As a part owner of Victory of Austin, a Victory motorcycles dealership, Mark custom built a turbocharged Victory Vegas for his own use. The 1927 Scott Flying Squirrel is also one of the other bikes that fill his garage. Mark tells us that he's had three to four dozen other 'interesting' bikes pass through his hands over the years.
With that background, the whole turbo conversion idea seemed like a good one to Mark. Of course, the devil's in the details and there were a few to get through. For example, the convertible had previously been treated to a Maximium Motorsports' conversion, so getting the turbo plumbing to fit around their k-member led to many issues. Other MM pieces that made their way onto the car included the strut tower brace, lower A-arms and coilover conversion. Tokico 5-way adjustable shocks and struts and Global west rear lower control arms also round out the suspension work.
Eventually, Mark had custom turbo piping fabricated for the car, but somehow, the supplier didn't include any expansion joints, so cracks started showing up in less than a thousand miles. Mind you, when they took the car back to the dyno in February of last year, the results were pretty impressive. Using race gas, along with 24 psi of boost, the rollers showed 655 RwhP, along with 692 RWTQ.
Additional work to support the Garrett GT40 turbocharger included an upgrade to Bosch 55 lb. injectors, a Bell intercooler, dual cobra fuel pumps, a Fluidyne aluminum radiator and a SPEC Stage 3 clutch. having previously gone through a couple of stock transmissions, this convertible now sports a shiny Tremec T-56, 6-speed gearbox, Ford Racing aluminum driveshaft, 3.73 ratio gears and rear axle girdle.
The cracking issues with the plumbing, though, were an ongoing headache. Near the end of last year, Mark contacted Motion Dynamics in Austin to get some new tubes done up, including expansion joints. The challenges, Mark points out, are not insignificant. The "...area of a 3-inch diameter pipe is about 7 square inches. At 20 psi, the force separating the pipe is 140 lbs!" Additional work was needed to refine a few of the connections, but everything looks solid now - at least at 20 psi. At that boost level, the motive force logs in at 611/625 on race gas. In street trim, using 14 psi and pump gas, the story still remains fascinating at 531/567.
Back in the days of "only" 440 RwhP, Mark had visited River city Raceway in San Antonio and came back with a timeslip for 12.37 seconds at 118 mph. considering the power increase since that point, Mark figures the car is good for some low 11 second performances, perhaps even dipping into the high 10's. Problem is... that's not going to happen. Mark likes the 'vert without a roll bar and there's just no way the track is going to let him run those times without one. Mark's Ok with that, though, because he'd rather have his kids in the back seat, as he often does. "This really is a 'drive around town' car and not a race car. The stereo and A/c work great."
Looking back on the road he's taken to get here, Mark acknowledges that there have been a few speed bumps. "Doing your own development is expensive. Go ahead and buy off the shelf stuff that someone else has had the pain of developing. I have used injectors in sizes 30, 36, 40, 42, 48 and 55 pound, as well as four different MAFS and two intercoolers."
Given that Mark picked up this car just when the 4.6 liter PI engine came out, he may be a little hard on himself. "If I had decided what to do up front, I would have skipped the middle steps. But then, maybe it would not have been as much fun." Doubtless, Mark has had a lot of fun - and plenty of it to share with his kids. As nice as it may be, that's a lot harder to do with a turbocharged motorcycle. Mind you, once the kids go to bed...