Refresher: Moroso billet catch cans and intake valve buildup in direct-injected LT engines

Today’s Daily Planet by Planet X Performance

Tech refresher for direct-injected LT owners: the PCV system feeds oil mist back into the intake, and a catch can is one way to cut down how much of it reaches the valves. LSX Magazine covered Moroso’s billet catch cans a year ago.

PCV stands for positive crankcase ventilation. Some combustion pressure always slips past the piston rings into the crankcase, and the PCV system vents those gases back into the intake to be burned. Those gases carry oil mist with them.

The problem: on a port-injected engine, fuel sprays across the back of the intake valves and helps wash deposits away. Direct injection sprays fuel into the cylinder instead, so nothing rinses the valves. SAE research points to engine oil as a major ingredient in those deposits, which can build up over time and cause unstable running.

A catch can, plumbed into the crankcase vent line, traps oil before it gets to the intake. It can reduce buildup, not stop it. LSX describes Moroso’s cans as internally baffled, meaning walls inside slow the air so oil drops out, with billet tops and bottoms and a clockable mounting bracket that can be rotated to fit your engine bay. They also have a replaceable breather element, -AN O-ring fittings (the threaded hose fittings common in racing plumbing) and a petcock drain, a small valve at the bottom. That drain matters, because a can has to be emptied as it fills. They can plumb to valve covers, vacuum pumps or dry-sump tanks. The cans are universal, and LSX doesn’t list LT-specific kits.

A street caution: Moroso’s own page for its single-inlet catch can says it is “not legal for sale or use on pollution-controlled vehicles,” so check your emissions rules before running one on a street-driven car.

Are you running a catch can on your direct-injected LT, and how much oil do you find in it?

Sources

1. LSX Magazine: Moroso billet catch cans
2. SAE: Intake valve deposits in GDI engines
3. SAE: How intake-valve deposits form (1990)
4. SAE: Reducing deposits in a DISI engine
5. EngineLabs: Gen V LT lifter failure and PCV
6. Moroso: Billet catch can, single inlet

Photos: Moroso Performance Products