Honda1985–1987Technical specifications

Prelude 2.0 DOHC: Technical specifications

Workshop data for the 2-litre petrol (engine code B20A1). Covers engine, fluids, service and torques: the figures to check before a job or a parts order.

Common faults & fixes

Summary

Match the engine code (B20A1) to the vehicle before ordering parts or applying these figures.

Vehicle specifications

Overview

Make: Honda
Model: Prelude
Years: 1985–1987
Fuel: Petrol
Engine code: B20A1

Performance & efficiency

Power: 101 kW (137 hp)
Engine size: 1,958 cc
Cylinders: 4 · DOHC
Compression ratio: 9.5:1
Fuel system: Honda

Fluids & capacities

Engine oil (with the filter): 4.0 litres

All 94 specifications below

Engine & identification

Vehicle identification

No. of cylinders Type	4/DOHC
Capacity (Fiscal) cc	1958 (1944)
Compression ratio :1	9,5
Suitable for unleaded petrol	Yes
Minimum octane rating RON	95 (S)=91
Ignition system Type	PGM-FI
Ignition system Description	Map-i
Fuel system Make	Honda
Fuel system Type	PGM-FI
Fuel system Description	MFI-s

Ignition system

Ignition coil Make	Nippon Denso
Ignition coil supply voltage + with ballast V	11,0
Primary resistance Ohm	1,2-1,5
Secondary resistance Ohm	11000-11500
Distributor (ECM) Make	Denso

Firing order

The firing order for the Honda Prelude 2.0 DOHC (1985–1987) is 1-3-4-2.

Firing order	1-3-4-2

Valve clearances

Valve clearances for the Honda Prelude 2.0 DOHC (1985–1987) are 0,08-0,12 mm inlet and 0,16-0,20 mm exhaust, measured cold.

Valve clearance - INLET mm	0,08-0,12 cold
Valve clearance - EXHAUST mm	0,16-0,20 cold

Engine oil & fluids

Engine oil

The Honda Prelude 2.0 DOHC (1985–1987) takes 4.0 litres of engine oil with the filter.

See the reference table for the complete engine oil entries and their conditions.

Manual gearbox

The manual gearbox has a listed capacity of 2.0 litres.

See the reference table for the complete manual gearbox entries and their conditions.

Coolant

The listed total cooling-system capacity is 5.9 litres.

Grades, filling conditions and capacities

Lubricants and capacities — complete reference
Engine oil options
Ambient temperature range	➞0°C
Engine oil grade SAE	5W-30
Engine oil classification API/ACEA	SG/A2
Ambient temperature range	-20°C➞
Engine oil grade SAE	10W-30
Engine oil classification API/ACEA	SG/A2
Ambient temperature range	-20°C➞
Engine oil grade SAE	10W-40
Engine oil classification API/ACEA	SG/A2
Ambient temperature range	-15°C➞
Engine oil grade SAE	15W-40, 15W-50
Engine oil classification API/ACEA	SG/A2
Ambient temperature range	-10°C➞
Engine oil grade SAE	20W-40, 20W-50
Engine oil classification API/ACEA	SG/A2
Engine with filter(s) litres	4.0
Other lubricants and capacities
Manual transmission oil grade SAE	10W-30, 10W-40
Manual transmission litres	2.0
Automatic transmission fluid Type	Dexron II
Automatic transmission (drain & refill) litres	2.8
Cooling system - total capacity litres	5.9

Service & electrical

Ignition timing

Basic ignition timing for the Honda Prelude 2.0 DOHC (1985–1987) is 15°±2° BTDC at 800 rpm.

CO level
Ignition timing	Without vacuum
Ignition timing - basic BTDC °Engine/rpm	15±2/800
Ignition timing - alternative °Engine/rpm	(S)=7±2/800

Battery

The Honda Prelude 2.0 DOHC (1985–1987) uses a 12 V, 50 Ah battery (reserve capacity 80 minutes).

Battery V/RC(Ah)	12/80 (50)

Spark plugs

The Honda Prelude 2.0 DOHC (1985–1987) uses NGK BCPR6E-11 spark plugs with a 1,1 mm electrode gap.

Spark plugs Original equipment	NGK
Spark plug Type	BCPR6E-11
Electrode gap mm	1,1
Spark plugs Make	Autolite
Spark plug Type	3923
Electrode gap mm	1,1
Spark plugs Make	Bosch
Spark plug Type	FR7DCX
Electrode gap mm	0,8
Spark plugs Make	Champion
Spark plug Type	RC9YCC4
Electrode gap mm	1,1
Spark plugs Make	NGK
Spark plug Type	BCPR6E-11
Electrode gap mm	1,1

Tuning and emissions

CO level
Tuning conditions	—
View more information	—
Ignition advance checks °Engine/rpm	ECM Controlled
Vacuum check	Ignition timing advances
Vacuum range °Engine	12
Vacuum ends mbar	666
Idle speed rpm	800±50
Idle speed - alternative rpm	(CH)=750
Fast idle speed - MT/AT rpm	1000-1800
Oil temperature °C	60
CO level at idle speed - tailpipe Vol. % CO	1,0±1,0
CO level at idle speed - tailpipe (Cat) Vol. % CO	1,0 Max
HC level at idle speed ppm	300
HC level at idle - alternative ppm	Cat=100
CO2 level at idle speed Vol. % CO2	13-16
O2 level at idle speed Vol. % O2	0,5-2,0

Starting and charging

Starter motor Make	Mitsuba
Starter motor Type	SM302-08
Maximum cranking amps A	135-165
Alternator output A/V/rpm	65/14/3500
Regulated voltage V	13,5-14,5

Service checks and adjustments

Compression pressure bar	10,5-12,5
Oil pressure bar/rpm	4,8-5,7/3000
Radiator cap bar	0,75-1,05
Thermostat opens °C	86-90
Drive belt tension - alternator/PAS/AC mm	6-9

Fuel system

Regulated pressure with vacuum bar	2,3-2,7

Tightening torques

Cylinder head bolt torque

The cylinder head bolts on the Honda Prelude 2.0 DOHC (1985–1987) are tightened in 2 stages: 30 Nm, then a final 68 Nm.

Cylinder head
Tighten	30 Nm
Tighten	68 Nm

Other engine tightening torques
Cylinder head instructions	—
Main bearings Stage 1	27 Nm
Main bearings Stage 2	55 Nm
Big end bearings Stage 1	22 Nm
Big end bearings Stage 2	45 Nm
Flywheel/driveplate	105 Nm/75 Nm
Crankshaft pulley/damper centre bolt	115 Nm
Spark plugs	18 Nm
Chassis tightening torques
Front hub	185 Nm
Road wheels	110 Nm

Frequently asked questions

What is the firing order of the Honda Prelude 2.0 DOHC?

The firing order for the Honda Prelude 2.0 DOHC (1985–1987) is 1-3-4-2.

What spark plugs does the Honda Prelude 2.0 DOHC use?

The Honda Prelude 2.0 DOHC (1985–1987) uses NGK BCPR6E-11 spark plugs with a 1,1 mm electrode gap.

How much oil does the Honda Prelude 2.0 DOHC take?

The Honda Prelude 2.0 DOHC (1985–1987) takes 4.0 litres of engine oil with the filter. See the reference table for the complete engine oil entries and their conditions.

What are the valve clearances for the Honda Prelude 2.0 DOHC?

Valve clearances for the Honda Prelude 2.0 DOHC (1985–1987) are 0,08-0,12 mm inlet and 0,16-0,20 mm exhaust, measured cold.

What is the cylinder head torque for the Honda Prelude 2.0 DOHC?

The cylinder head bolts on the Honda Prelude 2.0 DOHC (1985–1987) are tightened in 2 stages: 30 Nm, then a final 68 Nm.

What is the ignition timing for the Honda Prelude 2.0 DOHC?

Basic ignition timing for the Honda Prelude 2.0 DOHC (1985–1987) is 15°±2° BTDC at 800 rpm.