CHUMP CHANGE

Hunk-O-Junk Big-Block, Part 5: The eBay Turbo Test!

- Richard Holdener

It seemed like a match made in heaven. Take one modified, junkyard 454 and add some cheap boost from a $163 eBay turbo. Did it work? Sure. Did it work perfectly? Let’s take a look! The project actually started quite some time ago after we pulled a Gen 6 454 from the engine bay of a 1-ton Suburban. The Pick-a-Part special was then prepped for dyno use by replacing the factory EFI with a carbureted, dual-plane intake and non-computer-controlled distributor. Back in Part 1, the carbureted (but otherwise stock) 454 produced 378 hp at 4,700 rpm and thumped out 482 lb-ft of torque at 3,500 rpm. Our shortcut to power came in Part 2, with the installation of a Holley Sniper nitrous system. Nothing adds an extra 125 hp quicker (or easier) than a nitrous kit, and run with 125hp jetting, the 454 thumped out 519 hp and 646 lb-ft of torque.

The next step was to perform a cam and valve spring swap. Installation of the Comp XR276HR cam and 26120 springs resulted in a jump in power from 378 hp and 482 lb-ft to 427 hp and 504 lb-ft. The final upgrade came in Part 4 where we added a set of Dart Pro 1 275 (oval-port) heads and a custom Comp cam, which pushed the peak power numbers up to 503 hp and 492 lb-ft of torque.

After upgrading the 454 with the Dart heads and custom Comp cam (0.561 lift, a 233/239-degree duration and 118-degree LSA), the 454 still suffered slightly from low compression. The added chamber volume of the Dart Pro 1 heads reduced the static compression below 8.0:1. While not ideal for naturally aspirated power, it was just begging for boost. Knowing this, we decided it was high time the 454 received some positive pressure.