Low fuel mileage, ULSD & Timing

[RLDSL]

I'm working up a theory here folks , so bear with me . We're all taking it in the shorts with this new few when it comes to fuel mileage, that;s a fact.
Now we know that sulfur does not lubricate, but what does sulfur do.....BURN!
What if the reduction in sulfur has changed the point at which the fuel begins to ignite and the rate at which it explodes?
Well, actually. I have pretty good proof that it has. I worked on European diesels for many moons and it just struck me today that we always had two different sets of timing specs, one for north america, one for everyone else.
the Europeans have been getting ULSD for YEARS and they haven't been having the fuel mileage problems.

The Euro specs have always been WAY more advanced than the US specs. I've tried to run cars near the Euro specs before on the 500PPM fuel and they felt like they were about to self destruct from being too far advanced...but I haven't tried it since the ULSD came out.

The big problem I'm having is trying to figure out how to convert the timing figures to be able to translate the amount of advance difference to these engines, as all the cars I'm used to fooling with have Bosh injection systems and they are all static timed by measuring with dial indicators and that doesn't translate directly into degrees of flywheel rotation .

Are there any of you big rig techs out there who fool with the bosh pumps who might have ever got bored and bothered to convert those measurements into flywheel rotation? or know of a reference somewhere?

 

[funnyman06]

well you can determine the difference in timing between the US spec and the Euro Spec, convert that to a %. Then we the ratio between US spec and Euro Spec, say Euro spec is 15% more advanced than US spec. We can increase our degrees by an additional 15% also. That would then put us at "Euro Spec".

Does this make sense or is my logic way off?

 

[RLDSL]

well you can determine the difference in timing between the US spec and the Euro Spec, convert that to a %. Then we the ratio between US spec and Euro Spec, say Euro spec is 15% more advanced than US spec. We can increase our degrees by an additional 15% also. That would then put us at "Euro Spec".

Does this make sense or is my logic way off?

Not sure, becuase the method of timing is completely different. The bosch pumps do not measure rotation of the engine or even the pump, they measure the lift of the plunger stroke toward the injector, so It's apples to oranges ( advancing the pump timing in relatin to the plunger strroke directly advances he time the injector opens )

for one engine Euro spec 0.87-0.97 mm
US 0.77-0.85 mm

Some years had wider spreads than that . Someone who is a little better at math than me( I've got my socks on, I can't count any higher could convert that to a percentage and maybe a possible target figure other than 8.5 btdc (pulse )
Although I think that you may have to divide the figure by 6 if the number looks real high to come up with the correct timing figure, because that's off a 6 cyl engine and that pump has 6 lobes on it, just a thought.

If one owned a degree wheel it would be easy to translate the measurements, just slap a degree wheel on the crank and pop the dial indicator in and run the crank back and forth past he marks and record the readings.
Alternatively, if I had the smaller fuel pipe adapter for my Ferret pulse adapter I could get the figure with that and the advance timing light, but that would run me about $80 after shipping, not in the budget at the moment.

 

[FordGuy100]

If what I think I'm doing is right, then we should set our timing to around 9.7*.

.97mm / .85mm (timing for ULSD over LSD) = 1.14 (or 14% increase). 1.14 * 8.5 = 9.7* BTDC

 

[Agnem]

Funny you should mention this. I just refreshed the fuel system on the Moosestang, and was thinking this exact thing when I set the timing. I put it at 10.5 BTDC using the pulse method. This is the upper range of the 2 degree + - tolerance of the factory spec of 8.5. I want to see if it helps with the other issue I will post about in a bit.

 

[RLDSL]

If what I think I'm doing is right, then we should set our timing to around 9.7*.

.97mm / .85mm (timing for ULSD over LSD) = 1.14 (or 14% increase). 1.14 * 8.5 = 9.7* BTDC

Now THAT sounds like what I'm talking about

 

[FordGuy100]

Now THAT sounds like what I'm talking about

Well, now we need someone to experiment and do it . Maybe I'll have to do it as part of my fuel economy thread

 

[funnyman06]

haha, with all this brain power i knew we could figure something out. Well I would love to test this theory, and would in a heart beat, but i dont have the tools required to time the IP on my truck, i dont even know where it is now. Cant wait to see the results.

 

[RLDSL]

Funny you should mention this. I just refreshed the fuel system on the Moosestang, and was thinking this exact thing when I set the timing. I put it at 10.5 BTDC using the pulse method. This is the upper range of the 2 degree + - tolerance of the factory spec of 8.5. I want to see if it helps with the other issue I will post about in a bit.

Alright Mel Keep those fuel mileage records !
I took a run to the city yesterday unloaded and went through 3/4 tank and figured this noise has got to stop
For cryin' out loud, went to pickup a few chunks of steel today just out of town and had to drop another $20 in the tank

The timing advance should also help with the *mashing the gas and it feeling like yur standing on a marshmallow* side effect of the ULSD as well if my guess is correct.

 

[Diesel JD]

Wonder if biodiesel has the same effect, IOW should I be advanced to Euro Specs for running B100? How would one figure that for the luminosity method? Thanks!
JD

 

[FordGuy100]

Wonder if biodiesel has the same effect, IOW should I be advanced to Euro Specs for running B100? How would one figure that for the luminosity method? Thanks!
JD

I dont think so. In my eyes you have to advance it more for wmo cause it takes longer to ignite, while I dont see that happening for BioD.

What is the spec for the luminosity method, what degree is it?

 

[Agnem]

It depends on the Cetane rating of the fuel. See the timing proceedure doc in my albums.

 

[Diesel JD]

I've been using 1.5*ATDC for the luminosity value. In truth it could be anywhere from 1-3 or so, but I always would go with 1.5 or 2 by factory specs because bio tends to have a cetane rating of 47 or better and 1,5 was for cetane of 40 or better IIRC.

 

[FordGuy100]

I've been using 1.5*ATDC for the luminosity value. In truth it could be anywhere from 1-3 or so, but I always would go with 1.5 or 2 by factory specs because bio tends to have a cetane rating of 47 or better and 1,5 was for cetane of 40 or better IIRC.

Well then, what does centane do to when fuel ignites? I almost was thinking that it increases the compressability of the fuel before it ignites, but that is octane.

 

[Diesel JD]

Yes it is exactly backwards from Octane which as you mention resists compression ignition as the octane rating goes up, as cetane value increases so does a fuel's tendency to burn under compression only. So good gas has low cetane high octane and good diesel has low octane high cetane.