JWT modifies the compressor housings and builds the brackets for the wastegate cans to adapt them for use in the tight confines of the Z's engine compartment. The passenger-side turbo discharges up and then forward in order to accommodate the unit's scroll direction.
JWT modifies the compressor housing and wastegate brackets to fit within the tight confines of the Z's engine, as both turbos sit right next to the frame rails. These feature an internal wastegate and a friction-reducing ball bearing center section for less lag and better transient response. Even with its combined 700 wheel-hp potential, the two Disco Potatoes are relatively lag-free when coupled with the VQ35's displacement, which gives more than enough flow to exceed our power goals with ease.
Exhaust Manifolds
Cast exhaust manifolds, made from high-temperature-rated ductile iron, assure durability over many extended heat cycles. Ductile iron has a higher nickel content than regular iron, which helps with heat resistance and strength. Magnesium is also added to control the shape of carbon asperities within the metal to make it less brittle, hence the ductile nomenclature. The manifolds have stainless steel heat shields to help maintain a near-stock engine compartment temperature, a critical detail for extended durability of the car's underhood components.
The OEM-quality ductile iron manifolds should prove crack- and warp-resistant. JWT also cast in the bosses where the stainless steel heat shields bolt on. These shields help prevent cooking other parts in the engine compartment.
The turbos dump into cast O2 sensor housings with cast-in dividers to separate the turbine and wastegate discharge flows. These are the same as on the base JWT kit and modified to port-match the larger turbine outlet diameter of the 700 turbos, but still bolt onto the stock catalytic converters. Short nub extensions from the housings protrude into the turbine to separate the flow of the turbine and wastegate as much as possible. This little trick improves overall exhaust flow, helps reduce spool time by improving turbine efficiency and can be good for up to 30hp on a single Disco Potato when the wastegate discharge is separated from the turbine exhaust flow and re-merged over six inches downstream of the exhaust.
Normally, welding a separation plate into the turbine housing and re-merging the wastegate dump tube into the downpipe is something only high-end fabricators do. This cast extension on the JWT dump tube saves the trouble, although the wastegate discharge is merged earlier in the cast O2 housing so stock cats may be bolted directly to the housing.
Inside the engine bay, the passenger-side turbo sits almost on the frame rail. This varies between cars, as engine positioning tolerance on the OEM mounts and crossmember allow for almost a quarter-inch of slop.
Charge Piping And Intercoolers It's no easy task plumbing intake air to two turbos, sending compressed air from those turbos to a front-mount intercooler and then to a single throttle body. Doing it within the confines of the 350Z's engine bay-while making it reliable-becomes a serious feat of engineering. Plumbing in the JWT kit starts with a single top-mount POP Charger air filter, located behind the driver's-side headlight. Right after the ambient intake air is strained through a POP Charger filter and registered by the airflow meter, the air is split off through a cast 90-degree T-section and plumbed through 2.25-inch mandrel-bent aluminum pipes toward each turbo.
Once pressurized, the air is sent to JWT's large front-mount intercoolers to shed the heat created by the turbochargers' adiabatic compression, which further increases the intake charge density. All pressurized plumbing after the turbos is bead-rolled to prevent the hose connectors from popping off. The compressed charge exits forward and down from the turbo on the driver's side, next to the oil sump, through 1.7-inch steel pipes (to cope with the heat from the manifold), which are gold-cadmium coated (like OEM hard lines) to prevent corrosion. The remaining aluminum piping plumbs to the intercooler end tank of the two side-by-side front-mount intercoolers.
On the other side, the plumbing is more complicated. It routes up over the passenger-side turbo and sideways over the frame rail and down over the wheel well to the end tank on that side. At least sheet metal cutting is not involved.