22 replies to this topic

[MontpellierVanMan]

Has anyone ever tried this ?

 

I got tired of the messy pipe-work out of the engine breathers, and whilst I've kept the original pan-scrub-filled canisters down on the transmission housing and the timing cover, I've tried running the pipes into a modified rocker-cover.

 

 

The outlet it just that 5/16 pipe sucking out into the carb, just upstream of the butterfly, on the original stub.

 

I still need need to find a car with a pre-formed 90° bend on a length of 1/2" black pipe to suit the clutch-end connection, where the current pipe can't quite cope with the radius - anyone got a suggestion ?

 

It looks neat, but how do I know if it's working ?

 

 

Nothing leaks, yet, nothing's smoking out of the back, yet, after maybe 2.000km - but this may just be the beginning, and I've not had it over 4.500 rpm yet ................

 

Please advise.

 

 

[dyshipfakta]

Should work just fine basically just uses the rocker cover as a collector will still vent to the carb. Aslong as it has somewhere to go.

[GraemeC]

I would wonder if you're wearing the mixture and introducing extra oil vapour?
It's one thing burning of the products of (sort of) filtered crankcase vapours, but your now sending very oily rocker gear mist into the carb too.

[nicklouse]

My only concern is the height of the inlet pipes but they should be fine.

The connection to the carb should also be fine no different to how others are plumbed in.

[whistler]

Forgive an amateur's observation. Until the oil becomes really hot you have condensation emitting from the crankcase etc and that is entering the rocker cover where sump oil is running. Is that condensate likely to combine with the oil and return to the gearbox and so providing a circular route for it? Answers on a small bit of paper please, rolled up and flicked at me.

[nicklouse]

Forgive an amateur's observation. Until the oil becomes really hot you have condensation emitting from the crankcase etc and that is entering the rocker cover where sump oil is running. Is that condensate likely to combine with the oil and return to the gearbox and so providing a circular route for it? Answers on a small bit of paper please, rolled up and flicked at me.

As per the original design it is sucked into the carb and burnt/exited via the exhaust.

[Spider]

It certainly does tidy up the engine bay!

 

For the Crankcase ventilation to work properly, it really needs to draw fresh air in through an upper part of the engine (eg, Oil Filler Cap) and then draw that air through the engine, then be drawn out at a point far from where the air comes in.

 

Without doing this, there's a risk on shorter runs that there's pockets within the engine where vapour and fumes may reside without being drawn off via the Crankcase Ventilation System.

 

I think Rory's set up would work as long as it does longer runs, though overall, it wouldn't be as effective as the fresh air is not encouraged to be drawn through the crankcase. This will only become more noticeable as the engine does more hours.

 

<Edit: The other issue I see with your current set up Rory is that it by-passes the Oil Separators. I think you'll find in short time, you'll have high oil consumption as a result and an increased risk of Acid build up in the Oil. >

Edited by Moke Spider, 26 September 2016 - 09:44 PM.

[Spider]

Here's a couple of very good articles on Crankcase Ventilation Systems, though they are on the PCV System, they are still highly applicable in principal to our CCV System;-

 

https://en.wikipedia...tilation_system

 

http://www.agcoauto....2_articleid/197

[nicklouse]

For the Crankcase ventilation to work properly, it really needs to draw fresh air in through an upper part of the engine (eg, Oil Filler Cap) and then draw that air through the engine, then be drawn out at a point far from where the air comes in.
 
Without doing this, there's a risk on shorter runs that there's pockets within the engine where vapour and fumes may reside without being drawn off via the Crankcase Ventilation System.
 
I think Rory's set up would work as long as it does longer runs, though overall, it wouldn't be as effective as the fresh air is not encouraged to be drawn through the crankcase. This will only become more noticeable as the engine does more hours.

Yet again you remind me of how things were done. I always saw it as a sealed (well as far as a mini can be) and we had the net pressure in the casing to deal with blow by etc. Never really considered that some had a "flow" path.

Too long playing with race cars.

[grizzler73]

Try CBS for a 90 degree bend

 

http://www.carbuilde...ubber-hose-bend

 

So on a race car (which has to have a catch tank) you are basically venting from the clutch side up to the rocker cover the out of the rocker cover into the catch tank instead of the carb, does the catch tank also needs a vent?

The 3rd pipe in the picture that drops down by the fan is the one from the timing cover, so the only difference on a race application is that the pipe goes to a catch tank instead of into the carb. Do you need a bigger hole for drawing the air into the engine for race engines or is a standard cap ok?

Out of interest what metal pipe bends did you use to modify your rocker cover? I like them they look very neat!

[nicklouse]

race set ups don't draw air in as there is no vacuum (that is created by the carb connection) the breathers just breath to atmosphere. but with their ends in or connected to a container so and oil that is expelled is caught.

 

filters not required.

[Ethel]

^that^

 

If the throttle's nearly always open, there's rarely manifold depression to suck out fumes. You're also not likely to go thousands of miles between oil changes, so will be less worried by oil contamination.

[MontpellierVanMan]

Some interesting ideas here, even if you don't know until you try and since none of us has ever tried ..............

 

Thanks for the 1/2 bend Info G73, CBS looks like a good source, new to me ; the cover-bends are all stainless pipe fittings that a mate uses when making perfume stills, of all things, his TIG work is breathtaking. I had intended this cover to be a "rough" requiring refinement, and make the old original cover off the Van's 998 into the final version, but it all fell into place nicely so now I'm stuck with one that has no history.

 

I'm not sure I get the "dead-pockets" of air since the original breather set-up didn't seem to encourage any circulation in the bottom half of the motor either, did it ? But then I can't remember what the layout was, to be honest !

 

Have I ditched a vital FRESH-AIR-IN connection that would have gone from the air-cleaner into the lower crankcase ? Remind me please, Moke.

 

Since my new cap (Metro ? Late Mini ?) appears to have NO breathing capacity or venting, I have indeed strayed from the original design since the black-cap at least does have an air-passage.

 

Where would you suggest adding an extra fresh-air ingress ? It has to be neat - I'd rather have mayonnaise than compromise the layout ! And I don't want any smells either.

 

Who knows, I may yet find an excuse to modify the cover and be able to re-use the 998 one after all.

Edited by MontpellierVanMan, 27 September 2016 - 03:17 PM.

[nicklouse]

As Chris reminded me the fresh air in is through the cap.  the red Metro one should also allow this (some don't though).

 

the fresh air is draw into the engine and out via the assorted breathers. tappet chest (998 and the Ss) timing cover and transfer case- Assorted engines some had them some did not some from other cars had parts swapped out or not.

[Spider]

The hose with the bend that grizzler73 kindly linked up is not suitable for use here. It's only a coolant hose and will suffer a cholesterol type blockage in very short time if used with oil and even quicker with hot oil fumes.

 

As Nick's said, the Fresh Air enters the crankcase from the rocker cover, either via the Oil Filler Cap or via the Charcoal Canister. The fresh air is then drawn down in to the Crankcase, mixed with blow by and other combustion by-products, vapour etc and then drawn up in to the Oil Separators.

 

The Oil Separators are a simple and cleaver design. They have a big inlet at the bottom, so 'gas flow' is slow and also allows for the oil to run back. The 'Canister' is an even bigger diameter, to further slow the gases, then after going through the mesh / flame trap, the pipe reduces in size for a faster gas flow. All important details that make this set up work.

 

On all out competition engines, we're really not concerned with this type of set up as the oils only in the sump for a short time before changing it out All we really want there is for the crankcase to break, so it can 'spit' in a controlled way rather than just blow seals or the oil filler cap off.

 

Likewise, if you don't want to run some sort of crankcase breather set up like a PCV or CCV system, be sure to change the Oil often.

 

There's a bit to these systems and after reading many questions over several forums about which hose goes where and some of the answers, it seems to me that they are not properly understood or appreciated for what they are and how good they are. Eg; IMO an Oil Catch Tank on a road car is a 'chewing gum' measure to cover up a lack of understanding and also a shortfall in an engine build for something that should be considered from the outset. They are easy to do and set up and pay dividends. They can't be too difficult as even I understand them 

 

<Edit: I only run one breather on street cars. On the 1275's I only use the one on the transfer housing. The one on the Timing cover, apart from being in a bad location to get at is too low down on the engine and I have no trouble on right hand bends getting a load of oil to get in to it, resulting in that cloud of oil smoke on exit from these corners. >

Edited by Moke Spider, 27 September 2016 - 08:23 PM.