Although rain prevented data collection on our subsequent track date (it's crucial to have similar conditions), this became an ideal opportunity to get a feel for the Nitto Invo tires on a closed circuit under wet conditions. According to the Traqmate GPS system, lap times where understandably slow, about 18 seconds off the dry pace. However, the Invos proved to be excellent, instilling confidence through a high level of relative grip and an ability to channel away standing water. When playing around in some of the slower corners, even with the car's strong power, one had to be deliberate with the throttle and/or steering to loosen the Invos' grip.

When the dry weather finally arrived, we hit the track with the new Brembo brakes and the results were excellent. Again, same driver as for the original testing, similar line, and no in-car time display for motivation. At the previous dry outing, (described in Part 2), with both the front strut bar and the wheel/tire upgrade in place, the average lap time was about 95.1 seconds (the fastest lap being 93.9 seconds and represented by the blue line).

With the Brembo upgrade, that average was reduced to 93.1 with a fastest lap of 92.8, demonstrating faster, more consistent lap results. Also, the average total time under braking per lap was reduced from 15.9 seconds to 12.7 and the average peak braking g-force before turn one increased from 0.86g to about 1.05 (with a spike at 1.3-anomalous, but interesting). Looking at the graph (bottom right), where the red line represents the addition of the Brembo upgrade, one can see the improved brake effectiveness for turn one (from 125 mph down to 75 mph, a real brake test). Braking is now later and deceleration is increased as shown by the shifted and steeper negative slope.

Brembo engineers each kit for a specific model application, with unique piston size variation for optimum brake balance, increased brake torque and thermal capacity. With these larger rotor diameters, braking force is now more apparent due to the improved leverage. Also, this increased rotor thickness promotes efficient heat dissipation. I have yet to experience any fade or fluid issues whatsoever, even after several consecutive hot laps. Pedal feel is now constantly firm and linear, requiring less effort and providing improved confidence and control. In the next installment, the M Coupe will receive a few suspension upgrades from KW Suspensions and TC Kline Racing.

Behind the scenes of Project Z4M: bitten by the family dogThings don't always go as planned. I was invited to instruct at an advanced driving school, with the opportunity of some free track time before the start of the event. I did my usual diligent pre-track inspection (fluid levels, brake pad thickness, tire condition and cold pressure) and gathered my gear (air pump, tire gauge, extra fluids, mechanic's gloves and a few hand tools). I have well over 2000 laps under my belt here at my local track, but that was no help on this particular evening.

By Doug Neilson
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