Illustrations, photos and technical analysis by David Kimble
One year ago, the high banking of Daytona International Speedway shook with the thunder of Dodge V-Ss running flat out at nearly 9,000 rpm. It was the first time in 17 years that Chrysler engines competed in the Daytona 500, marking DaimlerChysler's long anticipated (and much celebrated) return to Winston Cup stock car racing.
Defying many skeptics in the NASCAR community, all 10 Dodge Intrepid-bodied racecars made the starting field. Sterling Marlin won one of the 125-mile qualifying races, and Bill Elliott qualified fastest for the big race in Ray Evernham's factory-backed No. 9 Intrepid. At the end of the day there were three Dodges in the Daytona top 10 and although they didn't win, a major objective had been completed.
By the end of the 2001 Winston Cup season, Dodge had scored four victories in the season's 36 races. More are sure to come this year. From any viewpoint, it's been a successful return to America's most popular race series. Dodge's new V4 actually made a double debut because NASCAR, in the interest of plifying its teams' engine programs, allowed the manufacturers to run their Winston Cup engines in the '01 Craftsman Thick Series. There, the Rams won all of the early season races and eventually the Manufacturer of the Year award.
Only four and a half months elapsed from the time the Winston Cup V-8 first ran in a car to when it rocketed "Awesome Bill" onto the pole in Daytona qualifying. That's a testament to a small team of dedicated Dodge Motorsports engineers and their clever use of design tools and suppliers.
World-renowned technical artist David Kimble was hired to chronicle development of both the Intrepid racecar and its mighty 5.9L engine, for a series of cutaway illustrations. And exclusively for Automotive Industries readers, he is permitted to share some of what his camera captured in the Dodge Motorsports inner sanctum.
For a profile of artist David Kimble, plus more of his illustrations and insight into Dodge's NASCAR program, see www.ai-online.com.
The Winston Cup Intrepid program is managed by veteran race engineer Bob Wildberger, with Tim Culbertson as lead engineer. Both are based at DaimlerChrysler's Auburn Hills, Mich., tech center. Ray Evernham, the superstar of Winston Cup crew chiefs, fields his own two-car factory-backed team and distributes parts to the other Dodge teams.
Last season the cars' only real problem was weight distribution -- their engines were 25 pounds heavier than the competition's. Though Cup cars are heavily ballasted to meet the 3,400-pound minimum, Dodge crew chiefs and drivers complained that this extra mass was in the wrong place and was making the cars understeer ("push"). There was also difficulty finding enough front-end downforce, which added to the push and led some crews to try correcting the problem by applying more tape over the grille opening. But that overheated some engines.
A week before the Brickyard 400 in August. NASCAR allowed Dodge teams to extend their front air dams to a total of 2.5 inches, the same as Chevy. The Dodge teams felt the change almost leveled the playing field. Of course, the rival teams felt it tipped the aero balance in Dodge's favor. For 2002, NASCAR has approved a Dodge package for the Busch Grand National Series, though it will not be factory supported. Dodge will also continue its winning Craftsman Truck program.
Heading the factory's race V-8 development are veterans Ted Flack and John Wehrly. who began their Chrysler power-train engineering careers during the 426 Hemi's heyday. They had less than 16 months to design and deliver a Winston Cup engine with competitive horsepower and durability right out of the box. The overall concept was defined in less than three months by splitting development into two sections. Engineer Rudy Sayn was responsible for all components above the head gaskets and Neil Loughlin covered everything below.
The engine team grew to five members with the addition of David James (lead designer), Dave Eovaldi (camshaft and valvetrain) and Patrick Baer (air and fluid flow). To speed development, they relied on DaimlerChrysler's rapid prototyping tools, which created parts in laser-cut-and-fused paper (LOM) or molded-in resin (SLA). The SLA parts were used not only to verify configuration and fit, but to help develop the interior contours of the intake manifold runners on early dyno tests as well. James also did extensive digital modeling assembly studies (DMA) bet ore the individual parts were sent out for tooling.
The final phase of winning their race against time was taking the foundry and machining work to local Michigan short-run prototype shops that are used to meeting tight production deadlines, instead of the usual motorsports sources.
The rocker arms are roller tipped and ride on needle bearings mounted on individual stub shafts. Magnetic steel valve springs are mandated, and during 9,000-rpm operation they are second only to combustion as an internal heat source.
NASCAR engine builders use oil cooling to control the valve spring temperature. They have to plumb the valve covers with tubing to spray oil on the springs and cooling oil passages and jets are incorporated in the valve covers.
The Dodge race motor is based on the 5.9L truck engine, itself evolved from the old 360 V-B from the 1960s. All Winston Cup cylinder blocks must have the same bore centers and center-to-center dimensions between the crankshaft and camshaft as the engines on which they are based. This distance on the 5.9L is greater than that on the Ford and Chevy corporate cylinder blocks, which allows the Dodge to have a larger diameter (60 mm) camshaft. GM cams are 50 mm; Ford's are 55 mm. This larger diameter makes it easier to keep the flat-faced solid lifters in contact with the cam lobes at race speeds -- over 9,000 rpm.
The Winston Cup block is designated AS. It's a deep-skirt design that incorporates a unique camshaft running in six sets of needle-roller bearings. This arrangement puts a single pair of cam lobes in the span between the bearings at either end, allowing the lifter bores to be aligned with the cylinder heed's splayed valves for zero pushrod angularity. The roller bearings are better suited for dealing with the high valve spring loading required in a race engine. The high cam location also allows larger diameter drive sprockets and shorter push rods. In addition, there is room above the crank to isolate the camshaft in a cast tubular chamber -- making the cylinder block stiffer.
To eliminate the potential for core shifting during the casting process (which can cause a major shortfall of horsepower), the Dodge team opted for an open-deck block design instead of the closed deck used by Ford and GM. The open-deck allows one-piece water jacketing cores. The crankcase is also formed by a one-piece core, assuring uniformity.
The block's structure and water jacket were shaped and evaluated using finite element analysis. The design process included a lot of "spin dyno" time that allows secondary heat sources and parasitic friction losses to be isolated and evaluated. Computational fluid dynamics (CFD) was used to assure consistent cooling through the water jacket. The block also incorporates oil jets aimed at the undersides of the piston skirts to cool the piston heads.
All of the Dodge V-8's internal components are made exclusively by aftermarket specialists such as Jesel (camshaft belt drive; see inset photograph), JE (forged pistons) and Crane Cams to factory specs.
The cylinder head design process essentially followed the same steps as the block, with a lot of attention being paid to the ports and combustion chambers. The tooling was done in England, with the casting by Zeus and preliminary machining handled by Raymond Industries.
There are far fewer regulations pertaining to NASCAR cylinder heads than to blocks, and the rulebook allows a very liberal interpretation of what's written. The heads are aluminum; there is a limit of two valves per cylinder and the valves can be any size. But the valve angles and location must remain as specified by the manufacturer.
This is where NASCAR leaves room for development. All of the approved smallblock V-8s originally had their overhead valves lined up in a row and inclined toward the center of the engine, away from the cylinder bore center line; to form a wedge combustion chamber. The valves in Dodge's P7 racing cylinder head are staggered on both sides of the combustion chamber's longitudinal center line; they're also angled inboard and splayed to the front and back, producing a semi-hemispherical combustion chamber similar to GM'S current Winston Cup heads.