Intake Plenums

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Intake

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Parts

The plenum is the chamber located between the runners of the intake manifold and the throttle body (on top of the engine). The OEM plenum is actually made of 2 parts: lower and upper. It has been shown through countless tests that increasing the internal volume of the plenum yields significant horsepower (up to 20!). This can be achieved by either:

installing a plenum spacer
installing an aftermarket upper plenum
custom machining work on the lower plenum

1 Overview
2 Upper Plenums
3 Lower Plenums
- 3.1 Nissan 2005 Plenum
4 1 Piece Plenums
- 4.1 Cosworth Twin Plenum

Overview

The stock plenum slopes down towards the front of the engine. Nissan designed this in order to clear the stock strut bar and hood on the 350Z (function after form). This sloping design restricts the airflow to the front cylinders, but an aftermarket plenum can help those front cylinders breathe. Aftermarket plenums either increase the overall height or remove the downward slope in the design, allowing more volume and greater airflow to all cylinders. Higher airflow is needed to achieve more power. Some companies are offering plenum spacers that utilize the stock plenum but still increase the overall volume and may alleviate the downward slope. Still others are offereing entire intake manifold replacements (upper and lower plenums). Personal preference and modding goals will play a part in which plenum is best for you.

Note: Some aftermarket plenums will cause you to loose the stock strut bar, however some offer a custom strut bar for those that wish to have one. Strut Bars

Addendum: The stock plenums on the HR (07+) engines have been revised, so an aftermarket plenum is unnecessary.

Upper Plenums

The upper plenum is the easiest to change out and provides good power gains. The stock forward sloping upper half starves the front cylinders out of much needed air. Below are the currently available upper plenums on the market.

APS Tall Boy Plenum

List Price: $499.00
Found For: $390
Design: Upper Plenum
Material: Aluminum
Application: N/A or F/I
Manufacturing: Casting
Notes: special strut bar needed, cast finish
APS

Crawford Plenum

List Price: ----
Found For: $350 / $550
Design: Upper Plenum
Material: Aluminum
Application: N/A or F/I
Manufacturing: Casting
Notes: special strut bar needed, powdercoated black, polished +$200
Crawford

Kinetix Molded Plenum

List Price: $399.99
Found For: $299.99
Design: Upper Plenum
Material: smooth, hi-temp, plastic.
Application: Bolt-On, N/A only
Manufacturing: injection molded
Notes: Stock strut bar clears, New V+ is stronger for FI application
Kinetix

Lower Plenums

Nissan 2005 Plenum

Image:Nissan 2005 Lower Plenum.jpg

List Price:
Found For:
Design: Lower Plenum
Material: Aluminum
Application:
Manufacturing: Casting
Notes: comes standard on 2005+ models, increases air flow to front cylinders
Nissan

1 Piece Plenums

Cosworth Twin Plenum

[1]

Image:Cosworth Twin Plenum 2.jpgâ€Ž

List Price: $1,313
Found For: $
Design: 1 Piece Plenum
Material: Light Weight Aluminum Alloy.
Application: Bolt-On, N/A or F/I
Manufacturing: Cast
Notes: Cosworth has engineered this manifold for the VQ35DE engine. It features increased plenum volume which improves high rpm power and torque enhancement from velocity stacks that maintain mid-range. Computational fluid dynamics analyzed from many hours of development have been utilized to perfect air flow into the combustion chambers making this ideal for N/A or F/I applications. This 1 piece part is cast from aluminum alloy and has carbon fiber end caps. This comes with all installation hardware and can be used with the factory fuel rail system or the Cosworth High Volume Fuel Rail kit for added performance. Stock strut bar fits on top of this for both Coupe and Roadster.