Straight-6 engines certainly need love, and Wayne Hafemeister has lavished plenty of affection on his Holden 202ci. Fully blueprinted and sporting a 4-71 Jimmy blower, this Australian 6-shooter pulled 280 horsepower under 10 pounds of boost on the dyno run shown above.
“In summary, it would have been more economical and less challenging to build a mild V8,” says Hafemeister, who runs the engine in a Holden Torana LJ from the early ‘70s. “But I have an affection for the old ‘Red 6’ and went the doctor on one. I’m glad I did.”
Hafemeister did start out with a “blue” block, which was the next generation following the “red” engines in the Holden straight-6 architecture. Following the first build, numerous problems surfaced during the dyno test, such as low oil pressure, water leaks and a bad damper. Hafemeister turned his attention to the body work until Karl Zerner offered to sort out the engine issues.
“First task was to grind out the oil galleries and bell-shape the oil returns,” explains Hafemeister. “One of the problems with these motors is that all the oil ends up in the rocker cover and none in the sump.”
Zerner fabricated a 6.5-litre pan, adding an external oil pickup. He also stretched a 2-inch breather pipe from the rocker cover to the pan.
“A large diameter was used to keep the crankcase pressure low. Oil and air are transferred to to a catch can with a tapered base,” says Hafemeister. “A filter positioned on top connects to a tube that continues approximately two-thirds the depth of the can. The oil is separated and plumbed from the base to the sump.”
Rotating assembly comprises a fully polished crankshaft with “blue” connecting rods, ARP bolts, ACL cast pistons (7.7:1 compression ratio) that were ceramic coated and a Ross billet damper modified to accept the 3-inch blower-drive pulley.
Up top is a Yella Terra cylinder head fitted with Holden XU1 valves and Yella Terra 1.6:1 rockers. Valve action is motivated by a Tighe billet flat-tappet camshaft (250 degrees at .050 and 114-degree lobe separation), Crane lifters and Crow pushrods.
Newby Engineering supplied the intake manifold, but it did require some welding and machining, including the addition of a backfire plate and a support base for the Russell Jones-blueprinted GMC blower. Rounding out the induction is a 650 cfm Holley double-pumper while a set of custom Tony Fleming headers exit the exhaust. The spark is handled by “blue” motor distributor and MSD 6 box.
“The motor was taken to Cragsted Performance for the tune,” says Hafemeister. “The engine responded well to fuel adjustments and timing increase up to 3,500 rpm. With the aid of a video camera, I discovered that the vacuum secondaries on the 600 Holley were not opening consistently, resulting in a lean out. A 650 was purchased and after sorting jet sizes, delivered a near perfect air-fuel ratio throughout the rev range. The results were 280 horsepower at 6,100rpm with 250 lb-ft torque on 98-octane pump fuel.”
The engine is backed up by a Powerglide tranny with a 3,000-stall Converter Shop torque converter. In order to clear the blower drive, the engine was moved back 40mm and the radiator was mounted on the front of its support panel. Finally, the hood was modified with a steel scoop so the car could be registered for the street.