Wonder if it would be any benifit plumbing this filter out behind the front bumper....
might be cooler there vs. the engine bay..

 

Spin:

Which breather would fit better?
Small
http://cgi.ebay.com/NEW-Breather-Air...QQcmdZViewItem

Medium
http://cgi.ebay.com/NEW-Breather-Air...QQcmdZViewItem

 

No clue, guess you'd need to measure the tube that's there...or if you extend it, the one you use. Anyone else know?

 

In the seventies (yeah I'm 'old') we used to put a 'reducer' into the vacuum line that ran to the EGR (Exhaust Gas Recirculator) Valve. We used a reducer instead of just disconnecting it to keep the fuel mileage from dropping too far. The reducer sent less vacumm to the valve and the valve did not open all the way. The reducer gave the best compromise of increased performance AND decent mileage.

The EGR dumped already burned gases back into the manifold and then the combustion chamber, (like putting water on a fire). this actually served TWO purposes - One was to recirculate any 'unburned' gases that might be left and Two was to take up VOLUME in the combustion chamber, this actually helped fuel economy because less fuel/air was required to fill the combustion chamber volume, but it did reduce power output.

While this is a bit different, any oil vapors that get intoduced into the Intake HAVE to take up some space, this space consists of a non combustible, or LESS combustible material and I wonder if that is why capping it off helps improve performance. If that is the reason, I would then expect fuel mileage to drop slightly (ugh!) since more air and fuel will be used to make up the difference in combustion chamber volume.

 

Why? You're not sucking any air in through that filter.

 

GOOD READ!!! THANKS!!!

 

CALLING ALL "OLDSCHOOLERS"
can any of you post how to put together a road draft tube for our 8's??? I'm assuming it should be placed a certain way in order to get some kind of positive flow to the atmosphere...

i think we should all be very frequent about checking the oil to make sure there is no condensation if running an open crankase. those of us in hot climates may not have as much of a problem but nonetheless, accumulated hydrocarbons in the engine are the biggest reason for condensation buildup...

 

No one knows what the track cars are doing? Can anyone tell me what the other two vaccum lines go to. I think one goes controls SSV. Thats two out of three. What is the last one?

 

My breather is pushing air out. If that is the case, would the hydrocarbons escape? I can not see why not. They are just recirculating hydrocarbons. From what I understand the new 8 has a different setup than we do. Tell Tell sign of design flaw. What they intended did not meet reality. For example, my CAT went bad. Probobly from this flaw. Never know.

 

Those filters are for Honda intakes.
The stock Honda system takes clean intake air from the air cleaner and vents the sump thru a PCV back to the intake.
When they put a CAI on, there is no provision for the air into the sump connection, they put this filter on.

On our cars it would do nothing, or less than nothing - being on the outlet it wouldn't reduce any of the emmissions, wouldn't filter any clean air and WOULD act like the mesh in a catch-can - it would coalesce oil mist into drips.

A soaked drippy mess drooling oil everywhere.

Leave them to the Honda owners.

S

 

there wouldn't be a big mess in the engine bay if we vented out underneath the car... so, i'm hoping someone will post up a DIY draft tube...

here's the deal based on all the input everyone has put in...

1. recycling the burnt gases into the manifold DECREASES performance *BAD*
2. recycling the burnt gases into the manifold INCREASES the temperature of air entering manifold *BAD*
3. the breather seems to PROPERLY VENT the gases *GOOD*
4. improved engine idling & smoother more responsive throttle response at lower RPM's *GOOD*
5. no condensation noticed so far while using breather *GOOD*
6. no more oil in intake due to removing the vacuum line & capping *GOOD*
7. possible oil mist accumulation all over engine compartment *BAD*

i think that as long as there is no condensation occuring... this is a good cheap mod. if i begin to develop any condensation, i'll be sure to install my catch can back on or just use an inline filter being that i never had oil in my intake. i have no emmision inspection in Florida & i like the added performance benefit of this mod... so, i'm keeping this on for now...

 

This quote is taken from Wikipedia (http://en.wikipedia.org/wiki/PCV_valve)on the subject of PCV Valve:
"Prior to the early 1960s, car gasoline engines ventilated directly to the atmosphere through a simple vent tube of some sort. Frequently this consisted of a pipe (the "road draft tube") that extended out from the crankcase down to the bottom of the engine compartment. The bottom of the pipe was open to the atmosphere, and was placed such that when the car was in motion a slight suction would be hopefully obtained, helping to extract combustion gases as they collected in the crankcase. The system was not positive though, as gases could travel both ways, or move not at all, if conditions were just right."

My first car was a 62 Plymouth Valiant with a slant 6 engine. The valve cover had two holes. One for adding oil, the second was for venting oil fumes. The fumes left the valve cover, went down a metal tube which had a slight bend at the end which pointed to the rear of the car. The movement of the air past the car would aid in sucking the fumes out of the crankcase. My later car a 68 Vailiant with the same engine was equiped with a PCV valve.
If you were to replicate this on the RX8, I would suppose that a rubber/plastic tube would work if it were secured in someway. A small funnel (1") on the end of the tube, in the underbody airstream would create negitive air pressure in the tube to pull the fumes out.
http://www.free-ed.net/sweethaven/Me...?iNum=01040404 provides some details and pictures of the road draft tube and pcv valve operations.

As allways, a search can bring up the information you need. In this case Google provided the links.

 

I would say that any attempt to hope for a venturi effect with a draft tube would be far surpassed by just allowing the positive pressure of the crankcase to vent itself through that same tube. The purpose of pcv valves is threefold. The first is emissions-control. The second is to help the piston rings last longer. Third is to positively vent corrosive gases out of the crankcase allowing the internal parts to last longer. How these concepts relate to the rotary/Renesis engine, I do not know for sure, but I am a little hesitant to go forward with this mod right now.

 

I wonder if the added oil fumes are figured in as part of the engine lubrication scheme. Taking it away might change this?? I really don't know, but a thought. Esp. if people think there is enough dif with this off to affect mixture richness.

 

*The purpose of this tube is to ventilate the engine .
*The reason for connecting it to the air intake is for emmissions.
Fullstop

 

Another thing to consider. Wankle's don't have a crankcase. Oil is injected to the engine. Oil is circulated throught the coolers and sump. There is more going on with a piston engine. That article from posted link above is good. It talks about oil contamination as a primary reason for design. This engine will consume the oil quicker than it could go bad. It has to run in order to get bad. Wankle's burn it faster than it could ruin it.

Did anyone read this thread. Midpipe passed inspection. Does not sound like this car is a problem for polution.


https://www.rx8club.com/showthread.p...hlight=midpipe

 

What is the aforementioned throttle body mod???

 

The thread isn't that long yet. Go back to the first post and start reading.

BTW: I will not be making this mod. I don't see a reason to. I am just providing some automotive engineering history that seemed relevent.

 

The only reason I am considering an alteration to the vent is:
1) I have oil build-up in the accordian portion of my intake, which has to be coming from the oil filler vent

2) It is logical to me the current design in my '04 will allow excessive carbon buid-up deep in the intake, affecting proper operation & expensive repairs

3) Mazda engineers redesigned this on the 2007 models, suggesting there is a problem

The only question left for me is: do I go catch can, or vent through a filter to the atmosphere? If I do the latter, there will be some type of draft tube configuration to keep the oil residue out of the engine compartment. If I do the catch can, there will be some type of mesh inside to help condense the vapors before entering the intake.

 

It's not really that difficult, just get a longer hose and route it down. Then secure it in a few places with zip ties. It's not rocket science

If there is any positive pressure coming from the oil fill tube then adding a filter at the end of the tube would impede airflow and wouldn't allow the crankcase to ventilate as well. I still say forget the filter and just run it to the bottom of the car. Negative pressure from underneath the car (at speed) will help a bit.

Now I feel compelled to go check that tube to see if there is any positive airflow...


BTW dont' forget that this little mod will help keep hot crankcase air from entering the intake; I feel like that defeats any cool air my CAI is drawing in.

 

How did they redesign it? How do you know? I didn't realize'07 were even out yet?

 

He means 06 I guess, which has PCV system.

 

Oh...why not just retrofit the new '06 valve, minimizing fumes sucked into the intake at hi-vac, reaping at least some of the supposed benefits, while keeping the system intact?

 

I dare you to go price the parts at the dealer.
I mean that would probably be one of the best options, if it weren't for the cost.

 

How much can a little plastic valve cost $5, $10? Or get a Pepboys alternative...is there any dif except physical size between them? I mean engine intake vacuum is pretty universal, yes, based on the atmospheric pressure?