Filtering veggie again

[GIRDLES]

Just posted this thread on Veggie site to see if we can clear up some questions asked.

[Apache]

All I want to do is settle any crud / water out, filter it and throw it in the truck at around 50 / 50 with dino.

Cant be assed with / dont have the space or time to do proper bio.

The oil I'm getting from my local (~60 litres a month) is pretty much 'chips only' so that will be fine as I understand it. From the indian I dont get so much (maybe 20 litres a month) and its had everything fried in it, though mainly onion / batter, so I'll have to be a bit more careful with that.

Does that all sound reasonable?

[GIRDLES]

Quote from a Veggy site

Veggy Oil And The Modern Direct Injection Diesel





Nearly all Post 2000 Diesel vehicles are of this type, There are the odd exceptions but not many...The reasons why the Makers have gone over to Di type engines are-Cheaper to produce, and an increase in Volumetric Efficiency--Less Pumping-Losses... (basically you can get more power out of the same capacity engine. However, This comes at a cost-The Di type engine is a lot more tempremental as to its fuelling and timing requirements with relation to its smoke and other emissions-

--
)

To get back on track, Now Ive done my soap-box bit, What does this mean for veggy oil as a replacement 'fuel' for these Direct Injection modern beasts?

It gets a 'little' technical, but not too bad, Worth plodding on, It is however assumed that the reader knows in principle the operation of the Diesel Engine.....

As has been described elsewhere, The first small Car Diesel-Engines were Indirect Injection, Meaning the fuel was sprayed by the Injector into a small Ante-Chamber known as a Pre-Chamber or Swirl-Chamber, normally contained within the Cylinder-Head. This chamber was connected to the main chamber by a tangentally arranged narrow passage or by small holes as in the case of the Mercedes Pre-Chamber type.


There are generally Two Types of 'Pre-Chamber' or Indirect Injection engine. The Mercedes System, where a small spherical chamber is connected to the main chamber by a blind ended tube with several small holes set at right-angles to the piston axis. Contained in this spherical chamber, there is a 'Hot-Spot', formed by a small rod with an enlarged central section. This is in direct line of 'squirt' from the injector and allowed to run at very high temperatures--Around glowing orange heat This promotes a good vapourisation and ignition of the fuel and a really well controlled progressive + quiet burn....

The other system, developed by the Combustion Engineers, Ricardo's (Yes, The same guys of the Infamous 'Report'), developed in the '30's and called the 'Ricardo Comet' design is used by nearly every other car engine maker using IDi technology. This as mentioned earlier is a semi-spherical chamber, with the Injector at the top, mounted at an angle as to Not direct its spray down the throat of the communicating passage from the main combustion chamber. This small passage is set at an angle to the sphere, so as air is compressed in the cylinder, it will be forced into the pre-chamber with some force and at just the right angle to cause the air-mass inside the chamber to swirl at very high velocity, just like a whirl-wind

The lower half of the sphere containing the tangental passage, is made from a special autenitic Stainless-Steel and deliberately allowed to run at very high temperatures, by reducing its contact area with the actual metal of the cylinder-head into which its pressed (Its outer cercumference has a recess in it, below the face of the head...)

This promotes excellent mixing and vapourisation of the injected fuel as well as a good progressive burn.

As can be seen, With the IDi system, There is MUCH less likelyhood of Unburned Fuel making it the distance involved to the cylinder-wall, without first vapourising and burning away.

Consider the Direct Injection type engine. Here, the Combustion chamber is formed in the top or 'Crown' of the piston. Usually it forms a bowl sometimes with a flat bottom sometimes with a raised bottom Often there is a small ridge of around 1mm around the top of the bowl, an attempt to contain the combustion 'charge' and promote turbulence during the last few mm of upward piston travel, causing 'Squish' of the air between the head and piston, forcing the air towards the centre of the chamber. The Inlet-Manifold and valve-tract is often very carefully designed to cause 'tumble' of the air as its drawn into the cylinder through the open valve, to promote as much Turbulence in the air-mass as possible.

There are NO hot-Spots or anything like that to assist in the vapourisation of the injected fuel, as well as the fact that the piston-bowl runs at a very much lower temperature than a Pre-Chamber or M.B 'Hot-Spot', as the piston is made of Autothermic Aluminium Alloy and cooled quite effectively by the cylinder-walls and the lube-oil from underneath, flung up from the crank-pin and connecting-rod...

Being a large open chamber, in comparison to the Swirl Chamber types, with nothing much between the cylinder-wall and the injector there is a Huge likelyhood even on the best designs and everything perfect that unburned and or partially burned or 'pyrolised' fuel will hit the cylinder-walls

Another factor in favour for us 'Veggies' of the Venerable IDi is the type of Injector used with the IDi system. Generally, this is a 'Pintle' type. meaning that its rather like a needle-valve, where the needle protrudes slightly from the hole, in the face of the nozzle and during normal operation the movement of the needle lifting will keep the hole and needle pintle fairly clean of coke (Carbon to us Mortals!)

The Di system generally uses a 'Hole' type injector Usually, up to eight tiny, and I MEAN TINY holes are arranged in the nozzle tip. these are Very short passages, their inner end is closed off by the nozzle needle when its not actually spraying fuel. They are kept as short as is mechanically possible to reduce the amount of fuel that will slowly boil off and vapourise due to the heat of combustion just after injection has finished, which would otherwise raise smoke and emission levels.

Consider the effect that even a minute amount of Carbon build-up would have on this type of injector nozzle...It would completely disrupt the correct operation of the nozzle, and instead of a very fine spray, one or two holes could literally produce a jet of un-atomised fuel, just like a water-pistol....

So,--Why should I care if unburned veggy hits the cylinder-walls of my pride and joy...?


Just Two Words....

RING-GUMMING.........

When exposed to heat and oxygen Veggy-Oil will start to break down. It starts to thicken and polymerise and as time goes on, it turns from a sticky brown 'goo' into a hard black Coke/Carbon material. Just take a look at the frying-pan in your favorite Greasy-Spoon!

Any unburned veggy or partially burned veggy hitting the cylinder-walls will find its way to the Piston-Ring grooves on the next upward stroke of the piston. This veggy will collect in the gap behind the rings and the small clearances either side of the ring and piston. As time heat and plenty of oxygen are available, it breaks down and sets solid, sticking the ring in its groove, so it can no longer follow the irregularities of the cylinder-wall and seal the piston, as it was intended.

This ring gumming is slow and progressive, The speed at which it happens is dependent on Many factors The main ones being the temperature of the combustion-chamber and the condition of the injector atomisation, but as it progresses, gets faster and faster, at a weirdly logarithmic rate...

This causes loss of compression pressure gradually over weeks/months of use. which contributes to the secondary effect....Often the slow and progressive slight power loss may not even be noticed, or blamed on other issues, such as blocking filters or the choice of veggy oil or even the weather (No one wants to admit even to themselves there's something nasty growing in the Crank-Case!)....

(A Diesel Engine relies on the fact that when air is compressed, it gets hot, just like the effect noticed when pumping up a bicycle tyre. It depends on this heat for the ignition of the fuel. If for some reason there is a loss of air, say, from leaky rings, the peak temperature attained by the air at the point where the piston is at Top Dead-Centre, A.K.A. Top of the cylinder, the point of maximum compression pressure, the air will be cooler than intended, thus there is a very real danger of incomplete combustion, or even a complete Misfire, where the veggy wont burn at all, Pale bluish or White-Smoke in exhaust and maybe an unsteady engine when idling)

Not all the veggy is burned Particularly when cold, so this just adds to the supply of 'Ring-Glue'

As it progresses, the amounts of unburned veggy in the combustion chamber/cylinder, increase where it will pass to the lubrication oil by the operation of the oil control rings scraping it off the bores. The Oil Scraper/Control rings, being the lowest on the piston are last to be affected, The Top ring, which is the main sealing ring and subject to the full force of combustion pressure is first to go...

(Just as well the Oil-Control ring is last to go, or the engine could have otherwise end up in a runaway condition where it burns all its lube-oil in a minute or two and hits revs the makers would never have dreamed possible...The danger to life when driving a vehicle when this happens is better not even imagined, You CANT SHUT IT DOWN!....although I dont need to imagine it...Its happened many years ago to me....)

This ring gumming is Progressive and Accelerating Process, Thats why its so Insidious!

The Veggy builds up in the engine lube-oil....

There comes a 'Critical Mass' point, (although before this, it can thicken to some extent but without careful testing the amount of contamination cannot really be assessed),- where the Mineral Lube-oil and the Veggy oil are in the right proportions with the normal engine heat and other forces to react to form a polymer, and on that fateful day the engine cools after the 'Critical-Mass' has been reached where the lube-oil will set solid, just like jelly!

There is alot more to read

[MattF]

Now there's some doom and gloom about expensive repairs if its not converted to biodiesel.

Take everything you're told with a pinch of salt and just judge from all of the info you collect. The VO fanatics make out as if biodiesel is evil and vice versa. Just take the opinions for what they are and rely on the facts, as you would with anything else.

[Apache]

Just ordered a couple of 10" filter housings from eBay, so when I get them I can work out what plumbing I need up to a tank in the loft of the garage. I'll take a feed from an inch or so up a side wall of the loft tank via a tap so I can shut it off to change filters. I'll fit a drain in the base of the tank so I can draw off shit / water that settles there.

I wont be using pumps, as there will be a 6ft drop from the tank in the loft to the filters, and there's plenty of advice suggesting that slower filtering is more effective.

I'm currently thinking of using a plastic domestic water tank in the loft. Any alternative suggestions?

From the filters (currently thinking 50micron then 5 micron) to a storage tank with a tap on it so I can draw off the oil to fuel cans.

Job done.

I'll still use a 50% blend, and halve my fuel costs, because I cant be bothered with the faff of fitting fuel heaters to the truck.

[gwh200]

i got halfway down that long essay from the veg site and started snorting.

since when does an oil "polymerise" what sort of monomers does it contain that need to combine to form a two part plastic

absolute bowlocks.

as i may have previously mentioned andy, settle it and sample it. look for crud in it. if there is any filter again. beware of wild claims of "1 micron" filters etc, this is the size of a decent molecule !!

as for adding methanol.you will make a methoxide, this alters the atomic number of the said oil molecule, in the samre way as nh4 will change to 2nh42cao with the addition of acidic salt......its all relative.

so to recap.


1. filter it progressively

2. settle it for as long as poosible.

3. sample it, and look for any volatiles , visible to the naked eye.

4. if you have settled solids, filter again using finer filters

5. if you dont have solids pour it in and smell like a mobile chippy.

6. add methanol if you want. as mentioned before its a 27/3 mix as in line with the bs standard for naking biodiesel.this will alter the oil , aid its lubricity, alter is ph balance and settle out any shoite, but its necessary only on very dirty samples.

6. if all is well and your still unsure..................give it to me

[GIRDLES]

Methanol will not mix with veg oil. Try mixing some in a bottle give it a shake then watch it seperate after a couple of hrs. Use Petrol 10% MAX or Diesel to thin.

[gwh200]

this is " biodiesel" (and i use the term lightly) with a ratio 0f methanol fuel


= to 27/3 as in the flash test mix.the solids were settled out after a 2 day settlement.the rest of the remaining liquor was analysed.


after analysis of its combined structure, it was found to have a higher cetane rating than wvo.this was measured with mass spectroscopy to find at least/above a 28 point molecule.
its atomic mass was altered to incorporate some ethanol molecules. the methoxide produced was below the limit deemed to be bi particulate so incorporated itself on a molecular level.this was confirmed by eventually measuring its ph value which was altered considerably by the addition of oxidising spirits.
petrol,methanol,ethanol, and pretty much any spirit WILL mix with oil if you dont try and add to much.the effect of a cetane rating change, is palpable and real
the biggest change was is in its lubricity, which meant rather than being an acidic, straight ,wvo its ability to self promulagate was increased by over 170%

this analysis was performed twice on a late line mass machine and its never wrong....unlike the conjecture you come across on the veg forums (they even guess about diesel compression internals..and polymers...please)
its quite easily achievable to mix oil and spiritoil and water...in fact oil and anything as long as its in the right quantities.

(look what happens to an oil slick...it eventually disapears due to wave action mixing)

[Apache]

errr yeah.

So filtering would be fine then?

[gwh200]

errr yeah.

So filtering would be fine then?

yes

just add a little something spirited (ethanol,methanol,petrol,white spirit,mcallans 12 year old malt etc) if its really manky

its always a good idea to add a little redex about every 3rd tank as well andy..keeps the veins clean

[Apache]

its always a good idea to add a little redex about every 3rd tank as well andy..keeps the veins clean

Oh yeah, cos a cars fuel system is just like a human circulation system innit?

[darkdezigns]

wasnt there somthing else you said to add?besides methanol?

[gwh200]

Oh yeah, cos a cars fuel system is just like a human circulation system innit?

dude.........i mean mate............thats why i will (but not in a pants off way)

im so looking forward to wales and just chewing the fat round the fire.

[darkdezigns]

dude.........i mean mate............thats why i will (def in a pants off way)

im so looking forward to wales and just chewing the fat round the fire.

omg

[GIRDLES]

I believe the 27/3 test is to check for fall out on processed oil ie Biodiesel. The bio 3 PARTS is mixed with methanol 27 PARTS and shaken to mix then settled,all the unprocessed oil and soaps will fall out showing an incomplete reaction.
The process of washing Biodiesel is to remove Methanol, so by adding methanol to a tank of WVO I cannot see the point.

Filtering after settling is all thats req, Thin with some Diesel when it gets cold. Using Veg oil as fuel not making it into Biodiesel.
I have had no problems running 80-100% all summer using the method above.Enjoy your cheap motoring.