Crankcase vapor vent/recirc system

[TitaniumTT]

Originally Posted by RETed

I'm assuming this is for an FC.
Is this purely a "crankcase" evac system?
Since I didn't read anything about the gas tank vapor purge, I'll assume this is not part of your system...

Yup, on an FC with a 13B-RE. There is nothing for the fuel tank. I built my own cell with an in tank surge tank and have the cell vented to atmosphere. Works well, no smell.

Originally Posted by RETed

I like the idea of running the crankcase with some vacuum.
Having the crankcase pressurized could possibly hurt power and / or cause headaches like smoking turbos.
The hard part is...how do you do it?
The stock system is overly complicated.
Mazda's stupid "purge valve" is another one of those engineering-bragging doohickeys that makes things a headache.

When we run race cars on the track, we 1) cap the bottom nipple on the center iron, and 2) run a single vent off the top of the oil filler neck.
Whether you want to run it as a recovery system or a purely purge / vent system is up to you.
Oil *will* creep up the oil filler neck to easily spew out the lower fitting in the center iron when you toss the car around the track.
Even with oil baffle pans, you can still get oil puking out that lower fitting.
We've never had too much problems with oil puking out the top of the oil filler neck.

I've got both nipples t'eed together and run to the puke tank. Yeah, it does creep up badly. But, if you cap the iron nipple, run the oil filler to a vac source, does that ceate enough flow through the crankcase to clean things out? I would imagine that you would want a constant flow of air in one port, out another. With that center iron nipple capped, the only source to relieve the vac is the blowby or the oil entering the pan. I would imagine that it would be a little more effective to leave the iron nipple open, but filter the air going into it, no?

[QUOTE=RETed;131045]I'm also assuming that this is for a turbo 13B.
This is good and bad.
Running vacuum in the crankcase relieves pressure that would end up puking oil out the piston compressor ring in the turbo turbine.
Effect?
Oil spews out the hot turbine section and burns in the exhaust causing embarassing oil smoke.
Bad?
Push the turbo hard enough and this causes the oil to foam more after the CHRA.
Foaming, hot oil causes more vapor crap, which causes more crap to get puked out the system.[QUOTE=RETed;131045]

Yes, you are correct, twin turbo 13B. The twins are notorious for not liking pressure and puking/burning oil easily. Even the rebuilds. Both my CHRA's are damp with oil, but she'll only burn and puff smoke if sitting for a LONG time or if overboosted slightyl. Kinda why I want to get a bunch of vac in the pan and was THINGKING about overcomplicating the whole thing with a vac tank..... but then slapped myself out of that idea.

Originally Posted by RETed

Another bad thing...
With a turbo engine, the only "spot" that has constant vacuum is before the turbo.
If we're talking purely vapor, this would not be a problem.
In reality, we're also ingesting (hopefully) minute amounts of liquid that's hitting a (delicately) spinning compressor wheel.
Mazda decided to do this full-time with their system.
It's probably the best, passive system that could be integrated into engine at that time.


-Ted

This is exactely why I wanted to run the vac source through the filtered puke tank before it heads to the turbo. Was also thinking about running a clear fuel filter inline as well just as a last ditch effort to catch anything that migh do damage hitting a comp wheel spinning way too fast. Like you said, purely vapor would not be a problem, but some sort of debris or the sludge that often collects, would be a huge problem hitting those comp wheels under full song.

So, would you change anything on the setup that I have in mind?

Thanks Ted, I appreciate it

[RETed]

Originally Posted by TitaniumTT

I've got both nipples t'eed together and run to the puke tank. Yeah, it does creep up badly. But, if you cap the iron nipple, run the oil filler to a vac source, does that ceate enough flow through the crankcase to clean things out? I would imagine that you would want a constant flow of air in one port, out another. With that center iron nipple capped, the only source to relieve the vac is the blowby or the oil entering the pan. I would imagine that it would be a little more effective to leave the iron nipple open, but filter the air going into it, no?

Interesting point...
We were just worried to keep the pressure out of the crankcase.
The point was just to relieve the pressure.
I wouldn't think circulation would matter.

This is exactely why I wanted to run the vac source through the filtered puke tank before it heads to the turbo. Was also thinking about running a clear fuel filter inline as well just as a last ditch effort to catch anything that migh do damage hitting a comp wheel spinning way too fast. Like you said, purely vapor would not be a problem, but some sort of debris or the sludge that often collects, would be a huge problem hitting those comp wheels under full song.

Ah, now I see why your design is so complicated.
It's sorta like running a "charcoal canister" system for the crankcase evac...
Yes, what you are proposing does make a lot of sense.
It looks like you've got all the bases covered - condensation of vapor / moisture, drainage, and purge to combustion.
The clear lines are a plus - this is why some (Japan) racers like to use those clear lines: to inspect the crankcase puke.

I've got mine current T'd, and you're right - there's a LOT of puke that comes out of those lines.
I had my hose pop off my pipe prior to the turbo inlet, and there was a LOT of disgusting coffee / mud colored liquid that came out of there.
I'm too lazy to redo right now, and the stock turbo puked it's seal a while ago.
When I change the turbo out, I think I'll redo the system too.

I like your plan of attack on this matter, and it should work.
I think it's just a matter of having enough volume in your catch can system...
We also know how tight space becomes in the FC engine bay with big turbo systems and FMIC's!


-Ted

[TitaniumTT]

Originally Posted by RETed

Interesting point...
We were just worried to keep the pressure out of the crankcase.
The point was just to relieve the pressure.
I wouldn't think circulation would matter.

I've heard that some sort of constant circulation is needed to keep some moisture out and to get rid of the blow-by gases... prolonging the life of the oil.

Originally Posted by RETed

Ah, now I see why your design is so complicated.
It's sorta like running a "charcoal canister" system for the crankcase evac...
Yes, what you are proposing does make a lot of sense.
It looks like you've got all the bases covered - condensation of vapor / moisture, drainage, and purge to combustion.
The clear lines are a plus - this is why some (Japan) racers like to use those clear lines: to inspect the crankcase puke.

Cool, thanks... I'll add this on the list of shit to do before the road trip. Give it a real test in short time.

Originally Posted by RETed

I've got mine current T'd, and you're right - there's a LOT of puke that comes out of those lines.
I had my hose pop off my pipe prior to the turbo inlet, and there was a LOT of disgusting coffee / mud colored liquid that came out of there.
I'm too lazy to redo right now, and the stock turbo puked it's seal a while ago.
When I change the turbo out, I think I'll redo the system too.

I couldn't believe it either. At one point I was draining about a pt every other run out of the thing. Drove me insane. Then after not checking it for a few days I pop my hood to see oil all over the back of the divider right behind the drivers side headlight and on the front of the drivers shock tower.... I'm thinking oil lines popped somewhere but instead it was the puke tank overflowing (mounted on the drivers shock tower) and the BO valve spraying it all over the engine bay. :faceplam:

Originally Posted by RETed

I like your plan of attack on this matter, and it should work.
I think it's just a matter of having enough volume in your catch can system...
We also know how tight space becomes in the FC engine bay with big turbo systems and FMIC's!


-Ted

I'm thinking about a pt off the center iron and ~2/3's of a pint off the oil filler. I took a SS turkey baster and cut it down, used the gasket between the oil filler and the center iron as a template, cut that out of SS and welded it together, a funnel to keep the oil from moving up the filler. This is why the capacity in for the filler will be less. There should be little to no oil traveling up that. I'm also hoping that what does creep up the center iron will be pulled back slightly as I want to have the vac being pulled from there, through the filler neck, through the SS wool packed ~2/3's pt tank, through some hose, through a clear filter, to the primary turbo. We'll see what happens. I guess I should try to log the vac seen by the TID. I've got that secondary boost MAP sensor that I only hook up on the dyno.... that could do it. If there's no vac present, or very little... I may have to think about a small vac tank somewhere....... Hoping it doesn't come to that though. That would REALLY overly complicate things....

Thanks Ted. i'll get some pics up in the fab section when I start creating.