Muscle Mustangs & Fast Fords
2011 AMSOIL GT Brake Upgrade - Brake Dancing
Our Fastest Project Car Ever!
Increased power and braking equals 9s at 139 mph, making our AMSOIL GT the quickest and fastest MM&FF project car ever.
Our AMSOIL Mustang has become near and dear to the MM&FF staff. After all, we started with a stock '11 GT with less than 3 miles on the odometer and turned it into a streetable track monster with nearly 800 crank horsepower. The initial build took place in seven weeks, where we thrashed to ready the GT for the 2010 SEMA show.
After a little more than a year of bolting on parts and testing, we've gone from 13s, to 12s, to 11s, 10s and now 9s. We're not claiming that a 9-second timeslip categorizes it as a monster, but tipping the scales at nearly 3,800 pounds with a driver, and laying down well over 650 rwhp through a stock 6R80 automatic is quite respectable in our opinion.
In our continued search for power, we've upgraded the top half of the engine with massaged heads and a quartet of Comp Cams bumpsticks. When the tuning was complete, we drove off the dyno making 683 rwhp and 557 lb-ft or torque. This is up from the 595 rwhp it had before the work. Not ones to rest with dyno numbers, we were anxious to see how the increase in power would effect our quarter-mile times and trap speed.
Since we love the challenge of building and driving high-powered cars, we rolled into Bradenton Motorsports Park (Bradenton, Florida) on a regular Thursday test-and-tune night to see how quick we could make the AMSOIL GT run. The air was cool, there was mild humidity, and we faced a 15 mph headwind.
Following our normal procedure, we warmed the car up to get the transmission and rearend up to operating temperature, we set the tire pressure, and rolled up to the line. We now had 88 extra ponies then when we ran 10.48 at 130 mph. That's quite a jump in power, and we hoped to drop serious e.t.
The GT hooked hard, then at the top of First gear it stumbled bad, then shifted and took off. It did the same thing in Second gear and then ran clean to the end of the track. The result was a 10.50 at 137.29. We feared that the engine ran into the rev limiter before it had a chance to shift. This is common when dealing with new programming. A second run resulted in the same problem, and a 10.52 e.t. at 136.19.
After collecting our thoughts, we noticed that our GT was also low on fuel, having slightly less than a quarter of a tank. Could our problem be that fuel was running away from the pickup? We hoped our problem was that simple.
Now, with a half tank of 100 octane, we inched into the staged beam with big hopes. And when the tree dropped, the GT rocketed from the line with no hiccups (1.506 60-foot time). It revved clean and shifted on command and our reward was a 9.996 at 137.67 mph. Needless to say, we were thrilled with the run, as this bested the 10.22/133 from our former MM&FF project truck The Fridge. Our Amsoil GT was now the quickest and fastest MM&FF project ever. A backup of 10.00/137.67 was a nice cap to the evening.
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.
We made a back-up about 40 minutes later and ran 9.880 at 139.49. On this run we tried to launch harder and had a lightly better short time (1.455), but the humidity rose to 43 percent and the baro was dropping (30.04), hence the slower e.t.
Our entire staff was excited with the improvement, and we now contemplated our next move. We could gut it and go for the 8s, tweak what we have and try to improve our times, or simply leave it alone.
Considering that we've now busted in the 9s, we need a certified roll cage and a few other items to make our car legal to race. This is something you'll be seeing in the coming months. And of course we want to go quicker, so more mods are in store.
We're pretty sure our converter is on the tight side, so look for us to do a converter swap and then more gear and a built rear. Who knows after that, so stay tuned as we push the limits of the new 5.0L deep in the 9s.