Crankcase Breathing Options

[Bulldog9]

As I round the final corner, I need to wrap up the crankcase breather and fuel tank vent system. The 912E has a fuel filler vent that runs from the tank to a canister up front, then runs a small vacuum line to the rear that plugs into what looks like a charcoal canister. This canister also has a larger inlet and outlet. I am assuming the outlet can go to the breather can, and also lines from breather can to the inside of the air filter on the carbs.

Looking at the left side of the fan housing on the type 4 motor, I see a nipple. I'm 99% sure that this is to go to the inlet side of the vac canister.

Based on some of my reading and files,, I've been planning a simple breather can.
http://www.hamincgroup.com/type4-test.php


I decided to draw out what I am planning, black lines are confirmed, the blue is what I am thinking. Anyone have recommendations or thoughts on this? I've seen breather cans that run from $80 - $300.

Thanks

[worn]

I would be better able to help if I knew more about what you want to accomplish. The original design was for efi, so it cycled between capturing vaor from the tank while parked to blowing the vapors into the intake while running. I also was wondering what you meant by chimney. Makes me think of stove pipe and Santa claus.
Thanks

[Bulldog9]

I would be better able to help if I knew more about what you want to accomplish. The original design was for efi, so it cycled between capturing vaor from the tank while parked to blowing the vapors into the intake while running. I also was wondering what you meant by chimney. Makes me think of stove pipe and Santa claus.
Thanks

My goal = Hooking everything up right.

Chimney is the oil filler 'chimney' thing with the nub for the hose that goes to the plenum on FI cars or breather box.

[Mark Henry]

If you want to retain the charcoal canister run a separate hose to the carb. You don't want fuel in your oil.
I'm not sure if it has any affect on the AF ratio, it's only a slight amount of vapour and bulk of it is suppose to to be blown in and burnt at start-up.
I'd personally just remove it and block it off for a carb app.

[Bulldog9]

If you want to retain the charcoal canister run a separate hose to the carb. You don't want fuel in your oil.
I'm not sure if it has any affect on the AF ratio, it's only a slight amount of vapour and bulk of it is suppose to to be blown in and burnt at start-up.
I'd personally just remove it and block it off for a carb app.

I'm mostly looking to see where the 'exit' from the charcoal canister goes.

I've seen 4-5 different configurations on the type 4 in 914's 912 Rebels, and all over Samba, not sure which way to go.

Simplest would be block off the fan outlet, and vent/vacuum line from the fuel tank, and run 1 line from the crankcase vent on the chimney to a breather box, but I'd like to do more than just block off.

[TheCabinetmaker]

The two original systems were independent of each other. I think mark was trying to say you don't want to vent gas vapors into the crankcase. All carb setups I've seen run the head vents into a catch can, then back to the crankcase.

[Mark Henry]

The black/blue line out from the charcoal canister, run that direct to a carb then you config diagram is good to go.

If you want to be anal you can put a "T" in the line and run it to both carbs.
I've only ever run the oil breather line to one carb, above #3 cylinder, I've been doing this for years, including the 2.6L T4 engine that is in my bug.

[stugray]

Just one observation:
The Oil "chimney" that clamps onto the case is already the first stage of an "Air Oil separator" as it allows the circulating crankcase vent products to settle out in liquid and drain back to the case before exiting.

So you dont need a really elaborate external system. Just keep it simple.
I use the stock breather and the exit routes through a 3/4" hose to just a catch can (no drain back to engine) with a vent.
The catch can has a sight-glass so I can see if it ever starts to fill up, but after ~6 track days and ~500 street miles, it hasnt collected anything worth draining.
That's with a fresh motor.
And I do not have head vents.

(IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1442786201.1.jpg)

[Dave_Darling]

My goal = Hooking everything up right.

The problem is that there is no "right" setup for this car with carbs. The factory never put them on the 912E.

In stock form, the hose from the fan shroud would go to one side of the charcoal canister, and the large hose from the other side of the canister would go to the air cleaner for the fuel injection system. The small hose from the canister would be hooked up to the expansion tank on top of the fuel tank in a 914; I assume the 912E would be similar but I don't know what the 911-chassis cars use for an expansion tank equivalent.

The oil breather would be a separate setup from the fuel tank ventilation system.

--DD

[Mark Henry]

My goal = Hooking everything up right.

The problem is that there is no "right" setup for this car with carbs. The factory never put them on the 912E.

In stock form, the hose from the fan shroud would go to one side of the charcoal canister, and the large hose from the other side of the canister would go to the air cleaner for the fuel injection system.

The VW bus has the exact same system in the carbed bus, it also blew into the common air cleaner.
Wasn't there a euro 914, 1800 that came with the bus carbs?

[Mikey914]

True, the OEM set up is injected. It's vented into the intake plenum. SO technically it should be "T"ed and ran into the carb intakes. Perhaps adding dual nippes to the top of the cab air cleaner assemblies?
Catch can works nicely too.

[Dave_Darling]

The VW bus has the exact same system in the carbed bus, it also blew into the common air cleaner.
Wasn't there a euro 914, 1800 that came with the bus carbs?

Note that neither of those was a 912E. So neither would be "right" in a 912E.

--DD

[Bulldog9]

The VW bus has the exact same system in the carbed bus, it also blew into the common air cleaner.
Wasn't there a euro 914, 1800 that came with the bus carbs?

Note that neither of those was a 912E. So neither would be "right" in a 912E.

--DD

So Dave a 912E with Carbs isn't right? (IMG:style_emoticons/default/blink.gif)

[Dave_Darling]

Correct. The "E", after all, stands for "Einspritzung", which is German for "fuel injection".

Mind you, that is following a pretty specific definition of "right". You can probably find a way to make it work, but it won't be "right". When you change stuff that the factory originally put on there, you more often than not have to do some re-engineering, or accept someone else's re-engineering. Even if it just means adapting something the factory did in different circumstances.

--DD

[EdwardBlume]

Correct. The "E", after all, stands for "Einspritzung", which is German for "fuel injection".

Hang around DD long enough and you learn so many new things... (IMG:style_emoticons/default/aktion035.gif) you should write a book Dave.

[Bulldog9]

Well, if that's the standard for right, my car is all wrong ;-)

Brakes - 1983 master cyl, vented rotors, calipers, pads all around
Suspension - Rebel Racing Bushings all 4 corners
Clutch/Pressure plate - 6 spring
Engine - 96MM P&C, Big cam, type 1 oil pump, 1.7 rockers with 911 swivel adjusters, big valves and ported heads, Pertronix Ign II billet dizzy, Dellorto carbs, Tangerine Exhaust, AFM, CHT added
Dash - added dual gauge out of 911, moved clock and fuel gauge to center of dash (ashtray area) and replaced with aux fan/in place of clock and fuel gauge.
Interior - Center console, door panels and armrests from 88 911SC, Blaupunkt Toronto 420 Head unit with 5 1/4" Infinity Kappa Door speakers. MOMO Steering Wheel, silver shifter arm, aluminum door pulls and window cranks.

Alas, SO much NOT right in my car. (IMG:style_emoticons/default/blink.gif) I think a better way to say it is 'factory-correct' not right ;-) My goal is to do all this wrong stuff .... well right, lol.

Seriously though, I appreciate everyone's help on my rebuild. I'm an old wrench, but this is my first P car, and the only thing I have to go on is the mess I disassembled over the last couple years and what I read and research in the forums and in manuals.

Its been a fun journey, and know that turning the key is just the beginning of a new phase of the project.

Correct. The "E", after all, stands for "Einspritzung", which is German for "fuel injection".

Mind you, that is following a pretty specific definition of "right". You can probably find a way to make it work, but it won't be "right". When you change stuff that the factory originally put on there, you more often than not have to do some re-engineering, or accept someone else's re-engineering. Even if it just means adapting something the factory did in different circumstances.

--DD

[Mark Henry]

I'm like that, if I had to settle for stock HP I wouldn't be into VW bugs and 914's, 90hp just doesn't cut it for me.
180 hp 2.6 litre in my VW beetle and my 914, if I ever get it done (IMG:style_emoticons/default/rolleyes.gif) has a 280 hp (on paper) twin plug /6 going into it.

You only need the oil breather going into one carb, it's all I've ever done.
Fuel vapor I'd likely start with one carb and see if it through off my carb balance, if it did then I'd add a Tee and run a hose to both carbs.