Eclipse Split Pulse Manifold

Eclipse Turbo Systems Flowed Landcruiser 4.2 (Multifit) Split Pulse Exhaust Manifold.

Engineered and manufactured from high quality stainless steel, using the lost wax/precision casting method, the Eclipse range of turbochargers are designed in conjunction for use with this “true split pulse” exhaust manifold for increased drivability.

Throughout the design and development of the Eclipse Turbo Systems ENGINE SPECIFIC turbocharger range, extensive testing has been carried out on the full range of factory Landcruiser 4.2 engine exhaust runners and exhaust manifold systems. Hot gas bench tests (fuel and gas flow based) as well as real world chassis dyno results confirm areas of the factory exhaust manifold system in need of improvements, in both design and execution.

Turbocharged 1HZ engine specific based tests have shown a lack of flow and interrupted pulse energy resulting in high thermal loads and exhaust manifold pressure in the engine’s lower rpm with the use of the 1HD-T factory exhaust manifold system. Thermal containment (loss of heat) is also noted. The development and introduction of a “split pulse” manifold, consisting of directional flow (with as little impedance and pressure changes as possible) and correct material/thickness for thermal containment has improved low rpm response and drivability.

“Split Pulse” refers to dividing the odd and even firing order of the engine. Landcruiser’s 4.2 1HZ, 1HD-T, 1HD-FT and 1HD-FTE firing order is 1-4-2-6-3-5 meaning every alternating cylinder fires from either the first bank of 3 cylinders at the front of the engine, or the second bank of 3 cylinders at the back of the engine. The introduction of a divider between the two banks now stops each pressure pulse from reaching the second bank of cylinders allowing for a stronger and uninterrupted pulse/flow. This design results in a stronger pulse in the lower stages of turbocharger spool, increasing the amount of energy sent to the turbine.

“Multi-Fit” refers to the design of the exhaust manifold where it bolts to the factory Landcruiser’s engine head. Flowing from the square 1HD-FT/1HD-FTE ported exhaust runners into a cylindrical shape for maximum flow, it also incorporates the shape/flow criteria for use with the 1HZ and 1HD-T engines.

The exhaust manifold runners are designed to harness and direct the exhaust gas flow towards the turbine with as little drag or pressure changes as possible, while maintaining velocity. Working within the conforms of the factory exhaust port runners and the Toyota CT26 turbocharger bolt pattern/position, this exhaust manifold has been flow tested to the highest standards achievable.

Results from a factory CT26 turbocharger running 11psi intercooled. A gain of 30nm at the wheels is achieved by only changing the Toyota factory turbo exhaust manifold to the Eclipse Turbo System’s Landcruiser 4.2 Exhaust Manifold. A 10% gain overall from 1100rpm is achieved. The Eclipse Turbo System’s Landcruiser 4.2 Exhaust Manifold exhibits these results by design.