Check the final gearing. All 89-93 1.6 models are 4.300, most 1.8s are 4.100, except for 95+ Eunos Roadsters, which are 4.300. 4.3 is better for hillclimbs, but its still not great. You can get a 4.7 rear end conversion on a 1.8 diff (open or LSD). Avoid factory non-powered rack; its slow (in terms of ratio). The power advantage of a 1,8 over a 1.6 might not mean anything if you find you are in a different class. The 1.6 might be one of the quicker of its class, but the 1.8 might end up being the slowest of its class. I used to hillclimb a 1.6, but I didn’t stand a chance against the bored out Minis and Corsas arriving on trailers with extra wheels (and they always seemed to be entered by guys who owned scrap yards, and thus an unlimited supply of shells if they ended up upside down. Because of the desire to drive home afterwards, and hopefully make it to work on monday, that tended to limit how we drove… If I had a 1.8, I would be up against cars with 2.5l engines.
If you are in it for light hearted motorsport, ie driving the car to events, forget about winning anything. You won’t. Its all about the craic. I came third once, which I was chuffed about, but only 4 cars turned up in my class on that day.
For the NB, the Japanese seem to favour the 1.6 over the 1.8 Their track specials are 1.6 NBs, with the 1.8 suspension and brakes.
Electrics, or lack of, are going to have no impact on your times. Aircon might weight a bit, but on WOT, the aircon clutch disengages. I would also say the factory LSDs (Torsen or VLSD)fitted to MX5s are irrelevant because of their lack of lockup. Additionally, a LSD will make you understeer through a corner. If the road is slippery, which is often the case on a closed road hillclimb, the back end will lose grip, and the car slides. Better off with a 1.6, because then there are options for relatively low cost clutch 1.5- and 2-way LSDs.
UK 90-93 and all NB 1.6s were fitted with a lightweight flywheel. For some reason, Mazda fitted these cars with a flywheel from a different Mazda (a Familia 1.4), with part numbers matching to Mazdaspeed and M2-Inc. Eunos Roadster and US Miatas were lumbered with a heavier flywheel (more than a kg heavier).
If you get an older car, you can legally decat it. It won’t make any different to your times, but sometimes, as I found, a WOT start can have fun results (bit of flame from the exhaust). And you can indulge in the pop-bang fantasy.
I put in a manky old Japanese seat, with zero padding. Used it for 6 months, sitting on an old camping sleeping mat.
