Zero Weight Project

Here is an update on the project. As many of you know the vehicle for the project is a Mazda RX8. Nothing compares to the responsiveness and sheer toss ability of the RX8. It has a 50/50 weight distribution and comes in just under 3000 pounds. I mention this because for all its benefits, the RX8 does have one short coming: power. Compared to the Nissan 350z or WRX or EVO, the RX8 is quite slow in a straight line. My old Audi A6 2.7t would dust it. (It would also put the hurt on a 350z and WRX ) That is until you take the first turn. Many of the performance upgrades for the RX8 is less that impressive. This is really the genesis of the project. Add as much performance without adding too much weight.

The first area of upgrade I am planning is the wheel tire upgrade. This is the first step and typically most common upgrade for a vehicle. I decided not to go to a larger diameter wheel. (Too much weight increase) I decided to look for a wider wheel.

The options I found fell into two camps: heaver/cheaper and lighter/expensive. Obviously, I had no choice. After comparing the “lighter/expensive” wheels, I decided on the Enkei RP-F1. (Click on a picture to launch the gallery)

The RP-F1 is a ultra lightweight wheel from Enkei that is a whopping 9.5 inches wide (1.5 inches wider than stock) and an equally impressive 17.5 pounds per wheel versus 23 pounds for the stock 18” x 8” Mazda wheel. With an offset of 45mm, the wheel and tire combo will come out flush to edge of the car. The planned tire size of 275/35 R18 will give the RX8 a two inch wider tire contact patch at each corner! Special thanks to Dave at OE Wheel Works for helping me out.

Lighter Weight Wheels = More Performance

With the combined weight of the wheel and tire, the RX8 will receive over a 20 pound weight loss. (Estimated at 20.4 but not confirmed) The result is a 5 pound per wheel less rotational mass. Reducing rotational mass on the car lowers the amount of drive train loss a car experiences. Mazda thought this important enough to equip the RX8 with a lightweight carbon fiber drive shaft. Depending on the math, every pound of rotational mass eliminated is equal to 1.5 to 2 pounds of regular mass. A reduction in rotational mass is supposed to increase the acceleration and deceleration capability of the vehicle. Does this mean I will see an increase in wheel horse power? I plan to Dyno the car with the stock and new wheels to see if there is a measurable power gain. This will be interesting.

It is also important to note that this is an unsprung weight loss. Unsprung weight refers to the weight of the car that is not supported by the springs of the vehicle. This includes the wheels, tires and brakes. (Ok and half of parts of the suspension) Less unsprung weight improves the suspension speed and performance by reducing the amount of weight and hence inertia that is affected by the road surface and cornering forces. The results are better steering feel and quicker suspension response that can deliver a smoother and faster ride.

Now I have 20 pounds that I can add of Dynamat and stereo.