Quote:
Originally Posted by 1der
Good to know, I will keep an eye out for this option and give it a try. I regularly use the B20 when traveling between SoCal and San Francisco as it is available on I-5 at a few convenient locations.
re your 31 gals added to "15" in your "46" gal tank.
If this a Transfer Flow "46" gal tank w/o any vent/harpoon mods then you likely did not have 15 gals in your tank but rather 10 to 11. If the mods were made then you might be closer to 46 gal fillable capacity, otherwise the most I was able to add to ours was 41.5 gals after just starting to suck air.
|
Ray,
You are of course quite correct in bringing up the subject of the "harpoon" mods to Transfer Flow tanks because the concentration of R99 diesel fuel in my "test" could either have been about 67% (15 gal. of Dino-Diesel present prior to fill-up), or about 76% (10 gal. of D-D), or somewhere in-between.
(Glenn, I really like that "Dino-Diesel" expression, and hope that you don't mind my borrowing it for use here.)
But either case suggests that a noticeable reduction in engine noise, i.e. "diesel clatter", may have occurred with fuel that was significantly less than 100% pure R99 diesel fuel. This implies that others wouldn't necessarily have to suck their tanks "dry" before adding R99 to try this experiment for themselves.
Unfortunately, there's only one Unocal station "near" me, and it's about 35 miles away in a mountain ski-resort community (read: near-monopoly situation), so their prices are correspondingly sky-high. So my further testing will have to wait until we visit SoCal again in our SMB. (Getting 50 MPG in the Prius is hard to pass up - but I'll admit, it can't make waffles.)
I'll try to arrange taking some baseline acoustic data while burning the last of a tank of mostly Dino-Diesel on the freeway near the 76 station in SoCal on our next "family" trip down south in the Silver Kitten, and will then refill with R99 and repeat the acoustic testing on the same stretch of road. This may be difficult to coordinate, but it seems worth doing.
Also, an update:
After researching "cetane" on Wikipedia last night, and sending a question to the folks at Unocal 76 about R99 diesel fuel, to my surprise I received an E-mail this morning - followed by a phone call no less. Unocal said that their new renewable R99 diesel consistently exceeds the upper limits of the ASTM D613 cetane test method (max. of 65) and the ASTM D7668 test method (max. of 70), and that this greatly increased ignitability (i.e. cetane rating) is the difference in the R99 fuel that accounts for the lower noise level that I may have noticed with our 7.3L diesel SMB. But even though their own testing yields even higher cetane ratings than these standard tests can detect, Unocal says that they can't advertise about this because the testing wasn't done according to either of these recognized ASTM standards (although there are also other recognized testing methods).
Later I found a really interesting paper on Cetane by the National Renewable Energy Laboratory (NREL) in the USA that explains how ignition delay caused by lower Cetane Ratings causes a sharper pressure peak (and more engine noise) due to a greater accumulation of unburned fuel prior to its ignition, which makes sense when you stop to think about it. I guess the two-stage fuel injection of the PowerStroke diesels and higher cetane fuel are two different approaches that address the same issue.
Perhaps someone on this forum with more knowledge about diesel fuel testing and n-hexadecane (a.k.a. cetane) than I have could explain this better.