Ad Radar
Car Craft
Click here to find out more!

Oldsmobile 468CI - 500hp Engine Combos

Anyone Can Build

Photography by ,

Chevy LS1 5.7L

The Gen III small-block is the engine of the future for hard-core car crafters looking for maximum power. This is also the smallest engine in our power combo at only 346 ci, yet it can achieve the power without resorting to an outrageous cylinder head/camshaft/high-rpm combination. To get the full skinny on a 500hp Gen III motor, we hustled out to Ken Duttweiler's shop in Saticoy, California. Duttweiler's experience is mostly based around fuel-injected combinations using the factory computer, but a carbureted version would make similar if not slightly more power. According to Duttweiler, all it takes to make 500 hp is cylinder heads that flow 310 cfm or better along with a little more camshaft than stock. For a first-generation small-block Chevy, that's a tall order in the cfm department. But for the Gen III, there are easily a half-dozen heads out there that would fill these airflow shoes. If we had to pick one, Duttweiler agrees the GM Performance Parts CNC-ported LS6 heads are a good choice. The heads come completely ported and fitted with very light, hollow-stem 2.00-inch intake valves and 1.55-inch sodium-filled exhaust valves. GMPP claims these heads can only accommodate up to 0.570-inch valve lift, so you may need some better valvesprings along with a few other pieces. But the airflow is solid at 290 cfm-plus at 0.500-inch lift. For a camshaft, Duttweiler says the hydraulic roller profile needs to be in the range of 224/236 degrees at 0.050-inch tappet lift with 0.580-inch lift and a lobe separation angle of 115 degrees advanced slightly with an intake centerline of 112 degrees. This is the smallest cam spec that would make this kind of power, as long as you combine the cam with good valvesprings and stiffer aftermarket 0.080-wall pushrods to prevent deflection. The pushrods are necessary because the stockers are weak. A close off-the-shelf cam we found was a Crane HR228 Zcam, but Crane can also custom-grind a cam if you choose to go that route, and the price is not as bad as you might think. Best peak power will also be achieved with a FAST LSX intake manifold combined with a 90mm throttle body. Compression would also help this program. Duttweiler says cutting the heads 0.020 inch might bump the squeeze to 11:1, and of course a good set of headers like Kooks long-tube 134- or 178-inch primary-size pipes will help make torque as well as horsepower. We've seen large-tube headers work on even mild LS1 motors. The only other caveat Duttweiler mentioned is to not spin a stock LS1 over 6,800 rpm because the stock rod bolts are a bit questionable above that rpm. That rpm is also very hard on the heavy hydraulic roller valvetrain.

Parts List
DESCRIPTION PN SOURCE PRICEGMPP CNC LS6 head, pr. 88958665 SDPC $1,996.50 FAST LSX intake, 90mm 30-54003 Summit Racing 869.95FAST 90mm throttle body 30-54019 Summit Racing 519.95Comp conical springs 26918-16 Summit Racing 179.95Comp pushrods, 516" 7955-16 Summit Racing 133.69Crane Zcam hyd. roller 1449601 Summit Racing 399.98Kooks 134 headers 6500RHS Kooks Headers 864.90

Crane Cams; Daytona Beach, FL; 386/258-6174;
Kooks Custom Headers; Bayshore, NY; 866/586-5665;
Scoggin-Dickey Parts Center; Lubbock, TX; 800/456-0211;

Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!
Car Craft