Manifolds

Chevy 292 exhaust manifold

The Chevy 250 inline-6 was designed as a solid workhorse, making it perfect for trucks and daily drivers. Unfortunately, these motors weren’t built for high performance, and most components need to be modified or replaced to defy those power constraints.

Despite the camera angle, the 292 has a 2.5” outlet

The stock exhaust manifold has a 2” outlet and narrow passages—a major bottleneck for larger turbos. Since Turbo Camaro is using 3” piping, we upgraded to a 292 exhaust manifold. The 292 version features larger internal passages and a 2.5” outlet. While 0.5” sounds small, it represents a 25% increase in diameter and roughly 30-40% better flow, which is a massive upgrade for a turbo setup.

Our 292 manifold was sourced from eBay (originally off a tractor) for about $100US. Because this is a factory-style manifold, it lacks a port for an external wastegate. While the SPA Turbo manifold comes pre-cast for a wastegate, it also costs over $400US. We will eventually modify this 292 manifold to accept the SPA Turbo 25mm compact wastegate.

Offenhauser 5416 Intake Manifold

For the intake, the stock unit simply won’t support a performance 4-barrel carb. We selected the Offenhauser 5416. It is a heated intake that mounts to the exhaust manifold like stock to prevent fuel puddling. This manifold is the perfect platform for the Holley 4776 600cfm Double Pumper.

Offenhauser 5416 outlets

Because the Offenhauser intake and 292 exhaust were never intended to be used as a factory unit, they don’t always mesh perfectly. We filmed a two-part video series covering the grinding, painting, and final fitment required to get these components sealed against the head.

More documentation on the carburetor installation can be found here.