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 Type 75/83, the 907 was engineered for lightweight sports car applications emphasizing responsiveness and rev‑happy character. Emissions compliance was achieved through carburetion (early) and later Bosch K‑Jetronic fuel injection, meeting applicable UK and European standards of the time (pre‑Euro era).
One documented concern is head gasket failure due to thermal stress at the siamesed exhaust ports, highlighted in Lotus Engineering Service Bulletin LTB‑07/78. The original design used a single‑layer steel gasket prone to blow‑by under sustained load. From 1980, Lotus adopted a multi‑layer steel (MLS) gasket and revised coolant passages to improve durability.
Production years 1975–1987 predate formal Euro emissions standards; compliance was based on national regulations (UK VCA Type Approval #VCA/EMS/907L).
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.
| Parameter | Value | Source |
|---|---|---|
| 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 |
The high-revving DOHC layout delivers spirited performance but requires precise valve clearance checks every 12,000 km or 12 months. The timing belt must be replaced at 48,000 km intervals to prevent catastrophic interference damage. Early carburetted versions are sensitive to fuel volatility and require balanced throttle bodies. The siamesed exhaust ports create hot spots; MLS head gaskets (post-1980) are strongly recommended for all rebuilds per Lotus LTB‑07/78. Use of modern 95 RON unleaded fuel is acceptable with hardened valve seats.
Oil Specs: Requires SAE 10W-40 meeting API SF/CC (Lotus Workshop Manual 1978). Modern ACEA A3/B4 oils are acceptable substitutes.
Emissions: Pre-Euro era engine; compliance based on UK national standards (VCA Type Approval #VCA/EMS/907L). No Euro certification applicable.
Power Ratings: Measured under DIN 70020 standards. K-Jetronic variants detuned for emissions (Lotus PT-Spec Sheet 907-Rev3).
Lotus Engineering Report LER-907/75
Lotus Workshop Manual (1978 Edition)
Lotus Technical Bulletin LTB-07/78
VCA Type Approval Database (VCA/EMS/907L)
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.
Locate the engine number stamped on the left-hand side of the block near the rear main seal housing (Lotus Workshop Manual 1978). Early carburetted units have twin Dell’Orto DHLA 40 carburettors and a black aluminium rocker cover; K-Jetronic versions feature a silver Bosch fuel distributor and air flow sensor. The 907 is distinguished from the later 910/912 by its 8-bolt crank pulley (vs. 6-bolt) and absence of turbo plumbing. Head casting number ‘907’ appears above the exhaust manifold flange.
The 907's primary reliability risk is head gasket failure between cylinders 2 and 3, with elevated incidence in sustained high-load use. Lotus internal data from 1979 indicated over 30% of early carburetted engines required gasket replacement before 80,000 km, while UK DVSA records show timing belt neglect as a leading cause of catastrophic engine seizure in surviving examples. High-revving operation and thermal cycling make MLS gaskets and strict belt intervals critical.
Analysis derived from Lotus technical bulletins (1975–1985) and UK DVSA failure statistics (2010–2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about LOTUS LOTUS-907.
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DVLA: Engine Changes & MoT
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Regulation (EC) No 715/2007
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Commission Regulation (EU) 2017/1151
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