Honda R18: Everything You Need to Know

Before succeeding in manufacturing great cars, the Japanese company Honda started as motorcycle manufacturers. And one of their most recognizable creation is the Honda Civic.

Its fuel economy, reliable engine, attitude in style, and low maintenance costs generate a comprehensive picture of what is yet to come.

Post-2006 Honda Civic (Non-Si) units are loaded with R-engines. It may vary on different cars, but the same engine family still runs it.

Let us start with the Honda R-engine family. R18A is a member of the 6-piece serialized R-series engine that replaced the D-series line of machines. R-engine is a water-cooled naturally-aspirated inline-four petrol engine fuel-injected, cylinder block and head made from aluminum, SOHC 16-valve design and uses Honda’s i-VTEC system.

It uses technologically advanced methods to maximize efficiency through improved fuel economy, weight and friction reduction, and using alternative materials such as plastics to ensure its optimum performance.

So today, we will talk about R18A Engines who powered the Honda Civic in its debut in 2006. Let’s get right to it.

Engine Specifications and Design

  • Production Run: 2006 – Present
  • Cylinder Head Material: Aluminum Alloy
  • Cylinder Block Material: Aluminum Alloy
  • Configuration: Naturally-Aspirated Inline-4
  • Bore: 81 mm
  • Stroke: 87.3 mm
  • Valvetrain: SOHC 4 Valve with i-VTEC
  • Displacement: 1.8 Liters
  • Compression Ratio: 10.5 – 10.6
  • Weight: 223 lbs.
  • Max HP: 139 hp
  • Max Torque: 128 lb-ft

Following the eight-generation Honda Civic release in 2006, the new 1.8 Liter, four-cylinder naturally aspirated R18 engines appear on Honda’s new R-series family. R18 engines or R18A, in its initial release, replaced the D17 of the previous D engine family.

Honda R18 engines have a 3.7-liter capacity and only weigh 223 lbs. On top of its naturally aspirated structure, it also has a new compact high-rigidity aluminum engine block and aluminum heads.

Inside, the block comprises top-grade components – forged high-strength cracked connecting rods, low-friction pistons with molybdenum disulfide, precision-balanced crankshaft, and an oil-based piston cooling jets that cools down the pistons during motion.

The cylinder block is covered with a 16-valve SOHC aluminum cylinder head which features four valves per cylinder (two each for both intake and exhaust valves), multi-point fuel injection.

The engine is equipped with a narrow timing chain, a change since the prior D-series used timing belt instead of a chain, which is designed to last until retirement.

It also has aluminum rocker arms, one-chain-driven camshaft, and Honda’s own i-VTEC technology, an intelligent variable valve timing and electronic lift control system that facilitates maximum performance to the engine, that allows the engine to function as a 2.0 Liter when needed with a better fuel-efficiency.

The auxiliary engagement starts at 3,500 RPM.

R18 engines also have a new 2-stage variable-length intake manifold that is triggered at 5,200 RPM, electronically controlled throttles – Honda’s drive by wire system and 2-stage exhaust system with enhanced catalytic converter placed just right after the exhaust manifold to meet different environmental standards.

R18s are California Air Resources Board (CARB) and ULEV-2 (Ultra Low Emissions Vehicle) compliant.

R18s has a 1.6-liter version, R16A, and a 2.0-liter version, R20A, for larger vehicles based on R18A engines.


  • R18A1
  • R18A2
  • R18Z1
  • R18Z4
  • R18Z6
  • R18Z9

R18A1 is the first variant of the R18 engine. It has a 1.8 L displacement, 81mm stroke, 87.3mm bore, chain-driven SOHC i-VTEC; 139 hp at 6,300 RPM, 128 lb-ft torque available at 4,300 RPM, and 10.5 compression ratio.

It appears in different number of cars, including 2006 – 2012 Honda Civic (Africa, Japan, India, Malaysia, Thailand, Indonesia, Philippines, Taiwan, and American-Canadian market FA1 and FG1), 2007 – 2009 Honda FR-V, 2008 – 2015 Honda City, and 2007 – 2014 Honda Stream

R18A2 is the analog version of R18A for 2006 – 2011 European Honda Civics. This engine is slightly different than 18A1s because VTEC engagement in R18A2s happens under cruising load only.

But they still hold the same displacement, torque, bore and stroke, and compression ratio.

The modified version of the R18A, R18Z1, replaced the previous release in 2012. It also became the elementary basis for the 2.0 Liter R20A engine. R18Zs are similar to R18A1/A2s, but it features a higher compression ratio with 10.6, it is also equipped with i-VTEC and new variable intake manifold settings.

This engine is prominent in the ninth-generation Honda Civic.

R18Z4s is the analog version of the R18Z1; it has the same compression ratio and holds the same level of performance as Z1s. It appears in ninth-generation civic for the European market.

R18Z6 is the R18Z1 adaptation for 2013 – 2017 Honda Jade Models, while R18Z9 is suited the Honda HR-V version of R18Z1.

R18 Engine Tuning and Upgrades

R18 engines or the R-series engine family, collectively, are designed for superior fuel efficiency, low emissions, and longevity. It is ideal for city driving or just enjoying the music in the stereo while immersing yourself in driving the freeway.

However, some itch cannot be tamed, like making it a bit faster than it is. Great news because of R18’s oil-cooled pistons, excellent cylinder head design – to cater the high-temperature exhaust gasses right into the turbocharger, and less-friction special cylinders are all great for a turbo kit.

You can build the turbo by buying a turbocharger kit, forged internals, and a turbo manifold design that is based on their Honda Integrated Manifold design.

You can also buy a supercharger kit with an intercooler to increase R18A’s power up to 220 – 240 hp. But take note that you should replace the stock internals for CP pistons and Eagle rods.

You may opt to buy a performance exhaust system, piping kit, blow-off valve, oil coolers, 630 cc fuel injectors, and fuel pumps for a better result, as these mods will give you at least 290 hp.

Problems Surrounding R18 Engines

Though engines are continuously modernized to fit the modern demands of people’s needs, we cannot separate the fact that even with delicate care and maintenance, our machines still end up retiring, and we have no choice but to buy a replacement.

But, still, we need to do our part as future owners or owners to alleviate the detrimental effects of age and mileage on our engines. Here are some issues that might appear, prematurely or later, in R18 engines:

First is the knocking engine sound. This is a normal thing for R18 engines, so don’t panic. The knocking sound comes from the Evap canister purge valve. R18 engines do not have hydraulic tappets, and most of the time, owners forget to check and adjust the valves on time hence the noise.

Checking and adjusting valve clearance is essential. Some recommend every 24,000 miles, and if you need a reference for the valve clearance, here it is intake valves 0.18mm-0.22mm, 0.23 – 0.27mm for exhaust.

The second is the noise from the tensioner pulley of an accessory drive belt. It can also be a result of a failed tensioner pulley. The typical useful life of a pulley is around 60,000 miles, so habitually check if that needs to be replaced.

The third is the unwanted vibrations. If you have a cold engine, start and start vibrating, don’t worry that much because the engine has low idle speed. However, if the vibrations persist and intensify, you might have to check the engine mounts, especially on the left side.

Some reminders regarding the choice of your engine oil, it is extremely important to find the right oil requirement and invest in that quality engine oil as this will keep your system in proper condition and prevent premature failure.

Even it does not occur on a lot of occasions. There are several known cases of oil pump replacement in the R18A engines, though it is the tail-end production. You might still check that and always look for possible leaks on crankshaft seals and camshafts after passing the 100,000-mile mark.


The likelihood of Honda R18 engines being troublesome is close to none and by far one of their most trusted engines in the industry today. Without any major issues and no harmful cues under its nose, its fuel efficiency to performance balance will entice potential buyers who want to experience economy and power.

R18s are technologically advanced and stylish, perfect for leisure driving around the urban, and can get a boost with some modifications. Maintenance is not that difficult and could give you a solid 300,000 miles of service with proper care and prevention.

I hope we cleared some clouds in your head regarding the admirable Japanese Honda R18 engine, and whether you already have one or planning to have one, this may be a tool for you to understand R18 engines.

1 thought on “Honda R18: Everything You Need to Know”

  1. i want to find mods for my 2014 honda civic can yall help me out since yall know so much about the r18


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