Honda H22A5 Specifications
| Engine Model: Honda H22A5 |
| Engine Type: 4-cycle inline 4-cylinder DOHC 16-valve VTEC liquid-cooled gasoline |
| Total Displacement: 132 cu.in (2.16 L) |
| Rated Engine Power: 182 Hp (136 kW) at 7000 rpm |
| Fuel System Type: Multi-point electronic fuel injection |
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The Honda H22A5 is a 2.2-liter, DOHC VTEC inline-four
engine developed exclusively for the European market. Serving as the standard
performance powerplant for the fifth-generation Honda Prelude between 1997 and
1998, it represents a specific calibration of the renowned H-series “big block”
engine family. Positioned as the European counterpart to the North American
H22A4, the H22A5 was engineered to balance performance with the stricter
emissions and fuel quality standards prevalent across Europe during its
production cycle.
This engine is distinguished by its use of an aluminum cylinder block
incorporating Fiber Reinforced Metal (FRM) cylinder liners, a technology
designed to reduce weight while providing exceptional wear resistance. The Honda
H22A5 is visually identifiable by its black crackle-finish valve cover, a
feature that differentiates it from other H-series variants. Its operational
character is defined by the hallmark Honda VTEC (Variable Valve Timing and Lift
Electronic Control) system, which provides a distinct two-stage power delivery,
transitioning from efficient low-lift operation to high-performance cam profiles
at elevated engine speeds.
While sharing core architecture with more powerful variants like the Japanese
H22A or the later European H22A8, the H22A5 tuning focused on drivability and
compliance with Euro emissions standards, resulting in a slightly reduced peak
output. It remains a revered engine for its robust construction, high-revving
nature, and the foundational role it played in Honda’s European performance
strategy during the late 1990s.
The H22A5 adheres to the fundamental design principles of the H-series engine
family. It utilizes a traditional inline-four configuration mounted transversely
to suit front-wheel-drive and all-wheel-steering chassis layouts. The valvetrain
is a dual overhead camshaft (DOHC) design actuating sixteen valves, with the
VTEC system operating on both the intake and exhaust camshafts to optimize
volumetric efficiency across the engine’s operating range.
Engine Layout: Transverse Inline-4.
Valvetrain: DOHC VTEC, 4 valves per cylinder (16 total).
Displacement: 2,157 cc (132 cu.in).
Bore x Stroke: 87.0 mm x 90.7 mm (3.43 in x 3.57 in).
Compression Ratio: 10.0:1.
Maximum Power: 136 kW (185 PS / 182 hp) @ 7,000 rpm.
Maximum Torque: 206 Nm (151 lb-ft) @ 5,300 rpm.
VTEC Engagement Threshold: 5,200 - 5,800 rpm (engine load dependent).
Engine Redline: 7,200 rpm (fuel cut at 7,400 rpm).
The cylinder block of the H22A5 is constructed from
cast aluminum alloy, a design choice aimed at reducing overall engine mass. A
defining feature of this block is the integration of Fiber Reinforced Metal
(FRM) liners. Unlike conventional cast iron sleeves, these liners are a
composite material consisting of aluminum oxide and carbon fibers embedded in an
aluminum matrix. This technology provides a highly durable, low-friction surface
for the pistons while maintaining material compatibility with the aluminum block
for superior heat transfer and structural integrity.
The block features an open-deck design, where the cylinder bores are unsupported
at the upper portion of the water jacket to enhance cooling efficiency around
the combustion chamber. The cylinder bore diameter measures 87.0 mm (3.43 in),
while the piston stroke is 90.7 mm (3.57 in), resulting in an undersquare
configuration that promotes high torque output. The block height is set at 245.0
mm (9.65 in), accommodating the long stroke crankshaft. Five main bearings
support the crankshaft, with the main journal diameter measuring 50.0 mm (1.97
in), a characteristic that distinguishes this early H-series block from later
variants that utilized larger 55.0 mm (2.17 in) mains.
The cylinder head is manufactured from cast aluminum
alloy and utilizes a DOHC arrangement with four valves per cylinder. The VTEC
system is integrated into this assembly, employing a rocker arm design that
engages a third, high-lift cam lobe at predetermined engine speeds. The intake
valves have a diameter of 35.0 mm (1.38 in), while the exhaust valves measure
30.0 mm (1.18 in). Both valves are constructed from heat-resistant steel and
feature a five-angle grind on the valve seat interface to optimize airflow.
Valve stem diameters are 5.5 mm (0.22 in) for both intake and exhaust,
contributing to reduced reciprocating mass. The camshafts are supported by four
bearings per shaft, with camshaft lobe height measuring 39.1 mm (1.54 in) on the
primary lobes and 41.8 mm (1.65 in) on the VTEC high-lobe profiles. The cylinder
head gasket is a multi-layer steel (MLS) design, providing superior sealing
against the FRM-lined block. Valve clearance adjustments are performed via
replaceable tappets, with the intake clearance specification set between 0.15 mm
and 0.19 mm (0.006 in to 0.007 in) and exhaust clearance between 0.17 mm and
0.21 mm (0.007 in to 0.008 in) when the engine is cold.
The fuel system employs a multi-point electronic fuel
injection (MPFI) design with sequential injection timing. The system operates at
a fuel pressure of 294 kPa (42.7 psi) measured with the vacuum line
disconnected. Four high-impedance injectors, each with a flow rate of 240 cc/min
(22.8 lb/hr), deliver fuel directly into the intake ports. The intake manifold
is constructed from aluminum and features a dual-runner design with a variable
intake manifold (VIM) system, which alters the effective intake tract length to
enhance low-end torque and high-rpm power delivery.
A throttle body with a diameter of 60.0 mm (2.36 in) houses a throttle position
sensor (TPS) and idle air control (IAC) valve. The engine management system
utilizes a P13-type Engine Control Unit (ECU) calibrated specifically for
European fuel and emissions requirements, incorporating a heated oxygen sensor
for closed-loop fuel control.
The lubrication system is a fully pressurized, wet-sump
design. A gear-type oil pump, driven directly by the crankshaft, generates oil
pressure throughout the system. The oil pump rotor dimensions are 70.0 mm (2.76
in) outer diameter and 32.0 mm (1.26 in) inner diameter. The oil pan,
constructed from stamped steel, has a capacity of 5.0 L (5.3 qt) including the
oil filter.
A spin-on oil filter with a bypass valve is mounted to the engine block. The
system incorporates an oil cooler, which is a water-to-oil unit integrated into
the oil filter mounting base, maintaining oil temperature within an optimal
range under sustained high-load conditions. A piston oil jet system is present,
with jets directed at the underside of each piston crown to reduce piston
temperatures during high-rpm operation.
The cooling system utilizes a cross-flow radiator with
a dual-speed electric cooling fan. Coolant circulation is driven by a
belt-driven water pump mounted to the cylinder block. The thermostat, a
wax-pellet type, is rated for a 78.0°C (172.4°F) opening temperature, with full
opening achieved at 90.0°C (194.0°F).
The total coolant capacity for the engine and radiator system is 6.0 L (6.3 qt).
The system is pressurized to 108 kPa (15.7 psi) via a radiator cap to raise the
boiling point of the coolant. Coolant flow is directed through the open-deck
block design, allowing efficient heat transfer around the FRM cylinder liners
before passing through the cylinder head.
The ignition system is a distributor-based design with
an internal coil. The distributor houses a crankshaft position sensor (CYP) and
a cylinder position (TDC) sensor. Ignition timing is controlled by the ECU with
a base setting of 15° BTDC at idle with the service check connector shorted.
Spark plugs are NGK PFR7G-11 or equivalent, with a gap specification of 1.1 mm
(0.043 in).
Exhaust System: The exhaust manifold is a cast iron
design merging into a single downpipe. The catalytic converter is a three-way
type with a length of 345 mm (13.6 in). An oxygen sensor is positioned upstream
of the catalytic converter, with a secondary sensor located downstream on
vehicles equipped with OBD-II diagnostics.
VTEC System: The VTEC system relies on oil pressure to lock rocker arms
together. A dedicated VTEC spool valve, mounted to the cylinder head, controls
oil flow to the rocker arm assemblies. Engagement is triggered by the ECU based
on engine speed, load, and oil pressure, with the transition occurring between
5,200 and 5,800 rpm.
The complete engine assembly, including the intake and
exhaust manifolds but without the alternator and power steering pump, has a dry
weight of 155 kg (342 lb). Overall engine length is 590 mm (23.2 in), width is
645 mm (25.4 in), and height is 680 mm (26.8 in). The engine block deck height
measures 245.0 mm (9.65 in) from the crankshaft centerline to the cylinder head
mating surface.
The H22A5 is classified as an interference engine;
failure of the timing belt results in contact between the valves and pistons,
causing significant engine damage. The timing belt replacement interval is
96,000 km (60,000 mi) under normal operating conditions. Drive belts, including
the alternator and power steering belts, should be inspected every 12,000 km
(7,500 mi) and replaced as necessary.
Engine oil capacity with filter is 5.0 L (5.3 qt), with a recommended viscosity
grade of 5W-30 or 10W-30 depending on climate. Coolant replacement is specified
at 96,000 km (60,000 mi) or 60 months. Spark plug replacement is required every
48,000 km (30,000 mi). Valve clearance inspection and adjustment are recommended
every 48,000 km (30,000 mi).
Cylinder Head Bolts: Stage 1: 29 Nm (21 lb-ft); Stage
2: 90° rotation
Connecting Rod Cap Bolts: 39 Nm (29 lb-ft) plus 60° rotation
Main Bearing Cap Bolts: 49 Nm (36 lb-ft) plus 60° rotation
Camshaft Bearing Cap Bolts: 24 Nm (18 lb-ft)
Flywheel Bolts: 93 Nm (69 lb-ft)
Intake Manifold Nuts: 23 Nm (17 lb-ft)
Exhaust Manifold Nuts: 28 Nm (21 lb-ft)
Spark Plugs: 18 Nm (13 lb-ft)
Oil Pan Bolts: 12 Nm (9 lb-ft)
Water Pump Bolts: 12 Nm (9 lb-ft)
Timing Belt Tensioner Bolt: 44 Nm (32 lb-ft)
Crankshaft Pulley Bolt: 177 Nm (131 lb-ft)
The H22A5 engine was utilized exclusively in the
European market for the fifth-generation Honda Prelude produced between 1997 and
1998.
Specific applications include:
1997-1998 Honda Prelude 2.2 VTi (BB6): European market variant with front-wheel
drive.
1997-1998 Honda Prelude 2.2 VTi-S (BB8): European market variant equipped with
the 4WS (Four-Wheel Steering) system.
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