BirdDoc: The Six-Speed GT500 Record Holder And Its High Flying Pilot

When Ford revealed the 2013 GT500 a few years back, we knew the car would make waves across the Mustang realm. With over 660 hp in stock form the car was a beast right off the showroom floor.

As the details of this car began to pour out, Mark Duber was following the story. Duber, or should we say Dr Duber, was serving in Afghanistan as an Army doctor. In the little downtime he had, if he wasn’t talking with his wife and kids stateside, he was finding out whatever he could about this new Shelby that was guaranteed to rain terror upon cars that cost triple the price. Little did Duber know the car he was about to buy, would, in just a few years be the six-speed GT500 record holder for quarter-mile ET.

Meet BirdDoc

Duber has been a life long fan of drag racing and muscle cars. His father had owned a Grabber Blue BOSS 429, a few years before Mark was born. When Mark was a 11, his dad purchased a ’67 Camaro, with a four-speed and began regularly drag racing the car at local tracks. That car snowballed into eventually getting an aluminum headed crate engine. Eventually, the elder Duber, replaced that one on the track with a tube chassis ’89 IROC.

“Then suddenly, just before I turned 16, my dad decided to get out of drag racing. So here I was, with this appetite for drag racing, that never got satisfied.” With the fast cars gone, and college on the horizon Duber headed to school, along the way he married his wife, Melissa.

I saw this car like my dad’s BOSS 429, it was the baddest thing in the muscle car market at the time. That’s what this car was to me -Ford’s modern day interpretation of that idea. -Mark Duber

Melissa’s family carried a long tradition of military service, with most of the men having attended the prestigious West Point academy, and served honorable careers in the Army. Mark and Melissa wanted to carry on that tradition of service to their country. They found a scholarship program with the Army, that allowed them to attend medical school, and then serve four years in the Army as doctors in return.

Today, both Dr Dubers are out of the military, with Melissa working as an ER Doctor, and Mark as an orthopedic surgeon -when he’s not banging gears in his GT500, or jumping out of planes, or off bridges with his wing suit, or BASE jumping gear. Duber’s thrill seeking and high flying antics, earned him the name BirdDoc, a handle he has proudly incorporated as his alter ego.

Not your typical GT500 Trinity engine, a BES built 5.8 is breathed on with a 4.7 liter Kenne Bell blower, tuned by Lund Racing, the combo is good for over 1,400 hp to the rear tires.

Muscle At Last

Upon returning from his tour of duty in Afghanistan, Duber went to see the sales staff at Knox Ford, in Radcliffe, Kentucky. He had contacted them while on deployment, from Afghanistan inquiring about the new GT500. A deal was made to honor full MSRP, with no markup, and the car was ordered the day Ford opened the order bank.

Duber originally purchased this car as a daily driver. “I was driving a new Focus, which was a great commuter car, but I wanted something more exciting. I didn’t want to go the BMW, or Mercedes route, and just blend in with all the other docs either.” As both an homage to the BOSS 429 his father had, and a way to stand out from the sea of gray and black luxury sedans and SUVs, Duber ordered his GT500 in Grabber blue, with black stripes. We’re sure it probably drew more than a few looks from his fellow medical professionals, this common man’s supercar parked in the same row as their uber luxury rides.

The TruCarbon hood lends to the mean looks on the front of Duber’s GT500.

After years of waiting, Duber finally had his muscle car, “I saw this car like my dad’s BOSS 429, it was the baddest thing in the muscle car market at the time. That’s what this was car to me -Ford’s modern day interpretation of that idea.” Duber began looking into ways to modify his GT500. “I’ve always been one to push the limits, whether it was in school, or my career, and this was just another way.” While many were hesitant at first to modify the ’13 GT500, speculating that the limited production cars would retain high collector value, Duber dove right in.

We started off with bolt-ons modifications, and then we started racing the car. Duber went back and forth several times with several others over holding the stock long block, TVS blown record for the GT500.

Since setting the world record the car has gone on somewhat of a diet, and upgrades to the cage for safety purposes. It is still surprisingly stock appearing for an 8-second car.

Bolt-Ons To All Out

Eventually, Duber was making enough power that he even competed in the King of the Street competition at his home race track of Beech Bend Raceway, in Bowling Green, Kentucky. He placed fourth in the horsepower category.

After the competition, Duber, decided to really get serious with the car. Lund Tuning, and Revan Racing were now heavily involved, and Chad Epperson of London Chassis Dyno was doing most of the work on the car. Revan Racing introduced Duber to Jim Bell, of Kenne Bell performance. After some discussion, Duber decided to switch to a 4.2 liter Kenne Bell Supercharger.

Other changes were underway for the GT500 as well. Duber wanted to go 8s in his car. Engine Masters champion, Bischoff Engine Service (BES), was enlisted to build a stouter engine. The end result was over 1,200 horsepower at the tires.

Epperson, worked his magic on the chassis over at the London Chassis shop, including building a custom braced 8.8 rear for the car, the cage work, suspension, and putting the whole car together. His hands have been all over the GT500, and its performance is a testament to the type of work that London Chassis does.

(click the video above to watch BirdDoc in action)

Breaking Records

Duber loaded the car up, and with Epperson, headed to the NMRA race at Maryland International Raceway this past summer. The car was untested and now putting down over 1,200 hp to the wheels, still with a Tremec T-56 Magnum transmission. Duber was supposed to make a half-track, eighth-mile pass as a shakedown. “The car just felt so good, I had to keep my foot in it. The engine was making power, the chassis was working, it was shifting right.” The end result was an ET of 8.95 at 161 mph, just 0.01 seconds off the record for a six-speed GT500.

“I think it was a bit of shock and awe, here we were, we came out of nowhere, and on our first pass nearly reset the national record.” It wouldn’t take much more for Duber and his crew to do just that. In eliminations, Duber granny shifted to a six-speed GT500 record quarter-mile ET of 8.80 at 164.23 mph. That record still stands nearly 9 months later.

Going Further

Coming back from Maryland, Duber’s internal drive to do more was talking to him again. A decision was made to switch the car to Kenne Bell’s massive 4.7 liter supercharger. As you can imagine the results were staggering. The car now made even more power,with no other changes, spinning the London Chassis Dyno rollers to 1,416 hp to the rear tires.

Photo gallery


I think it was a bit of shock and awe, here we were, we came out of nowhere, and on our first pass nearly reset the national record.

Duber took part in a private rental, and test ’n tune, at Beech Bend, just before the NMRA World Finals. The additional horsepower, was proving too much, when combined with a street car level transmission. “You get to a point where running a manual transmission like that, with that much power, and trying to race it, is like hitting yourself in the head with a hammer. It was amazing to us that we were able to go as far as we did, for as long as we did with the T-56 Magnum.”

Unable to get the car where they wanted it for the weekend, Duber regrouped with Epperson to brainstorm ideas for 2015. As it turns out this was a good thing. Duber missed the lane calls for his class at Bowling Green, and as such didn’t make any passes after the Saturday night qualifying rounds.

Back at London Chassis Dyno, Epperson began tearing the car apart, and sent the engine back to BES for some more work, and more power during the off season. Two things were found during that teardown. First, BES reported that the factory forged crank on the GT500 was cracked in three places. Second, Epperson found that the slip yoke for the driveshaft was twisted, and binding. Either of these, could have ended in catastrophic failure for Duber, and his car on the race track. The combination had seen all the abuse it could take.

New Year, New Goals

For 2015, Duber is planning to go racing in the NMRA’s Renegade class, following a discussion with officials at the PRI show. Over at London Chasiss Dyno, Epperson is tearing into the GT500 to get it ready for the highly competitive class, and BES is working on the engine to provide even more power, and durability.

Perhaps the biggest change is going to be the loss of the six-speed transmission and SPEC ST clutch. Consistency and power handling will be necessary, if Duber is to make a run at the championship.

Also gone is the stock computer. “We were at the limits of what the stock computer could do at this power level, and the Holley Dominator system looks to be our best choice.” We’ll be following the conversion of Duber’s car to Holley’s stand alone EFI, as that project progresses.

Duber feels confident about 2015, having broken into the 8s, he has his sites set on 7s. He’s also working on more ways to get his kids involved in racing, while all are under the age of 7 right now, his oldest son is already a competitive go-kart racer. Duber wants to pass on his love of racing to the next generation. “This is something I think we’ll be doing for a long time.”

In between races, and race seasons, Duber can be found pursuing some of his other passions, which includes BASE jumping, and Wingsuit flying. It seems a fitting way for an adrenaline junky to spend his time. We’re looking forward to his premiere in NMRA Renegade, and seeing how he fares in a season of tight heads up competition. Until then, if you’re driving through Kentucky, be sure to keep an eye on the sky, as you might find the BirdDoc soaring over head.

About the author

Don Creason

Don Creason is an automotive journalist with passions that lie from everything classic, all the way to modern muscle. Experienced tech writer, and all around car aficionado, Don's love for both cars and writing makes him the perfect addition to the Power Automedia team of experts.
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