Very original 6 on BAT, Quite the example Options

[gandalf_025]

My car never had vent screens.. Build date 2/70

[JeffBowlsby]

You know Michael, my only concern with the two different layouts of the carbon cans...and I admire your research and agree with it for the most part...is that the actual carbon cans and the cans depicted in the emissions diagrams are physically different.

The vapor flow route in the later emissions diagrams indicate a can that has an internal extension pipe directing vapors to flow through the carbon media which preserves the function of the carbon filtering. However the cans themselves (the plastic cans anyway - I have not seen a metal can dissected) do not have the internal extension pipe, and the way its plumbing is revised without the extension pipe, creates a direct short of the vapor flow which bypasses the carbon filtering media, greatly limiting the carbon filtering process intended.

Your insight please...

[wonkipop]

You know Michael, my only concern with the two different layouts of the carbon cans...and I admire your research and agree with it for the most part...is that the actual carbon cans and the cans depicted in the emissions diagrams are physically different.

The vapor flow route in the later emissions diagrams indicate a can that has an internal extension pipe directing vapors to flow through the carbon media which preserves the function of the carbon filtering. However the cans themselves (the plastic cans anyway - I have not seen a metal can dissected) do not have the internal extension pipe, and the way its plumbing is revised without the extension pipe, creates a direct short of the vapor flow which bypasses the carbon filtering media, greatly limiting the carbon filtering process intended.

Your insight please...

earlier VWs used the same metal early cans. (talking about USA beetles, type 3s and 411/412s). and used the consistent VW hose plumbing layout that VW had been using since they introduced the Evap system 1970-71 on. which became what the 914s adopted with the move to engine bay can location.

yes. the cans changed from metal to plastic in 74 also. but its a furphy as we say in australia - given only the cans changed on the general VWs not the hose layouts.

the other data is the schematics in the emissions warranties which tell an accurate story. those schematics are also there for all the lesser VWs in their emissions warranties from earlier model years of VWs and they accord with the schematics in the 74 on 914s. despite the metal cans in the earlier VWs.

the other definitive bit of info is that the 911s themselves were also changed in 1974 by porsche.

that cannister is not a porsche designed cannister. its a VW part. it was used by porsche.

if anything the canister in changing from metal to plastic was an improvement by VW of the function of the can within the parameters of the VW layout. thats the way i look at it.
from the viewpoint of VW. not the viewpoint of porsche.

the principle of the VW layout is to maximise the amount of carbon between the fume line from the tank+connection to the air cleaner and the fan hose. those fist two hoses are sealed - the third is not sealed from the atmosphere.
although in the case of the aircleaner its only the airfilter that provides that final seal there. which can let fumes through i will admit. nevertheless its a seal of sorts. the line to the fan port is completely unsealed and open to the atmosphere. no valve. just carbon. its the weakest link.
so once the carbon becomes fully saturated the fumes can escape easily straight to the atmosphere. thats the VW logic. maximum carbon before getting to the weakest link point.

the porsche idea is that the can gets loaded from both ends. the fume line is the smallest load. by far the load from the carbi bowls is the heaviest. by a huge amount more. their assumption with the 911 and the 914/6 with carbs is that can gets saturated far faster than it does in any VW. far far faster by a quantum amount.
hence proportionally by the time the fume line saturates the small amount of carbon between it and the fan hose the rest of the carbon (the greater proportion by a lot) is also saturated by the extreme vapor load from the carbs. and its extreme. its two triple barrel carbs with 6 bowls.

my opinion is the porsche layout is nothing more than a coping mechanism that got them through the strictly specified USEPA test. which involved driving a car for a half hour or so according to a speced routine then parking it in a sealed shed where it stayed for a spec period of time after hot shutdown and instruments sniffed the air. if it made it with the hydrocarbon ppm in the air inside the shed staying below a certain level it got a tick and certification. that was it. that was the test. and if you ask me that was all porsche were intent on. passing that test.

whereas VW had the luxury of EFI (For the most part, i will admit the beetle still had a carb but is a very small vapor load compared to a 911 or 914/6). as such they could do a layout that was focussed on longevity or as long as they could get it to go for. it would have walked through the standard USEPA test backwards on one toe.
the other half of the regulations stated the system had to last 5 years or 50,000 miles.
as always VW would have been focussed on that. if they could get it to last.
otherwise they had to replace the system free of charge. porsche would not have cared about that. they had owners they probably believed were happy to keep replacing the unit if they were required to.

thats my view.

and the 914/4 copped the porsche design because porsche designed the car.
and VW just built it.

and the system did not get looked at closely again until 1974 with the introduction of the L-Jet cars. thats when someone probably put their hands up inside VW and said why is this evap system the way it is on a 914 when we always do it the other way at VW.

they would not have got an argument at porsche end of things either at that time because porsche themselves were busy flipping it to the VW way after they ditched carbs.

so thats my view as to why the cans themselves are a furphy.
VW never changed their plumbing, despite updating the cans.

porsche did change their plumbing and wasn't just the cans that got updated.
they also did control alt delete on carbies. (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif)

[Cairo94507]

I have owned 2 '70 914-6's and my current '71 914-6; none of them had the black vents in the door jamb. (IMG:style_emoticons/default/beerchug.gif)

[wonkipop]

@JeffBowlsby

the joke down here now jeff is we have put the evap system back into three "classic" cars now on behalf of owners down here in the last couple of years. (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif)
a mini moke. a lancia beta. and now an 80s citroen.

no 914s. thank christ. (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif)

all for the same reason. they were stinking out their owners garages.
all had been ripped out years ago. the owner of the lancia had disconnected his himsef way back in the day. he had owned the car since new. (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif)

if you think a 914 has anything approaching a complexity think again.
its dead simple.
the lancia was the most convoluted piece of junk italian thinking i have ever come across.
6 hoses all connected to various different points on the upper surface of fuel tank.
a lash up by the italians to cope with the australian market which in one of the few instances of long ago vanished australian innovation led us to follow the yanks within 3 years of requiring evap way back in 1974. while europe languished on this stuff until the 80s.

anyway we got it all back in and all working. it all got triggered because his fuel tank leaked and we fixed that. and it still stunk out his garage. we found where all the hoses had been cut and reinstated the system with a new charcoal filter.

it was just laughable listening to the owner initially tell us he thought it was a feature than affected engine performance.

i have a feeling we will be doing more of this as wives complain about petrol fumes in garages from faded status symbols parked there by their husbands on hot 40C days in australia getting to their noses in the newly renovated live/kit/dine complexes in their fancy houses. (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif)

enough.

but i do find it funny that a 914/6 would be remarked upon for its intact evap system.
oh how the world changes. (IMG:style_emoticons/default/beer.gif)

i am a believer in evap systems personally and just cannot understand why anyone would have torn them out of cars. other emissions junk sure. but an evap system is harmless and only does good.

[JeffBowlsby]

Would you agree that the plastic charcoal cans, as manufactured without the internal extension pipe and plumbed as per my sketch below, provides maximum carbon filtering as compared to a 180-rotation arrangement of the can where the vapor in and out ports are at the same end of the can, opposite the air supply in port?

[wonkipop]

Would you agree that the plastic charcoal cans, as manufactured without the internal extension pipe and plumbed as per my sketch below, provides maximum carbon filtering as compared to a 180-rotation arrangement of the can where the vapor in and out ports are at the same end of the can, opposite the air supply in port?

no.

because

1. the fan hose connection is the one you should be concentrating on.
it needs to be max distance from the fume source - which is purely and simply the only source of hydrocarbons in the EFI engine - the fume line from the tank.

2. the way the can works is draw from the engine induction system. this is the strong force. the purpose of the fan hose is not to push air through the can to force the fumes out. the fan hose is simply to flood the can with oxygen. this releases the hydrocarbon from the charcoal. once released it is immediately drawn by the hose to the aircleaner adjacent to the fume hose connection when the engine is running.

VW are stacking all the saturated charcoal at one end close to the draw line where the strong suction force is. and at same time maximising distance or amount of charcoal where the fumes accumulate at one end of can from where they can escape down the fan bleed line.

i will concede that in their layout VW are reliant on the air cleaner itself and its filter to prevent fumes percolating out at that end. but its a stronger barrier than the open line to the fan bleed. thats why they chose this layout for all VWs in my view.

porsche had an entirely different problem. they were trying to use 100% of the charcoal.

another point to remember that when the 914/6 was running it would have had a very strong purge function from those twin triple barrel carbies. would have purged the can in double time. its the carby draw that purges the can. and its the carby load that saturates the can for the most part. the fan bleed is just there to flood the cannister. its very vivid in a 6. the sheer volume/force of suction compared to the smaller fan bleed and weaker flow.

i think VW definitely knew what they were doing with their set up tailored to the smaller 4 cylinder EFI engines. and porsche had to do what they were doing with their carb engines. and the poor old 914/4 earlier on slipped under the radar of attention by the porsche engineers who just transferred their system in to the early 4s without thinking properly about them. to me its amazing that VW did not intervene or notice.
i guess it was the early days of this stuff and it was just ticked off as being done.

but i believe in think about the system jeff you have to take into account first of all hot shutdown loads and secondly purge rates. the two things are very different on both occasions in the two different engined cars.

that is my take.

----------

the most humorous thing about all this since researching the L jets and getting to the bottom of it mike has now put me in charge of researching the evap systems on the other cars that have come in here. to find out how their original evap systems worked and to try and source the parts. very funny. (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif) but i guess i have done something useful with what was otherwise a completely useless bit of dopey nerd research previously.

as i say the lancia system was the most stoopid thing i have ever come across.
but i guess if we have to do more of these reinstatements i am going to stumble across something even more stoopid. (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif)

[JeffBowlsby]

Thanks for the extra detail - engine intake vacuum pulls and engine fan pushes the fuel vapor laden air thru the can into the engine intake manifold. Simple enough.

The intake vacuum should be ~-15-20 in/hg in a healthy engine right? I would be curious to know what the engine fan pressure supplied is and how it compares to the intake vacuum. It’s not critical though as they both do the same thing. In fact if the intake manifold vacuum is sufficient, the engine fan air would be redundant and unnecessary.

Either way the can is a plenum with only three ports. Fuel vapor is supplied from only one port, from the fuel tank. Carbed cars may have a different fuel vapor source…the subject has not been discussed before, so I am thinking conceptually.

The other two ports in the can either vacuum out the air in the can by applying intake manifold vacuum (purging) or by pushing air out of the can by positive engine fan air pressure. Both sources direct the fuel vapor laden air into the intake manifold.

The basic issue then is that as long as fuel vapor laden air is directed through the charcoal media, either pushed or pulled though it, then the can is functioning to cleanse the airflow. My diagram requires the air to flow through all of the media, it has no other route.

If the can is plumbed such that the small fuel vapor supply hose is at the same end of the can as the port to the intake manifold vacuum, then the fuel vapor only permeates the media at one end of the can and filtering would be much less effective. Basically a short circuit. This effect would be magnified by the engine air fan pushing air into the media, which further reduces fuel vapor permeation into the media.

Conceptually, with both air movement sources, it would not matter how the can is plumbed. Fuel vapor can only be drawn into the can, the other two direct the air out, into the engine intake. One configuration may be more effective than the other, depending on the airflow balance directing air into the intake manifold.

What am I missing here?

[wonkipop]

Thanks for the extra detail - engine intake vacuum pulls and engine fan pushes the fuel vapor laden air thru the can into the engine intake manifold. Simple enough.

The intake vacuum should be ~-15-20 in/hg in a healthy engine right? I would be curious to know what the engine fan pressure supplied is and how it compares to the intake vacuum. It’s not critical though as they both do the same thing. In fact if the intake manifold vacuum is sufficient, the engine fan air would be redundant and unnecessary.

Either way the can is a plenum with only three ports. Fuel vapor is supplied from only one port, from the fuel tank. Carbed cars may have a different fuel vapor source…the subject has not been discussed before, so I am thinking conceptually.

The other two ports in the can either vacuum out the air in the can by applying intake manifold vacuum (purging) or by pushing air out of the can by positive engine fan air pressure. Both sources direct the fuel vapor laden air into the intake manifold.

The basic issue then is that as long as fuel vapor laden air is directed through the charcoal media, either pushed or pulled though it, then the can is functioning to cleanse the airflow. My diagram requires the air to flow through all of the media, it has no other route.

If the can is plumbed such that the small fuel vapor supply hose is at the same end of the can as the port to the intake manifold vacuum, then the fuel vapor only permeates the media at one end of the can and filtering would be much less effective. Basically a short circuit. This effect would be magnified by the engine air fan pushing air into the media, which further reduces fuel vapor permeation into the media.

Conceptually, with both air movement sources, it would not matter how the can is plumbed. Fuel vapor can only be drawn into the can, the other two direct the air out, into the engine intake. One configuration may be more effective than the other, depending on the airflow balance directing air into the intake manifold.

What am I missing here?

not quite jeff. but kinda close to what i am saying.

drop the idea the fan pushes air through the canister.
i think conceptually that is what is clouding the matter in the way you are conceiving of it.
it just "gently" floods it with oxygen. its a very small bore hose coming off the very side of the fan casting. its not in the stream of the full air flow.

the draw from the engine intake is far stronger.

and the two ports so to speak, the fan port and the air cleaner port are not equally neutral in terms of the connection to the atmosphere. the fan port is the most open "door" - when the car is sitting around not running and everything is static - if the charcoal is overcome.

-----------

here is another fly in the oitment to consider as to why VW changed the internal arrangement of the cans (in particular the fume hose internal pipe you have noted).
the plastic can and slight redesign also co-incides with VW phasing out oil bath air cleaners and going to paper elements. the internal chemistry of the air cleaner in VWs alters at that point. now its a paper element that will be the barrier to vapors from a fully saturated can flowing back into the air cleaner. thats very different to fuel vapors mixing with oil. i am no chemist. i'm just saying there are a few factors in the mix here that all overlap when it comes to why VW changed the cans to plastic and slightly revised the internals. its not as simple as a redesign of the can prompted the change in the plumbing -------which i might add i finally proved did in fact indisputably happen - its a few things that are changing at that time. BUT - in capital letters (IMG:style_emoticons/default/biggrin.gif) the one thing that VW never changed from 1970 on was the way the hoses hooked up on every VW except the 914/4.

----------

i got one more for you too. i got to scan the diagram. but i will post it next after i scan it. it comes from the clymer manual. i just decided to look at it again after about 20 odd years. i found something very interesting (IMG:style_emoticons/default/biggrin.gif)


i'm not trying to argue with you. as much as you are i am trying to understand how that system actually worked that explains why it existed in the different forms it did over those few short years. because its a marvelously simple system that VW came up with as well as porsche. using just a dumb simple can with no valves.

part of it is they always had the benefit of the engine cooling fan to flood the can with oxygen and no other manufacturer had that bonus element. it was thanks to air cooling.
every other manufacturer used a valve, sealed off their can and had to rely on drawing in whatever fumes they could get the charcoal to release. but VW (and porsche) could also flood that can with extra air during purge. its a bit like their dumbo windscreen washer off the spare tyre. very analogue and mechanical and very very german. or more correctly very post war german. making everything work to its maximum out of a minimum. they don't do it anymore but they really used to do it. now they just do maximum (as i stare into the horrors of my uncle's merc CL500 currently in the shop! (IMG:style_emoticons/default/biggrin.gif) )

also the one other factor you are missing in relation to the 914/6 is the vapor load.
its huge in the 914/6 from the carbs. via the air cleaner hose.
and its virtually non existent in the 4 via the same route (there is no fuel hanging aournd in the EFI intake system - the fuel injectors are shut off. there is a (IMG:style_emoticons/default/stromberg.gif) load of fuel just sitting there in a carb bowl off gassing freely and happily).
thats when the car is sitting there. right after you drive it into the carpark after driving to work or going home and turn the key and shut the engine off.
and thats when the can is supposed to do its job.
can you see where i am coming from.
you are an architect. just think like one. thats how i am thinking of this. regs. compliance. pass the test. whatever it takes. it has to pass the test. thats the measure?
stop thinking in pure terms. i get how you are reasoning it. but what i am saying is it wasn't so pure. it might have been a little more desperate. like just pass the test.
the one the EPA has written the parameters for.

[wonkipop]

@JeffBowlsby

here is the diagram for EVAP i found in cypress manual.
i think i mistakenly referred to it as the clymer manual in post above.

i had not thought to look at this little manual. its been sitting on my shelf unmolested for about 20 years +. i just use the factory workshop manuals these days.
but lo and behold its the hose diagram for EVAP that applies to the 74 engine bay can cars onwards.
mind you, no notes, no heading to indicate that. its just presented as the hose diagram for evap. its in no other manuals. its got no source for it noted. no index to state source (very academically unsound in the world i used to mix in. (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif) )
but there it is.

anyways. as mike, the resident genius mechanic in here keeps telling me, there is lots of things to consider when you are trying to unravel why a manufacturer did things the way they did them...........and you got to know all the factors.

i suppose we could be accused of derailing the thread here -------but i don't think so.
its interesting why some 914/6s got an evap and others didn't - and then why the system got changed in 1974. it was not just done one way and one way only as if there was a single right way. and to be honest its the only reason anyone would ever really want to be interested in "orginality". the only value in originality is to chart the course of technology and understand it. the objects themselves hold the knowledge. not what someone has said about them in the years since or whatever false mythology has built up around them parading as knowledge. or am i wrong?

i am not a concourse guy. i could not give a rats arse about that stuff.
but i am into technology and how it evolved and the why behind it.

[wonkipop]

My car never had vent screens.. Build date 2/70

i am fairly convinced by what you say that some folks might have "improved" their 6s over the last half century. (IMG:style_emoticons/default/biggrin.gif)

[rick 918-S]

What I am wondering about is why a car that nice is sitting at $55k with less than 7 hours to end the auction. (IMG:style_emoticons/default/confused24.gif)

Wrong time of the year? (IMG:style_emoticons/default/wacko.gif)

[gandalf_025]

I'm pretty sure the price of that car will go up dramatically in the closing minutes


There are advantages and disadvantages to having known
your car since it was still under Factory Warranty and had only
been serviced by the Dealer.
One thing you can be pretty sure is that it wasn't modified much that early.

The disadvantage is you are your own DAPO..
You have nobody but yourself to blame for the way the car is now...

[ctc911ctc]

I'm pretty sure the price of that car will go up dramatically in the closing minutes


There are advantages and disadvantages to having known
your car since it was still under Factory Warranty and had only
been serviced by the Dealer.
One thing you can be pretty sure is that it wasn't modified much that early.

The disadvantage is you are your own DAPO..
You have nobody but yourself to blame for the way the car is now...

The Snipers have entered the room right now

70->75->76->80 still going! Hammered at $80,000 - no bids in the last 3 minutes.

[Steve]

And didn’t make the reserve. I wonder if it would have done better in the spring. Market kind of sucks right now.

[rgalla9146]

I'll bet the reserve was 100k
I think the value of originality is not widely understood.
It's the best unmolested car in a looong time.

[johnhora]

I'll bet the reserve was 100k
I think the value of originality is not widely understood.
It's the best unmolested car in a looong time.

Absolutely!

What a very nice original 914-6

[sixaddict]

Pre Christmas pretty much bad time to sell stuff……..unless it’s a steal then we can all seem to rationalize spending on “ourselves”. To me topping out at 80k says only bottom feeders were playing. Personally wondering how Glenn collection on Hagerty is going to shake out.

[914043]

dr914 please share your pick list on this beautiful 6. Much appreciated.

[dr914@autoatlanta.com]

I have one, but did it for a client who paid for it


However I can say that this is an impeccable car and well worth the current 125 asking price. I had called out the material mismatch on the drivers seat and the owner then remembered that he had the original so that is included as well.
good buy in my opinion

dr914 please share your pick list on this beautiful 6. Much appreciated.