G15 engine & gearbox

G15 Technical Guide - Engine & tuning

The standard engine is one of the Imp variants (typically 875cc Imp Sport, 930cc or 998cc) and in standard form is covered in Imp workshop manuals.  What follows are notes and datasheets compiled over years of preparing and racing G15s.

Carburettor jetting

Camshafts • ARP rod bolt fitting

Twin 40 DCOE Installations:  The standard Webber linkage fits on top of the forward carb.

A tidy engine bay with several of the mods described in the Guide.

G15 Technical Guide - Gearbox and transmission

The standard gearbox and transmission is all Imp and in standard form is covered in Imp workshop manuals.

Gear Ratio/Speed in Gear Charts

Rotoflex Couplings:  For competition use Lotus Elan ones with cap head high tension bolts and shallow Nyloc nuts.