Most people know what a catch can does, it provides an area for crankcase gasses to accumulate safely and not cause issues with the engine operation. But we thought we could explain it in more detail, so people can really understand what is happening inside their engine.

Piston rings do not seal 100% and as a result, pressurized gasses from the combustion process will leak out into the crankcase area of the engine, known as "blow by". This is just a fact of our modern internal combustion engine. Pressurizing the crankcase is, of course, not desireable. It can lead to blown out crank seals, oil leaks, etc. So the crankcase gasses have to be vented through the PCV system, which recycles the air back into the intake stream. The vented gasses contain oil vapor that, if not dealt with, can coat the intake tract of the engine with oil and sludge.

Our innovative catch cans have been lurking in the depths of our website for sometime now and we thought now would be a good time to shed some light on their design aspects.

Radium Oil Catch Can

These beautiful components are machined from 6061 billet aluminum, vibratry deburred and then anodized and laser engraved. It is a two part design, with a removable bottom that can be unscrewed and easily drained.

-Increased engine performance through cleaner inlet air
-Prevents oil buildup in the intake or intercooler system walls, throttle body, and intake manifold
-Excessive oil collection can be an indicator of a damaged engine
-Lowers hydrocarbon emissions
-CNC billet 6061 aluminum
-Powder coated aluminum mounting bracket
-Anodized & laser engraved finish
-O-ring sealed two-piece design
-Integrated oil separator
-Canister body unscrews for easy dumping of fluids
-Stainless steel cleanable and reuseable filter media
-Safe to use in pressurized applications
-Accepts 7/8-14 (-10AN) fittings
-Capacity: 8 fluid ounces
-Height (without fittings): 5.75 inches Outside Diameter: 2.45 inches

How does the oil separation in the Radium Engineering catch cans work? Keep reading to find out....


Gasses enter the catch can through the top port and immediately pass through a stack of stainless steel condensers. These provide surface area for the hot oil vapor to cool and condense. This creates a phase change within the oil makeup converting it from a gas to a liquid. All of the liquid oil collects and drips down to the bottom of the canister. Remaining gasses continue through the catch can chamber where they slow down allowing time for more oil vapor to condense on the interior surface walls. Then "clean" gasses exit through the front port and back into the engine's intake stream.

Close up view of flow analysis, showing only 1 condenser disc.

When designing our turbocharger kit for the Lotus Elise, we searched the market high and low for a catch can with built-in oil separation, removable fittings, the ablility to handle turbo boost pressures, and contained in a small package. We did not find any that matched our criteria, so we designed our own. While this was originally designed for the Lotus Elise, it is a universal part that can be used with any engine. It has the flexibilty to be plumbed with -AN fittings, or traditional hose barbs.

We recently designed a kit specifically for installation on the Lotus Elise/Exige. Shown below is the kit which consists of mounting bracket, two Radium catch cans, fittings and hoses.

Dual oil catch can kit for the Lotus Elise/Exige

Installed on a superchaged Exige. Also compatible with all Elise models.

The RADIUM Engineering Lotus Catch Can kit includes all of the necessary hardware including a laser cut mounting bracket that uses 2 factory M6x1mm threaded holes on the Toyota 2ZZ-GE valve cover.
If you have a superchaged Exige, pop off an intercooler pipe and look down into the bottom of the intercooler. See oil? You need some catch cans. Cars driven at high RPM for extended periods of time (such as track driving) will see more blow-by than a normal street engine. For this reason, catch cans should be a mandatory upgrade on track cars.

Depending on the engine configuration, multiple oil catch cans may be required. Two oil catch cans are required for the Toyota 2ZZ-GE crankcase ventilation system.

One of the Radium oil catch cans is used for the valve cover breather hose. After condensing the oil vapors, this hose is routed upstream of the throttle body (or turbocharger). Depending on the throttle position and the positive crankcase ventilation (PCV) valve, the flow through this oil catch can will freely move in either direction.

The other Radium oil catch can is mounted inline with the PCV hose. The PCV is a one way valve that allows crankcase pressure to discharge through the catch can, condense and seperate the oil vapors and then vent into the engine while the intake manifold is in vacuum (throttle closed). When the throttle opens, the PCV closes and boost (if equipped) will pressurize this specific Radium oil catch can. This is why catch cans should be sealed units, especially in boosted applications. Our catch cans use o-rings on all three ports.

This kit is available now, click here for details: Radium Store

We hope this has been helpful in understanding more about our catch cans and all the function they provide in a small package.