Two things make the Renault 5 GT Turbo the performance-winning hatchback it is. The first is its weight, which at not quite 17cwt gives it a head start on most of the opposition that it so comfortably outruns, coupled with tolerably good aerodynamic efficiency. The second is its immensely lusty power unit, which is a further development of the unit in the original R5 Gordini Turbo.
That had a relatively simple turbocharged engine which turned out a believable 110bhp at 6,000rpm and 108lb ft torque at 4,000rpm. The new transverse-engined successor (which came out as a prototype only at the same time as the main R5 range, in September 1984) has the same surprisingly humble sounding basic engine - a bored out version of the 1289cc engine in the old 5TS, which even if it inherited an aluminium-alloy cross-flow head, continues to mean that its valve-gear is pushrod OHV.
However, there was never anything too much amiss with the strength of the block and the reciprocating parts, or with the breathing efficiency of that head, which Renault has exploited further by adding a small air-to-air intercooler crammed in to the left of the radiator. Combine that with Garrett's smallest turbocharger, the always impressive little T2, Iet it run a bit harder, and you have what Renault says is a maximum of 10.3 psi boost - a very high figure for a production road car instead of the old engine's 6.6.
The static compression ratio is dropped from the former 8.6 to 7.9 to 1, all of which adds up to a claimed – and, judging by the performance, equally credible 115 metric bhp at a slightly lower speed of 5,750rpm. There’s an even more impressively improved torque peak of 121lb ft, pushed very usefully further down the scale, 1,000rpm lower than before at 3,000rpm.
