Quick Test: Carbs Vs. Fuel Injection On Holley's New Hi-Ram Manifold

First on the dyno was the EFI upper intake. Naturally, the fuel-injected combination was run with Holley's new Dominator EFI system. The Holley Hi-Ram upper intake was designed to accept either a 92mm or massive 102mm throttle-body. Equipped with an aggressive Comp hydraulic roller cam, the injected 468 stroker produced 713 hp at 6,900 rpm and 614 lb-ft at 5,200 rpm.

To get his photo in the magazine, the author offered to swap the EFI upper intake to make room for the dual quads.

A pair of Holley 750 HP carburetors was installed on the Hi-Ram upper intake in side-by-side configuration using a traditional dual-quad (tunnel-ram) throttle linkage. The injectors were retained to eliminate vacuum leaks. Although we still used Holley's EFI system to control ignition timing, it is also possible to employ an MSD timing control on this carbureted application.

Only minor jetting was required to dial in the air/fuel mixture. We tuned the carbs in an attempt to replicate the air/fuel curve achieved with the fuel injection. Despite offering more than 1,500 cfm worth of airflow, the twin HP Holleys provided impressive part-throttle operation.

This thing runs like it looks, so you're not going to sneak up on anyone. With 724 hp and 631 lb-ft, you won't have to.