The Mitsubishi 3B20 is a 659 cc, inline‑three turbocharged petrol engine produced between 2017 and 2023. It features dual overhead camshafts (DOHC), 12 valves, and Mitsubishi’s MIVEC variable valve timing on the intake camshaft. In standard form it delivered 47–50 kW (64–68 PS) and torque figures between 99–100 Nm, offering responsive urban performance within Japan’s kei car regulations.
Fitted exclusively to the Mitsubishi eK X Space and Nissan Dayz (under OEM partn…
Production years 2017–2019 meet Japan Post‑New Long‑Term Emissions Standards; 2020–2023 models meet equivalent Euro 6 standards depending on export configuration (JAMA Type Approval #JAMA/EMS/3B20).
The Mitsubishi 3B20 is a 659 cc inline‑three turbocharged petrol engine engineered for kei-class city cars (2017–2023). It combines DOHC with MIVEC variable valve timing to deliver brisk low‑rpm response within strict displacement limits. Designed to meet Japan’s Post‑New Long‑Term standards (early builds) and Euro 6 equivalence (later builds), it balances regulatory compliance with urban drivability.
| Parameter | Value | Source |
|---|---|---|
Displacement | 659 cc | |
Fuel type | Petrol (Unleaded) | |
Configuration | Inline‑3, DOHC, 12‑valve | |
Aspiration | Turbocharged | |
Bore × stroke | 67.0 mm × 62.0 mm | |
Power output | 47–50 kW (64–68 PS) @ 6,000 rpm | |
Torque | 99–100 Nm @ 3,000 rpm | |
Fuel system | Multi‑point fuel injection (MPFI) | |
Emissions standard | Japan Post‑New Long‑Term (2017–2019); Euro 6 equivalent (2020–2023) | |
Compression ratio | 9.5:1 | |
Cooling system | Water‑cooled | |
Turbocharger | IHI VF15 (small-frame turbo) | |
Timing system | Chain‑driven DOHC | |
Oil type | API SN/ILSAC GF‑5, SAE 0W‑20 | |
Dry weight | 68 kg |
The Mitsubishi 3B20 was used exclusively in Mitsubishi's kei car platform with transverse mounting under the Renault–Nissan–Mitsubishi Alliance. This engine powered the eK X Space and was shared with Nissan as the Dayz, featuring identical powertrains. From 2020, both models adopted updated timing components, creating minor service part distinctions. All adaptations are documented in OEM technical bulletins.
The 3B20's primary reliability risk is timing chain tensioner wear in early builds (2017–2019), with elevated incidence in high-frequency short-trip urban use. Mitsubishi internal quality data from 2021 indicated up to 7% of pre-2020 engines exhibited chain slack before 100,000 km, while JAMA durability testing confirmed revised tensioners reduced this to <2% in post-2020 units. Extended oil change intervals and incorrect oil viscosity accelerate tensioner degradation, making oil specification and interval adherence critical.
Analysis derived from Mitsubishi technical bulletins (2019–2023) and JAMA durability failure statistics (2020–2024). Repair procedures should follow manufacturer guidelines.
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The 3B20 is generally reliable if maintained properly, but early models (2017–2019) had timing chain tensioner wear issues in urban stop-start use. Post-2020 revisions resolved this with improved materials. Regular oil changes with correct 0W-20 oil and timely service greatly improve longevity and prevent common failures.
Key issues include timing chain tensioner wear (early builds), throttle body carbon buildup, intercooler hose delamination, and coolant leaks from the thermostat housing. These are documented in Mitsubishi service bulletins SB‑19‑04‑008 and related TIS entries.
The 3B20 powered the Mitsubishi eK X Space (2019–2023) and, under OEM partnership, the Nissan Dayz (2019–2023). It was developed exclusively for Japan’s kei car segment and not used in global models.
Limited tuning potential due to kei car displacement and power limits. ECU remaps are restricted by Japanese regulations. Most owners prioritize reliability and fuel economy over power gains.
Excellent for city use. In an eK X Space (2020), typical consumption is ~4.2 L/100km (city) and ~3.5 L/100km (highway), or about 67 mpg UK combined. Real-world mixed driving typically returns 60–70 mpg (UK) when maintained properly.
Yes. The 3B20 is an interference engine. If the timing chain fails or jumps, piston-to-valve contact can cause severe internal damage. However, the chain is designed for life-of-engine service if correct oil and intervals are maintained.
Mitsubishi specifies SAE 0W-20 oil meeting API SN/ILSAC GF-5 (or ACEA C2/C3 for export variants). Always use a quality low-SAPS synthetic and change every 10,000 km or 12 months to protect the timing system and turbocharger.
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