Pete Epple Technical Editor
March 30, 2012

Back at MM&FF Headquarters

Once we were back in the shop, we wanted to see what gains, if any, were available from increased braking power on the starting line. In the past, we have only been able to foot-brake the car to 1,700 or 1,800 rpm. Our thought was if we could bring the revs closer to the flash point of the Circle D converter, which is 3,200 rpm, it should improve track times. The ability (or lack there of) to hold the car on the starting line is based on the brakes. But when the cams start to move (which begins close to idle in the stock calibration) the reduction of engine vacuum decreases braking power. Add our FRPP twin-screw supercharger, and any application of throttle on the line makes the car creep forward.

Last month, Jim D'Amore of JDM Engineering spent some time working on the tune in our Copperhead ECU. One of the parameters he altered was the rpm that the cam timing starts to change. By delaying when and how rapidly the cams start to move, we improved ability to powerbrake the car before the rear brakes were overpowered. Beyond the tuning aspects, there are ways to mechanically increase holding power on the starting line. For this we turned to Summit Racing and EBC Brakes for some help.

Until now, we've powerbraked the car in the burnout box to heat the rear tires. While you can do a burnout this way, this method has negative effects. When the rear tires are spinning, the rear brakes are still applied. This equals a lot of heat, which glazes the brake pads and the rotors. And because we've been to the track quite a few times without a line-lock, our rear brakes were basically toast.

To take this problem out of the equation, Summit Racing sent us two of its line-lock kits, along with an installation kit. Now you might ask, why two line-locks? Simple--ABS.

The anti-lock brake system makes the installation slightly unconventional. Instead of installing the solenoid at the master cylinder before the brake fluid is distributed to both front wheels, two solenoids have to be installed, one at each wheel, after the ABS block. By installing it this way you retain all of the ABS functionality, and the installation is straightforward and simple.

We installed the solenoids where the hard lines met the stainless braided lines in the wheelwells. Note: A line-lock uses one-way solenoids, so you can hold the momentary button, then pump the brakes to build pressure. It is not necessary to first pump the brakes and grab the button, as many racers do.

With the line-lock installed, we still needed to remedy the glazed rear brakes. A call to EBC Brakes netted us a set of its Sport Rotors and Yellowstuff pads. The Sport Rotors are stock size with slots and cross drilled-style dimples them to help vent gasses between the rotor and pads, and to add an aggressive look.

We picked the Yellowstuff pad for its low operating range (heat). Being that the pad doesn't require a lot of heat for maximum bite, we can roll right up to the water box, heat the tires, and have all the brake power we need to hold the car on the line before the lights turn green. Wanting to see how it would help on track, we headed back to Bradenton Motorsports Park.

Back to the Track

With our line-lock, new brakes, and a better weather report, we returned to BMP the following Thursday. The headwind was gone, temp was in the high 60s, the barometric pressure was 30.07 and at the time of our first run the relative humidity was just 38 percent.

After a short and sweet burnout, we staged, brought the revs up to 2,100 (now with the car holding very well) and let it rip. It jetted from the line and started to rip once the engine got above 4,500 rpm. The AMSOIL GT poured on the coals (1.463 60-foot time) and our first pass was a winner—a 9.844 at 139.53 mph.