Mazda RX-7 FC, Frequently Asked Questions

What is the FC RX-7?

The FC is the second-generation Mazda RX-7, produced from 1985 to 1992. It’s a front-engine, rear-wheel-drive sports car available as a coupe or convertible, powered by the 13B twin-rotor Wankel rotary engine in either naturally aspirated (112kW/150hp) or turbocharged (150kW/200hp) form. The FC was larger, heavier, and more refined than the FB it replaced, with the Turbo II model featuring independent rear suspension, LSD, and four-wheel disc brakes.

Should I buy the NA or Turbo?

The Turbo II. The naturally aspirated FC is a pleasant car, but the 112kW NA engine is underwhelming in the heavier FC body (1,200-1,300kg). The Turbo II’s 150kW gives the car the performance it needs to feel genuinely sporting. Equally importantly, the Turbo II comes with independent rear suspension, LSD, and better brakes, it’s a fundamentally more capable chassis. The NA model uses a simpler semi-trailing arm rear and may have drum rear brakes. For the typically modest price difference, the Turbo II is worth the additional complexity.

What are coolant seals and why do they matter?

The coolant seals are rubber O-rings that sit between the rotor housings and side housings (end plates), sealing the coolant passages that run through the engine block. Over time, these O-rings harden, shrink, and lose their sealing ability. When they fail, coolant can enter the combustion chamber (causing white smoke and coolant loss) or leak externally. On a 30+ year old FC, the coolant seals are the single most important engine concern. Replacing them requires a full engine teardown, which is why most owners do a complete rebuild (all seals, bearings, gaskets) at the same time. Cost: $3,000-5,000 for a turbo engine.

My FC smokes on startup, is the turbo dying?

Blue-grey smoke on startup that clears within 30 seconds is a classic symptom of worn turbo shaft seals. Oil drains past the seals when the engine is off and collects in the turbine housing, then burns off on the next start. This is common and not an emergency, the turbo can run like this for a long time. However, it does indicate the seals are wearing, and a turbo rebuild ($500-800) should be budgeted. If the car smokes under boost (during acceleration), that’s more serious and requires immediate attention.

How much boost should the FC make?

Factory boost on the Turbo II is approximately 6-7 psi (0.4-0.5 bar). Use a boost gauge to verify. Significantly less than 6 psi indicates a boost leak, failed wastegate actuator, or failed boost control solenoid. More than 8 psi without intentional modification suggests a stuck wastegate (boost creep), which is dangerous, uncontrolled boost causes detonation that destroys the engine.

Can I increase the boost on my FC?

Yes, but proceed carefully. A boost controller (manual or electronic) can increase boost beyond the factory 6-7 psi. Moderate increases to 8-10 psi are generally safe on a healthy engine with adequate fuelling and cooling. Beyond 10 psi, supporting modifications become necessary: larger injectors, uprated fuel pump, better intercooler, and potentially a larger turbo. The rotary engine is sensitive to detonation, if you increase boost without increasing fuel delivery to match, you will damage the engine. Always monitor with a wideband air-fuel ratio gauge and a boost gauge.

Should I still pre-mix two-stroke oil in a fuel-injected FC?

Yes. The fuel injection system has no bearing on the apex seal lubrication requirement. The oil metering pump (OMP) handles seal lubrication, but it’s a mechanical component that can fail silently on a 30+ year old car. Pre-mixing two-stroke oil at 1:200 ratio (25-30ml per 10L of fuel) provides insurance against OMP failure. This is standard practice across all rotary engines regardless of induction system.

What’s the difference between Series 4 and Series 5?

Series 4 (1986-1989) is the initial FC. Series 5 (1989-1992) is the updated model with revised engine management (improved fuel injection calibration, better cold-start behaviour), updated interior trim and materials, refined suspension tuning, and minor exterior changes. The Series 5 is considered the most refined FC and typically commands a small premium. Mechanically, they are very similar, the differences are incremental improvements rather than fundamental changes.

How much fuel does the FC use?

The NA model: 12-15 L/100km mixed driving. The Turbo II: 14-18 L/100km mixed driving, up to 22+ L/100km during spirited driving. Use 98 RON premium unleaded. The turbo model’s consumption increases significantly with boost, gentle driving is noticeably more economical than aggressive driving. Highway cruising at moderate speed gives the best economy.

Is the FC good for long-distance touring?

The FC is arguably the best RX-7 generation for touring. The cabin is well-insulated, the seats are comfortable over distance, the air conditioning works well (when the vacuum system is intact), and the Turbo II has enough power for effortless highway cruising. The hatchback provides reasonable luggage space. The ride quality is more compliant than the FB or FD. Many FC owners have done extensive road trips, the car’s grand touring character is one of its defining strengths.

What about the power steering whining?

The FC’s power steering pump is a known weak point. A whining noise from the pump area that increases with steering input indicates internal pump wear. The pump can be rebuilt ($200-400) or replaced with a remanufactured unit ($300-500). Check the fluid level and condition first, low or contaminated fluid causes pump noise. Dark or metallic-looking fluid indicates internal wear and the pump needs attention.

What modifications should I do first?

Priority order: (1) Complete cooling system, aluminium radiator, silicone hoses, new thermostat and water pump. (2) Replace all vacuum hoses with silicone, this one job fixes boost control issues, 4th port operation, and climate control problems. (3) Ignition upgrade, quality leads, coil, and spark plugs. (4) Exhaust, stainless steel system. (5) Suspension, shocks, springs, and bushings. These five items transform a tired FC into a sharp, reliable driver. Resist engine modifications until the car is fully sorted.

My climate control is stuck on defrost, what’s wrong?

The FC’s automatic climate control uses vacuum-operated actuators to control airflow direction. When the vacuum system loses pressure (usually from cracked vacuum hoses), the actuators default to their rest position, which is defrost mode. Start by replacing all vacuum hoses, they’re inexpensive and this resolves the problem in most cases. If individual actuators have failed (the diaphragms develop leaks with age), they need replacement. Some are accessible, others require dashboard disassembly.

Can I fit an FD engine in my FC?

The 13B-REW twin-turbo from the FD can be fitted to the FC, but it’s a significant undertaking. The engine mounts, wiring harness, ECU, cooling system, exhaust, and fuel system all need modification. The FD engine is physically similar to the FC’s 13B but the twin-turbo system and engine management are completely different. Cost: $5,000-15,000 depending on the build. A more practical upgrade is to improve the FC’s existing single-turbo 13B with a larger turbo, better intercooler, and supporting modifications.

Is the FC convertible worth buying?

The FC convertible is a lovely car for open-air rotary motoring. The structural reinforcement means it’s heavier and slightly less rigid than the coupe, so it’s not the choice for track days or spirited canyon driving. But as a touring car for summer driving, it’s excellent. The main concern is rust, convertibles have additional drain channels for the folding roof that clog and redirect water into the body. Inspect very carefully behind the rear seats and along the sills. Values are comparable to the coupe.

How often does the engine need rebuilding?

With proper maintenance (pre-mixing, regular oil changes, adequate cooling, and regular spirited use), the turbo 13B can last 80,000-120,000 km before needing a rebuild. The NA 13B, running at lower stress levels, can last 100,000-150,000 km. These are guidelines, not guarantees, an engine that has been overheated once may need rebuilding at 50,000 km, while a pampered engine might make it to 150,000 km. Annual compression testing is the best way to track engine health.

What’s the 4th port issue?

The FC’s 13B uses a variable intake port system. Below approximately 4,500 rpm, only two intake ports per rotor are open. Above 4,500 rpm, the 4th port opens via a vacuum-operated actuator, increasing airflow and power. If the vacuum hose to the actuator cracks (extremely common after 30 years), or the actuator diaphragm leaks, or the solenoid fails, the 4th port stays closed and the engine loses its top-end power. The car feels flat above 4,500 rpm. The fix is usually as simple as replacing a vacuum hose, check this before assuming the engine has a deeper problem.

Is the FC a good first rotary car?

The FC is an excellent entry into rotary ownership. It’s more refined and comfortable than the FB, the turbo model offers genuine performance, and the electronic fuel injection is more reliable than the FB’s carburettor. The enthusiast community is knowledgeable and supportive, parts are available, and the car is well-documented. The main caveat is the coolant seal issue, budget for an engine rebuild on any high-mileage FC that hasn’t had one. Beyond that, the FC is a rewarding, capable sports car that teaches you about rotary ownership without the extreme costs of an FD or the fragility of an FB.

What oil should I use?

For the engine: 10W-40 or 15W-50 semi-synthetic oil. Change every 5,000 km. The turbo engine benefits from semi-synthetic’s better thermal stability compared to mineral oil, but avoid full synthetic oils with high friction modifier content, this is debated in the rotary community, but many engine builders prefer semi-synthetic. Oil capacity is approximately 4.5-5.0L. For pre-mix: quality two-stroke oil (Penrite MC-2, Idemitsu) at 1:200 ratio in the fuel.

How do I cool down the turbo properly?

After spirited driving, idle the engine for 60-90 seconds before shutting off. This allows oil to continue flowing through the turbo bearings while the turbo cools from its operating temperature (which can exceed 800 degrees Celsius at the turbine). Shutting the engine off immediately after hard driving allows the oil in the turbo centre housing to “coke”, the residual heat bakes the oil into hard carbon deposits that restrict oil flow and damage bearings. A turbo timer that automatically idles the engine after you leave the car is a worthwhile $50-100 investment.