Catch can tech, how to, theories, and install on S2000

Catch can tech, how to, theories, and install on S2000

Lets talk catch cans, and why you need one.  A catch can, put simply will help relieve excess crank case pressure that has built up in your engine. This excess pressure is caused by blow by. Blow by is the small amount of air that will sneak past your piston rings during the compression stroke of the engine. All engines get blow by, new and old. This is why all cars come equipped with a PCV (positive crankcase ventilation) system installed form the factory. However, the more performance you squeeze out of your car, the more likely this OEM system will no longer be adequate. This is why you will want to upgrade to a catch can style setup that will be more suited to the needs of a more powerful engine, or an engine that lives high in the RPM’s. The problem with a factory PCV set up is that it is designed to take those gasses/vapors caused by blow by and feed them back into the engines intake manifold/intake tube which then gets burned up during the combustion cycle, and is turned to exhaust and blown out the car. This is a save the planet way of getting rid of blow by, however this will have some negative effects on the engine.

  1. Crank case vapors are filled with oil, spent fuel, and other gasses that will actually lower the octane of the gas you are feeding to the engine, thus lowering over all power, or in extreme cases can cause knock/detonation which can be detrimental to a high horsepower/performance engine.
  2. Will cause your intake manifold, throttle body, valves, and fuel injectors (if you have port injection) to get black tar caked all over the insides, and building up deposits on the top of the valves. Which of course will rob your car of power.
  3. Can cause excess oil to flow out of the PCV and get burned in the combustion chamber (causing your car to smoke). The S2000 is notorious for this under hard right turns.
This is where a catch can comes in to play. Catch cans are a very touchy subject for a lot of people that have very strong opinions about which one is right for you, or if you need one at all. The goal of this article is to help you understand more about what they do, the different types of set ups, if you need one, and how we set it up on Patricks s2000.
Starting off, there are basically two different types of setups you might run…With out getting into systems that use electric pumps to suck out the pressure, or systems that tap into the exhaust and use a Venturi effect to “suck” the gases out. These will be more complicated to set up, and are not typically what the average enthusiast is running. The average person will use one of the two below.
  1. One that is vented
  2. One that is recirculated
A vented one will have a filter on top of the can, and will rely on the forces of the crank case pressure built up and atmospheric pressure to expel the gasses. This is why vented set ups use a larger diameter hose, or even multiple ones to help reduce any sort of restrictions when evacuating the gasses. The less resistance the gasses have to escape, the quicker and easier it is for them to escape.
For a recirculated set up, it will use the vacuum of the intake systems to draw the gasses out. This is pretty much what the set up is that your car comes from the factory with. Except you would put a catch can in line between the valve cover, and the intake manifold. Since there is a vacuum pulling the air out, the lines can be much smaller. Again which is why the OEM PCV set ups have much smaller hoses.
I would say that the majority of people will use the vented one. This method seems to be best because you are not recirculating any of that contaminated air back into the engine which could potentially lower engine performance, and the fact that engines at WOT (wide open throttle) create little to know vacuum. So even if it was recirculated there would be no vacuuming sucking out the vapors anyway, and you would be just relying on the pressure building up to expel the gasses/vapors. There are some people that believe that you must have the can mounted above the engine to stop it from filling the catch can to quickly. But I think there are a few to many variables with the theory, and thus you should just do what works best for you. To properly set up a vented system you must cut all connections of PCV, or valve cover venting to the intake tube, or intake manifold, and remove the PCV completely. This will ensure you are not getting any “contaminated” air sucked into your engine, and all your getting is fresh air. Yes, there are companies that have very high quality filters, and baffle systems in their catch cans, that will cut down on the amount of “contaminated” air that is recirculated back into the intake system, but I feel that the best thing is to just let it vent to the atmosphere.
There are different reasons for running different types of catch can set ups. Turbo, supercharged, NOS, or maybe your motor is just notorious for having blow by. The set up you chose to run is completely up to you and what ever you think will work best for your situation. Remember that either way, the goal of the catch can is to help relieve the built up crank case pressure. Crank case pressure during extreme conditions can cause you to blow out seals, can rob your motor of power, and can even harm an engine. The reason you see really high horsepower cars, race cars, or track cars with catch can set up’s is because they are subjecting the engine to extremely strenuous conditions that it wasn’t designed to run in. Prolonged high revving and super high boost pressure that stock engines weren’t designed to do, like when you put a turbo on a stock motor that was N/A from the factory.
I must warn you though, if you are planning on doing a catch can in your car purely for the fact that it “looks” cool. This is a stupid idea because an actual catch can set up will cost at least a few hundred dollars, and won’t actually help do anything for you if you just drive your car normally on the street. You will look like an idiot, and when people that actually know about racing see what you did they will laugh. Also please don’t buy the cheapest catch can you can find on amazon, buy something that has been engineered, and has baffles and filters in it. Its not so bad if you’re running a vented setup, but if you run a recirculated one then these cheap cans will just allow the oil vapors to flow right into your intake system. Which is why you put a catch can on in the first place… to eliminate oil vapors going into your intake system. But in all seriousness please install quality parts.
Now lets go through how we installed one on Patrick’s S2000.
He ordered a Radium dual can setup, with breather setup to vent to atmosphere. -10 push lock fittings, and push lock hose. On the S2000 AP2 the PCV is on the valve cover and is threaded so you can simply un-thread and thread a -10 bung into it. This is a very easy set up. unlike most B/D series Honda’s the S2000 does not have that black box on the back of the block that the PCV comes out of which makes a catch can set up for S2000’s very easy.
you can see above the -10 blue bung threaded into the old PCV hole.
This is what the car looked like before we installed the catch cans. Keep in mind that he had just swapped this motor in, and the “catch can” set up on the car in this picture was merely there to catch anything while he drove to my house.

So start off by removing the intake.


Rigby loves being right in the center of the action.


This is what the Radium 2 can set up looks like, Its such an amazing piece. The quality and craftsmanship is amazing!


Next you are going to want to test fit all the lines and make sure you have proper clearance for the intake once its reinstalled. As you can see in the picture above everything is just getting test fitted, nothing is bolted down.


Here is Patrick measuring out the hose length before cutting.


Rigby being in the way again


We marked where we wanted the holes to be drilled to mount the bracket.


Here is what it looks like with both holes drilled.


Next we used a Nutsert tool to add threads so we just use a bolt to tighten the bracket down, no need for a nut. This tool works like a rivet tool, you thread a nutsert on to it, insert it into the hole, and then squeeze like you would with a rivet tool.


Here is what the hole looks like with the Nutsert installed. As you can see our once thread-less hole now has threads. This is a very handy tool.


Here is the bracket and catch cans all bolted in.



Here it is with the lines all installed. As you can see the original PCV was removed and replaced with a -10 bung threaded in, then we just ran a fitting off that threaded bung to one catch can. (so there is no more PCV on the motor) its just a line to a catch can with a breather. and the other valve cover vent that originally went to the intake is now ran to the other catch can. So there is two -10 lines ran to two separate catch cans providing all the crack case ventilation.


As you can see above on the intake manifold there is a green plug where the hose once went for the OEM PCV. Which has now been removed, so now there is no more “contaminated” air going in the motor.


Here it is all put back together. As you can see the nipple coming off the intake has been capped. (note the radiator cap being off has nothing to do with it, we were just re-bleeding his coolant system)



My dog Rigby loves to hang out with us in the garage! he doesn’t care how hot it is outside.

A couple of things to note from this install… Yes the catch cans were mounted at a slight angle so the dipsticks that come with the radium cans wont read accurately. This was not an issue for Patrick since he is frequently maintaining his car, for someone that wants to set it and forget it they might want to make sure they are mounted level. Its also worth noting that radium makes a S2000 kit, but that would require removing cruise control which he did not want to do. Although I did give him a hard time about why he needed cruise control in a race car.

Finally, if you set up a catch can on your car by welding bungs to the valve cover but still have the PCV connected to the intake manifold/tube you are only half way helping. Yes you are venting extra crank case pressure, but you are still getting that “contaminated” air going into the engine thru the OEM PCV. its best to not have anything get sucked into the intake system except only fresh air.

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