posted on March 11, 2009 22:00
When evaluating the factory exhaust system on the Nissan 370Z we were amazed how restrictive it was. The tubing diameter of the downpipes is tiny, less than 2" in dimaeter which is really small for an engine with the output of the 370Z's VHR37. Imagine a Sentra SE-R trying to breath though a 2" pipe and that is about whats going on with the 370Z.
To help address this issue we decided to start uncorking the exhaust system by evaluating a set of high flow Catalytic Converters and Downpipes from Berk Technology. In this article, we will performance test these parts on the dyno and show you how to install them, but first let's talk about what catalytic converters are and how they affect your vehicle.
|Berk Technology downpipes feature high quality all stainless construction, pre-cat bungs for wideband tuning sensors, gussets, proper rear o2 sensor attachment and big bore smooth mandrel bends for good flow.
What is a catalytic converter?
Introduced in the mid 1970s, catalytic converters are exhaust parts installed on cars to help clean up exhaust gasses before they are released into the atmosphere. They ingest toxic exhaust stream pollutants, like unburned hydrocarbons, oxides of nitrogen and carbon monoxide created by the engine and converts them to eco friendly carbon dioxide and water vapor.
Catalytic converters are part of the car's exhaust system, usually found right after the exhaust manifolds. The 370Z has two catalytic converters, one bolting up to each exhaust manifold on one end, and the factory y-pipe on the other end.
What effects do catalytic converters have?
Aside from cleaning up your car's emissions, there are a few other issues with catalytic converters. We will touch on weight, and performance. Inside most factory catalytic converters is a ceramic substrate which is where the pollutants are converted into less harmful emissions via an oxidation/reduction reaction. This creates a lot of heat, which requires OEM catalytic converters to have big heavy metal heat shields and heavy gauge construction. OEM cats and downpipe are usually double walled with insulated heat shields as well. All this leads to a very heavy, yet restrictively small part. The Berk Technology high flow catalytic converters and downpipes that we are about to install use a lighter metallic substrate with larger diameter but single wall tubes which will generate less heat and save weight. The Berk parts are also made of a higher grade material, 304 stainless steel to be exact which enables the use of thinner casings and tubing to save even more weight.
|Berk Technology also offeres these solid blow out resistant copper gaskets for high temperature applications like turbos and NOS.
The second issue is performance. The general rule of thumb is, the less restriction an exhaust system has, the more power the car will make. With most modern cars, the use of catalytic converters is not that restrictive to a car's exhaust system. On the 370Z the issue is both restrictive piping and a corked up cat robbing the VHR37 engine of potential power.
The Berk Technology high flow catalytic converters are designed to be much less restrictive than stock, letting you unlock some of that lost power while still serving the function of converting harmful exhaust gasses into something less poisonous. The Berk Technology cats have a 200 cell count spiral wound metallic substrate. The substrate is the catalyst saturated honeycomb-like stuff inside the cat that the exhaust gasses pass though that does the cleaning of the exhaust stream. A metallic substrate has thinner walls with less cross sectional area than the ceramic material used for the honeycomb in most factory cats. Thinner walls mean larger internal passages in the honeycomb and thus less backpressure. Each passage is called a cell and a 200 cell count means that this honeycomb has large diameter cells for low restriction. Stock cats usually have cell counts in the 400 range and thicker walls on the cells making for much more flow restriction.