Gutted cat vs straight test pipe observation on 355

Bought a set of test pipes to replace the cats in my 355 as I was getting some hot temps I thought in my rear engine compartment and wanted to prevent potential fire hazards.

After considerable work removing the cats I found they were already gutted unfortunately, I replaced the gutted cats since i bought the test pipes anyway thinking they might possibly make a difference.

Interesting results, using Peters's infared temp gauge the gutted cats had a temp of 335'-340'F, the test pipes are around 230'F thats almost 100' F cooler, my assumption is the metal in these and airflow are designed to hold heat, the gasses must swirl around in them vs going straight out the back, the test pipes are also significantly louder then the gutted cats as well the car seems to have much better low end response, I would expect this with a fuctioning normal Ferrari cat but not a gutted one

That’s what the kids think: remove the stuff in the cats and find more HP... sorry, no. Any transition from high (in the tube) to low (in the cat) and vice versa is power consuming. That’s what you see with the infrared and fell in the pants. Best is to use conical metal cats with smaller diameter that are better shaped for gas flow. You stay legal and will have only unnoticeable power loss. These cats stay much cooler on the outside.
If you don’t mind look here:
http://www.ferrari-talk.com/discus/m...tml?1158591219

I tried to do these right. Maybe it is a inspiration for your car.

Good job on those

Where I live I am not required to emission test the car as its rural, I am also convinced many so called isues with headers and valves on 355s is cat related from overheating or failure of the cats, even catless I am sure the 355 puts out less emissions driving it all day vs just starting my carb BB and letting it idle for a minute or so.

Theory:: When moving air encounters a larger volume inwhich to occupy, that air will slow down! This slower air has more time to release energy into the container, so the container will get hotter.

Changing air into exhaust gasses, and container into gutted cat and we have the senario above. As the MythBusters woudl say:: Confirmed.

I did notice, when running test pipes, that the engine bay was significantly cooler, water and oil temps went down several degrees at 60 MPH, and it would take significantly longer for the water temp to rise from 185dF to 205dF when transitioning from interstate cruise into city traffic.