Buying and Modding the 2000 Civic Si
The 2000 Civic Si Coupe is one of those cars that nobody really talked about when it was new. It had a B18C5 engine, 170 horsepower, a limited-slip differential, and a six-speed manual. You could drive it hard for years without anything breaking. That is basically the entire appeal. The car sits somewhere between a daily driver and a project, which means you are not paying Lexus money for it anymore, but it is also not a joke car that falls apart if you look at it wrong. I bought one in 2003 with 68,000 miles on it. The paint was faded, the interior had some wear on the driver seat, and there was a small rust spot on the passenger door rock panel from a curb. Nothing structural. I drove it hard for two years, then sold it. I have since helped a dozen friends sort through their own Si problems, so I have seen both the good ones and the ones people tried to sell you on a budget.
The 2000 Honda Civic Si Coupe How A Modest Sedan Became An Enthusiast Legend
The legend part came later. When the Civic Type R came out in the US market with the B18C1, people noticed the Si had basically the same block and valvetrain, just de-tuned. The B18C5 makes power differently than the Type R version. It has a smaller cam profile, a different intake manifold, and a lower compression ratio. That means it revs smoother, makes less peak power, but it is also less stressed. A lot of people swap in the C1 engine because they want the higher RPM power band. It works. But it also means you are now dealing with a different intake setup, different motor mounts, and potentially different wiring concerns. Not impossible, just something you need to plan around. The B18C5 is a robust engine. I have seen them at 200,000 miles with just basic maintenance. The VTEC switchover around 5,100 RPM is clean, the valvetrain stays quiet, and there are no known catastrophic weaknesses like timing belt failures destroying the engine. You still need to change the belt, obviously. But if you do it on time, the engine itself will outlast just about everything else on the car.
What Actually Breaks on These Cars
The transmission is the first thing to worry about. The close-ratio six-speed in the Si is generally strong, but the synchros wear out, especially second gear. If you are launching it hard from a stop frequently, second gear synchronizer rings will go sooner. I replaced mine at around 90,000 miles and the old synchro was basically smooth plastic at that point. Not ruined, but worn enough that cold shifts into second required double-clutching or rev-matching to stay clean. The suspension components are the next thing. Control arm bushings, especially the rear lower control arms, crack and flatten over time. You will feel it as vague steering on light steering inputs and a slightly loose feeling in the rear end over bumps. Replacing the rear control arms is a half-day job if you have a socket set and a breaker bar. Do not skip the rear camber bolts while you are in there. The factory setup has zero adjustability, and if you are running anything wider than stock tires, you will want at least a little negative camber in the rear for grip. Rust is mostly a cosmetic issue on these cars, but not always. Check the floor pans, especially the driver side footwell area. Water gets in through the cowl drains and sits there. It also shows up along the rear wheel wells and under the trunk lining. One real problem I ran into: the trunk drain tube on my car was cracked and water was pooling in the spare tire well, slowly eating through the floor from the inside out. I replaced the rubber tube and added a drilled drainage hole in the floor pan. Fixed it permanently.
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Engine Mods That Actually Work
The simplest upgrade is the Mugen intake manifold and throttle body. Swapping the Si intake for the Mugen setup from a Type R or an aftermarket Mugen reproduction gives you about eight to twelve horsepower at the wheels. That is not a ton, but it changes how the car feels in the mid-range. The stock Si manifold is tuned for low-end torque. The Mugen one opens things up above 4,000 RPM. If you only drive normally, you will not notice much difference. If you track the car, it matters. A full exhaust system makes more difference than people expect. The stock Si exhaust is adequately restrictive. A cat-back like the APEI or even a well-built aftermarket system from companies like Greddy will free up roughly ten to fifteen wheel horsepower and improve throttle response noticeably. The real gain is not peak power. It is the engine breathing better through the entire RPM range, which makes the VTEC engagement feel sharper instead of lagging behind. Intake cams are a real option if you want more power. The B18C5 uses a single overhead cam per head, so you are replacing the entire camshaft. A decent cam like the K20A cam from a Honda K-series swap can work in a B-series head with some modifications, but that is a different conversation entirely. For a straightforward cam swap, the Acura Integra GS-R cam (B18C1) gives you about 15 to twenty more horsepower but loses some low-end torque. The engine will feel lopey at idle and need to be revved harder to make power. Not ideal for a street car unless that is exactly what you want.
The biggest mistake people make is trying to bolt on a turbo without addressing the internals first. The B18C5 block is strong, but the stock pistons and rods are forged aluminum and steel. They can handle maybe twenty to twenty-five pounds of boost before you start worrying about ring land failure or rod stretch. If you want more than that, you are looking at aftermarket pistons and rods, which gets expensive fast. A well-built naturally aspirated setup with a good cam, intake, and exhaust can make 190 to 200 wheel horsepower reliably for a fraction of the cost of a turbo kit.
Handling Upgrades Worth the Money
Coilovers are the most common upgrade, and for good reason. The stock suspension is soft and floaty. A set of decent coilovers from brands like BC Racing, Tein, or KW can transform the car. But here is the thing most beginners miss: the front subframe on these Civics has built-in flexibility. Even with the best suspension in the world, the front end will flex under hard cornering. The solution is a subframe brace. A simple $150 brace from a company like Spoon or APEI makes a noticeable difference in turn-in sharpness because it reduces that subframe deflection. sway bars are another big improvement. The stock front and rear bars are adequate but not aggressive. Upgrading to a thicker front bar, like a 25mm or 27mm unit, reduces understeer significantly. The rear bar can stay stock or go up to 22mm if you want more rotation. Just be aware that too much rear bar thickness without corresponding spring rate adjustments will make the car snapRotate unpredictably, which is dangerous on a track day. Tires matter more than any suspension upgrade you can buy. Stock Civic Si tires from 2000 were probably Michelin MXM4 or something similar. These are all-season touring tires. A set of summer performance tires like Michelin Pilot Sport 4S or Hankook Ventus V12 evo2 will improve lap times by seconds per lap on a road course and make the car feel completely different every day. I put a set of Pilot Sport 4S on my Si and the difference was dramatic. The car tracked straighter, braked better, and the steering feel improved because the tire contact patch was more consistent.
Brakes and Safety
The stock brakes are decent but not great. The front rotors are vented and the pads are reasonable, but the calipers are single-piston floating units. For street use, they are fine. If you are doing any track days, you will want to upgrade to a larger rotor kit and better pads. Good brake pads like EBC Green Stuff for street use or Hawk HP+ for track will cut stopping distance by roughly thirty percent. Upgrading the brake lines to stainless steel braided lines also helps because the stock rubber lines expand under heavy braking, which gives the pedal a spongy feeling. One thing nobody talks about is brake fluid. The Si uses DOT3 or DOT4 fluid. If your brake fluid has not been changed in five years, it is probably contaminated with moisture. DOT fluid absorbs water over time. Boiling point drops. Fade happens. Flushing the system every two years is cheap insurance. I once saw a Si at a track day where the driver complained about pedal fade after three laps. We flushed the brakes and the problem went away completely. The calipers and rotors were fine. The fluid was just boiled.
Common Problems and How to Fix Them
The automatic transmission version of the 2000 Civic Si exists, but it is rare and not recommended. The four-speed automatic is slow and the torque converter locks up late, which kills acceleration. If you can find a manual, get the manual. The difference in driving experience is massive. The air conditioning system is another weak point. The condenser on these cars tends to leak from the inside due to internal corrosion. If your AC is blowing warm air, the first thing to check is the condenser. Replacing it is straightforward, but you also need to flush the accumulator and dryer at the same time. If you skip that step, the new condenser will fail within a year because the old moisture and contaminants are still in the system. The electrical system is generally reliable, but the main ground points corrode over time. There is a ground strap from the engine to the chassis that runs along the passenger side. I found mine was completely corroded through after six years. Replacing it with a fresh copper braid ground strap cost about twenty dollars and fixed a random idle issue I had been chasing for months. If your car is running poorly and you cannot find the problem electrically, check every ground point before you spend money on parts you think you need.
The fuel pump relay is a known failure point on many Honda models from this era. The relay gets hot and the contacts inside weld together, causing the fuel pump to run continuously even when the key is off. This can drain your battery overnight. The fix is to replace the relay with an updated version from Honda, or install an external relay holder so you can swap it easily. The relay is located in the passenger side dash panel, accessible by removing the trim cover.
What to Look for When Buying One
Pricing for a 2000 Civic Si in good condition ranges from about eight thousand to twelve thousand dollars depending on mileage, condition, and whether it has been modified. Modified cars are usually a bad buy unless you know exactly what was done. A stock example with clean maintenance records is always preferable to a modified one with unknown history. Check the VIN to confirm it is actually a Si and not a delux model that has been badge-swapped. The Si has a different engine code and different wheels. The wheel size is 16-inch on the Si versus 15-inch on the base models. The brakes are also larger on the Si. If the car has 15-inch wheels and stock brakes, it might be a LX or DX with some Si trim pieces added. Under the hood, look for oil leaks. The valve cover gasket on the B18C5 is a common leak point. It is not expensive to fix, but it indicates whether the previous owner did preventive maintenance or just drove it until something failed. A leaking valve cover gasket suggests the person may have been neglectful about other things as well.
The timing belt should have been changed at least once on a car this old. If you cannot find evidence of it, assume it has never been changed and budget for an immediate replacement. The B18C5 is an interference engine, which means if the timing belt breaks, the valves and pistons will collide and destroy the engine. A timing belt kit with water pump costs roughly two hundred fifty dollars in parts and six to eight hours of labor if you do it yourself. A new engine from a junkyard runs about eight hundred to twelve hundred dollars depending on mileage.
The Long-Term Ownership Reality
These cars are cheap to own if you keep them stock or moderately modified. Parts are available from every aftermarket company, and the community is huge. You will never have trouble finding someone who knows how to fix one. The downside is that the car is not fast by modern standards. The 0 to 60 time is roughly seven seconds, and passing power at highway speeds is adequate but not thrilling. If you want something faster, you will spend money on mods that add up quickly. Insurance is low, which helps. Registration is cheap in most states. Maintenance is straightforward and DIY-friendly. The car is light, so tire wear is moderate. Gas mileage is decent at around twenty-eight to thirty-two miles per gallon depending on driving style. All of this adds up to a car that is genuinely affordable to live with day to day. The 2000 Civic Si Coupe started as a competent compact car and became an enthusiast icon because it was built on a platform that rewards mechanical sympathy and incremental upgrades. It does not have the raw power of a Supra or the reliability reputation of a Toyota, but it sits in a sweet spot where you can learn how to build a car without spending thousands of dollars. That is why people still talk about it.
