Lotus LOTUS-907 Engine (1975–1987) – Specs, Problems & Compatibility Database

The Lotus 907 is a 1,973 cc, inline‑four, dual overhead camshaft (DOHC) petrol engine produced between 1975 and 1987. It was Lotus’s first mass‑produced four‑valve — per — cylinder engine, featuring an aluminium block and head, and a belt‑driven twin‑cam layout. In standard form it delivered 160 PS (118 kW) at 6,500 rpm with 177 Nm of torque, providing strong high‑rpm performance for its era.

Fitted to models such as the Jensen — Healey, Lotus Esprit S1/S2, and Lotus Elite Ty…

Lotus Engine
Compliance Note:

Production years 1975–1987 predate formal Euro emissions standards; compliance was based on national regulations (UK.

Lotus LOTUS-907 Technical Specifications

The Lotus 907 is a 1,973 cc inline‑four DOHC petrol engine engineered for lightweight sports cars (1975–1987). It combines a 16‑valve cylinder head with belt‑driven camshafts to deliver high‑revving performance and crisp throttle response. Designed before formal Euro standards, it met contemporary UK and European national emissions requirements through carburetion or K‑Jetronic injection.

ParameterValueSource
Displacement
1,973 cc
Fuel type
Petrol (Unleaded, min. 95 RON)
Configuration
Inline‑4, DOHC, 16‑valve
Aspiration
Naturally aspirated
Bore × stroke
84.45 mm × 88.0 mm
Power output
140–160 PS (103–118 kW) @ 6,000–6,500 rpm
Torque
163–177 Nm @ 4,500 rpm
Fuel system
Twin 2‑barrel Dell’Orto carburettors (early); Bosch K‑Jetronic (late)
Emissions standard
Pre‑Euro (UK National Standards)
Compression ratio
9.4:1 (carb); 8.4:1 (K‑Jetronic)
Cooling system
Water‑cooled
Turbocharger
None
Timing system
Toothed belt (front‑mounted)
Oil type
SAE 10W‑40 (API SF/CC)
Dry weight
136 kg

Lotus LOTUS-907 Compatible Models

The Lotus 907 was used across Lotus's Elite and Esprit platforms with longitudinal mounting and licensed to Jensen for the Healey. This engine received platform-specific adaptations—revised sump for the mid-engine Esprit and front-engine cooling ducts for the Elite—and from 1980 the Esprit S2.2 adopted Bosch K-Jetronic injection, creating fuel system interchange limits. All adaptations are documented in OEM technical bulletins.

Make:
Lotus
Years:
1976–1987
Models:
Esprit S1/S2
Variants:
Type 79, Type 82
View Source
Lotus Workshop Manual (1978)
Make:
Lotus
Years:
1974–1982
Models:
Elite Type 75/83
Variants:
Type 75, Type 83
View Source
Lotus Engineering Report LER-907/75
Make:
Jensen
Years:
1975–1976
Models:
Healey
Variants:
907 Twin-Carb
View Source
Jensen Motors Ltd. Parts Catalogue JC-75

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Common Reliability Issues - LOTUS LOTUS-907 Compatible Models

Field reports and technical service bulletins highlight component wear patterns under high-load operation. Adherence to manufacturer service intervals and approved fluid specifications is critical for long-term reliability.

Head gasket failure (cylinders 2–3)
Symptoms: White exhaust smoke, coolant loss without external leak, overheating, bubbling in expansion tank.
Cause: Thermal stress at siamesed exhaust ports with original single-layer steel gasket design.
Fix: Install multi-layer steel (MLS) head gasket and ensure cylinder head surface finish meets OEM flatness spec per LTB-07/78.
Timing belt failure
Symptoms: Sudden engine stop, metallic clatter on restart attempt, cam/crank misalignment.
Cause: Belt degradation due to age or oil contamination; interference design magnifies consequences.
Fix: Replace belt, tensioner, and idler pulleys as a set every 48,000 km; verify cam timing after installation.
Carburettor imbalance (early models)
Symptoms: Rough idle, hesitation on acceleration, uneven exhaust temperatures.
Cause: Wear in throttle shafts and linkage; fuel evaporation in float bowls during storage.
Fix: Rebuild carburettors with OEM kits, synchronise throttle plates, and install inline fuel filters per workshop manual.
Oil leaks from rear main seal
Symptoms: Oil dripping from bellhousing, low oil level, clutch contamination in manual models.
Cause: Age-hardened rope-type rear main seal; crankcase pressure from worn piston rings exacerbates leakage.
Fix: Replace with modern lip-seal conversion kit (if available) or OEM rope seal with proper seating tool; address PCV system if clogged.
Research Basis

Analysis derived from manufacturer technical service bulletins and industry workshop records. Repair procedures should follow manufacturer guidelines.

LOTUS LOTUS-907 FAQ Common Questions Answered

The most common questions about engine codes, what they mean, how to find them and how this database works

The 907 offers excellent performance for its era but requires diligent maintenance. Early engines (pre-1980) are prone to head gasket failure, while all variants demand strict timing belt changes. With MLS gaskets, fresh belts, and regular valve adjustments, well-cared-for examples can be robust and rewarding.

Head gasket blowouts (especially between cylinders 2–3), timing belt failure due to age, carburettor imbalance on early models, and rear main seal leaks. These are documented in Lotus service bulletins and owner club technical archives.

The 907 powered the Lotus Esprit S1 and S2 (1976–1987), Elite Type 75/83 (1974–1982), and the Jensen-Healey (1975–1976). It was Lotus’s first production 16-valve engine and formed the basis for later 910-series turbo units.

Aftermarket ECU tuning is common on the LOTUS-907 platform, but increasing boost or altering engine parameters accelerates component wear, impacts emissions compliance, and may void vehicle warranties. Any modifications should be evaluated carefully by a qualified specialist.

Typical consumption is 10–12 L/100km (24–28 mpg UK) in mixed driving. Carburetted Esprits may use more under spirited use, while K-Jetronic versions offer slightly better consistency. Fuel economy is secondary to the engine’s performance character.

Yes. The 907 is an interference engine. If the timing belt fails, pistons will strike open valves, causing severe internal damage. This makes belt replacement at or before 48,000 km absolutely critical.

Lotus originally specified SAE 10W-40 meeting API SF/CC. Modern high-quality 10W-40 or 15W-50 semi-synthetic oils meeting ACEA A3/B4 are acceptable. Avoid low-viscosity oils due to bearing clearances and high-RPM operation.

Research Resources

Comprehensive technical documentation and regulatory references

Platform Overview

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Primary Sources

EUR-Lex

EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).

GOV.UK: Vehicle Approval & V5C

UK vehicle approval processes, import rules, and MoT guidance.

DVLA: Engine Changes & MoT

Official guidance on engine swaps and inspection implications.

Vehicle Certification Agency (VCA)

UK type-approval authority for automotive products.

Regulatory Context

Regulation (EC) No 715/2007

Euro emissions framework for vehicle type approval.

Commission Regulation (EU) 2017/1151

WLTP and RDE testing procedures for emissions certification.

GOV.UK: Vehicle Approval

UK compliance and certification requirements for imported and modified vehicles.

VCA Certification Portal

Type-approval guidance and documentation.

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