Engine exhaust system

An engine exhaust system comprising:

• an exhaust pipe assembly having an engine exhaust system inlet configured to receive engine exhaust and an engine exhaust system outlet
• a first selective catalytic reduction (SCR) catalyst device positioned downstream in exhaust flow from the engine exhaust system inlet wherein the first SCR catalyst device includes:
• a substrate with a metallic catalyst coated on the substrate;
• an electric heater configured to heat the metallic catalyst
• a second SCR catalyst device positioned downstream in engine exhaust flow from the first SCR catalyst device and upstream of the engine exhaust system outlet
• wherein the first SCR catalyst device and the exhaust pipe assembly define an empty chamber between the substrate and the second SCR catalyst device such that engine exhaust flows directly from the substrate to the second SCR catalyst device through the empty chamber:
• the first SCR device has a generally cylindrical housing;
• and
• the substrate has a circular inlet face generally perpendicular to the direction of engine exhaust flow, and an oval outlet face angled with respect to the direction of engine exhaust flow.

A vehicle comprising:

• a diesel engine having an engine exhaust outlet;
• an engine exhaust system including:
• an exhaust pipe assembly having an engine exhaust system inlet configured to receive engine exhaust and an engine exhaust system outlet;
• a first selective catalytic reduction (SCR) catalyst device positioned downstream in exhaust flow from the engine exhaust system inlet;
• wherein the first SCR catalyst device includes:
• a substrate with a metallic catalyst coated on the substrate;
• an electric heater configured to heat the metallic catalyst;
• a second SCR catalyst device positioned downstream in engine exhaust flow from the first SCR catalyst device and upstream of the engine exhaust system outlet;
• wherein the first SCR catalyst device and the exhaust pipe assembly define an empty chamber between the substrate and the second SCR catalyst device such that engine exhaust flows directly from the substrate to the second SCR catalyst through the empty chamber;
• a diesel exhaust fluid (DEF) injector disposed in the exhaust pipe assembly upstream in engine exhaust flow of the first SCR catalyst device;
• and
• wherein the substrate of the first SCR device has an inlet face generally perpendicular to the direction of engine exhaust flow, and an outlet face angled with respect to the direction of engine exhaust flow.