Most catch cans on the market are a can with a fitting on each end and a handful of baffles thrown in. They collect some oil. Under sustained boost with a big ring gap, they also pass a lot of it straight through to the track.
The ASE Outlaw catch can uses four separate separation stages. This article walks through each one and explains why it is there — the same teardown shown in the video below, written out.
Watch the teardown
Why capacity matters more than people think
The job of a catch can is not only to collect oil. It is to keep crankcase pressure down.
Race engines are built with larger ring gaps than street engines, which means more blowby, which means crankcase pressure climbs. High crankcase pressure works against the rings sealing, and an engine whose rings are not sealing pushes more oil past them and more smoke out the exhaust. It compounds.
A larger can volume gives that pressure somewhere to go. The Outlaw holds 5 quarts, which is why it is sized to mount in the rear of the car or in the passenger compartment rather than tucked in an engine bay. It is atmospherically vented toward the rear.
The four stages
Stage 1 — Perforated entry plate
Vapor enters through the inlet port and immediately meets a fully perforated plate under the cap. Nothing exotic here; this is where separation starts and where the incoming charge gets broken up before it reaches the body of the can.
Stage 2 — Drain ramp
Oil vapor and residue that make it past the first plate land on an angled drain ramp. The ramp carries them down and out through slotted holes into the main collection volume. This is what turns caught mist into liquid that actually ends up in the bottom of the can rather than re-entrained in the airflow.
Stage 3 — Stainless wool coalescing section
Above the collection volume sits the only packed section in the can, filled with stainless wool. Fine mist that survived the first two stages coalesces on the wool into droplets heavy enough to fall back down.
Position is the point. This section sits at the highest point in the can, so by the time anything reaches it, all the liquid has already settled below. The wool only ever sees vapor, which is what keeps it from loading up and clogging.
Stage 4 — Dual-stage perforation before the exit
Past the wool, a second slotted plate with smaller holes forms the final stage before the outlet.
The detail that ties it together
Four stages accomplish nothing if incoming vapor can find a shortcut to the outlet. The exit is chambered in its own section, and the top of the perforated exit tube is solid. Assembled, there is no path from the inlet side directly to the outlet — everything is forced through the full sequence. Only hot vapor leaves the can.
Draining it
A standard ball valve sits at the bottom of the can. Most racers put the car on jacks as soon as they are back in the pits, so the practical approach is a single hole in the floor pan with a rubber grommet, a hose down through it, crack the valve, and drain into a pan under the car.
Plumbing and port options
Inlet and outlet can both be configured as -16 AN, -20 AN, or 1.5 inch hose. Most builds use the 1.5 inch hose connection — standard tube and hose is far cheaper to plumb than large AN, and at these diameters the fitting style is not doing anything for flow.
For the firewall pass-through, ASE makes billet plates in single and dual 16AN and 20AN configurations, plus bulkhead plates sized for 1.5 inch hose.
Construction
Every component is precision laser cut and bent from sheet metal, then TIG welded. The modular internal design is what makes the four-stage layout practical to build consistently.
Get one
Outlaw Catch Can — In Car, available as the can alone, with a firewall plate, or as a complete kit with the hose. Running four inlets on a Pro Mod combination? See the Outlaw Pro Mod Catch Can with four 10AN inlets.
Questions about sizing or plumbing for your combination — contact us through the site. We would rather answer before you buy than after.