Nissan Spec-V: Part 18:The Interior
10/19/2006
A race car’s interior is very spartan. Every bit of the vehicle’s insides that do not have a vital function is removed. Although this sounds simple it is quite a bit of work. There are scores of brackets, studs, bulkheads, unneeded reinforcements and other bits that should be removed from the inside for safety and to reduce weight. These things can have sharp edges that can hurt the driver in an accident and the clutter of unused brackets welded to the chassis is not very attractive. We spent several days with a spot weld drill and an angle grinder removing every bit of excess sheet metal and bits and pieces from the cars interior and engine compartment. This included the door intrusion beams and the inner door panels. In total this probably amounted to over 70 lbs of unneeded metal or half the weight of the cage.
Howard Watanabe tackles the job of simplifying the wire harness.
If this looks scary, it is!Howard Watanabe of Technosquare also spent a lot of time with the wiring harness. Today’s cars have multiplexed controls and much of the car is on an internal bus just like a PC. SAE calls this CANBUS and it makes removing unneeded wiring and accessories difficult. Unplugging the dash might make the car rev to only 2000 rpm or removing and alarm box might make the car not start. Removing door switches might have a negative outcome elsewhere.
For a race car simplicity means reliability. The more you simplify things, the less likely it is that something can go wrong. Howard removed much of the factory wiring harness leaving the basic systems to run the car in place. In all, over 30 lbs of wiring were removed. When it came time to start the car nothing happened. CANBUS struck us the first time.
A call to Nissan guru, JWT’s Clark Steppler, revealed that we had damaged Nissan’s NATS antitheft system. Clark had a solution, switch our ECU with a non-NATS one and rewire the wiring harness so the pin outs would match. The car started but would not rev past 2000 rpm. Clark then determined that the ECU was not seeing flyback voltage from the check engine light and was tripping an anti tamper system in the ECU. He suggested we power the check engine light circuit through a pull up resistor. Finally the problem was solved. Tadashi Nagata of Technosquare then re-flashed our ECU to raise our low 6100 rpm redline to a more respectable 7000.
The Odyssey dry cell battery was held down behind where the passenger seat would normally go by this sturdy bracket.Howard carefully routed the wire harness after rewrapping it using multiple hold downs to prevent it from vibrating and the possibility of fatigue failures. Then, Howard mounted our Odyssey 680MC gell cell battery to the passenger side rear floor of the interior, holding it down with a secure bracket. The gell cell is much safer as it is not full of acid like a conventional battery and it weights 25 lbs less than the heavy stock battery. The low rearward position lowers our CG and helps with weight distribution. In fact this lowers our overall CG by almost an inch and improves our weight distribution by one full percent!
The Longacre switch kills all power from the battery and the alternator.
This bracket relocates the ECU from inside the engine compartment to inside the car on the firewall.
This box contains the ignition power, start and light switches.
This tower moves the shifter close to the steering wheel like a WRC car. It also holds the nozzle for the fire system and the brake proportioning valve.
Our completed wiring is simple, easily accessible for troubleshooting, if need be and cleanly laid out.
The MSD/Racepack Ultra Dash performs the same function as a multitude of conventional gauges plus more in a compact, lightweight and easy to wire package. The G2X data logger, Boost gauge and shaft light are all visible here.
Here is the driver’s view with our Sparco quick release steering wheel in place.
Our cleanly laid out interior is a nice place for a driver.
Ritchie Watanabe rolls our fender lips for additional tire clearance.Summit Racing silicone coated cables were used to route the power back to a Longacre main power shut off switch, then on to the engine compartment to a marine battery isolator post. The power went from there to the starter and the alternator.
Since our cage tubes went right through the area where the ECU used to be in the engine compartment, a new bracket had to be constructed to move the ECU to the inside of the car. The inside is probably a better place to put the ECU as its cooler and drier.
Our ignition power, the lights and starter switch were relocated to a small aluminum box next to the shifter within easy reach of the driver, eliminating wiring that used to live under the dash.
We wanted the shifter to be high and in easy reach of the steering wheel just like what we had seen in WRC rally cars and World Challenge racers. Ritchie Watanabe built an aluminum tower to move the shifter next to the steering wheel, a super cool original touch.
Now that we had power to all of the systems we needed some instrumentation. We had done away with the dashboard full of airbags and heavy reinforcement. The stock instruments are also known to be inaccurate so we discarded them as well.
In the old days racers would have went to a sheet metal panel full of gauges but that’s an electrician’s nightmare and it just doesn’t look that safe. Instead we borrowed some Indy and F1 technology and installed a racing electronic dashboard. We turned to Racepack/MSD for their Ultra Dash racing dash. The Ultra Dash has the ability to monitor; RPM, fuel level, fuel pressure, oil pressure, oil temperature, boost pressure, speed, turn signals, high/low beam, warning alarms for all critical functions, battery volts, odometer, parking brake, shift light, external warning light, control fans, rpm dependent switching and data log up to 32 additional channels. All of this in one compact dash unit! This whole system retails for much less that a suite of Defi or other Japanese gauges and is probably much cheaper than the conventional Autometer gauges needed to monitor a race car.
To add a level of sophistication to our data logging capability, we added a Racepack G2X GPS data acquisition system to add track mapping and suspension related data logging to our system. The G2X can draw maps of the track and gives instantaneous speeds, G levels and split times over any segment of the track automatically. A control unit that we installed to the left of our dash displays lap time and number plus any 4 other analog channels you choose with a sequential shift light. This powerful system retails for under $1000 and is an indispensable tool for any racer at an affordable price.
It was now time to put the car down on the ground. We bolted on our lightweight forged 17 x 8Volk TE37 wheels with a 38mm offset wrapped with 235/40-17 Nitto NT01 race tires and found that they hit the chassis in several places. This is probably one of the biggest wheel/tire combinations possible with this car and our car has a very low ride height.
This makes this dash a no-brainer for a race car or even a hot street machine! Ritchie Watanabe built a simple pod to attach the dash to our steering column. Since we wanted a separate gauge to monitor boost, the pod accommodates an Autometer Ultra Lite boost gauge to the right and an Autometer shift light activated by the dash on top of the pod.
Our car is running and on the ground at last! Howard and Ritchie are happy to see it leave finally.
This final photo before loading it up on the trailer shows some of the many details of the car.Ritchie Watanabe operated a dolly and body hammer, pounded the rear fender lips flat, and worked over a few seams on the unibody in the front wheel wells. The main wire harness in the driver’s side front wheel well had to be relocated so it would not snag the tire at the same time.
With fingers crossed, we pushed the start button and the engine immediately started and ran cleanly. We warmed up the engine and bled the cooling system carefully. Next we reassembled much of the body.
After a blast around the parking lot the car was ready to ship to Brian Kono at Afterhours Automotive to continue its transformation from a mild street car to a time attack terror.
Thank You to the staff of Technosquare; Howard and Ritchie Watanabe, Tadashi Nagata and Yoshie Shuyama for your hard efforts to build the car quickly and to the highest degree of finish as well as putting up with me living at your shop for the past few months.