Tech blog: Converter cell basics

So you are looking at a performance converter to pass that annual emissions test but to free the performance that your OEM converter is restricting. Or maybe you just want to improve reliability and have a cat for the rest of your car’s years. You will have to make a choice between several alternative cell alternatives. Here’s our basics guide to converter selection.

1. There are two basic cell types – ceramic and metallic. Ceramic is the OEM choice for 99% of vehicles on our roads. It’s cheap to manufacture and does the job unless something strange happens. That can be a misfire, a bump from a stone on a countryside road or simply too many years on the unit. By looking at a converter, you always spot the ceramic cell for the brick wall appearance. The shape of the cells is square and the cells are located in neat order. Here is a picture of a ceramic cell.

The other alternative is a metallic cell. A metallic cell in general withstands a great deal more abuse in both thermal load and impact. If manufactured with the highest standards, it will also have a much longer operating life expectancy. You will recognize a metallic cell from a spiral construction where the cell rows are twisted over a center point. Here is an example picture.

2. The converters are classified by a mystical numerical value, which most sales people don’t even understand themselves. 200-cell, 300-cell, 100-cell, they tell you. This number is an industry standard for the density of cells within the converter. A “200-cell” converter is really any converter, which has a basic cell structure with 200 cell units in a square inch area. Now this is pretty difficult for you to actually measure, but for an idea we present three different metallic converters with different cell densities.

In the above picture we have a Magnaflow metallic converter, the cell density of which is not public. My educated guess is around 400 cpsi (cells per square inch). This will flow well in most tuner applications and warm up for emissions cleaning purposes very quickly.

Here is our sample two, which is a 200 cpsi FIA approved metallic converter of Finnish origin, as used in our race converter applications. You notice the cells are physically larger with less cell units per covered area.

And finally the last sample, a 120 cpsi large diameter converter cell for the most extreme applications, such as Rallycross Supercars. Again you can notice a larger cell size and less cell units per area.


The actual flow ability is a combination of overall area and cell density. The emissions cleaning efficiency on the other hand is a combination of cell density, area and the quality and quantity of the precious chemical metals used to coat the cells.

If you need any help choosing the right type of converter, feel free to contact us. We stock every variation and ship worldwide. Customer service is always included!