History Of Skidmark | The Quest for Speed
In 1990 Team Skidmark began building a BMW 2002 for autocrossing . However, competing priorities lead to a rather long timeline for this project. By 1995 the autocrossing project evolved into a car strictly for BMWCCA driving schools. The car was originally conceived as an aesthetically intriguing, well-prepared vehicle with a great deal of attention paid to reliability and functionality. A BMW built for racing with a wink towards the street rod level of preparation. A main roll hoop, lower springs, Bilstein shocks, Delrin bushings and larger sway bars were the main improvements. The motor was a mild 300 degree cam with a Stahl header and dual Weber 45’s. HP was about 140. By 1998 Lance had completed numerous driving schools and was ready to go racing. The car would now be prepared for BMWCCA club racing events. A fire system, full roll cage and fuel cell were added along with the number 20.
The second purpose built car by Skidmark began in 1999 after a long vintage race weekend at Mid-Ohio where 2 engines and a header were broken! Given the long off-season, the decision was made to apply lessons learned to create a new Skidmark car. This car would carry the number 202. Of course it HAD to be pretty but functional as well. The passenger floor was raised to allow the fitment of a big header and large muffler. Turbo flares were added to accommodate a wider track and the use of 20” x 9.5” cantilevered racing slicks. The location of the fuel cell, fire system, accusump and battery were carefully considered to improve corner weighting. This car was to be full race and so a unique dashboard was designed and fabricated. Last but not least a much improved cage to enhance safety and structural integrity was designed and installed.
As the 202 car was taking shape, the original 20 car was to be updated to equal the improvements of the 202 car. Essentially the two cars would now be the same with regard to development. To commemorate the dramatic improvements made to the original Skidmark car the number was updated to 201. Both cars entered the racing scene in 2000 running in BMWCCA, SVRA and HSR events.
As the statistics show, they were fast, reliable and successful from the start!
However, the quest for speed has led the Skidmark team to dramatic improvements in the basic 4-cylinder M10 power plant though unique and successful innovation. The list is long but includes proprietary pistons, rocker arms, connecting rods, valves and even a camshaft. Further, ongoing improvements to the basic oil sump and breather systems have been made. Follow the link to find out more …
When Lance’s son, Ian was ready for his first car, the 2002 was the obvious choice. Ian had been going to the track with Lance and Perry since he was 10. He wanted a street version of what Lance and Perry were driving on the track. From July 2002 through April of 2003, Lance and Ian built a street version of the race car. The car had an Miller-Norburn racing motor with a 300 degree cam, 5 speed overdrive and a 4:22 limited slip differential. The brakes were upgraded to discs on the rear and Big vented brakes on the front. Lance developed and refined is painting skills with this car and he now does all the painting for Skidmark Racing.
Bob Breed (www.oftenlastracing.com) was well known to team Skidmark as a DE instructor with the BMWCCA and fellow BMW and vintage racer. Bob’s ride was a 1980 BMW 320. Bob longed for a 2002 and spent many hours pouring over the 201 and 202 cars. With a good bit of encouragement from Lance and Perry, Bob developed a strong interest in building a 2002 of his own. The project began in January 2004 and progressed through October of that year. Perry, Lance, and Bob combined all of the lessons learned over the past 7 years and built Bob his Inka BMW 2002 racecar. Naturally, this car should carry the Skidmark numbering and so has been blessed with the number 204. This car represents the best efforts of Lance, Perry and Bob and is truly one of the nicest examples of a vintage racing BMW 2002 in the country.
Performance tuning a bmw2002 almost always begins with the venerable Weber 32/36. Either one is being installed as a replacement for the original equipment Solex or one is being replaced most likely because of a worn out and leaky throttle shaft. Mine was the latter scenario. A 38/38 synchronous 2 barrel was chosen for the job. The intake manifold was opened to accommodate the larger bores and the 38/38 was installed. The improvement was substantial and the concept of further gains intriguing. A header came next, a 1 3/8” Stahl, then a 304 Schrick camshaft – all used parts. The bottom end employed well-worn OEM rods and Mahle 9.5:1 pistons for the 121 head. The head was built with used rocker arms and shafts, valves and springs. After some sorting out, the 38/38 was replaced with a Dual Weber 45 side draft setup. This engine was run in the original 202 car for DE schools and racing for 3 years and logged over 50 race track hours.
Ultimately, a rod bearing spun at an October race at Mid Ohio and so it became time to complete the new car and power plant. Meanwhile, the 201 car had been experimenting with a 316 camshaft. This setup proved to make excellent power and so we decided this would be the basis for the new engine in the 202 car. After researching combustion chamber and piston design a domed piston was developed along with a tool to cut the chambers to match. This approach would provide for high compression and efficient combustion. The head received significant porting work, new valves, springs, rocker shafts, rockers and a 316 Schrick cam. A stepped header, designed by a header expert was the finishing touch .
The new 202 car debuted in April 2000 and was fast out of the box winning its class in every BMW and Vintage event entered that year. That is until the season finale SVRA event at VIR. The 202 car was running well all weekend when, on a flying lap during qualifying the number 3 connecting rod let go and on entry to a fast sweeper called Hogpen. This would be the last Skidmark engine to use stock connecting rods! Winter was spent replacing 1 bent valve and building a new bottom end. This time, billet connecting rods were sourced and more attention was paid to baffling the oil pan . Back on track in 2001 the 202 resumed its winning ways. However, at the big SVRA event at Watkins Glen on the last lap of the feature race on Sunday a rocker arm broke Skidmark Racing had heard about this weak link especially with high lift high duration cams but had not experienced this failure. However, after the first one it seemed to befall the team in a big way with the 201 car breaking a rocker arm at nearly every event that year! As we learned the hard way, rocker arms fail. All successful race teams from the early 1970’s would replace the rocker arms before every event, and still they had failures! The only way to avoid rocker arm failure is to keep RPM levels below 7,200. However on the Dyno, the M10 motor showed increased horsepower at above these RPM ranges.
The OEM rocker arm is a cast aluminum part. This piece is reasonably strong and will provide a long service life under less-than extreme conditions although it is inherently flawed for racing applications. For example, once the camshaft lift and duration reach race appropriate levels (>11mm lift, 305 degrees duration) the rocker becomes over stressed and the clock starts ticking. It is a matter of time until it fails – not if, but when! Skidmark Racing now had a new engineering project! Over the winter of 2001/2002 the rocker arm was modeled in ProE, a 3-D CAD tool . The first prototype rocker arms were then CNC machined from grain aligned 7075 aluminum . A cam follower wear pad was machined from tool steel and inserted into the aluminum arm. Two sets of these were run throughout the 2002 season with great success. Requests for these arms poured in and so the Skidmark team arranged with a manufacturer to produce over 300 rocker arms. They were distributed over the winter and Skidmark was ready to run the production rocker arms in the April 2003 season opener at VIR. It didn’t take long before the team noticed significant degradation of the cam lobe surfaces. Clearly there was a difference between the prototype and production parts. Immediately, the team notified all those who purchased the arms to wait until further notice before using them in racing applications. Solving this problem would prove to be the biggest challenge the Skidmark team had yet faced. The team spent hours, days, weeks and months studying the problem. They flew to Rhemscheid Germany and met with Schrick engineers. Even Schrick was stumped. Ultimately through research, prototyping and hours of testing on a dyno and on the track, the current solution was developed . These new rocker arm pads have proven to be quite durable and have been run for many hours with no cam lobe degradation. In fact, a weekend-long track test designed to provoke wear or breakage consisted of running the engine to 9,000 RPM for extended periods. The results were extremely positive with no signs of wear.
With this challenge behind us, Skidmark Racing is now focusing their attention towards optimizing the port design to maximize flow. In conjunction with this work, a new higher lift camshaft is undergoing development. The objective of this R&D is to build a carbureted M10 engine that produces in excess of 240 HP at the crankshaft! So far the computer simulations show promise but the real proof will come from actual testing. Stay tuned as the initial dyno runs are planned for early July 2005!
Along the way, the Skidmark Racing team has continued to innovate under the hood. Currently, we are the only known domestic manufacturer of billet aluminum under drive pulleys for both M10 and S14 crankshafts . These pulleys were designed to work with crankfire ignition systems such asElectromotive. 125mm billet aluminum alternator pulleys have also been developed to further limit parasitic losses .
As our motors continue to run at higher and sustained RPM levels, we needed to develop special valve cover designs and catch cans to handle the increased oil flow to the head.
Throughout the development of the Skidmark Racing cars and technology we have not lost sight of the significance of reliability. As our impressive statistics demonstrate, Skidmark Racing cars have proven to be quite fast but reliable as well. Despite the impressive specific power output by our engines, they typically last 3-seasons between teardowns!! We expect that as we continue to develop this platform – chassis and drive train – the reliability will not be compromised. After all, what fun is a race weekend if you can’t race?!?