Dual Intake

A Dual Intake is a common upgrade for the Z32's intake system. The stock system draws all intake air through a single MAF, before splitting into two tracts (one for each cylinder bank). A dual intake setup isolates the two cylinder banks' intake tracts, giving each one it's own air filter.

A single-intake setup.	A JWT-style dual-POP setup.	A Selin Dual MAF/POP setup.

History & Differences in Setups

The Z32's stock setup uses two air filters (pulling air through the fender wells), which combine into a single channel that flows through a single MAF sensor. It then T-s off to the two separate intake tracts, one for each bank of cylinders. But because both intake tracts are routed through a single sensor, it's a bit of a restriction on the stock intake.

The MAF also has a bit of an inherent restriction. It can meter enough air for approximately 500 HP. To get around this, JWT devised their Dual-POP setup for the car.

A JWT dual-pop setup.

The JWT setup runs a single MAF sensor, and has a "dummy MAF" on the side without a sensor, to ensure the intake lengths are even. The ECU is also modified with a doubled (approximately) K-Value. Because the ECU only sees half of the intake air, the doubled K-value makes the ECU inject twice as much fuel for the metered air, so the proper amount is still injected. Also in doing so, this basically doubled the MAF's ceiling to around 1000 HP. Because the MAF is only reading half the intake air, the car can basically inhale twice as much air as on a single POP setup before the MAF hits it's ceiling. Some owners also use an air/fuel controller (which modifies the MAF signal being sent to the ECU) instead of an ECU upgrade.

The downside to this setup is that it's somewhat inaccurate. After all, only half of the intake air is metered. It also requires a "low speed driveability kit" which helps to balance the intake tracts, so that the car can idle properly.

Z1's Low-Speed Driveability Kit. Click for full size.

More recently, Jim Selin released the Selin Dual MAF Translator. This device allows users to run two MAF sensors in parallel. It has two modes, ADD and AVG (average). In ADD mode, the two MAF signals are added together, then sent to the ECU as a single value. This allows even a stock ECU to properly meter both intake tracts, making a totally plug-and-play dual intake kit. In AVG mode, the two MAF signals are averaged, then sent to the ECU as a single value. This is useful for owners who previously installed a JWT-style dual-pop ECU, or those who require the > 500 HP ceiling from such an ECU upgrade, but still want to benefit from the added accuracy of running two MAF sensors (or don't want to install the low-speed driveability kit).

The Selin Dual MAF Translator.	The complete Selin kit installed.