Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSMAZDA1991RX-7 TURBOREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCEENGINE CONTROLS - SPECIFICATIONSMECHANICAL CHECKSENGINE COMPRESSIONEXCEPT RX7
1991 Mazda RX-7 Turbo
Except RX7
1991 Mazda RX-7 TurboSECTION Except RX7
- Warm engine to normal operating temperature. Remove all spark plugs. On Navajo, use remote starter switch to crank engine (DO NOT crank engine with ignition switch). On all other models, disconnect ignition coil primary wire connector.
- On all models, hold throttle plate fully open. Crank engine at specified cranking speed.
COMPRESSION RATIO
| Application | Specification | |
|---|---|---|
| B2200 | 8.6:1 | |
| B2600i | 8.4:1 | |
| Miata | ||
| Automatic Transmission | 9.4:1 | |
| Manual Transmission | 9.0:1 | |
| MPV | ||
| 2.6L | 8.4:1 | |
| 3.0L | 8.5:1 | |
| MX-6 | ||
| Non-Turbo | 8.6:1 | |
| Turbo | 7.8:1 | |
| Navajo | 9.0:1 | |
| Protege | ||
| DOHC | 9.0:1 | |
| SOHC | 8.9:1 | |
| RX7 | ||
| Non-Turbo | 9.7:1 | |
| Turbo | 9.0:1 | |
| 323 | 9.3:1 | |
| 626 | ||
| Non-Turbo | 8.6:1 | |
| Turbo | 7.8:1 | |
| 929 | ||
| DOHC | 8.9:1 | |
| SOHC | 8.5:1 | |
COMPRESSION PRESSURE SPECIFICATIONS
| Application | Specification | ||||||
|---|---|---|---|---|---|---|---|
| Compression Pressure | |||||||
| B2200 | 173 psi (12.2 kg/cm2 ) @ 300 RPM | ||||||
| B2600i | 182 psi (12.8 kg/cm2 ) @ 270 RPM | ||||||
| Miata | 192 psi (13.5 kg/cm2 ) @ 300 RPM | ||||||
| MPV | |||||||
| 2.6L | 185 psi (13.0 kg/cm2 ) @ 280 RPM | ||||||
| 3.0L | 164 psi (11.5 kg/cm2 ) @ 300 RPM | ||||||
| MX-6 | |||||||
| Non-Turbo | 162 psi (11.4 kg/cm2 ) @ 270 RPM | ||||||
| Turbo | 139 psi (9.8 kg/cm2 ) @ 260 RPM | ||||||
| Navajo | (1) | ||||||
| Protege | |||||||
| DOHC | 182 psi (12.8 kg/cm2 ) @ 300 RPM | ||||||
| SOHC | 173 psi (12.2 kg/cm2 ) @ 300 RPM | ||||||
| RX7 | 85 psi (6.0 kg/cm2 ) @ 250 RPM | ||||||
| 323 | 192 psi (13.5 kg/cm2 ) @ 300 RPM | ||||||
| 626 | |||||||
| Non-Turbo | 162 psi (11.4 kg/cm2 ) @ 270 RPM | ||||||
| Turbo | 139 psi (9.8 kg/cm2 ) @ 260 RPM | ||||||
| 929 | |||||||
| DOHC | 179 psi (12.6 kg/cm2 ) @ 300 RPM | ||||||
| SOHC | 164 psi (11.5 kg/cm2 ) @ 300 RPM | ||||||
| B2200 | 121 psi (8.5 kg/cm2 ) @ 300 RPM | ||||||
| B2600i | 142 psi (10.0 kg/cm2 ) @ 280 RPM | ||||||
| Miata | 135 psi (9.5 kg/cm2 ) @ 300 RPM | ||||||
| MPV | |||||||
| 2.6L | 142 psi (10.0 kg/cm2 ) @ 280 RPM | ||||||
| 3.0L | 121 psi (8.5 kg/cm2 ) @ 300 RPM | ||||||
| MX-6 | |||||||
| Non-Turbo | 114 psi (8.0 kg/cm2 ) @ 270 RPM | ||||||
| Turbo | 98 psi (6.9 kg/cm2 ) @ 260 RPM | ||||||
| Navajo | (1) | ||||||
| Protege | |||||||
| DOHC | 128 psi (9.0 kg/cm2 ) @ 300 RPM | ||||||
| SOHC | 121 psi (8.5 kg/cm2 ) @ 300 RPM | ||||||
| RX7 | 43 psi (3.0 kg/cm2 ) @ 250 RPM | ||||||
| 323 | 135 psi (9.5 kg/cm2 ) @ 300 RPM | ||||||
| 626 | |||||||
| Non-Turbo | 114 psi (8.0 kg/cm2 ) @ 270 RPM | ||||||
| Turbo | 98 psi (6.9 kg/cm2 ) @ 260 RPM | ||||||
| 929 | |||||||
| DOHC | 125 psi (8.8 kg/cm2 ) @ 300 RPM | ||||||
| SOHC | 114 psi (8.0 kg/cm2 ) @ 300 RPM | ||||||
| Maximum Variation Between Cylinders | |||||||
| Miata, Protege & 323 | 28 psi (2.0 kg/cm2 ) | ||||||
| Navajo | (2) | ||||||
| RX7 | 21 psi (1.5 kg/cm2 ) | ||||||
| All Others | (1) | ||||||
|
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.