Renault F4R / F4RT

Renault's 2.0 sixteen-valve — the F4R, and turbocharged as the F4RT — in the Mégane, Laguna, Clio V6 and the Mégane RS.

It is the last of Renault's long-running F family, an iron-block design going back to the 1980s that ended up making 275 horsepower in the Mégane RS. That lineage is why it tolerates boost: the block was never the limiting factor.

On the naturally aspirated cars the recurring items are ordinary — coil packs, a carboned throttle body, and a timing belt that is an interference design and drives the water pump, so they are one job.

On the F4RT the known items are heat and boost plumbing: charge-air hoses that split and give a sudden loss of power with no fault code worth reading, and a turbocharger whose oil feed is what the interval protects.

These are heavily modified cars, and a remapped F4RT is a different engine from a maintenance point of view. Ask before diagnosing.