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Catch Can Install

If you want to keep your intercooler working at peak efficiency and keep the entire intake tract clean inside, installing a catch can is the way to go. Pressure is built up inside the crankcase by the movement of the pistons, blow-by, etc. Without a way to relieve this build up of pressure inside the crankcase, it would make short work of the weakest links, like seals and gaskets. Oil dip sticks popping out on modded DSMs is a very common occurrence...guess what causes it? The Positive Crankcase Ventilation (PCV) system is the "vent" for this build up of pressure inside the engine. The problem is, the gases vented through the PCV system contain oil vapors and they are dumped back into the intake system to be burned. Since they are rerouted back in to the intake pipe of the turbo, over time, everything between the turbo and the cylinders will get a build-up of oily residue. Even worse, charged air containing the oil vapors is condensed through the intercooler and much of the oil will build up inside the FMIC. A catch can "catches" oil vapor before it is sent back to the intake pipe, substantially reducing the amount of oil that can build up inside the intake tract and winds up a greasy mess inside everything between the intake pipe and intake valves. There are a few ways to setup a catch can, however, since the majority of crankcase pressure and blow-by occurs during boost/high RPM, we will be installing our catch can the "usual" way: using the heavy vacuum created in the MAS hose/pipe by a spooling turbo to pull vapors out of the valve cover.

1. We are installing a WeaponR catch can that is specific for the Evo 8. This catch can fits nicely inside the center of the stock (or most triangulated) strut bars. Other universal catch cans will be connected to the engine in the same manner, but mounting options will obviously vary from can to can and car to car. NOTE: In addition to the supplied clamps, having two extra clamps and/or some tie straps would be recommended.
2. Prior to installing the WeaponR catch can, the rubber boot must be removed from the stock strut bar to make room for the can. The stock strut bar does not need to be removed to this, however, we removed this one to show you how to do it. There are 4 rubber "snaps" that hold the piece together. Simply "unsnap" all of them and then remove the boot from the bar.
3. Remove the (2) 14mm bolts holding the strut bar to the firewall. The WeaponR catch can will bolt over the strut bar using these factory bolts.
4. Prior to installing the catch can, you may need to remove the drain bolt to allow the can to be angled into the center of the strut bar (top). Note to step 5
5. Angle the catch can backwards to get mounting bracket between the strut bar and overhang of the cowl. With the bracket in place against the mounting point, lower the body of the can into the middle of the strut bar (bottom). Replace the drain plug in the bottom of the catch can.
6. Reinstall the (2) 14mm mounting bolts through the catch can bracket and through the strut bar to attach both to the firewall. No specific torque specs were found in the service manual for these guys, so use your best judgement ;) After the bolts are tightened, grab the can and firmly push/pull to tweak the position so that it sits inside the middle of the strut bar without touching it (that would make one annoying rattle). Also ensure that the barbs are high enough to allow clearance of the hoses over the strut bar.
7. Plumbing the can is relatively easy. One barb from the catch runs to the barb on the valve cover (circled) that connects the vent hose to the MAS intake hose/pipe (top). With the hose connected to the barb on the catch can, route it as you wish to the front/right side of the valve cover. Remove the stock hose from the barb. Cut the hose from the catch can to the appropriate length and attach it to the barb on the valve cover (bottom). Note to step 8
8. NOTE: The supplied clamps are likely supposed to be used here and on the MAS hose/pipe connection (no instructions included). This type of vinyl tubing becomes extremely pliable once heated, so we recommend clamps on all hose connections to prevent leaks. If you do not have extra clamps on hand, we would at least recommend using tie straps to hold the hose to the catch can barbs (which are a tighter fit) and use the supplied clamps on the valve cover and MAS hose/pipe connections.
9. Now we need to make the connection at the MAS hose/pipe. You can follow the hose you disconnected from the valve cover down to locate its position on the MAS hose/pipe (facing backwards just under the BOV) if it's not plainly obvious (top). Note to step 10
10. Using the remainder of the supplied hose, clamp one end on MAS hose/pipe barb after removing the stock hose (bottom).
11. All that needs to be done now is to run the hose from the MAS hose/pipe connection to the other barb of the catch can. Again, route the hose as you wish, leaving adequate clearance around the waterneck and lower radiator hose. Cut the hose to length and attach it to the barb on the catch. When all hoses are connected, tie strap them to keep them in place and you are done!
12. To recap, the two hose connections to the catch can are shown. In essence, all this work simply replaced the stock hose between the valve cover and the MAS hose/pipe with the catch can. Oil vapors will now accumulate inside the can instead of being redirected right into the intake tract. If your catch can does not have a sight glass, drain the catch can during every (or every few) oil changes, depending what your situation dictates. And remember, all the oil you drain out of the catch can is oil that would've been building up inside the intake tract!

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