Geoff Turk Converts “Blackbird” HEMI Drag Pak To NMCA Extreme Street

Geoff Turk Converts

Former NMCA Factory Super Cars champion and class record-holder Geoff Turk is returning to competition after a year and a half hiatus with a very familiar car in a not-so familiar place.

Turk won the NMCA title in 2018 — the same season he became the first driver in the factory-built shootout (NMCA and NHRA) classes to record a 7-second elapsed time, doing so behind the wheel of his “Blackbird” supercharged Dodge Challenger Drag Pak. In the latter part of that season, Turk changed direction, transitioning to Ford’s Cobra Jet Mustang program for 2019; but behind the scenes, his family was fighting a much bigger battle than any on the racetrack— one that ultimately took his wife, Sandy, from this world. 

In the year and a half since he last competed, Turk moved from Illinois to Bowling Green, Kentucky, after being named Chief Operating Officer at Holley Performance Products. But he never parted with his “X-51” Cobra Jet, and certainly not with his prized “Blackbird,” fully intent on racing again but unsure of when or where.

In his wife’s final months, Turk proposed installing a passenger seat in one of the cars to take her down the racetrack — her choice, without hesitation, was the Drag Pak. That opportunity, sadly, never came. But with that, even after her passing, the “Blackbird” — above and beyond the historical value of its barrier-breaking past — has gained irreplaceable sentimental value to Turk. And when he began devising a plan to return to racing, it simply had to be the “Blackbird.”

Turk has called upon a number of talented individuals he’s worked with throughout his racing career — Mike Roth at MR2 Racecars, Tony Bischoff at BES Racing Engines, and others — to help him transition the Drag Pak from Factory Super Cars and NHRA Factory Stock Showdown trim to the NMCA’’s Extreme Street category (and by association, Ultra Street).

This, of course, has been no small feat, demanding a fresh engine build from the ground up, a new supercharger, driveline modifications, and changes to the car itself. And Turk intends, when all is said and done, to have a competitive Extreme Street car, without performing any permanent modifications to the Drag Pak that would hinder him from returning it to its shootout-legal, production state. To remove some of its hefty poundage, though, Turk removed the factory doors, hood and trunk lid and replaced them with carbon-fiber pieces.

Turk tasked Bischoff and company, who built the barrier-busting Hemi already in his Challenger, with assembling an all-new Gen III Hemi that takes advantage of the rules package in Extreme Street that affords him some 80 additional cubic-inches of displacement. Bischoff used the same aluminum Hemi production block and a set of Thitek aluminum heads. The difference-maker, though, is the Gen V 3.0-liter Whipple supercharger that’s on the latest-generation Cobra Jet and has pushed those cars into the 7.50’s.

“I tried to get that Gen V supercharger approved for factory shootout competition to no avail, but I was just destined to put that supercharger on a Hemi, and so that’s what we did,” Turk explains. “The rules on Extreme Street allow you to have 440 cubic-inches, and the rules are more open in several ways. This is not a max-effort engine, but it’s a pretty serious-effort engine.”

BES stroked the Hemi, stretching it out to 426-inches. 

Turk noted this is a step-down effort from Rob Goss’s record-setting X275 Hemi combination, which BES developed. “Everybody kind of helps each other in developing things along the way — we’re using different parts from what Rob does, but clearly, Bischoff’s broad portfolio of Gen III Hemi prowess has been applied here.” 

Turk and Bischoff achieved 1,712 horsepower and 1,198 lb-ft of torque on the engine dyno upon completion.

“We’re making great power, and there’s more where that came. We didn’t have the right pulleys on it at the time — we didn’t want to publish the best power curve we have,” he says.

Turk will retain the four-link-ish Factory Super Cars-legal front and rear suspension — again, choosing to keep the world-class-level car production car intact, rather than cut it up for a max-effort Extreme Street build. 

“I hope it runs 4.60’s and 4.70’s and it’s competitive and I can have fun in that class, but we’ll see,” Turk says.

The combustion process is lit in the hemispherical chambers by 16 of MSD’s coils, with a Holley EFI system providing directions. With the more open rules of the class, the technologically-minded Turk can now play with traction control, wheelie control, and other toys not as his disposal in Factory Super Cars. A Coan transmission delivers those 1,700-plus horses out to the rear tires.

“I’m looking forward to playing with all of that…it’ll be a new challenge. But we’ll be a couple hundred pounds overweight, so I’ve got make some extra power to carry all that weight, and figure out how to make a suspension work that really isn’t an all-out race suspension. Everyone will skeptical that we can make it work, and that’s what I like,” Turk says with a laugh.

Turk will display the almost-finished product at this weekend’s inaugural Holley Moparty in Bowling Green, and hasn’t ruled out making a competitive debut with the new combination later this fall.

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