Mods and Consequences
BMW Z3
Some saw the Z3 as the perfect roadster when BMW launched it in 1996, thanks to its affordability, build quality and range of engines. Some road testers were disappointed with its suspension design, but it’s not really much of a hindrance unless you drive everywhere on the door handles.
Z3 buyers could choose between a ‘narrow body’ pre-facelift with the 1.9-litre 16-valve four-cylinder engine, or a ‘wide body’ pre-facelift with the 2.8-litre 24-valve six-cylinder engine. Post-facelift, there was the choice of a 1.9-litre eight-valve four-cylinder, a 24-valve six-cylinder (in 2.0, 2.2, 2.5 and 3.0 guises) plus 3.2-litre M roadsters and coupés. The six-cylinder cars sound great and provide greater muscle, but the four-pot cars are more nimble. European Z3s got an all-alloy straight-six, while US models got a castiron block.
Although the Z3 was available with relatively small engines, enthusiasts tended to focus on the larger sixcylinder powerplants. Plenty of companies will sell you aftermarket parts, but the advice is to stick with BMW bits where possible, such as those from an E36 M3, which often cost no more than components bought in from a third party.
There’s little point in trying to tune a four-cylinder engine when one of the six-cylinder engines offers so much more power and torque. By the same token, there aren’t that many things that are worth doing once you’ve got a six-cylinder car, because by the time you’ve spent money on modifying one of the smaller-capacity sixes, you might as well have invested in a larger capacity unit from the outset, which will generally yield more power and torque without any changes. On that basis, instead of heavily reworking a 2.2-litre straight-six at huge expense, it would be cheaper to simply buy an M3 motor that will already have well over 300bhp as standard.
Having said that, you can get 152bhp from a Stage 1 remap for the 1.9 M44 engine, which is similar to the 2.0-litre six-cylinder, but in a lighter, more nimble car with better weight distribution.
Finally, don’t bother with turbocharging. The engine bay is cramped even with a four-pot in there, so the engine bay will get so hot that you’re guaranteed to encounter cooling and reliability issues.