The one-and-only 1965 Koch Chevy Special, a mid-engined sports racer, won the 1967 American Road Race of Champions at Daytona in D-Mod. When SCCA abolished D-Mod in 1968, the car with its big 2.5l four-cylinder engine was forced into a class where it was no longer competitive and was retired. It is now restored and most recently competed in the 60th Rolex Monterey Historic Reunion, Group 7a.
In my discussion with the builder, Wayne (Cookie) Koch, a civil and aeronautical engineer, and a national model airplane winner at 12 years of age, he knew about structural integrity. To determine torsional and structural strength requirements, he designed the Koch frame out of straws – twisting and turning the model and adjusting the design as necessary. After completing the straw model, he built and welded the space frame chassis out of 1 inch mild steel tube. The body was inspired and designed based upon a 7/8-sized Chaparral and built out of aluminum panel and fiberglass utilizing molds crafted by Koch. He utilized SU carbs since he could not afford Webers! The build process took about one year to complete. This was truly the height of the home-built era.
Designed as a mid-engine sports racer, the transmission of choice at the time, readily and economically available, was the Porsche 356 swing-axle. A balanced and blueprinted four cylinder 153 c.i. Chevy II engine was selected as it was a common and successful USAC midget racing engine, which easily revved to 7000RPM. Two SU carburetors were utilized as Webers were too expensive for this one-off home built. The custom flywheel was designed and built by Koch and mated to a clutch and pressure plate from a VW Transporter. At about 1050 pounds, the Koch Chevy Special achieved an aggressive weight to horse power ration of 5.5 to 1.
The car originally rode on Firestone tires with 7” wide 15” Triumph rims in the front (with a Triumph TR3 hub and brakes) and 8” wide 15” wide-5 Porsche/VW rims in the rear, which were custom fabricated by Koch out of 3 VW rims cut and welded together to achieve the desired width. After winning the Mid-West SCCA Regional Championships with Firestones, a good friend – a Goodyear dealer – insisted on outfitting the car with Goodyear race tires to attend the 1967 SCCA American Road Race Championships in Daytona.
The Koch Chevy Special was very successfully raced during the 1966 and 1967 Mid-West SCCA division in the D-Mod classification, where Wayne Koch won 7 out of the 8 races he entered. His successes won him the 1967 SCCA Mid-West Regional National Championship, which also earned him the opportunity to attend the 1967 SCCA American Road Race of Champions at Daytona, where he out-distanced the class for an impressive win.
After the car was retired in 1967, it was discovered in the mid 80’s at Can-Am Cars, Ltd. where it was resurrected and raced sporting a Porsche 2L six engine and 901 transaxle. In the early 90’s it was sold to Waren Mosler, owner of Mosler Automotive, where it was restored to its original configuration with the Chevy II engine and Porsche 356 swingaxle for authentic historic racing. At that time, the chassis was set up by Consulier Engineering and raced by Chet Filip, their head of engineering and factory driver.
To regain the original weight to power ratio – with the additional weight of the upgraded frame – the engine was upgraded to a full race GM 3.0 liter inline 4 (stroked 2.5 liter Chevy II inline 4), configured with a roller camshaft, roller rockers, big-bore valves, custom J&E domed pistons, and dual 45 DCOE side-draft weber carburetors producing around 246 HP at 6500 RPM and 212 FP of torque at 5000 RPM.
The current owner has owned the racer since January of 2014, taking about 7 years to fully sort it to its current racing condition. Since that time the Porsche swingaxle has been upgraded to a 356C along with necessary race modifications completed by 356 Enterprises. The engine has been rebuilt and maintained by Nickens Brothers Racing Engines and the car is now fully sorted resulting in a very competitive and fast car! When it runs in SVRA, it competes in the group with GT40s, Chevron B16s, Lotus 23s, Porsche 910s, Porsche Carrera 6, Porsche 908s, Elvas, Bobsys, etc. It is an eclectic, exciting group! In CVAR, it runs comfortably in Group 4, where it is rev-limited to 5800 RPM although it pulls to 6500.
Submitted by Scott Barrett
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