DIY: Catch Can for 6th Gen Accords

^^ I don't agree. That's why we don't have catch cans. we have PCV's. But they don't work as good as they are supposed to. That's why Honda thinks we should change this every 3k miles. Its purpose is to remove the air in the crank and head while not allowing oil to pass by, but as we know some does get through. The way AFACCORD has his allows more oil to be vacuumed though the left side because its just a hole, nothing to block oil from being sucked through. I'm thinking about getting it drilled out to where you can put a rubber seal along with a PCV just like the other side, then setting up the catch can like AFACCORD has it.

SOMEONE POST PICS OF IT ON A v6... grrrrrr


its not hard to do, i just want to see where people have it mounted w/o using 4ft of hose lol caz that ziptie to strut bar is fugly

PSYCO G 305 said:

^^ I don't agree. That's why we don't have catch cans. we have PCV's. But they don't work as good as they are supposed to. That's why Honda thinks we should change this every 3k miles. Its purpose is to remove the air in the crank and head while not allowing oil to pass by, but as we know some does get through. The way AFACCORD has his allows more oil to be vacuumed though the left side because its just a hole, nothing to block oil from being sucked through. I'm thinking about getting it drilled out to where you can put a rubber seal along with a PCV just like the other side, then setting up the catch can like AFACCORD has it.

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Honda's interval to CHECK the PCV valve is 30,000 I believe.

The technically correct way to do this would be to either have a breather filter on the left orfice, or have it connected to the intake. Honda intended that orfice to allow fresh air to enter, while the PCV valve draws air out, effectively flushing the contaminated gasses out with fresh air.

My concern is that at idle, that left orfice is actually expelling the contaminated gases, and if connected to the intake, would be contaminating the intake charge. On the other hand, with a breather filter air would be allowed to enter or exit as it pleased, but the filter would likely get very dirty very quickly on the inside if there were significant amounts of oil being expelled from there.

You also have to understand, that I drove over 700 miles with this setup, and barely had 1/8" of oil accumulate in the catch can. Like I said earlier, 75% of what's in there was the result of mulitple passes at the drag strip.

Isn't the whole to keep air/gases out of the crank and head so there is no pressure?...

The design isn't to keep air out, it's to prevent that area from becoming pressurized. You actually want to keep it at slightly less pressure than the atmosphere to help the contaminated gasses escape. That hole allows fresh air in to flush out the blow-by gasses.

Ok first off, sorry for the dirty engine bay and shadows on these shots - the sun was at a bad angle.

Second, I didn't make the DIY catch can - I bought one, but I just hooked it up today.




You can see how I ran the hoses - PCV --> Can (near CAI) --> IM.
The catch can intake and corresponding hose is lower than the PCV valve, but catch can outlet and corresponding hose is higher than IM inlet. This doesn't matter really in my case, because I just need vacuum - no oil will go to IM anyways due to distance of can.

Next I explored the hoses again. Mainly the hose that comes off CAI --> left valve cover hole. My theory was correct! There is no way that oil is coming out of that hole ever due to a strong vacuum being pulled into the left valve cover hole.

Conversely, the PCV (center) hole on the valve cover has pressure pushing out of it (air, oil, gasses, etc).

In conclusion, I think that connecting both of those holes and running them to IM is an incorrect way to hook it up, because left hole draws air (vacuum) as opposed to center hole pushing air out (hence functionality of catch can).

The left hole is hooked up to an intake source to draw in clean air. If you hook it up with recirculated air/oil/gasses, it hinder functionality of it's original intent.

AFAccord said:

You also have to understand, that I drove over 700 miles with this setup, and barely had 1/8" of oil accumulate in the catch can.

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This I think may be due to recirculation of oil coming out of center hole and going in through left hole, due to the vacuum. Furthermore, this could be the case because the IM line is at a 90 degree angle to both of the other lines, which are straight towards each other. The IM line and left hole line are both fighting for suction from the PVC center hole, and left hole is winning due to the angle.

AFAccord, would you agree with what I'm saying? It sounded like a good idea to hook it up like you did at first, but after looking at it I don't know if that's the correct way. What do you think bro?

I agree with Russian. With both holes connected like that, you are simply circulating gasses until there is positive pressure in the VC, in which case high pressure moving to low pressure, vapors would finally move towards the catch can. WOT increases vacuum tons and, you mentioned the drag strip, is probably why you caught all that oil. Any oil you get from driving without WOT is probably just oil condensate running through the hose.

Sorry if that makes no sense at all... It's been a long day at work and I'm tire. Weekend woot!

So where saying that the left hole is allowing fresh air in so the PCV can bring air and gas mix out?... makes sense but when the left hole is connected to the intake system it still has somewhat a vacuum instead of air being pulled in the head.

Finch, what you said makes sense.


Psyco..

PSYCO G 305 said:

So where saying that the left hole is allowing fresh air in so the PCV can bring air and gas mix out?... makes sense

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Correct.

PSYCO G 305 said:

but when the left hole is connected to the intake system it still has somewhat a vacuum instead of air being pulled in the head.

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Rephrase this - I do not know what you are trying to say. The vacuum you are talking about is from where to where? The only vacuum present is the suction into the valve cover through left hole. This causes the fresh air (from the intake hose connection) to be sucked into valve cover. Not the other way around. The air intake hose does not cancel or reverse the suction being created by left hole of the valve cover. I think you are trying to say it creates more suction, and the air ends up in the throttle body? This is incorrect.

Here:

Under normal conditions with AFAccord's setup, this is what I expect:



Under WOT (drag strip) conditions, this is what I expect:



This is what the correct hose routing should do: