You can't think of Bonneville without thinking about insane speeds.
Danny Thompson’s dream of setting a land speed record in his father’s 46-year-old car at the famed Bonneville Salt Flats almost came true last year. Thompson, son of the late innovator Mickey Thompson has been working toward taking his father’s final streamliner named Challenger 2 through the five-mile speed traps on the salt to set the record for a piston-powered, normally aspirated streamliner at more than 439 mph.
Following in Mickey's footsteps
Thompson was using the same chassis - albeit somewhat modified - as his father and similar ideology. Mickey built the Challenger with a pair of of Ford SOHC V8 engines, the rear one with a supercharger and the front naturally aspirated, due to sizing constraints. The car had been sitting since Ford pulled out of competition in 1968 but Danny felt the need to bring it back, modernize it and make it go as Challenger 2.5.
He changed the running gear, using drag racing-based, nitromethane-burning V8s with their origins from Brad Anderson Enterprises. Like his father, he sat between the two but used an interesting solution to get the two engines to “talk” to one another. While his dad used a convoluted split throttle pedal, Danny Thompson sourced a pair of Hadley boxes that link the two “rear ends” mechanically via a three-piece driveshaft. It consists of two blower belt pulleys linked by a Gates 14mm chain belt transfer box.
Five years in the making
It’s been more than five years in the making, many adjustments forward for the car itself (the BAE blocks and heads are much wider than 1960s-era Ford V8 engines) and lots of grief - and money - getting prepared for this type of endeavor. The car didn’t run until this past summer, when it went to El Mirage, local to his Southern California base, and made a single shakedown 180mph pass. That was good enough as a tryout for Thompson, who prepped the car for the famous Speed Week.
Thompson did a test-and-tune before Speed Week on the three-mile course, making two runs that resulted in speeds of 246 and 317 mph. He then returned for the Speed Week meet - only to be rained out. Three weeks later, it was dry enough to run World of Speed and that was when the new Challenger 2.5 showed its worth. While his equipment hadn’t been thoroughly tested at the speeds Thompson needed to achieve, he felt he had the goods to make it all work.
Making the old new again
The beautiful blue machine last saw salt in 1968 and one observer from that era, Thompson’s mother came to Bonneville with him to watch this plot evolve. “She was up there for every bit of it and hadn’t been there since, I think 1962. She was there when my dad went over 400 and she was there when I went over 400 so it was pretty sweet,” he said.
Yes, over 400mph. The 22-person volunteer team (there were only two people on salary) that accompanied Thompson to the Bonneville Salt Flats set up Challenger 2.5 to run on 70 percent nitro (they started at 50% for the initial tests).
Thompson only had an opportunity to make two passes on the five-mile course. His first run was 391 with the second at 419mph. “Both engines worked good and the Hadley box was seamless,” he said. “I think the two engines ran between 15rpm of one another, which is just incredible.” The engines were turning 6500 rpm through a three-speed gearbox and Danny admitted to “shifting at 5700 into high gear. We still weren’t sure of things - I mean that was only the second full pass on the car - but now we’ll run ‘em 6500 and shift both times at 6500,” he said. “We didn’t have any issues at all until we had the clutch problem.”
Both engines worked good and the Hadley box was seamless. I think the two engines ran between 15rpm of one another, which is just incredible
Yes, there was a clutch problem. “I’ll take blame for that,” Thompson said. “It didn’t wear at all on the first few runs, then on the 391 and the 419, evidently it wore a bunch and I was negligent in checking the clutch, because everything [else] was perfect to begin with so we didn’t think it would be an issue. The guy that laid the clutch system out for us told us we should be able to make six runs without any kind of issues, so we looked at that and, that was the only issue we had!”
An impressive feat
With such an old, restored car, an innovative engine solution and financial challenges, to have only that one problem gave Thompson hope that he can make the two-way pass next year that will bring the speed record back to his family. The FIA mark is 414 mph but Thompson wants to be the fastest piston-powered car; the current record-holder, George Poteet’s Speed Demon, crashed this year but owned the 439-mph mark for the past couple of years.
The clutch issue has been addressed since then, of course. “We changed all the placements of where the clearances were and we’ve got all new disc and everything. It was wear - we didn’t have any wear, just only 7 thou - and then the last run it evidently wore a lot and then stripped the throttle bearing, came back against the fingers, then slipped. Then the rear engine came up real quick because it’s a rear clutch - we accelerated harder on that run than we had on the 419 - we were going for it… “
A long time coming
It might seem like a lifetime of work that Danny Thompson’s invested in Challenger 2.5 - indeed it’s been more than five years and well too much of both his own money and some sponsor funding - but the dream still isn’t finished and Danny’s ready to have at it again. “It was so awesome; it was incredible. Everything went well, it felt good, it drove well, steered right, the parachutes came out (when intended) and the engines ran so good. We were only at 70% [nitro] so we need to make more power to go faster, but just the gear change, those little things we did, the ratio change, shifting at a higher rpm - I don’t know how fast it’ll go but it will go faster. I just hope it goes a lot faster!”
HIs father’s aerodynamics were validated as there was very little - if any - lift at all in the front (“We have a lot of downforce on the front”) and he added downforce to the back by building a flat under tray. “It moved the center of pressure back just a little bit more and it’ll put a little bit of downforce to the back without adding too much drag.”
This kind of “backyard” ingenuity is what made Mickey Thompson such a great innovator and his son is carrying on that familial ideology. All Thompson needs now is money to get back to the salt next summer. You can help by going to: www.thompsonlsr.com and lend a hand.