After the test day at BIR, we had a list of changes to try and get some more speed out of the car. First on the list was to stiffen things up a bit. We started by dropping the whole rear subframe and removing the rear subframe bushings. The previous owner had installed a set of lockouts, but those are just a bandaid. We replaced the whole bushing with solid aluminium pieces. The solid bushings also act as a riser. By pushing the subframe closer to the body, it fixes some of the unwanted geometry changes that come from lowering the car.
Speaking of lowering. The Tein lowering springs for the G turned out to be just too soft, even with the car a quarter ton lighter than it was from the factory, it still felt a bit floaty. After looking though lots of parts books, I discovered an optional spring for the 350Z that was significantly stiffer than the Tein springs, while still maintaining factory style fitment. We ordered them up and installed them when re-installing the subframe. We swapped the front springs as well. After installing we discovered that the new springs caused the rear to sit more than an inch higher than previous, so we removed the thick spring isolators from the rear control arms to gain an extra 1" of drop.
Car all washed up and ready for another round of testing. This time a BIR performance driving school would serve as the venue. I wasn't able to make it, so Evan and Jaret went, and brought along 2 new drivers to test them out in the car and see how they would perform.
During the test day, the engine developed a significant rear main seal leak. It was bad enough that we all felt it was worth repairing. We also had acquired a spare transmission which allegedly didn't have any grinds, so we would nail 2 birds with 1 stone. Jaret took the car into work to put on the hoist over a saturday, where he removed the trans and replaced the rear main, as well as the transmission. Soon after he hauled the car back to my house.
I had a few little projects lined up. First on the list was to removed the intake plenum spacer installed by the previous owner. Again, due to rules, we could not install any performance parts between the throttle body engine, so the spacer had to go. The plenum itself was quite dingy, so I media blasted it, polished the inside, then I sprayed the outside with some of Turbo Yoda's favorite Wrinkle black.
Around the same time, I also scored a spare set of front Brembos and some used race pads in a few different compounds from a team that was moving to a new setup. Always good to have extra race pads. Never know when you might need them.
Now it was time to dig into the main task. In the old car, we had always relied on a cell phone based telemetry system to give the driver real time information like lap times. The race times are calculated using a chassis mounted transponder, but in the car there is no access to the timing, so its impossible to know how you're. The transponders also aren't used outside of a race setting, so its hard to know if your changes are working during a test session. We decided to take the major step and move to a full Race Capture onboard telemetry system. It has its own accelerometers, GPS antenna, 4G cellular data connection, OBD2 connection as well as a variety of digital inputs and outputs.
The RC system is interfaced via a dash mounted tablet. It has the ability to display a wide variety of data, and has configurable warnings.
The predictive timing function is by far the most beneficial to a driver as it tells you throughout the lap, what your ideal lap is based on the cars optimal performance on a given lap. That theoretical lap is displayed in the center in large numbers so its easy to read mid lap.
Its also possible to display a large number of analog gauges to help monitor different systems. Besides the standard OBD2 available data, we also installed Oil pressure and temperature sensors, a fuel pressure sensor, and also a cooling system pressure sensor. The last one being an often overlooked parameter. A failed radiator or coolant hose may not be noticed by a driver until an over temp warning is received, and by then it may be too late. By monitoring coolant pressure, we can warn a driver the moment a large leak occurs, before the engine temp has had an opportunity to rise to unsafe levels.
The RC system also uploads its data in real time via the 4G connection allowing us to monitor the car from the pits. All the data is also saved to the cloud allowing us a macro view of how the car was performing. Its an increadibly powerful system, and I feel we have just breached the surface of its total capabilities.
To test out all our new gadgets, suspension, and alignment changes, we headed back to BIR for Proving Grounds 2.0 which would be our last chance to test before racing the car at Road America in late October.
All things considered, the day went swimmingly. The telemetry system was functioning well, and the suspension changes allowed me to reset out best ever lap time by a solid couple seconds without really feeling like I was pushing the car. The only issue we discovered was that the rear main seal leak was back.....
I guess we'll have to get a bit more "involved".
