OC94Rx7

Damon - Please post some pictures when your finished

After work on Friday. I had a chance to start making my oil stopper, not sure what to call this thing I still need to purchase another oil cap / 90 degree fitting and drill out smaller holes in the different chambers. So, after some parts shopping. I should have this thing ready by the middle of next week and see if it works? Will have to find a parking lot or something because I won't be heading to a track until late summer

Anyway, here's a picture...........

//Oliver

CrispyRX7

iTrader: (139)

Oliver...THAT looks damn impressive. I presume you have access to a milling machine (lucky you!). I really REALLY hope it works. That way we can all ask you to make more. I only ask you put me at the top of your "buyer list" (Denmark, Mars, Jupiter who cares...I'll pay for shipping!)

I do have a question though....how will you seal the sides to the filler neck? Will the tolerances be so tight that no seal is required? Without a good seal the baffles will be pointless.

Regards,
Crispy
- man I hope Olivers design works!

clayne

BTW: I've also come to the conclusion that the JAZ can is way too f'ing small.

OC94Rx7

Crispy - Thanks for the kind words. I really hope it works too.

The company I work for has a full work shop. The oil stop was made on one of our lathes.

To answer your question. When I measured the inside of the filler tube. I found it changes. Larger at the top, smaller at the bottom. The piece I made in the photo fits nice and tight at the bottom and does have a crack under 1 mm at the top. So, it has a good bottom seal. I have also thought about using o-ring/rings but decided at the time, to just try it this way for now (one size top/bottom). It may take 3 or 4 before I get everything right and I might find I need o-rings. I have already found a few things that I am going to change. We may find that each oil filler is different enough that one size does not fit all? This is definitly at the prototype stage.

Today, I purchased a new oil cap and 90 degree fitting. I hope by thursday I will have it together. I just have to find the free time.

Crispy, I would be happy to send you the one I have (with new cap/ 90 degree fitting) or just the insert if you have a cap/fitting? Your website has been very helpful to me in the past and this is a way (maybe?) I can pay you back. I will try it first to see what happens. But, I really need someone like you who is creative (you have tried more test than anyone) and could also try it under track conditions (since you know which tracks you have had problems).
Like I said before, I won't be on an open track until late summer and I have only had problems on the track.

Let me know what you think,
Thanks
Oliver

VTAOE

I don't know a whole lot about this whole catch can business so I decided to do a little bit of research. So here is what I found:

Several people are doing things similar to what Crispy, Brad, and others are doing regarding this catch can. This is not a new concept. The way they are trying to do it is new, but the concept is not. For example here are a few people using catch cans on other cars.

Mini Cooper S
http://outmotoring.com/alta_oil_catch_can.html

Subaru WRX
http://www.wrx.com.au/htmll/Connecti...atch%20Can.pdf

Mazda Rx-7 (Crispy)
http://reganrotaryracing.tripod.com/catch.htm

Mitsubishi Eclipse (somewhat strange approach)
http://www.tgilmore.com/talon/catchcan.html

Toyota Supra(?) (Jaz Catch Can)
http://cjsupra.kendra.com/PCV-Can.html

All of these sites have some good info/insight on the problem. My understanding is that the point in the catch can is to keep oil out of the intake hoses, intercooler, and misc. other places as much as possible right? So check this out:

http://www.perrinperformance.com/pro.../catchcan.html

Pay attention to the content on the page and not so much the quality of the catch can. This made sense to me. What it was saying that an oil vapor was in fact condensing and causing a collection of oil in various places. I did not see anything about pure oil (in a non vapor form) going all over the place in your intercooler and other places.

This made sense to me because if you look at any large air compressor there will be a collection tank of sorts where vapor is collected into an oil/water mixture which can then be emptied. In some of compressors this "storage tank" even has a sight glass on it.

So my next question was where is the proper place to tap into the engine with the catch can then. I think I found the answer. It is after the PCV check valve.

http://www.c-speedracing.com/howto/c...n/catchcan.php

From what I read and understand the PCV check valve on our cars is a one way valve (hence a check valve) and so the valve is opened because of pressure buildup. When the check valve opens both oil and pressurized air are directed into the intake manifold. Hence the reason for a catch can to filter this air.

Now for the downfall. From what I have read if you leave the catch can open to the air then you may have emissions issues AND an oily film may accumulate on the filter over time. If you close the container then it may not be as effective though. So there is a trade off.

http://www.volvospeed.com/Mods/catchcan.htm
http://cjsupra.kendra.com/PCV-Can.html
(see the results section on the second link)



So here is my solution to this problem. Tap in the catch can after the PCV check valve and perhaps into the second location Crispy is talking about in his first paragraph on here:

http://reganrotaryracing.tripod.com/catch.htm

I hope that helps at least some.

- Cody

VTAOE

Here are all of my sources of info where I came up with all of that. There are several pages of good info on a Greddy unit that appears to be pretty well made.


General Concept:
http://www.perrinperformance.com/pro.../catchcan.html
http://www.c-speedracing.com/howto/c...n/catchcan.php
http://www.tgilmore.com/talon/catchcan.html
http://www.wrx.com.au/htmll/Connecti...atch%20Can.pdf


Different Models:
http://www.nipponpower.com/accessori..._catchcan.html

Greddy Catch Can:
http://store.dragracing.com/product....=1278&catid=40
http://www.roadraceengineering.com/i...dycatchcan.htm
http://www.rxecret7.com/grdy12003506.html

Mini Cooper:
http://outmotoring.com/alta_oil_catch_can.html

Jaz Catch Can:
http://cjsupra.kendra.com/PCV-Can.html
http://reganrotaryracing.tripod.com/catch.htm
http://www.volvospeed.com/Mods/catchcan.htm


- Cody

VTAOE

I had one last question/comment and then I am leaving this alone.

Aren't you going to get some oil in the catch can if you tap into the oil filler neck like Crispy did? With all due respect Crispy I just don't get it.

I guess I will put it this way. If you take a bucket of water half full and then you begin to spin in a circle. As you spin faster and faster you can begin to raise the bucket up away from the ground until it is 90 degrees to you. If you are spinning fast enough you can do this without spilling any water at all. This is kind of a neat fluids trick, but it is interesting. By spinning faster and faster you create an centripetal acceleration (I think that is the correct term), which can be though of as g's. This is the same way that the introduce pilots and astronauts to high g's is by spinning them in a circle at very fast rates.

The point is that as your g's increase the oil will gradually creep up that oil filler neck. Since the cap is no longer stopping the oil it now flows into your catch can. Hence the reason you get a lot of oil when you are turning at high g's where the oil can creep up the oil filler neck. If you are turning high where most of the force is in the direction of the driver then the oil will creep up the oil filler neck. When you turn in the direction towards the passenger the oil has no "oil filler neck" on the passenger side and thus no place to escape to.

This is the reason that your large ocean liners and tankers use baffles also known as bulkheads. They divide up the large amounts of fluid (in some cases oil) into smaller compartments so that they can control sloshing. This sloshing also does a number on controling the center of gravity and thus effecting the buoyancy of the ship also, but that is a different discussion also.

I hope that helps. I think everything is correct there, but feel free to correct me. I mean no disrespect I just wanted to add my understanding of the problem.

Cody Anderson
MS and BS in Aerospace and Ocean Engineering at VT

VTAOE

Disclaimer:

Bulkheads are actually structural supports. In this case it is just a convenient way to break up the ship into cargo sections/areas. Just thought I would mention that before somebody also had a chance to correct me.

- Cody

DamonB

Cody, the big problem with the filler neck isn't necessarily the fact that oil sloshes up it, it's the fact that there are two vac lines attached to the top of the neck. One line goes to the primary turbo inlet and so has vac 100% of the time. The other goes to the pcv and so has vac anytime the engine is off boost. Once the oil sloshes up the neck anywhere in the vicinity of those lines they will immediately vacuum the oil out of the neck and send it through the entire intake system (since the majority of it will get dumped into the primary turbo) and then the engine will burn the oil.

A catch can will catch the oil rather than letting it into the intake system but will still "use" oil from the pan because now you have it caught in the catch can. You keep the oil out of the intake but you still loose oil from the system. I'm convinced ditching the two vac lines from the oil filler and instead venting it with a breather is the way to go.

VTAOE

Let me look at my car a little bit and think about this and I will get back to you.


That is similar to what I was suggesting. Except that you are venting from the filler neck instead of aftet the PCV check valve. My point was to collect the oil vapor rather than just collect straight oil, which it seems that Crispy is doing right now.

Is that in fact what Crispy is doing right now? I didn't get that impression from his website and what little I know about his setup.

Give me a little bit and I will see if I can come up with anything that might be able to help the problem. I appreciate the response though. Any additional info into what is going on is very helpful.

- Cody

RX-Heven

iTrader: (1)

Why not loosely fill the stainless turkey baster attached to the bottom of the filler cap with steel wool. This would help prevent oil in it's liquid form, or at least slow it down from reaching the catch can. It will still allow the crankase to breathe and might even accumulate the oil vapor and allow it to drain back into the oil pan. It would be easy to clean with brake clean and some compressed air through the top of the oil filler cap. Might be some concern with steel wool escapaing and getting into the oil system though. Perhaps a coarser material or synthetic mesh or something....

clayne

There is no way in hell I'm putting steel wool anywhere near the oiling system OR intake to the primary turbo.

I don't care how resilient it is, it's a disaster waiting to happen.

BTW Cody, what you're asking is pretty much what this entire thread is about. Check out the previous 6 pages.

The reason oil is getting into the catch can is due to the filler neck design. What Damon is saying is tapping the housing from an entirely different area - or atleast baffling the exit much better than the current system.

G-forces and lack of proper baffling are what create this problem. The PCV is pretty much innocuous to the problem.

DamonB

Actually what I am saying is different. If there were no vac lines or catch cans attached to the filler tube the oil would slosh up the tube when cornering and then merely fall back down into the pan. There's no way the oil could either leave the pan or be ingested by the engine.

If the vac lines on the filler are capped we now have no way to vent crankcase pressure though so a breather must be added in place of the cap on the filler.

So....remove the pcv and cap its nipple at the manifold. Remove the vac line from the primary intake to the filler and cap it. Remove the cap from the oil filler and instead plumb a breather to it so that crankcase pressure may vent. Not emissions legal but there is absolutely no way the engine can ingest oil through the intake or loose oil by dumping it into a catch can since there is no longer a path for it to do so.

My plan is to build an entirely new filler because it could be simply done and it will probably need to have a flange at the top for the breather as well as slightly shorter in height to provide hood clearance for the breather.

clayne

Right. We're on the same page.

But don't put a breather in place of the filler neck without adding a baffle to the oil pan. You WILL get oil everywhere. The breather will not stop oil from passing when it rides up the side of the housing due to g-forces.

Also, it's good to have a source of vacuum pulling crankcase byproduct gas instead of relying on positive pressure. Some domestic guys even install vacuum pumps just for this purpose.

CrispyRX7

iTrader: (139)

Damon,
The "tap" for the line that runs to the catch can on my setup comes off the highest point in the filler neck - a hole drilled in the oil filler cap itself. Replacing the filler cap with a simple breather filter will have no effect IMO. If oil can make its way into the tapped line in the filler cap it will also makes its way out through a breather directly on top of the filler neck.
The principle is to stop the oil from getting that high in the first place. I'd though about venting crankcase pressure out through the dipstick tube but it comes off the bottom of the filler neck so would probably be worse. Drilling and tapping another "vent" off the oil pan might also work but you run the risk of using a line that is too small that any time the crankcase is prssurized it woudl "pump" out oil through the line and never allow it to drain back.
This issue is really frustrating because the only real solution is to use a dry sump...all these hypotheses are mere bandaids.
Regards,
Crispy

DamonB

I understand you Crispy but IMO merely keeping the oil from penetrating through the breather filter is a much easier problem to solve. The breather isn't just an open hole, it's filtered so the oil can't merely slosh out. With the vac lines gone the oil will no longer be drawn or pulled through anything, merely sloshed around. I figure all I have to do is attach a corkscrew shaped line inside the new filler leading to the breather, should be easily enough done with copper tubing for example. At the same time if I extend the breather over towards the passenger side of the car any oil that is sloshed up the neck in right turns will sit in the top of the neck and not inside the breather filter since the g forces will force it away from the filter. The oil won't be drawn into the breather because there is no vac assisting it and at the same time it won't climb that spiral and out the breather merely due to slosh; sloshing won't be enough to make it exit the breather.

I realize I have to build this thing first and then try it, but I'm convinced it's going to work

clayne

I am convinced you're going to dump oil all over the side of the car. I'm seriously not kidding. The breather filters do not filter liquids effectively at all.

For most of us, a primary concern is that catch can filling up and dumping oil everywhere. That's why I'm moving to a larger catch can, personally.

DamonB

It's not going to have to. Since the filler will extend horizontally towards the passenger side off the top off the neck any oil sloshing up the neck will stay in the neck because of g forces. Slosh is only a problem in right turns and in right turns the oil will be pulled away from the breather.

I'd love to post a simple drawing to show you guys but the server hasn't felt like uploading pics for a few days now...

clayne

I know what you're talking about - who was the one who originally said "redesign the filler neck" ?

Rotate current filler neck clockwise 90 deg for visualization.

edit: clockwise, not counter.

DamonB

Then that guy must have been wrong, because you want to rotate the filler neck 90 deg CLOCKWISE in order to make it point to the passenger side

clayne

CORRECT. You know what I meant.

ptrhahn

iTrader: (9)

I was thinking of ways to baffle tthe top of the filler neck to force the ventilating air to turn corners that would be difficult for liquid oil, BUT:

I'm wondering if there really ISN'T a way to let air escape out the breather neck WITHOUT the oil as well once they are both in there. I think we're all assuming that there are two seperate substances involved: the "air" and the liquid "oil". The assumption is that the oil climbs the walls of the filler neck and is then sucked out at the nipple, but since Crispy runs the turkey baster, its clear that the oil is able to "float" to the center of the neck to be sucked out as well. If you look at what you get in you Jaz can after a track session, it doesn't look like oil at all, its very aerated, like a foamy milk shake.

I'm thinking that what your dealing with is almost entirely an oil/air "vapor", where the oil is able to "go" anyplace that air does, because the oil has almost been atomized the way fuel is by a fuel injector... it doesn't behave like a thick liquid anymore.

I don't think Crispy has hit the track yet w/ his new baffle plate (a copy of which is sitting in my garage, thanks chris), but i'm thinking this may do more to limit the amount of oil thats mixed with the ventilating air... Chris, has anyone else gotten any miles on the baffle?

Note: I'm an artist, not an engineer, so don't flog me for innacurate fluid- or aero- dynamic assumptions.

DamonB

There is some vapor but the far majority is oil that literally climbs out the pan and up the filler neck.

VTAOE

This is exactly what I was talking/thinking about. If you run an air compressor for a long period of time then you will collect sort of an oil/liquid mixture in the bottom of the tank. This is a combination of moisture in the air (thus the water) and then oil vapor from the compressor itself. So when it is more humid/hot outside you will collect more of this oil/water mixture in the bottom of your tank simply because there is more moisture in the collected in the air.

At any rate......I think the correct way to solve this problem is to collect the oil vapor into a catch can rather than pure oil. It sounds like Chris's catch can design is also collecting the oil vapor (according to Peter), which has kind of slowed me down as far as trying to come up with an improvement to this.

I'm still thinking about this and will let you guys if I come up with anything worth while.

Peter, don't worry about not being an engineer. Engineering really isn't that complicated it just takes time to learn everything one piece at a time. Technically I am a rocket scientist, but I don't think there is any difference between myself and the person who works at the local grocery market. The only difference is that I took the time to sit down and try to figure out why things work like they do. Anybody can do it. There is no real big secret. So don't let anybody make you seem like you are inferior just because you aren't an engineer.

- Cody

VTAOE

Really!?!?! Humm...............

- Cody