New for the '09 season on...
New for the '09 season on the Pro Stock V-Rod are the four-valve cylinder heads, necessitating different length exhausts. Note the belt drive running to the rear cylinder's OHC chain drive.
The '09 season marked the debut of the new four-valve head on the Screamin' Eagle/Vance & Hines V-Rod and the transition went smoothly at the track, if not politically. Switching from a two-valve pushrod to a four valve overhead cam twin (like the production street version of the V-Rod) didn't produce many surprises. "It wasn't huge," Matt Hines said. But the opposition to the engine in the paddock was significant.
"At the time, NHRA had given [the green light for] a brand new engine and four-valve head [for the Suzuki]. Harley said, 'We want what you gave to Suzuki, to be fair,'" Vance recalls. It would be two seasons before the NHRA allowed Harley the four-valve.
Meanwhile, the deal to build the four-valve Suzuki fell apart and still remains unresolved.
The billet engine was designed over a year by Byron Hines, son Matt, and V&H's Nubia Munoz working with SolidWorks software. After initial design and prototyping, Harley-Davidson engineers contributed their wealth of resources. "[Byron Hines] did an incredible job of designing and initially developing that engine," said Bob Farchione, H-D's Vice President for Engineering Platform Teams. It was, after all, the biggest engine Hines had ever designed. The V&H Suzukis were 101 CID (cubic inch displacement) inline fours, each cylinder a little over 25 CID. This was a 160 CID twin-meaning two massive 80 CID cylinders. "I have to say he did an incredible job...in accounting for as much as he could, not knowing what to expect once he actually ran the engine."
Hines had been noticing aspects of the valve job not lasting as long as they should, which meant that he was likely having valve train dynamics issues. Once on the Spintron, they discovered "the cam dynamics were further off than even what he anticipated," Farchione said. "So neither one of us recognized initially that the opportunity would be as great. So we were delighted that we found an issue that would make a significant difference." H-D introduced V&H to Comp Cams and "they were very willing to help us understand how important the valve train dynamics and the cam design were for the engine," recalls Farchione. Using the Spintron, "we found out there was opportunity there, and so they designed some camshafts for us and made some recommendations on spring and other valve train component changes that had a significant difference in the performance of the engine." Other important contributions from H-D were its successful lobbying efforts with the NHRA to allow the air intake scoops and fuel injection.
The engine of the Pro Stock...
The engine of the Pro Stock H-D is a custom design by the legendary Byron Hines, with help from son Matt and V&H's Nubia Munoz; H-D factory engineers also contributed. The carved-from-billet-aluminum unit displaces 1737cc (106 cubic inches) and cranks out about 370 horsepower.
The engine displaces 5 cubic inches (82cc) more than the Suzukis, but also weighs more. After the NHRA tacked on 20 pounds earlier this year, it now has a combined bike and rider weight of 640 pounds (bike is about 470 pounds). The internals include a Falicon crankshaft, Axtell cylinders, CP pistons from Pankl, and connecting rods from MGP, a Colorado company. Exhaust pipes are built in-house; Matt Hines tried 10 different combinations before settling on the current ones. "The duration of the cams dictates pipe length. The two valves run longer duration."
The rear tire is 27/10-16 M ET Drag Mickey Thompson that's screwed into the rim. How many runs is it good for? "Could be six, could be 35," Andrew Hines said. They run it at between five and six psi; adjustments are as little as an eighth of a pound. The front tire is 2.50-2.75/18.
The V-Rod runs a Motec M600 ECU, a Racepak V300SD data logger, and a Powerdex AFX air fuel monitor. Traction control is banned. "We can do timing retard in first gear to keep the tire calm or we can advance the timing if we think it needs more power," Andrew said. "We can do every 50 rpm if you wanted to and just have some chainsaw-looking graph for ignition timing."
"The main thing right now is it's picked up some power, but I'd say it's picked up more torque than anything." Andrew said it makes around 370 hp. "And reliability is a lot better. On the other motor you had rocker arms and lifters, and you've got a valve spring that's 1000 pounds of load; when you look at it from the pushrod side of things, that's 2000 pounds of load. So that was a lot of stress, and every now and then we'd take out a lifter or a rocker arm. [Now] you don't have the valve train issues, and the valve job and the valve springs last longer. The motor's happier."
And so are the riders. "Just kind of everywhere," Hines said of the difference between the new and the old. "It's a more linear run. It's not any faster down the track." The biggest difference is the sound. "It sounds different with the intake noise."