Honda F20B engine (F20A)

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

Honda F20B engine specs

Honda F20B (F20A) engine reliability, problems and repair

Manufacturing of F20 engines had started in September 1989, and the first cars fitted with them were Honda Accord and Ascot. This engine used a 219.5 mm high aluminum open deck cylinder block. It is similar to other F-engines. Inside it has an 88 mm piston stroke crankshaft and balancer shafts, the rod length is 145 mm, pistons diameter is 85 mm, and their compression height is 31 mm. This kit ensures 2 liters displacement.
For F20A and F20B3/F20B6, the 16-valve non-VTEC SOHC head is used. Honda Accord SiR and SiR-T F20B were fitted with DOHC VTEC head engines. The diameter of intake valves is 34 mm, of the exhaust valves – 29 mm.
Engines F20A and F20B use a timing belt to be replaced after every 60,000 miles (90,000 km) of mileage. If the belt breaks, F20B engine will not bend valves, but if the timing belt breaks in the VTEC mode, the valves will be bent. If the timing belt breaks on F20A engine, valves are always bent.
Here valves are to be adjusted after every 15,000 to 20,000 miles (25,000-30,000 km) of mileage. For a cold engine, intake valves clearance is 0.24-0.28 mm, and exhaust valves clearance is 0.28-0.32 mm.
Valve clearance for DOHC F20B VTEC: intake valves – 0.17 mm, exhaust valves – 0.19 mm.
For F20A and F20B3, the fuel injectors size is 240 cc. For F20B engines, it is 310 cc.
Honda F20A/F20B firing order: 1-3-4-2.
Engine F20 was part of the Honda F-family, and had several related models: F18, F22, F22C and F23. Along with F engines, sports H engines (H22 and H23) were made, they were technically very close to the F-series.
F-series also included the dynamic F20C engine for Honda S2000.
Honda F20A and F20B had been manufactured until 2001, when they were replaced by the everyone’s favorite K20A engine.

Honda F20 engine modifications and differences

1. F20A – DOHC head version. 152 HP @ 6,100 rpm, the torque is 186 Nm @ 5,000 rpm. Such engines can be found in Honda Accord and Prelude.
2. F20A2/F20A3/F20A6 – SOHC head and carb version. Can be found in Honda Accord. 110 HP @ 5,700 rpm, the torque is 150 Nm @ 3,500 rpm. F20A6 reaches 90 HP @ 6,000 rpm, the torque is 150 Nm @ 3,500 rpm.
3. F20A4/F20A5/F20A7/F20A8 is an analogue to F20A2, but with the electronic fuel injection system. Such engines were used in Honda Accord and Prelude. 133 HP @ 5,600 rpm, the torque is 180 Nm @ 4,400 rpm.
4. F20B VTEC Bluetop is a sports engine created based on H22A. It uses DOHC head, which is very close to the head of H22A4. They also increased the compression ratio to 11, installed Type S cams, VTEC system and the 62.5 mm throttle body. The F20B engine was used for JDM Honda Accord and JDM Honda Torneo.
F20B specs are very much superior to those of F20A, the engine develops 200 HP at 7,200 rpm and the torque of 197 Nm at 6,400 rpm. Its rev limit is 7,800 rpm.
For vehicles with automatic transmission, a simpler version was used with 180 HP @ 7,000 rpm, and the torque of 192 Nm @ 5,500 rpm. This F20BVTEC engine uses JDM H22A Black top cams and 60 mm throttle body.
5. F20B3 is analogous to F20A with multipoint fuel injection for the European market.
6. F20B6 is analogous to F20B3, but with the VTEC system.
6. F20C is a sports engine for S2000. A separate article about it is located HERE.
7. F20Z1 is an analogue of F20A SOHC for Europe.
8. F20Z2 is an analogue of F20Z1 with low compression pistons (CR = 9), with different camshafts and new ECU setup.

Honda F20B (F20A) engine problems and malfunctions

All engines F20A, F20B, and F20Z are technically very close to engines H22A and H23A, and their problems are also the same. Honda F20 also can often have oil leaks, high oil consumption, coolant leaks, loss of power, and more. You can learn more about these problems HERE.
The F20B engine has its own problem: sometimes it can run unevenly. Most often this happens due to faulty Idle Air Control Valve. Have it checked.

Honda F20 engine tuning

F20B naturally aspirated

To add power to your F20B VTEC, find the following aftermarket performance parts: H22A intake system, cold air intake system, H22A fuel injectors, 4-2-1 headers, 2.25″ performance exhaust system. After ECU adjustment, you’ll get additional 10-15 HP. You can go even further and increase the cylinder bore to 87 mm, for H22A pistons. The cylinder block can withstand the bore of 87.25 mm, sometimes even 87.5 mm. To get even more power, you will have to buy an H22A head, and H22A headers and intake system. These mods will make your engine more powerful. If you want to get 250 horsepower with your F20B block + H22A head, then improve your engine according to the recommendations in THIS article.

F20A twin cam

Improving engines F20 SOHC (F20A, F20B3) makes no sense, its money down the drain. But if you really want to get a twin cam head, then buy a F20B VTEC head. However, it has different holes, and will require some reworking. You will also need F20B timing belt, gears and covers, F20B intake and exhaust system, ignition system, power steering belt, coolant pipes (thermostat to water pump), water pump gear, and VTEC solenoid. Then you will have to configure the ECU to make the VTEC system work, or buy an F20B ECU.
This is the only good possibility to build an F20A VTEC. Sometimes they install an H22A head on an F20A block, but the result is worse. The cylinder bores are different, and we get something like a mushroom. It is better to use a F20B VTEC head.
Considering the complexity and duration of all works, it may be easier to swap an H22A engine.

F20B turbo

For a start, it is desirable to do what has been described above: increase the cylinder bore to 87 mm, install H22A pistons, H22A head and H22A intake and exhaust system. As a result, you will get almost H22A engine, but with cast iron sleeves, instead of the weak H22A cylinder block.
Boosting an F20B in this variant is no different from boosting an H22A. You will need low compression pistons, H-beam rods, ARP head studs, turbokit and a few important components. We wrote about this in detail HERE.

F20A turbo

Probably the most useless business in the world is building an F20A turbo. You will get much less that your money’s worth. But if you really want, buy something like a TD04 turbocharger, order a turbo manifold and a downpipe for it. It will be nice if you install a 2.5″ aftermarket exhaust system. You will also have to make the oil feed line and oil return line for your TD04.
Buy an intercooler, intercooler pipes, silicone hoses, blow off valve, a wideband air/fuel oxygen sensor, and a boost controller. But that’s not all, OEM fuel injectors will not be sufficient, you will have to buy 630 cc injectors, aftermarket fuel rail, and a Walbro 255 lph fuel pump. After adjusting all that to the boost pressure not exceeding 7 psi (0.5 bar), you will get 200 to 220 HP. But after assembling a good turbokit, you will still have to buy forged rods and pistons (compression ratio ~8.5), don’t forget to buy ARP head studs. This will increase reliability and will allow increasing the boost pressure to the limit.

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