69 Chevelle Convertible - Ken Duttweiler, Saticoy, CA If you kneel daily at the altar of horsepower, Ken Duttweiler’s name should be familiar. Duttweiler has been racing and building race engines for more than four decades and just keeps pushin’ ’em out of his small Saticoy, California, shop. We dropped by for a visit the other day and witnessed this “mild” Magnuson-supercharged LS engine that Duttweiler had just rolled up on the dyno. The engine is going into New Jersey customer John Ventura’s 69 Chevelle convertible. The engine may not look like much, but check out the dyno curve: At 3,500 rpm, this motor’s twisting almost 900 lb-ft of torque. That’s enough torque to flat-tow the Empire State Building! And this is the detuned, pump gas version. With VP16 race gas, this 434 twisted the dyno to 975 hp. That’s enough power to push even a 3,600-pound 69 Chevelle deep into the 9s—assuming it can hook up. One secret to this engine’s success is a very small fitting located on the inlet side of the blower that mounts the Snow water/methanol injection. Duttweiler used the Snow Stage 2 GM MAF Boost Cooler that uses the GM mass airflow sensor frequency data to match a proper water/methanol mixture to the engine. This is especially beneficial with a supercharger like the Magnuson, as it builds boost very quickly off idle. Duttweiler was running straight methanol to feed additional fuel to offset the 60 lb/hr Bosch injectors fitted to the intake manifold. The methanol both cools the inlet charge and adds fuel to keep the air/fuel ratio safe under boost. This allows Duttweiler to run more conservatively sized injectors. Duttweiler used a GM Performance Parts iron LSX block as his foundation. Combined with a massive 4.155-inch bore, a Scat steel 4-inch stroker crank, and Diamond 9:1 compression pistons to create those 434 inches, it’s plenty stout to handle this power level. Completing the bottom end is a Moroso wet-sump oil pan with Lucas Break-In oil keeping everything lubricated. The Comp cam measures 236/244 degrees at 0.050 with 0.614-inch lift using 1.8:1 CHE-modified rocker arms from RPM Motors. The heads are a set of LS7 castings ported by Richard Reyman at West Coast Racing Cylinder Heads and fitted with titanium intake and Inconel exhaust valves. The headers are 17⁄8-inch Kooks. The supercharger is a Magnuson sixth-generation MP 2300 that Duttweiler has set up to push only 14 psi for the pump gas horsepower pulls. On race gas, he cranks the boost only slightly up to 16 psi and adds a few more degrees of timing. The 1,000-cfm throttle-body is connected to a Lingenfelter Performance Engineering MAF that supplies the needed information to the factory ECM. What is difficult to see from this angle is the jack shaft that runs the length of the supercharger to spin a second set of pulleys that actually drive the blower. As this is a rear-entry-style supercharger, for muscle car applications, the blower is installed with its rear inlet facing forward. How good are the factory LS ignition coils? At just 25 hp shy of 1,000 hp on race gas at 6,500 rpm, it appears these factory coils work just fine. 69 Chevelle - Dyno Chart RPM TQ HP Boost 3,500 893 600 14.5 3,700 891 628 14.6 3,900 887 659 14.5 4,100 848 662 14.3 4,300 826 676 13.9 4,500 827 708 13.8 4,700 843 754 13.9 4,900 851 793 13.9 5,100 854 829 14.0 5,300 838 846 13.8 5,500 836 875 13.7 5,700 828 899 13.8 5,900 816 917 13.8 6,100 791 919 13.9 6,300 773 928 13.9 6,500 747 924 13.9 By Jeff Smith Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!