Viscocity effects

[tbird650 Senior Member Find all posts View Profile Close tbird650]

I noticed there's been no new topics for a week so I figured I'd start a discussion on the effects of viscocity of fuel, on a diesel engine.
A kind of "use the forum or lose the forum" approach. No doubt it costs money to have.

For the last 15years, my vehicles have both had Bosch VE IP's. "Experiments" began nearly 10years ago.
What I notice with more viscous fuel is higher internal lift pressure and consequently more timing advance.
This can make the engine sound more "diesely" than otherwise.

It's a shame that Bosch uses lift pressure to control timing as it's not the ideal for higher viscocity fuels.
I'd thought how cool it would be to fit a manually adjustable pressure regulator. Adjustable from the cabin of course.
In this way, compensation for viscocity and these three: fuel, engine & ambient temperatures could be achieved.
The regulator setting is so super sensitive that I doubt the success of the idea.

It occurred to me that a mechanical method of timing advance like centrifugal weights system would be more adaptable to fuel variables.
Grafting such a set up on an existing engine would be difficult.

Diesel viscocity according to Google is somewhere in the region of 2 - 5.
Getting blended veg to this level has pros and cons.
One advantage is the oil would be able to flow around the IP, through strainers, filter, galleries etc will relative ease.
A disadvantage is the amount of blend needed to achieve the desired target.

So, one view is to adapt the fuel at/near the viscocity of diesel.
The other approach is to modify the IP, filters, etc to be happy with increased viscocity fuel.
...or some combination.

That's enough for now... Any ideas out there? (especially ideas for adapting IP for more viscous)

[Jeffrey S. Brooks Banned Find all posts View Profile Close Jeffrey S. Brooks]

Re: Viscocity effects

I noticed there's been no new topics for a week so I figured I'd start a discussion on the effects of viscocity of fuel, on a diesel engine.
A kind of "use the forum or lose the forum" approach. No doubt it costs money to have.

Content removed by moderator.

For the last 15years, my vehicles have both had Bosch VE IP's. "Experiments" began nearly 10years ago.
What I notice with more viscous fuel is higher internal lift pressure and consequently more timing advance.
This can make the engine sound more "diesely" than otherwise.

It's a shame that Bosch uses lift pressure to control timing as it's not the ideal for higher viscocity fuels.
I'd thought how cool it would be to fit a manually adjustable pressure regulator. Adjustable from the cabin of course.
In this way, compensation for viscocity and these three: fuel, engine & ambient temperatures could be achieved.
The regulator setting is so super sensitive that I doubt the success of the idea.

It occurred to me that a mechanical method of timing advance like centrifugal weights system would be more adaptable to fuel variables.
Grafting such a set up on an existing engine would be difficult.

Diesel viscocity according to Google is somewhere in the region of 2 - 5.
Getting blended veg to this level has pros and cons.
One advantage is the oil would be able to flow around the IP, through strainers, filter, galleries etc will relative ease.
A disadvantage is the amount of blend needed to achieve the desired target.

So, one view is to adapt the fuel at/near the viscocity of diesel.
The other approach is to modify the IP, filters, etc to be happy with increased viscocity fuel.
...or some combination.

That's enough for now... Any ideas out there? (especially ideas for adapting IP for more viscous)

You bring up some pretty good ideas. The Ford 7.3 Di engine is completely programmable, so people who are blending waste-oil diesel fuels for use in that engine just purchase a chip which changes the engine parameters to meet the fuel characteristics. Otherwise designing an injector pump to monitor fuel viscosity and adjust for variabilities in fuel viscosity sounds like a good idea for an IP manufacturer, such as Bosch, to consider.

On the other hand, fuel blenders really should be monitoring their end product and adjusting it to meet the characteristics of diesel fuel.

[tbird650 Senior Member Find all posts View Profile Close tbird650]

Re: Viscocity effects

You bring up some pretty good ideas. The Ford 7.3 Di engine is completely programmable, so people who are blending waste-oil diesel fuels for use in that engine just purchase a chip which changes the engine parameters to meet the fuel characteristics. Otherwise designing an injector pump to monitor fuel viscosity and adjust for variabilities in fuel viscosity sounds like a good idea for an IP manufacturer, such as Bosch, to consider.

On the other hand, fuel blenders really should be monitoring their end product and adjusting it to meet the characteristics of diesel fuel.

No doubt Bosch would do a fantastic job of designing such a IP. With this thread, I was hoping to stimulate a few ideas on adapting what we have and what we can afford. Even a 5% saving in blend additive would be worth the effort.

Something I notice with higher viscocity blends is that the IP pressure starts out higher at start up, then reduces as the engine temps come up.
This has the effect of over-advanced timing during the first minutes of running and it's something I'm having to tolerate. I reason that diesel,
with the low viscocity it has, doesn't get affected as much. For example, heat diesel and its' viscocity might reduce from say 5 to 4.
The same heat on a 10 weight blend would possibly drop to 8. A drop of 2 against 1.

Another interesting phenomena is with the IP lift pressure gauge behaviour. Because I've put everything back to standard as far as filtration, etc goes, it looks
like the fuel can't get through the filter element with ease. The needle gyrates when there's heavy demand on the throttle. It immediately settles once the pedal
is let up. The fuel is heavier to look at though I haven't measured the viscocity.
This would appear to be a limitation with regard to viscocity and filtration. The inlet strainer and other internal IP galleries could also be some or part of the problem though.
The IP gauge I regard as a "snapshot" of the realtime goings on inside the IP. It's a fascinating tool.

[Jeffrey S. Brooks Banned Find all posts View Profile Close Jeffrey S. Brooks]

Re: Viscocity effects

Well, if I remember correctly, tbird650, your engine does not like petrol blends in excess of 5 or 10%, which should be pretty viscous. I suppose to solve your startup problem on your viscous blend would be to install a startup tank that you start your engine on with petroleum diesel, or biodiesel, or a higher blend, maybe 20% petrol to start, then you switch over to your lower blend when your engine heats up. You woiuld not need more than a 20L startup tank for that.

[tbird650 Senior Member Find all posts View Profile Close tbird650]

Re: Viscocity effects

then you switch over to your lower blend when your engine heats up.

Sorry, I believe you've understood wrongly?? Cold starts are fine. Couldn't hope for better.
It's hot starts that were causing the prob.
So far, I've determined that the issue is pressure related. Viscosity plays a role because it's proportional to the pressure.
Initially, I solved the immediate problem with a sniff of ether. Later I found that by adjusting the internal lift pressure upward, starting came good.
I don't think there's much hope of restoring the existing IP in situ but I have another ready to plug in as soon the the current one becomes totally unusable (or intolerable).
I'd have to allocate 3 or 4 hours to the task of the swap, not a pleasant job on a van. The Ip has done nearly 6 years of fuel it wasn't intended for so I think it's done OK.
Even funnier is the fact that it has saved more money than the value of the vehicle itself! The replacement IP I paid 5 or 10 bucks for though history is unknown.
If it goes, I may need to adjust the max fuel. Because the radiator, timing cover, etc, etc needs to come off, I'll fit up the IP with only the basics and test run. If it goes, Ill continue with the refit of radiator, cowlings etc. If it fails, I'll run down to the wreckers and buy an IP. (Best I wait till wreckers come back from xmas holiday before I even think about the swap out)

Viscocity ideas...
One item that warrants investigation is the IP inlet banjo strainer. This tiny cylindrical gauze is not much bigger in dameter than a pencil!
It could easily be causing restriction with higher viscosity blends. My plan is to remove the strainer and remake it multiple times larger, and situate it further upstream.
The strainer is a "last line of defence" so I feel it's essential. Indeed a good few years ago when I was heating the veg, the paper filter gave up and the strainer
was the only thing stopping the bits from entering the IP. So, yeah, I need a strainer but I want it bigger.

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

Re: Viscocity effects

Tbird

Does your fuel return go back to the tank or is it T'd into the line just before the main filter ?

Michael

[tbird650 Senior Member Find all posts View Profile Close tbird650]

Re: Viscocity effects

Thanks for the reply
Currently entire system is back to stock while I sort apparent failing IP.

Have had return a number of ways on various set ups at different times.
Are you suggesting a return loop to filter, to retain heat and thin fuel so element & strainers etc can cope better?

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

Re: Viscocity effects

What type of IP do you have?
VP 37 or VP44?

[tbird650 Senior Member Find all posts View Profile Close tbird650]

Re: Viscocity effects

VE non turbo.

It's a similar pump to this:
ve injector pump rebuild in colour - The Brick-yard
Main differences I can see are:
Mine has a diaphragm on top, evidently for altitude compensation.
Mine doesn't have the electric advance unit.
The top cover and throttle arm are different.

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

Re: Viscocity effects

Tbird
can you describe back to stock and what changes have been made ?
I can safely assume you are not using WVO and is running ok on Dino ? What I was looking for was to remove the heat returned to the tank.
This forum is great , I'm slowly becoming a diesel mechanic as you can tell , I have very little knowledge in IP's but am happy to look.

your previous posting in the other area of the blending forum looked like you had it resolved with a reduction in the amounts of Dino and ULP. Is it possible to lose part of the blend in vapour with the heated fuel returning to the tank ?

Michael

[tbird650 Senior Member Find all posts View Profile Close tbird650]

Re: Viscocity effects

can you describe back to stock

By "back to stock", I mean everything standard. Stock filter, fuel lines, tank, etc. The Toyota original items.

I can safely assume you are not using WVO and is running ok on Dino ?

My current issues were when I finally switched back to dino. Hard starting with hot motor. Cold start excellent.
Boosting the internal lift pressure plus returning to blend which is noticeably more viscous, has sorted the issue for now.
My guess is the IP is getting tired from nearly six years, of fuel the maker never intended.

What I was looking for was to remove the heat returned to the tank

Ok, yes, I've had the gummed up tank syndrome before.... Cleaned it out. And moved on. Hot veg returning to cold steel tank appears to be the issue.

This forum is great

Yes, we learn a lot, share experiences & help each other. Brilliant!
Also it's why I started this thread about viscosity. There hadn't been a post for a week or so in any thread on the Blending forum.
We'd all be the poorer if admin decided it wasn't getting enough use.... so please keep talking!

your previous posting in the other area of the blending forum looked like you had it resolved with a reduction in the amounts of Dino and ULP

With regard to the IP, I'd say that I've compensated for 6 years of wear and saggy tolerances. Probably its' days are numbered.
Be interesting to see how long it lasts from here.

Is it possible to lose part of the blend in vapour with the heated fuel returning to the tank ?

I'd have thought that vapour (if any) would re-condense in the tank.

I'm slowly becoming a diesel mechanic as you can tell , I have very little knowledge in IP's but am happy to look.

When my Ip finally gets swapped out, I intend looking into it.... and repairing it myself. Be good learning.

[tbird650 Senior Member Find all posts View Profile Close tbird650]

Re: Viscocity effects

Continuing on the subject of viscosity,
I'd like to have a look at viscosity measuring and so get an idea
of when a blend is within tolerance, how much I can get away with and product comparison.
I saw JSB's Youtube with a cool looking viscosity cup. They make good sense and are easy to use.
Google images shows plenty of good pics: viscosity cup - Google Search
My first thought was to make the item. It looks easy enough though I think I should duplicate known dimensions.
Easiest and best might be to buy. Two interesting cups on Ebay for US$7 each, amongst others.
Should I make using random measurements, all I can do is compare. However with a correctly sized cup,
accuate data could be collected that is infinitely more meaningful to the wider bio community and others.

Back in the dark ages, when I started with SVO, I used to compare fuels using the "straw method".
Basically, I would fill a drinking straw with the oil to be tested and time the number of seconds to drain out.
It was crude, but I was able to quickly determine the relative weight of similar oil.

Any thoughts on the cups? Who's got one, who's used one, who knows what the best/worst features are?
What number cup works within the range for diesel, bio, ulp, wmo, svo, blends, etc, etc, etc?
Thanks.

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

Re: Viscocity effects

Tbird,
If you can get hold of a Burette (laboratory glassware = graduated cylinder with a valve on the bottom) and a suitable stand, you can measure the time for a specific number of mL to flow. eg, with a 50mL Burette, fill to above the top line, turn the valve on full (90&#176 and use a stopwatch to measure how long it takes for the level to fall from the top mark to the 25mL mark. repeat 3 or 5 times to get the average.
Do this for water, diesel and petrol at a specific temperature (same for all samples) these give you known reference times.
Repeat at the specified temperature with the fuels you wish to test, averaging the times to increase the accuracy of measurement.

You can then compare the fuel time with the time for water, diesel and petrol.
I think that viscosity is linear (not logarithmic) so 50% more viscous than diesel would equate to 50% more time to flow.

The same rules apply using viscosity cups, but it is a lot easier to measure using a Burette given that it is tall and graduated accurately. Supported in a stand, you will have both hands free to operate the valve and timer.

I hope this is of assistance,

Tony

[tbird650 Senior Member Find all posts View Profile Close tbird650]

Re: Viscocity effects

Tony, thanks, it's an interesting thought. I'd been thinking of a burette just recently when I wanted to calculate the compression ratio of
my dragbike. It seems that the bikes' compression isn't enough to achieve relative efficiency. That's another story tho.

I could even make one out of clear conduit tubing, fit a valve and perhaps swapable orifices.
I plan to swing by the paint supply shops before doing anything. Spray painters often use these,
but wether they're within range is another question.
There's a major price difference on Ebay, from $4.95 to $90something.