Honda D15B engine (D15A)

1. Specifications
2. Overview, problems
3. Performance tuning

Honda D15B/D15A engine specs

Honda D15B (D15A) engine reliability, problems and repair

Production of Honda D-series engines started in 1984, and the first representative of this family was D15A created for Honda CRX. The D15A cylinder block was made of aluminum and had cast iron sleeves, and its deck height was 207 mm. Inside it, they installed a 84.5 mm stroke crankshaft, 74 mm pistons and 134 mm long connecting rods, which resulted in the displacement of 1.5 liters.
The cylinder block was covered with a non-VTEC SOHC head with 3 valves per cylinder. Later, versions with 8 valve head and 16 valve head were produced. Some models had the VTEC system. This information can be found below.
For D15, a timing belt was used to be replaced after every 60,000 miles of mileage.
Valves were to be adjusted after every 24,000 miles.
The valve clearances for D15B were 0.2 mm for intake valves, and 0.25 mm for exhaust valves.
Electronic injection system was mainly used in these engines, but the first versions used carburetors.
Honda D15 firing order was 1-3-4-2. The size of D15B throttle body was 56 mm. The size of D15B fuel injectors was 240 cc.
Along with D15, D-series also included D12, D13, D14, D16, D17, and ZC.
Since 2002, they started replacing this engine with L15.

Honda D15B (D15A) engine modifications and differences

1. D15A1 was the first version with a 12-valve SOHC head with a carburetor fuel injection system. The compression ratio was 9.2, the power was 76 HP @ 5,500 rpm, and the torque was 114 Nm @ 3,500 rpm. It was installed in Honda CRX.
2. D15A2 was a version with a 8 valve SOHC head and the compression ratio of 10 with an electronic fuel injection system. The power was 60 HP @ 5,500 rpm, and the torque was 99 Nm @ 3,500 rpm. It was also installed in Honda CRX.
3. D15A3 was an analogue to D15A1, but with a multipoint fuel injection system. The compression ratio was reduced to 8.7, its power was 92 HP @ 5,500 rpm, and the torque was 126 Nm @ 4,500 rpm. The European version had 100 HP @ 5,750 rpm.
It was installed in Honda Civic Si and CRX.
4. D15B was the dual carb version (later – with electronic fuel injection) with a 16-valve SOHC head. Here 29 mm intake valves, and 25 mm exhaust valves were used, and the valve stem diameter was 5.5 mm. The compression ratio was 9.2, the power was 105 HP @ 6,800 rpm, and the torque was 133 Nm @ 5,200 rpm.
This engine may be found in Honda Civic, CRX and Capa.
5. D15B VTEC was an enhanced JDM D15B, here 137 mm long connecting rods and 27.4 mm high pistons were used, which increased the Rod/Stroke ratio up to 1.62. Besides, a VTEC system was added, the compression ratio was increased up to 9.3, and the engine power reached 130 HP @ 6,800 rpm, and the torque was 138 Nm @ 5,200 rpm.
In the period between 1995 and 2000, the D15B 3-Stage VTEC version was made.
6. D15B1 was a version with a dual point injection system and a 16-valve SOHC head. The compression ratio was 9.2, the power was 71 HP @ 5,500 rpm, and the torque was 112 Nm @ 3,000 rpm.
7. D15B2 was an analogue to D15B1, but with a different camshaft, with an improved exhaust manifold and another ECU. The power was 92 HP @ 6,000 rpm, and the torque was 119 Nm @ 4,700 rpm.
8. D15B3 was an- analogue to D15B2 with a carburetor. The power was 105 HP @ 6,000 rpm, and the torque was 121 Nm @ 4,500 rpm.
9. D15B4 was a dual carb version of the D15B3 engine. The power was 101 HP @ 5200 rpm, and the torque was 122 HP @ 3,800 rpm.
10. D15B5 was an analog to JDM D16B VTEC for operation on compressed natural gas.
11. D15B6 was the version for maximum fuel economy. Here a 8-valve SOHC head was used. The compression ratio was 9.1, the power was 63 HP @ 4,400 rpm (73 HP after 1990), and the torque was 113 Nm @ 2,200 rpm.
12. D15B7 was an analog to JDM D15B non-VTEC with an MPFI system.
13. D15B8 was an analog to the D15B6 for Civic CX. The power was 71 HP @ 4,500 rpm, and the torque was 113 Nm @ 2,800 rpm.
14. D15Z1 was an analog to JDM D15B VTEC, but with an improved head; it uses the VTEC-E system, 27.75 mm high pistons, and a new ECU. The compression ratio was 9.3, the power was 92 HP @ 5,500 rpm, and torque was 132 Nm @ 3,000 rpm.
15. D15Z3 replaced D15Z1, and features a slightly modified VTEC system and a new ECU.
16. D15Z4 was a version with a new non-VTEC 16 valve SOHC head, modified pistons, sequential fuel injection system and a new ECU. The power was 105 HP @ 5,800 rpm, and the torque was 140 Nm @ 4,200 rpm.
17. D15Z6 was an analogue to D15Z4 with a modified head equipped with a VTEC-E system, and a multipoint fuel injection system. The compression ratio was increased to 9.6, its power was 114 HP @ 6,500 rpm, and the torque was 134 Nm @ 5,400 rpm.
18. D15Z7 was an analogue to D15Z6 with a 3-Stage VTEC system. The power was 130 HP @ 7,000 rpm, and the torque was 139 Nm @ 5,300 rpm.
19. D15Z8 was an analogue D15Z6 with a slightly modified VTEC system.
20. D15Y3 was a version with a 16-valve non-VTEC SOHC head. The power was 120 HP @ 6,200 rpm, and the torque was 142 Nm @ 4,500 rpm.
21. D15Y4 was an analogue to D15Y3, but with a VTEC-E system.

Honda D15 engine problems and malfunctions

1. Crankshaft pulley problem. Crankshaft pulley often breaks here; this problem can be solved depending on how it all happened, starting from replacing the crankshaft pulley to replacing the crankshaft.
2. Rough idle. This mainly happens due to a dirty throttle body or idle control valve. The reason may be in the O2 sensor, have it checked.
3. Sounds like a diesel. The “diesel” sound of the D15 engine is a symptom of a crack in the exhaust manifold, have it checked. It makes no sense trying to weld up this crack, this exhaust manifold cannot be restored, you should buy a new one.
These were the most significant problem, but in D15B, distributor often fails, the engine starts misfiring and losing power, starts with problems, etc. The O2 sensor does not last long here, the oil pressure switch sensor may start leaking, etc.
However, it is an excellent engine, and it was incredibly reliable in its age. Life expectancy of the D15B/D15Z is long, and exceeds 150,000 miles, after which piston rings are to be replaced. Use high quality motor oil and perform periodic maintenance.

Honda D15B (D15A) engine tuning

Naturally aspirated

The most correct step in performance tuning is replacing its head with a D15B VTEC head. You then need port and polish, you should buy a cold air intake system, a 60 mm throttle body, a Skunk2 intake manifold, a Skunk2 cam, a cam gear, valve springs, NGK spark plugs, a 4-2-1 header, a 2.5″ exhaust system, and a Hondata ECU. In the end, these mods will give you about 160 HP.
This is not the limit, you can get more power and spend a lot of money, but any modern VW Golf GTI Stage 2 will be faster.

D15B and D15Z Turbo

First, you need to bring your old engine to the normal condition, and then buy a turbo kit. You can build a good turbo D15 even using stock internals, they can withstand about 200 WHP, but it is better not to risk it and make the power a bit lower.
Buy a turbo kit from eBay, or build it yourself on the basis of a TD04 turbocharger. You will need a turbo manifold, an FMIC, a wastegate, a BOV, a piping kit, a 2.5 inch exhaust system, a wideband air/fuel o2 sensor, and a Hondata ECU. Buy a Walbro 255 lph fuel pump, an aftermarket fuel rail, a fuel regulator, and 450 cc fuel injectors.
For the turbocharger, an oil feed line and an oil return line are to be installed.
These performance parts will be enough to get 180-200 WHP, and make your dead car a bit faster.
Want more power? Then you have to replace fuel injectors with more efficient ones, buy Vitara pistons or forged pistons, H-beam rods and ARP head studs. With these upgrades, you can increase the boost pressure to the maximum, and get up to 250-280 HP – is the limit for TD04. Replace it with a TD05 or something similar, and you will get 300+ HP, and a huge turbo lag. However, making this turbo build work fine, you have to do head porting, buy a performance cam, a cam gear, valves, valve springs, valve guides, valve spring retainers, etc.

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