California Cetane is 53 minimum (and 48 Texas)

BeetlePD

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Powder Hound

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Back when the ALH was a relatively new engine, Bosch pointed out that a cetane number over 50 was a waste of chemistry - it wouldn't make a difference.

So if certain bodies, such as CARB, specify more than 50 as the minimum cetane number, it is, IMO, yet another piece of evidence that they don't really know about diesels. This is nothing new, if you've followed CARB activities and pronouncements in relation to diesels.

Now if they would boost the lubricity requirement, then they'd get my attention.

Cheers,

PH
 

BeetlePD

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CARB’s primary goal is clean-burning fuel. Oxygenated gasoline & high cetane diesel burn more completely (reducing unburned hydrocarbon and soot pollution)
 
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Matt-98AHU

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Back when the ALH was a relatively new engine, Bosch pointed out that a cetane number over 50 was a waste of chemistry - it wouldn't make a difference.
So if certain bodies, such as CARB, specify more than 50 as the minimum cetane number, it is, IMO, yet another piece of evidence that they don't really know about diesels. This is nothing new, if you've followed CARB activities and pronouncements in relation to diesels.
Now if they would boost the lubricity requirement, then they'd get my attention.
Cheers,
PH
I wonder if that stance has changed with the large advancements in injection technology since then?

Here in California, we also have 70 cetane 'renewable' diesel. But, it also seems that fuel has less BTUs than normal diesel. With 70 cetane, cars definitely start easier and idle smoother on that fuel, but I do notice a lack of low end torque and loss of fuel economy, which I can only assume is due to lower actual energy content (cetane being how easy/fast the fuel can ignite, BTUs or calories being the actual energy content). BUT, high RPM power seems better than on standard ULSD.

It gets better. The 'renewable' clean burning diesel we have at a few locations here is chemically very very similar to Shell's synthetic, GTL from natural gas diesel, right down to the cetane rating.

When Audi was racing at Le Mans with their R10 TDI starting in 2006 (commonrail 5.5L V12, twin wastegate turbos, AND, equipped with DPFs, interestingly enough) they were using a blend of 70% normal ULSD, and 30% of this 70 cetane synthetic stuff.

They apparently took the time to figure out that was the ideal ratio to retain enough of the energy content of the ULSD and get a very solid cetane boost to make it ideal for the higher RPM running of those race engines (6000+ RPM) as well as a small percentage increase in fuel economy. I can only assume Bosch played a large part of developing the fuel system in the race car as well.

So, given that information, I have actually tried to replicate that mix by blending our 'renewable' diesel and normal ULSD. There is a noticeable difference, I can empirically say that much just by seat of the pants feel as well as USUALLY a small increase in fuel economy... except for when I'm enjoying the added power and response a little too much... especially in the Touareg.

That blend makes the engine feel more responsive and powerful throughout the entire RPM range. It's fun. Particularly fun with 5 liters and 10 cylinders worth of TDI power.

 

Powder Hound

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I wonder if that stance has changed with the large advancements in injection technology since then?
I would certainly hope so! Back then, piezo injectors were still in R&D, and DPFs probably weren't defined well yet.
... But, it also seems that fuel has less BTUs than normal diesel... BUT, high RPM power seems better than on standard ULSD...
So it revs better and is peppier for more fun when driving.
...That blend makes the engine feel more responsive and powerful throughout the entire RPM range. It's fun...
So maybe the answer to the mileage question is really the fun factor - heavier right foot pressure resulting in lower mileage and the perceived lower BTU content maybe? ;)

Meh - if the fuel has a lower specific gravity, then you can safely assume it has fewer BTUs, whatever other sterling qualities it exhibits. For me it is a moot point; I'm on the wrong coast to be able to sample it.

Cheers!

PH
 

showdown 42

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The only thing I care about is the HPFP. I use Power service and have for 12yrs with every fill up. My pump is still fine so It must work. LOL. I have no idea if any of this really makes a difference. I hate to say this but diesel cars are now history and won't be coming back. Damm shame,because they are head and shoulders better than gassers. Politically correct politicians rule the day now.
 

CleverUserName

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I’ve been researching the viability of Renewable Diesel and used it exclusively in 3 different vehicles for a few years. I also found the research paper based on 70/30 blend of ULSD to RD and posted my findings on here. I have not tried the blend as going to two different stations is logistically difficult and for the reasons below.

While I would call myself an RD fanboy, now I no longer use it. I get better performance from CARB 53 cetane ULSD w/ an effective fuel additive than with straight RD. When I say “better performance” I mean better low end torque, fuel economy, and lower soot production.

The loss of low-end torque with RD is very noticeable in my GMC Canyon 2.8 Duramax CCLB 4x4. There is a steep hill on Hwy 1 near my mothers house and I cannot climb it in 6th gear when fueled with RD. The truck must downshift into 5th when throttle gets to 50%. When I have a tank of additized ULSD it can get up the hill at 65 mph in 6th gear and 1750 RPM.

One of the research papers also mentioned engine control parameters could be adjusted to offset some off the fuel economy losses if tuned exclusively to run on RD. I’m guessing primarily injection timing could be adjusted for the high cetane fuel and lower ignition temp. However in CA this would be illegal under current smog laws. Hopefully someone with tuning expertise like Kerma or Malone can explore this possibility and develop a switchable tune for optimized RD and ULSD options.
 

Matt-98AHU

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I’ve been researching the viability of Renewable Diesel and used it exclusively in 3 different vehicles for a few years. I also found the research paper based on 70/30 blend of ULSD to RD and posted my findings on here. I have not tried the blend as going to two different stations is logistically difficult and for the reasons below.

While I would call myself an RD fanboy, now I no longer use it. I get better performance from CARB 53 cetane ULSD w/ an effective fuel additive than with straight RD. When I say “better performance” I mean better low end torque, fuel economy, and lower soot production.

....
Same basic sentiments I mentioned above. Low end torque is noticeably lower on the RD and there is less fuel economy. I keep attributing it to lower energy content, so I don't think there's going to be much tuners can do to optimize it, nor would I want them to since chances are high at some point that you'll likely have to run normal diesel anyway.

I am surprised, however, at you noting lower soot with regular ULSD. My experience has been the exact opposite. I notice significantly less visible soot with the RD than I do ULSD. And apparently every regulated form of pollutant is also less while using it.

But I definitely understand not wanting to run 100% RD due to the odd rubber band feel to the torque curve, particularly noticeably loss of low end grunt.

Running to two different stations isn't so bad, though. If you've had your car long enough, you have a good feel for how much fuel it's going to take to top it up when it gets to a certain point on the fuel gauge and you can roughly estimate it.

For example, with the Touareg it normally takes me 22-24 gallons to top it off once the fuel light has come on depending on how deep into the red I've gone. So, it'll take 6.6-7 gallons of renewable diesel, then drive a short distance before I get to a ULSD station to top it off.

I figure anything from 20-35% is fine, doesn't need to be exact, you keep most of the energy content of the ULSD and get a healthy cetane bump that helps power all around and even may prove to be more efficient than ULSD by itself with the blend in that range. I do seem to prefer it being at or just below 30% to retain as much low end torque and efficiency as possible. And maybe with CARB diesel already being higher cetane, closer to 20-25% blend might make more sense.
 

IndigoBlueWagon

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I used to play with percentages with biodiesel (54 cetane) and pump diesel. Bio has about 10% fewer BTUs than dino diesel, so I'd take a fuel economy hit if I ran B100. But some bio made the car run smoother (probably because of lubricity more than cetane) and more responsive. B20 was a sweet spot. Used to run that on track days, and other drivers were amused by the slight french fries smell.
 

CleverUserName

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Same basic sentiments I mentioned above. Low end torque is noticeably lower on the RD and there is less fuel economy. I keep attributing it to lower energy content, so I don't think there's going to be much tuners can do to optimize it, nor would I want them to since chances are high at some point that you'll likely have to run normal diesel anyway.
I am surprised, however, at you noting lower soot with regular ULSD. My experience has been the exact opposite. I notice significantly less visible soot with the RD than I do ULSD. And apparently every regulated form of pollutant is also less while using it.
But I definitely understand not wanting to run 100% RD due to the odd rubber band feel to the torque curve, particularly noticeably loss of low end grunt.
Running to two different stations isn't so bad, though. If you've had your car long enough, you have a good feel for how much fuel it's going to take to top it up when it gets to a certain point on the fuel gauge and you can roughly estimate it.
For example, with the Touareg it normally takes me 22-24 gallons to top it off once the fuel light has come on depending on how deep into the red I've gone. So, it'll take 6.6-7 gallons of renewable diesel, then drive a short distance before I get to a ULSD station to top it off.
I figure anything from 20-35% is fine, doesn't need to be exact, you keep most of the energy content of the ULSD and get a healthy cetane bump that helps power all around and even may prove to be more efficient than ULSD by itself with the blend in that range. I do seem to prefer it being at or just below 30% to retain as much low end torque and efficiency as possible. And maybe with CARB diesel already being higher cetane, closer to 20-25% blend might make more sense.
I did not say lower soot was observed with regular diesel #2. I said ADDITIZED CARB diesel #2 had better performance and lower soot production. This is in modern diesels with high EGR flow rates and also an ALH 1.9 Dinosaur.

In my testing, CARB diesel #2 w/ additive containing MMT, 2-EHN and aromatic hydrocarbons dosed at 400:1 performs better than RD with lower soot production and no loss of power. I’ve gotten the lowest soot % in oil analysis as well. You should try it and you won’t need to go to two different stations to fill up anymore.

I also said a switchable tune for RD was desirable. That means a DSP-4 switch and two different programs on the ECM. One program with advanced timing for RD and another Stock-ish tune for ULSD.
 

NewTdi

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Matt, I have started my 70/30 experiment and I will report back if there are any amazing findings since I do fill my tank every 3 days ... . I filed up the tank tonight with D2 (13.2 gallons and the rest R95 from 76. The car did appear to run smoother.
 

NewTdi

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I am on my 5th tank 70% D2 & 30% R95. These are approximate numbers because it is difficult to have exactly a 70/30 mix the way I fill my vehicle. Mileage is slightly better but engine response is MUCH better. I am still running Stanadyne as well with every tank. I will be experimenting with the 70/30 blend in the sedan and see if that engine with a few upgrades will also like the same combo.
 

BeetlePD

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76’s renewable diesel is made from vegetable oils, so naturally it has less energy content (just as ethanol has less energy than pure gasoline).

Unfortunately no 76s in Southern California sell this biodiesel. I would have to drive 370 miles to Sacramento to visit the nearest station, and that’s not happening.
 

NewTdi

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76’s renewable diesel is made from vegetable oils, so naturally it has less energy content (just as ethanol has less energy than pure gasoline).

Unfortunately no 76s in Southern California sell this biodiesel. I would have to drive 370 miles to Sacramento to visit the nearest station, and that’s not happening.
You have a Propel Fuels in Fullerton. I am extremely surprised that the 76 stations that sell R95 and R99 are only in Northern California. Something does not make sense.
 

CleverUserName

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76’s renewable diesel is made from vegetable oils, so naturally it has less energy content (just as ethanol has less energy than pure gasoline).

Unfortunately no 76s in Southern California sell this biodiesel. I would have to drive 370 miles to Sacramento to visit the nearest station, and that’s not happening.
It’s not made solely from vegetable oils. It’s hydrotreated and distilled from waste fats, so it’s an animal and vegetable sourced product.

There is a search function where you can look for RD based on location. https://www.76.com/station-finder?a=rd
 

BeetlePD

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Yes and the website says the closest 76 station with RD is over 300 miles north of L.A. which is quite a trip. Maybe it costs too much to ship the vegetable/animal diesel to Socal, so it’s only sold at/near the farmland (where it’s sourced)
 

Matt-98AHU

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Yes and the website says the closest 76 station with RD is over 300 miles north of L.A. which is quite a trip. Maybe it costs too much to ship the vegetable/animal diesel to Socal, so it’s only sold at/near the farmland (where it’s sourced)
You have Propel HPR at a few locations in the Southland...

https://propelfuels.com/locations
 
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