Isuzu 4XE1 (4XE family, 1.6 and 2.0)

Isuzu's 1.6 four — the 4XE1 — best known for an unexpected fitment: it is the engine in the Lotus Elan M100.

⚑ That fitment is why this page exists. An Elan owner searching Lotus finds chassis and body material and almost nothing about the engine; searching 4XE1 finds Isuzu's own service material, which is what the engine actually needs. The turbocharged 4XE1-T is the SE, and it is the one most Elans have.

General Motors owned a stake in both firms when the car was designed, which is the whole explanation for a Japanese engine in a British sports car — and it also means the Isuzu Gemini and Impulse share components with it.

It is a conventional belt-driven twin-cam with no unusual failure mode of its own. The turbo installation is the part that ages: heat, oil condition and the boost plumbing, in that order.

Parts are Isuzu parts, and that is good news — the supply is better than anything badged Lotus from the same era.