IHRA Drag Review Magazine DRM - October 14, 2011 : Page 59
By Paul Plummer achieved via porting, “getting things out of the way” so air can more easily get to and through the seat area. In classes like stock eliminator where port-ing is not allowed, optimizing the valve seat becomes even more crucial. • Never sacrifice head flow for compression. Decking a cylinder head for maximum flow vs. maximum compression will always net better engine performance. It was amazing to see a flow increase of 50+cfm after decking on my stocker heads. Deck relative to valve placement is critical. • Make the cylinder heads and intake manifold the best that they can be and tune the engine for maximum performance using the camshaft as a tuning device. Designing an engine around a particular camshaft is a back -wards approach. • For any given engine combination, the maximum vacuum signal to the intake runner track is typically constrained based on the engine’s mechani-cal design, i.e. bore, stroke, camshaft, etc. Understanding the engine design parameters is crucial in approximating the available vacuum signal to use for cylinder head development. Unlike a real engine, the flow bench vacuum signal can easily be “cranked-up” to overcome deficiencies in the cylinder head, often resulting in overstated flow numbers and cylinder heads that do not perform. Remember that flow bench numbers can easily be manipu -lated, published in glossy magazines and accepted as truth when in fact the published numbers may not even be close to attainable in your combina-tion. Developing cylinder heads for peak performance requires an extensive knowledge of not only induction systems but overall engine design and de-velopment. Al Dickson’s success in developing high-performance cylinder heads for nearly 40 years has been based on a simple mission, ” I try to make every set of cylinder heads I am working on better than the set I just finished.” Here is brief summary of the costs to convert my 1970 Buick GS 455 from C/SA to F/CM and summary of my 2011 season using HRD’s cylinder heads on my 455 Buick Stocker: • Raw Castings Shipped to HRD: $2500 (Stage1 SE -TA Performance, Scottsdale, AZ, 480-922-6807) • Intake Manifold: $400 (SPX -TA Performance, Scottsdale, AZ, 480-922-6807) • Holley 850 Carburetor (Used): $400 • HRD Parts and Labor: $1750 (HRD, http://hrdracingheads.com/, 208-762-9600) Total: $5050 Season results: *Eagle Motorplex Summit Pro-Am, No. 1 qualifier, 3570lbs, 10.48 at 128.05mph, 1.370 under 11.85 index (D.A. 3193 ft.) *Salt Lake Nitro Jam, No. 1 qualifier, 3560lbs, 10.87 at 124.17mph, 1.280 under 12.18 index (D.A. 7266 ft.) *Rocky Mountain Nitro Jam, No. 1 qualifier, 3560lbs, 10.56 at 125.35 mph, 1.309 under 11.87 index (D.A. 3774 ft.) *Altitude track As a racer on a limited budget, I could only afford to make three races this season (31 passes total). I didn’t dyno or even test the car prior to load -ing it in the trailer and driving 9 hours to Ashcroft, B.C. The first pass in the car right off the trailer as an F/CM stocker was 10.43 @ 127.33 mph. It was hard to remove the smile from face, and it put the fun back in Stock Elimina -tor drag racing. Thanks to HRD for their sponsorship and IHRA for the class and Division 6.