.30 mm	7.38	MLS	Cometic	C4194-051
85 mm	1.42 mm	8.06	MLS	Cometic	C4194-056
85 mm	1.52 mm	8.63	MLS	Cometic	C4194-060
85 mm	1.68 mm	9.53	MLS	Cometic	C4194-066
85 mm	1.78 mm	10.10	MLS	Cometic	C4194-070
85 mm	1.91 mm	10.84	MLS	Cometic	C4194-075
85 mm	2.03 mm	11.52	MLS	Cometic	C4194-080
85 mm	2.13 mm	12.09	MLS	Cometic	C4194-084
85 mm	2.18 mm	12.37	MLS	Cometic	C4194-086
85 mm	2.34 mm	13.28	MLS	Cometic	C4194-092
85 mm	2.49 mm	14.13	MLS	Cometic	C4194-098
85 mm	3.05 mm	17.31	MLS	Cometic	C4194-120
85 mm	3.56 mm	20.20	MLS	Cometic	C4194-140
86.5 mm	0.69 mm	4.05	MLS	Cometic	C4242-027
86.5 mm	0.76 mm	4.47	MLS	Cometic	C4242-030
86.5 mm	0.91 mm	5.35	MLS	Cometic	C4242-036
86.5 mm	1.02 mm	5.99	MLS	Cometic	C4242-040
86.5 mm	1.14 mm	6.70	MLS	Cometic	C4242-045
86.5 mm	1.30 mm	7.64	MLS	Cometic	C4242-051
86.5 mm	1.42 mm	8.34	MLS	Cometic	C4242-056
86.5 mm	1.52 mm	8.93	MLS	Cometic	C4242-060
86.5 mm	1.68 mm	9.87	MLS	Cometic	C4242-066
86.5 mm	1.78 mm	10.46	MLS	Cometic	C4242-070
86.5 mm	1.91 mm	11.22	MLS	Cometic	C4242-075
86.5 mm	2.03 mm	11.93	MLS	Cometic	C4242-080
86.5 mm	2.13 mm	12.52	MLS	Cometic	C4242-084
86.5 mm	2.18 mm	12.81	MLS	Cometic	C4242-086
86.5 mm	2.34 mm	13.75	MLS	Cometic	C4242-092
86.5 mm	2.49 mm	14.63	MLS	Cometic	C4242-098
86.5 mm	3.05 mm	17.92	MLS	Cometic	C4242-120
86.5 mm	3.56 mm	20.92	MLS	Cometic	C4242-140

Gasket volume: the space the gasket leaves above each cylinder. It enlarges the combustion chamber, and the larger it is, the lower the compression ratio. Values compare with one another at identical gasket bore.

Preparation and fitting

Fasteners	Engines	Tightening torque
Original cylinder head bolts M12x1,25 x 150	B18B1	29 Nm, then 85 Nm
Original cylinder head bolts M12x1,25 x 150	B18A1	29 Nm, then 83 Nm (1990-1991) or 85 Nm (1992-1993)
ARP cylinder head studs ARP-208-4303	B18A1, B18B1	36 Nm, then 72 Nm, then 108 Nm
ARP cylinder head studs ARP-208-4302	B18A1	36 Nm, then 72 Nm, then 108 Nm

Before fitting, check the flatness of the cylinder head and of the block with a straight edge and have them skimmed if necessary. None of these gaskets requires sealant: Athena and Cometic both supply them already coated.

Reinforced ARP cylinder head studs B18A1 B18B1 →

Technical guide

The two constructions offered

Athena MLS
Two to five layers of AISI 301 stainless steel, laser cut, stamped and riveted. Around each cylinder, a layer folded over on itself, the Gas Stopper, concentrates the clamping load on the combustion chamber, while beads seal the water and oil passages. The outer layers receive a two-coat finish: the first withstands high temperatures and fills small irregularities on the block and cylinder head, the second, silicone based, keeps the gasket from sticking on disassembly. This is Athena's all-steel choice, from a prepared naturally aspirated engine to moderate forced induction.

Cometic MLS
Several stamped and riveted stainless steel layers. The outer layers carry active beads around each cylinder and each fluid passage. Sealing is achieved with a moderate clamping load and limited bore distortion. This is the versatile choice, from a prepared naturally aspirated engine to light forced induction.

Choosing bore and thickness

Gasket bore. The Athena MLS comes in 82, 83, 84 and 85 mm, the Cometic MLS in 81, 81.5, 82, 83, 84, 84.5, 85 and 86.5 mm.

Thickness. Honda does not publish the thickness of the original gasket. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.

Your goal	Thickness to choose
Keep the original compression ratio	The value closest to the thickness of the removed gasket
Skimmed cylinder head, make up the lost height	The thickness of the removed gasket + what was removed
Forced induction build, lower the ratio	A thickness above that of the removed gasket
Naturally aspirated build, raise the ratio	A thickness below that of the removed gasket

With a thickness finer than that of the removed gasket, measure piston protrusion above the block with a dial gauge: it is what determines the remaining clearance between piston and cylinder head.

The two brands

	Athena S.p.A. is an Italian manufacturer of engine gaskets and components, with its head office and main plant in Alonte, in the Veneto region. The group also produces in Spain, the United States, Brazil and India. Its multi-layer gaskets are fitted as original equipment by car manufacturers, and its racing range is designed and made entirely in Italy.
	Cometic Gasket, Inc. is an American manufacturer of engine gaskets and sealing solutions, founded in 1989 and based in Concord, Ohio. Its speciality is the made-to-order gasket, in the bore and thickness required. All its products are made in the United States, from American materials.

Advantages over the original gasket

Criterion	Original gasket 12251-P3F-005	Reinforced gaskets
Construction	Multi-layer steel (MLS)	Multi-layer stainless steel
Gasket bore	84.5 mm	81 to 86.5 mm
Thicknesses available	Not published by Honda	0.69 to 3.56 mm, 19 values
Compression ratio adjustment	None	Through the thickness chosen
Resistance to overpressure	Limited to standard output	Designed for forced induction

When a reinforced gasket becomes necessary

Adding forced induction, or raising boost on an already turbocharged engine
Cylinder rebored beyond what the 84.5 mm bore of the original gasket covers
Looking for a compression ratio different from standard, higher or lower
Engine that has already lost its gasket, or is consuming coolant
Competition use, where the gasket goes through repeated temperature rises

Vehicle compatibility

Model	Engine code	Power	Years
Acura Integra	B18A1	132 and 142 hp	1990-1993
Acura Integra	B18B1	141 and 144 hp	1993-2001
Honda Integra (DA)	B18A1	131 hp	1989-1993
Honda Integra (DA)	B18B1	131 hp	1989-1993
Honda Integra Coupé (DC)	B18B1	137 hp	1993-2001

OEM part number: 12251-P3F-005, 12251-P8R-004 (B18A1, B18B1).

Important: these gaskets only suit the hybrid build. The stock VTEC B16A, B17A1 and B18C, the stock B18A1 and B18B1, as well as the B20B and B20Z, take other cylinder head gaskets: they are not covered by this page.

Why switch to a reinforced gasket?

A reinforced gasket holds where the standard one reaches its limit: at higher combustion pressure it keeps its shape instead of being crushed.

As soon as power goes up, turbo, supercharger or raised compression ratio, the head gasket becomes the weak link of the top end. Switching to a reinforced gasket is then not a comfort but a safeguard: it is what prevents the failure and the head removal that comes with it.

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