Do we really need to heat WVO?

[Nuddy Senior Member Find all posts View Profile Close Nuddy]

As a few of you know, I bought a 93 model Merc W124 300D in July last year. It has a 6 cylinder 3litre NA engine supplied by a Bosch in-line injection pump. - - - - - I delayed converting the car due to work pressures and health issues, and ran the car for much of the time on a 50/50 blend. In March/April I started testing the limits of the blends and was stunned when the car was able to start almost instantly on cold veg oil. - - - - - - I had huge plans for a dual tank system - - - - - Well, none of this eventuated, because it wasn't necessary.
Anyway, as I mentioned, I was more than happy when the car started easily on cold veg oil, so I started filling up the main tank with used cotton seed oil. However, I decided to add 3 litres winter-blend diesel fuel to each tank of oil as a flow improver for the cold winter mornings. This continued through the whole of winter, and on 4 mornings, the temperatures outside were below zero, the coldest morning being 4 degC. Glowing the plugs twice helps the car start on the 2nd revolution of the engine. Holding the revs at 1200 for about 10 secs and easing back on the throttle results in a nice smooth idle. If I didn’t do that, the engine would cut or idle lumpily for the first 30 seconds or so.
Anyway, the car has now done 15000km on this treatment and it runs beautifully, with very little smoke compared to my 1976 W123 300D. Now that the warmer weather has arrived, I have not been adding any diesel to the oil.

I got my initial info on WVO from Marcus Deuchar's book. I was from his book that I came across this forum. Marcus states that WVO must be heated to a minimum of 70oC and presented to the injectors at this temp for proper combustion.
Many of us have found that "it aint necessarily so".
It has been said that the WVO needs to be at least 120oC as it leaves the injector for proper combustion but there is no easy way of telling the temp at this point so that is an academic argument.
It is important that we have proper combustion but do we need to heat the WVO to achieve that?
I have previously opined that we only need to heat the wvo, using a heat exchanger, to ease the passage of the WVO through the filter, that the IP and the injectors themselves will add sufficient heat to ensure proper combustion.
With the Nissan RD28T I started with a 50/50 blend of WVO and distillate and got good results including easy starting from cold. I went up to 75% WVO/25% distillate and had good running but difficult starting so I cut back to 60/40. As soon as I got time I set up a very basic 2 tank system and for the last few days have been starting on 100% distillate and immediately switching to 100% WVO - unheated. The engine runs perfectly from cold on cold WVO but needs the distillate for the first start each morning. Further starts through the day are just fine on cold WVO and I only purge for 3 minutes at idle at the end of each day.
I have a 20 plate HE in the system but it is not yet connected to the cooling system. I will connect it eventually but the pollak valve is a higher priority - currently using a 3 port ball valve - manual underbonnet switching.
Subjective impression is that the patrol has more power when running on WVO - seems to go up hills better.

[Tony From West Oz Vice Chairperson of WARFA Find all posts View Profile Close Tony From West Oz]

Re: Do we really need to heat WVO?

We have a few options for using vegetable oil as a diesel fuel, Heating, Blending or Transesterification are just 3 of these.

Each has its advantages and disadvantages. These have been discussed many times on this forum.

Make the choice which option suits your risk profile and lifestyle.

Regards,
Tony

[pangit Moderator Find all posts View Profile Close pangit]

Re: Do we really need to heat WVO?

To me it's pretty simple. Why take the risk for the sake of a tiny amount of startup fuel? It seems to be good practice to wait until the engine is up to temperature before changing over, especially as David says you won't know if you are damaging your engine with cold WVO until it's too late. So why take the risk?

I make biodiesel for my startup fuel anyway so it's not as if I'm saving much $ by switching to WVO earlier. But even for people using dino would only be spending something like 60c worth each time (based on a 3km warmup)

We are already getting most of our fuel for nothing but our own labour, what's the point of quibbling about the last little bit?

[dagwill Senior Member Find all posts View Profile Close dagwill]

Re: Do we really need to heat WVO?

all good info dave, i also like tonys [suit your RISK profile ]
it seems to me that far too often people have to push things to the limit for no reason
i mean why push things as fine as 60/40 65/35 or could i even get 67/23
ease off a bit 50/50 gives peace of mind as well as cheap fuel
same with change over 2 tank sys.
why on earth experiment and try to find to a degree C. the absolute earliest it is possible to hit that switch
let it get up to temp properly ,and then can anyone give me a reason not to just wait say one whole km more before changing
same with purge, i reacon 3km from home gives me good purge,but i always hit the switch [as i go past a familiar spot ] 4ks from home
it saves me from constantly worrying about that knife sharp point between damage and no damage

[bruceT Senior Member Find all posts View Profile Close bruceT]

Re: Do we really need to heat WVO?

I got my initial info on WVO from Marcus Deuchar's book. I was from his book that I came across this forum. Marcus states that WVO must be heated to a minimum of 70oC and presented to the injectors at this temp for proper combustion.
Many of us have found that "it aint necessarily so".
It has been said that the WVO needs to be at least 120oC as it leaves the injector for proper combustion but there is no easy way of telling the temp at this point so that is an academic argument.
It is important that we have proper combustion but do we need to heat the WVO to achieve that?

It's a good question and the answer is generally quite simple.

* For filtering before use, the answer is NO, and cold filtration is preferable although slower.

*For the purposes of in-car filtration, the answer is YES. Some heat, but only enough to melt the HMP and wax components is all that is necessary to ensure adequate flow through the filter.

*For the purposes of ensuring that your IP can process the higher viscosity of WVO, the answer is not that simple. It depends on the brands and design of the IP in your vehicle. For example, the Bosch in-line pumps found in the older model W123 and W124 Mercs, the viscosity is non-critical as these pumps easily handle veg oil of any temperature, as long as it's liquid. However, many of the rotary pump designs are not so tolerant, so quite a lot of heat is required in order to get as close as possible to the viscosity of diesel oil, for which the pumps are designed. So the answer to this part of the question is vehicle dependent. Research and the experiences of others should be the guide to designing the system required.

*For the purposes of combustion, the heat that is imparted to the oil before the injectors is of little consequence. Diesel engines impart plenty of pressure and if it ignites in the cylinder it won't be because of the heat from your heat exchanger! Anyone who has ever used a bicycle pump will know that compression causes heat. Combustion then adds more heat and so the chain reaction starts.

If your car will start on SVO, lucky you, you don't need a dual tank system. If it starts on diesel only or a blend then that is your starting fuel and you must have a dual tank system. My dual tank W123 300D won't start on SVO, but it starts perfectly on a 50/50 diesel/SVO blend, so that is what's in the start-up tank. In summer it can be switched over to SVO as soon as the engine is running. However, in winter, it is the fuel filter that dictates that the svo needs some warmth in it so that it can pass through the filter OK. Otherwise it starves and will cut out. The amount of heat needed to achieve decent flow through the filter is nowhere near 80degC. 20 degrees is fine for the filter system in use, so that means it can be switched over after about 500m or so. Full changeover on this car takes another 900m.

[Nuddy Senior Member Find all posts View Profile Close Nuddy]

Re: Do we really need to heat WVO?

*For the purposes of ensuring that your IP can process the higher viscosity of WVO, the answer is not that simple. It depends on the brands and design of the IP in your vehicle. For example, the Bosch in-line pumps found in the older model W123 and W124 Mercs, the viscosity is non-critical as these pumps easily handle veg oil of any temperature, as long as it's liquid. However, many of the rotary pump designs are not so tolerant, so quite a lot of heat is required in order to get as close as possible to the viscosity of diesel oil, for which the pumps are designed. So the answer to this part of the question is vehicle dependent. Research and the experiences of others should be the guide to designing the system required.

*For the purposes of combustion, the heat that is imparted to the oil before the injectors is of little consequence. Diesel engines impart plenty of pressure and if it ignites in the cylinder it won't be because of the heat from your heat exchanger! Anyone who has ever used a bicycle pump will know that compression causes heat. Combustion then adds more heat and so the chain reaction starts.

If your car will start on SVO, lucky you, you don't need a dual tank system. If it starts on diesel only or a blend then that is your starting fuel and you must have a dual tank system. My dual tank W123 300D won't start on SVO, but it starts perfectly on a 50/50 diesel/SVO blend, so that is what's in the start-up tank. In summer it can be switched over to SVO as soon as the engine is running. However, in winter, it is the fuel filter that dictates that the svo needs some warmth in it so that it can pass through the filter OK. Otherwise it starves and will cut out. The amount of heat needed to achieve decent flow through the filter is nowhere near 80degC. 20 degrees is fine for the filter system in use, so that means it can be switched over after about 500m or so. Full changeover on this car takes another 900m.

Research by High Compression II has shown that Lucas clone rotary IPs need WVO to be 40oC but Bosch clone rotary IPs are reliable on 'stone cold' WVO.

If the WVO is cold filtered it should not need to be heated to get it through the filter as there should be no HMP fats present.

For the purposes of combustion, once the engine is running, cold WVO should be OK as it will get plenty hot by the time it gets to the injector tip.
However for starting (from cold) there is negligible heat at the injector tip so either the WVO needs to be heated (as in 1 tank systems) or a starting fuel must be used (2 tank system). I am not confident in pre-start heating so I use a starting fuel (2 tank).
So my assertion is that if the WVO is cold filtered there is no need for a heat exchanger in the 2 tank system.
I agree: "For the purposes of combustion, the heat that is imparted to the oil before the injectors is of little consequence."
I will connect up my 20 plate HE before next winter in case my cold filtering is not removing all the HMP fats.

[Nuddy Senior Member Find all posts View Profile Close Nuddy]

Re: Do we really need to heat WVO?

I believe the heating of the oil is relevant to the lowering the viscosity of the oil to a level closer to which the injectors were designed to function with so they are able to spray the oil, rather than just squirt it. As there is no way to heat oil in the injectors on a cold engine, we use a thinner fuel to start so it can be properly atomized and burn completely in the cylinders.

It seems the easiest and safest thing to me is to stick to proper warm up times on suitable fuel

I agree with the above. Will say more soon.

[Nuddy Senior Member Find all posts View Profile Close Nuddy]

Re: Do we really need to heat WVO?

I am convinced of a middle ground and that is for certain vehicles, heating the fuel only enough to melt any fats and allow them to pass through the filter would be sufficient for safe engine running, AFTER the engine was well up to temp.

If the WVO is filtered at sufficiently low temp that it easily passes through the filter, do we need a heat exchanger at all (on a 2 tank setup)?
I think probably not.

[Tim-HJ61 Donating Member Find all posts View Profile Close Tim-HJ61]

Re: Do we really need to heat WVO?

Paul,

Following up your observation that the vehicle appears to have more power on WVO.

My thoughts are that this can come from two, no, three sources:

1. The fuel itself. What I understand is that vege based fuel has a lower calorific value than dino diesel, so there cannot be more power from the same given amount of fuel.
   
2. Some mechanical change. I note from Geco's experience with his failing IP that in fact WVO got them an extra 2000kms down the road. His vehicle would not start or run on diesel, but would run on WVO. Why, because when his pump was pulled apart, and I have seen this myself, the shaft on the rotary IP that turns and distributes the fuel from one cylinder to the next had a tiny amount of visible wear. A tiny amount of visible wear made the IP dysfunctional as tolerances are in microns. His IP worked better on WVO because of the higher viscosity hence keeping the pressures higher, even with a Fitian twin HE setup - or so it would seem to me.
   
3. Your perception

Given your oil is not heated point #2 may be the relevant one and maybe your IP is a trifle worn, or #3.

Tim

[Nuddy Senior Member Find all posts View Profile Close Nuddy]

Re: Do we really need to heat WVO?

Paul,

Following up your observation that the vehicle appears to have more power on WVO.

My thoughts are that this can come from two, no, three sources:

1. The fuel itself. What I understand is that vege based fuel has a lower calorific value than dino diesel, so there cannot be more power from the same given amount of fuel.
2. Some mechanical change. I note from Geco's experience with his failing IP that in fact WVO got them an extra 2000kms down the road. His vehicle would not start or run on diesel, but would run on WVO. Why, because when his pump was pulled apart, and I have seen this myself, the shaft on the rotary IP that turns and distributes the fuel from one cylinder to the next had a tiny amount of visible wear. A tiny amount of visible wear made the IP dysfunctional as tolerances are in microns. His IP worked better on WVO because of the higher viscosity hence keeping the pressures higher, even with a Fitian twin HE setup - or so it would seem to me.
3. Your perception

Given your oil is not heated point #2 may be the relevant one and maybe your IP is a trifle worn, or #3.

Tim

1. Calorific value is only one factor relating to power output. If one type of fuel is burned more efficiently than another this may overcome a calorific value deficiency, resulting in more power. Also more fuel may be being burned on one fuel compared to the other, resulting in more power as long as there is sufficient oxygen to maintain the combustion. I found this many years ago when comparing petrol with LPG. My vehicle was so much more efficient on LPG that it produced more power while burning less fuel, when tuned and optimised for LPG.

2. Yes, the higher viscosity could be compensating for some wear in the IP.
It has done 270,000 km. Also since I am using a 'pusher' pump to assist the integral lift pump on veg only, that could also be compensating for wear in the IP.

3. Most likely. On the troopy I found through dyno testing the same power on veg as on diesel. It may have been burning more veg or may have been burning it more efficiently, or both - who knows.
I certainly can't trust my perception and once the conversion is complete I will do some dyno testing with the patrol.

[Nuddy Senior Member Find all posts View Profile Close Nuddy]

Re: Do we really need to heat WVO?

*For the purposes of combustion, the heat that is imparted to the oil before the injectors is of little consequence. Diesel engines impart plenty of pressure and if it ignites in the cylinder it won't be because of the heat from your heat exchanger! Anyone who has ever used a bicycle pump will know that compression causes heat. Combustion then adds more heat and so the chain reaction starts.

I'm not sure if Bruce is implying that pressurising the fuel in the IP or injector makes it hot. Perhaps not, however the fact is that compressing a gas does make it hot due to the reduction in volume, as in the bicycle pump. Pressurising a liquid does not reduce its volume so it doesn't get hot. Forcing it through a fine orifice does cause heat through friction.
Compressing air in the engine cylinder makes the air very hot due to the reduction in volume. That's how a compression ignition engine works. Then spraying (atomising) a liquid fuel into the hot air will cause the fuel to vapourise and ignition can occur. If the fuel is too cold the compressed air may not be hot enough to vapourise it and ignition may not occur.
If the injector is cold it will cool the fuel. If the injector is hot it will heat the fuel. WVO needs to be hotter than distillate to ignite so a cold engine may start on distillate but not on WVO. As soon as the engine starts the injector starts heating rapidly as it is exposed to the combustion flame. As soon as the injector is hot enough to heat WVO sufficiently for the atomised WVO to vapourise in the hot air, proper combustion can occur and it is safe to switch to WVO.
I certainly agree with Bruce that "for the purposes of combustion, the heat that is imparted to the oil before the injectors is of little consequence".

So it may be necessary to heat the WVO to get it through the filter and it may be necessary to heat the WVO to preserve the IP (Lucas clone) but I do not believe that it is necessary to use a heat exchanger to heat the WVO for combustion.

I will connect my FPHE by next winter to ease the passage of the WVO through the filter.

[hobie1kanobie Donating Member Find all posts View Profile Close hobie1kanobie]

Re: Do we really need to heat WVO?

hey all,

it's been a while...

seems to me that everytime i get on the site, some raises the same questions, which in turn, raises a few negative thoughts.

i have suffered a few filter problems, re, my first trip post, BUt have since realised that i probably pushed my up flow filters too hard to try and get up and running too quickly, thus not allowing the oil to settle enuf. this has now been sorted by an over supply of oil and way too many drums sitting around plus a NEW company vehicle.

i have read and re read many times, the posts on heating WCO, whether it be hot or cold filtered. my preference is to Cold filter, this way i know the fats and gritty bits stay in the first bag, or in the first drum. the end result being really good oil.

my setup is a 2 tank system and i only heat the WCO. ie, tank>he>filter>pollak>ip/engine. i only change over to wco when engine has reached max operating temp, which for me gives peace of mind knowing that the oil is really thin and ready to burn.

i am still unsure about ip shock, NOT STARTING ANYTHING NOW, but it does make sense to me. at the moment i am still trying to decide whether i heat or not heat the deso, as i am not sure on the plumbing. that's my fault for not looking further.

as for pushing the limits to get even more????????? why bother, my oil comes for free, yes i spend a bit of time out the back filtering, having a beer or three, keeps me out of her hair, but to me it's a hobby that pays divedends.

if you can get away with cold starts, half yer luck and god speed to your engine, but why take chances.

as for purge time? well i take as much time as i think is needed, depending on the day. if i have had a long trip i might give it a bit more on the deso before shut down to really cleanse the system. and as far as purging goes, (who else uses injector cleaner in their tanks on a regular basis.|????????????)

i know i am playing with an alternative fuel, and i know the risks involved, but, i also know that i am doing my part for the environment and that makes it all worth while. ( does anyone know about the carbon emissions and other nasties from using WCO to using straight deso?) and i know that me NOT buying so much deso is a good thing. i only wish my company car was a deso....

so i guess, for me, do what feels right.

any ways that my 2bits.

cheers

H1K

[gilligan Junior Member Find all posts View Profile Close gilligan]

Re: Do we really need to heat WVO?

i have read and re read many times, the posts on heating WCO, whether it be hot or cold filtered. my preference is to Cold filter, this way i know the fats and gritty bits stay in the first bag, or in the first drum. the end result being really good oil.

Hi Hobie and everyone else.
I'm trying to make up my mind about filtering temp.
I'd always suspected (more a gut feeling than anything concrete I'd read) that higher filtering temps may let more (HMP?) fats through the filter and therefore into the tank.

My situation is a bit different than everyone else's; I have a constant high ambient temp here in Darwin (usually 30+C in the daytime, when I'll be doing my (pre-tank) filtering.

So should I possibly be thinking about cooling my oil?

If you think about it, this is perhaps as valid a question as someone further south asking if it is Ok to heat it before putting it through the filter.

I'm talking about pre-car filtering here.
The question of whether it's a good thing that hot HMP fats will make it through your in-car filter and end up getting burnt is one I'll ask later.
(I do understand that this is likely better than constantly clogging your filter, but I'm referring to any negative in-chamber effects)

I'll restrict my question to the out-of-car filtering temps for now though.

Thanks,

Dave

[Nuddy Senior Member Find all posts View Profile Close Nuddy]

Re: Do we really need to heat WVO?

Would be better to do your filtering at night when it ia a little cooler.

[Tony From West Oz Vice Chairperson of WARFA Find all posts View Profile Close Tony From West Oz]

Re: Do we really need to heat WVO?

Dave (Gilligan)
I have copied your post above, to its own thread Heated filtering vs Cold filtering before filling fuel tank so that we can discuss out of car filtering there.
Perhaps we can leave this thread for discussion of in-car filtering.

Thanks,
Tony