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ALFA ROMEO - GIULIA / STELVIO - OCC System (oil catch can)
  • GMS OCC (Oil Catch Can) system, the only, plug and play solution on the market, to keep your Giulia / Stelvio petrol DFI engine clean of carbon build-up and potential reliability issues.


    According to the amount of OCC waste the 2.9T V6 engine is generating, this is a very wise choice of the upgrades, regardless of the type of use - daily, track, race. The 2.9T V6 is quite heavy on the PCV (positive crank case venting) waste as the engine displacement is relatively large, the engine runs pretty hot and therfore it generates lots of oil and gas vapours. The OEM PCV is designed to collect the PCV waste from both banks (cyl 1, 3, 5 and cyl 2, 4, 6) and then flow it all into the left bank (cyl 1, 3, 5). That's quite a lot of PCV waste to drain into the intake and one of the main reasons the port injection was added on newer 2.9T V6 engines. Preventing carbon build up and other PCV related issues. For engines without port injection, the OCC is an essential thing, while on updated, port injection engines, it's a highly recommended nevertheless.


    GMS OCC system features filtered, drainable, oil catch can setup for maximal efficiency. All the parts are aluminum CNC'd and incognito black anodized and the entire assembly is prebuilt for plug and play installation.


    What is OCC? OCC is short name for - Oil Catch Can. Relatively simple device that can greatly benefit modern petrol engines, especially newer generation of engine with DFI (direct fuel injection). OCC prevents oil and other contaminants from causing carbon build-up inside the engine and greasy engine bay area. Clean air intake has also reduced chance of engine knocking, commonly an issue on tuned engines with excessive oil vapors in the intake. With GMS OCC system, all this issues are solved.


    How does the OCC work, and why you might care to install one in your own car? Alfa Romeo Giulia / Stelvio with 2.0T and 2.9T V6 engine has a modern DFI engine and a single PCV (positive crankcase ventilation) system that allows the breathing of the crankcase. While the engine is rotating, a pressure is generated within the crankcase. This pressure has to be relieved, otherwise the pressure would build up and push the oil out of the engine, either through the oil pan, oil dipstick or any other path it can find. PCV prevents that by circulating the air within the engine. The PCV collects the oily fumes and vapors circulating within the engine crankcase and separates the oil from air and then returns the partially cleaned air (oil, unburnt gas) back into the intake path where this partially filtered air, then mixes with fresh air and goes through the combustion process, once again. This provides maintenance free and emission friendly system.


    Where is the problem?

    Recirculated and partially cleaned air (oil, water, unburnt fuel) enters in two locations. One is right before the turbo compressor and the second is right after the intake throttle body. The bad thing is, that this partially cleaned air is messing up your engine internals, by traveling through entire intake system. That is why you find oil in charge pipe, charge cooler, intake, throttle body, turbo, etc. Excessive oil in the intake system, significantly increases the chance of knocking due to lowered octane rating, caused by air being contaminated with oil and after time, the engine bay will get greasy as well. Not good and not nice either.


    The second and even more common issue which is especially a concern on DFI engines, is a carbon build-up on the valves. Why? The oily air from the intake, travels through intake valves and exits through the exhaust valves. The exhaust valves are very hot, so most of the oily air burns, but the intake valves are not so hot and so this oily air turns into carbon deposits and sits on the valves and inlet ports of the head, contaminating your valving area with carbon build-up. Older, non DFI engines, injected gasoline before the intake valves, which greatly helped to keep the valves clean, but DFI engines inject gasoline directly into the cylinder, so the valves can not get cleaned by the gasoline and therefore are far more prone to the carbon build-up. Depending of your driving style and the engine oil you are using, your engine starts to build-up carbon deposits, from the day one you turn on the engine. You slowly start losing engine performance as the carbon build-up takes the volume and head flow starts to decrease. In worst case scenario your valving gets filled up with carbon deposits to the point, that the valves cannot operate properly anymore, causing engine issues and lack of performance. There is also a chance, that a chunk of carbon build-up tears off and drops in to the cylinder, jamming piston rings messing up the engine internals, leading to a complete engine failure. Having a quality GMS OCC system installed on your DFI engine, the issues mentioned above are not a concern anymore.


    Why GMS OCC? The OCC itself is not too complicated, but there are some details that are often missing in DIY projects and universal OCC setups. First, it’s the position of the OCC. OCC should be positioned higher than PCV, to prevent the flowback. If the OCC is lower than PCV, than the oil from PCV hoses, once it gets condensed on the wall of the hoses, will have natural tendency to flow to the OCC instead of back to the engine, filling the OCC at much faster rate for no good reason. It's OK and correct to have the oil flowing back to the engine, but not to the intake. With OCC positioned higher than PCV, the condensed oil will flow back to the engine, while the air will get cleaned and pass through the OCC into the intake and pre-turbo inlet.


    Second, it’s the sizing of the fittings and the fittings themselves. There is a reason why OEM PCV uses different size of inlet and outlet ports. Failing to respect this and using same diameter ports all around causes imbalance in flow. We use specific size aluminum AN fittings and reducers to achieve OEM level flow rate.


    Third, it’s the position again. We prefer to keep the OCC away from hot engine parts, to avoid potential fire hazard. GMS OCC is positioned safely and discrete, making untrained eye impossible to notice it.


    A recommended reliability upgrade for street, track and race driven Giulia's and Stelvio's, rated highly on priority to-do list.

    ALFA ROMEO - GIULIA / STELVIO - OCC System (oil catch can)

    PrezzoA partire da € 330,00
      • Aluminum T6-6061, billet, CNC, single 300ml, OCC tank (enough capacity for full day race track use)
      • Safely positioned to prevent potential fire hazard
      • Correctly positioned above PCV to prevent reverse flow of the condensed oil causing excessive OCC fill rate
      • Smart filtering system (baffled, height split and filtered)
      • Dip stick for checking the OCC oil level
      • Twist & drain system for quick draining of the OCC
      • Drain port on the bottom of the OCC for optional bottom oil draining
      • AN, full flow, aluminum, pushlock fittings with specific sizing for correct flow properties
      • Fully serviceable (washable and replaceable mesh filter)
      • Incognito black anodized
      • CNC'd GMS logo
      • Plug and play
      • Lightweight 990g
      • Fits all Alfa Romeo Giulia, Stelvio
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