Catch Can - Motion Raceworks

[GCguy2169]

Motion Raceworks only has one catch can at the moment, and that’s what I have. It is the new Cleetus Freedom Edition of that helps.

I suppose I am confused hence my post, that if you capped the valley the air in the lower portion of the engine below the pistons would pressurize and thus overtime blow out seals. Either the front or rear main. An improperly vented engine with too much pressure can leak and I want to avoid that.

If you look at almost every catch can on the market, they all connect the same way.
1. Mount Can
2. Run line from valley to input port on can.
3. Run line from output of can, to clean side at the intake.

However, this can from motion must be different. They are stating to cap off the valley vent, and intake vent, and strictly vent the valve covers. That means I’ll have to Capp those off and vent just my valve covers to both ports on the Motion Raceworks can. That’s easy and can be done.

What concerns me, is by capping off the valley is the pressurized air. If it’s a non-issue then I don’t need to worry. But it’s just odd to me that every catch can on the market just about vents differently than what I was told by Motion Raceworks.

I’m not trying yo avoid their recommendation by any means, but I’m one to check on this before hand regardless. You can’t exactly run back to the manufacturer and state “you told me yo do it this way and now my engine…” It needs to be done right so I’m just pretty confused.

[Badbubba]

Originally Posted by GCguy2169

Motion Raceworks only has one catch can at the moment, and that’s what I have. It is the new Cleetus Freedom Edition of that helps.

I suppose I am confused hence my post, that if you capped the valley the air in the lower portion of the engine below the pistons would pressurize and thus overtime blow out seals. Either the front or rear main. An improperly vented engine with too much pressure can leak and I want to avoid that.

If you look at almost every catch can on the market, they all connect the same way.
1. Mount Can
2. Run line from valley to input port on can.
3. Run line from output of can, to clean side at the intake.

However, this can from motion must be different. They are stating to cap off the valley vent, and intake vent, and strictly vent the valve covers. That means I’ll have to Capp those off and vent just my valve covers to both ports on the Motion Raceworks can. That’s easy and can be done.

What concerns me, is by capping off the valley is the pressurized air. If it’s a non-issue then I don’t need to worry. But it’s just odd to me that every catch can on the market just about vents differently than what I was told by Motion Raceworks.

I’m not trying yo avoid their recommendation by any means, but I’m one to check on this before hand regardless. You can’t exactly run back to the manufacturer and state “you told me yo do it this way and now my engine…” It needs to be done right so I’m just pretty confused.

The bottom end, under the pistons (crankcase), is not sealed off from the top end (heads/valve area). They "share" the same air. There are return oil paths, open areas, that return oil back down to the oil pan from the valve, camshaft and timing chain area. So any pressure will be equalized in all these areas. I'll supply some info about the oem pcv system for a LS3. Air circulates from the clean side: the hard line goes from the intake tube, to the passenger side valve cover, through the passenger side valve/head area, down into the crankcase, up through the valley cover to the port, (this is now the dirty side), then a small line connects the valley cover port to the port on the intake manifold. The vacuum in the intake manifold is what actually pulls the air through pcv system. The intent for this system was to capture and burn any vapors in the crankcase and not allow these emissions to vent to the atmosphere. A benefit from this, besides emission control, was fresh air circulating through the system and not allowing contaminated vapors from staying in these areas. Which if mixed with condensation, could create acids. That is why oil has a TBN, total base number, to combat any acids. The downside of the system is that the intake manifold will pull these contaminated oil/blow by vapors into the intake. Thus a correct catch can is added between the valley cover and intake manifold. But at higher rpms, you lose the vacuum effect. When the throttle body opens, the differential pressure between the clean side and dirty side port is almost equalized. Therefore, very little air is now circulating through the normal route of the pcv system. And at these higher RPMs, there is more blow by, thus creating more crankcase pressure. So now the pressure builds and pushes through the dirty side. And if there is enough pressure, will push back through the clean side. So a catch can can be added to the clean side as well. But if the dirty side and clean side can not process enough of the vapors, then crankcase pressure can build and cause leaks at the rear and/or front seal. A solution to this is to replace the oil filler cap with a check valved breather. Such as one from CFM. Which allows excess crankcase pressure to vent, but not to allow fresh air into the system. The Motion can configuration eliminates the factory air flow through the crankcase and provides a vent to atmosphere at all times. Some may see this as a negative, since contaminated vapors are not evacuated from the crankcase. It appears the can portion is to capture any vapors from exiting the breather or saturating the breather filter element. If a Motion can is used, I would block off the clean side too. Since it would now be a parallel path. And possibly change the oil more frequently.

[1LE_ROLL]

I’ve had the motion can on for about 6 months since my cam install, I have been to the drag strip a few times and definitely go to Mexico and have had no issues. Changed the oil once at 3k and it looked fine. Clean side is blocked off, valley port and port on intake are blocked off. I ran 3/8 hose from both covers to the can, I bought these fittings off Amazon to adapt to the hose size and they worked fine.

[GCguy2169]

Originally Posted by 1LE_ROLL

I’ve had the motion can on for about 6 months since my cam install, I have been to the drag strip a few times and definitely go to Mexico and have had no issues. Changed the oil once at 3k and it looked fine. Clean side is blocked off, valley port and port on intake are blocked off. I ran 3/8 hose from both covers to the can, I bought these fittings off Amazon to adapt to the hose size and they worked fine.

Yes! I bought the exact same things. My mind is just blown that you’d have to cap off the valley. I thought that was the primary source of oil vapor. I’m glad you’ve set it up and ran with it this long. I feel confident now that it will be ok!

[GCguy2169]

Originally Posted by Badbubba

The bottom end, under the pistons (crankcase), is not sealed off from the top end (heads/valve area). They "share" the same air. There are return oil paths, open areas, that return oil back down to the oil pan from the valve, camshaft and timing chain area. So any pressure will be equalized in all these areas. I'll supply some info about the oem pcv system for a LS3. Air circulates from the clean side: the hard line goes from the intake tube, to the passenger side valve cover, through the passenger side valve/head area, down into the crankcase, up through the valley cover to the port, (this is now the dirty side), then a small line connects the valley cover port to the port on the intake manifold. The vacuum in the intake manifold is what actually pulls the air through pcv system. The intent for this system was to capture and burn any vapors in the crankcase and not allow these emissions to vent to the atmosphere. A benefit from this, besides emission control, was fresh air circulating through the system and not allowing contaminated vapors from staying in these areas. Which if mixed with condensation, could create acids. That is why oil has a TBN, total base number, to combat any acids. The downside of the system is that the intake manifold will pull these contaminated oil/blow by vapors into the intake. Thus a correct catch can is added between the valley cover and intake manifold. But at higher rpms, you lose the vacuum effect. When the throttle body opens, the differential pressure between the clean side and dirty side port is almost equalized. Therefore, very little air is now circulating through the normal route of the pcv system. And at these higher RPMs, there is more blow by, thus creating more crankcase pressure. So now the pressure builds and pushes through the dirty side. And if there is enough pressure, will push back through the clean side. So a catch can can be added to the clean side as well. But if the dirty side and clean side can not process enough of the vapors, then crankcase pressure can build and cause leaks at the rear and/or front seal. A solution to this is to replace the oil filler cap with a check valved breather. Such as one from CFM. Which allows excess crankcase pressure to vent, but not to allow fresh air into the system. The Motion can configuration eliminates the factory air flow through the crankcase and provides a vent to atmosphere at all times. Some may see this as a negative, since contaminated vapors are not evacuated from the crankcase. It appears the can portion is to capture any vapors from exiting the breather or saturating the breather filter element. If a Motion can is used, I would block off the clean side too. Since it would now be a parallel path. And possibly change the oil more frequently.

The worlds most in depth post on the PCV system right here! Thanks so much for this information!

[Badbubba]

Originally Posted by GCguy2169

The worlds most in depth post on the PCV system right here! Thanks so much for this information!

Just wish I had a qwerty keyboard whilst typing, lol.