Bio Diesel VS Diesel

I just filled my motorhome at a Loves in Oregon today and it said between 5-20 % bio on the pump.

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Just a speculation but I would guess that hilly country has less wind than does prairie landscape. Biofuels are also more likely to show up near typically windy flatlands because the crops are raised there, so Biofuel use may be likely less available in the hills. So fuel economy may actually seem, or even be, worse on flatter roads since hills may be a wash and not be as bad as wind.

Furthermore, if the hills are not too steep, mileage might even improve for another reason. A diesel engine gets more efficient as the turbo loads effective compression ratio upward. On the mandatory corresponding downhill, the engine idles (very thrifty in diesels) as the rig coasts back to the bottom. Where this extra efficiency would not be the case is when the hills are so steep that braking (engine or brake shoes) must be engaged to maintain safe speeds. In that case part of the saved "fuel-heat" energy during driving uphill is wasted by the useless heat dissipation by the braking system going back down.

Running a diesel engine at high load specifically for efficiency is demonstrated by the fact that we were often required to disable some multiple locomotives in our rail consist so that all the required HP was produced by the least number of engines, therefore the fewer running at higher load levels. According to railroad engineering studies, it saved a significant amount of fuel. So it seems quite possible that cylinder cut-out on our single engine diesels would pay off, and I surmise, is the same reasoning gas engines have been doing so (at lower power levels) for a few years.

Some of the earlier V8 Ford diesels (6.9L, 7.3L) did not have turbo's, so the static compression ratio was set higher than later turbo'd units. Intermediate engines also did not have intercoolers to "waste heat energy" to the atmosphere. I assume the same is true of the early Cummins designs. Both series of engines, seldom needing to run at max power, seemed to get the maximum fuel economy possible under ordinary light towing conditions, and especially empty. They were gutless wonders though, and consumer demand for more available power soon thwarted fuel economy as usual.

My F-250 only gets about 11-11.5 towing in low wind (not often in ND). And the tank is a PITA to fill (Got shut-off backwash 1st time on my shirt until I learned). I once drove an earlier F-250/slide-in camper with the 6.9L at 55 mph/no-wind and got 15 mpg. By contrast, my old 1/2 ton Chevy 400 gasser got 14 empty on a good day, maybe 9 with an 8' slide-in.

Wes
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therink wrote:

jus2shy wrote:
If you bought any diesel in Oregon and Washington, it's guaranteed to have some degree of Biodiesel in it. Up to B5, they don't have to post the Bio diesel content.

Same here in New York State.

oregon diesel #2 is 5% bio at a minimum. B20 is also available in oregon w/o any state roadtax, saves you $.30/gallon with the same mileage.

jus2shy wrote:
If you bought any diesel in Oregon and Washington, it's guaranteed to have some degree of Biodiesel in it. Up to B5, they don't have to post the Bio diesel content.

Same here in New York State.

Oregon bumped the minimum biodiesel percentage from 2 up to 5 a few years ago.

I've run anywhere from straight dino juice to B99 in my Jeeps without any big change in mileage driving around town.

Don't really know what the differences are, but I just finished a trip from SoCal to Arkansas and back. Got Bio Diesel at a couple of stations. I did notice a difference with mileage. With the Bio I got under 10, #2 as much as 12.8. Not a big difference, but noticeable. No difference in the way the truck ran or sounded. 2014 Duramax and a Jayco 321 RLTS. Given a choice I would avoid the Bio just because of the mileage difference. I have also heard it is not good to let Bio Diesel "sit" for longer periods of time. No idea if that is true or not.

GoPackGo wrote:
My 2013 F350 seems to run quieter on Biodoesel too. Don't know why.

one reason may be that B20 usually has a noticeably higher cetane rating, which will reduce the diesel clatter especially in older diesels that don't have pilot injection, or the pilot injection quites at higher rpm. On my 15 denali I can't tell a difference it's so quite already. on the 04LLY B20 was as quite as #2 with a big does of cetane booster.

I run it as often as I can in my 6.0. I can tell a difference in the sound level versus straight diesel. But, I do notice a very slight decrease in mileage when towing with the bio.

The issue with the noise is the reformulation of diesel fuel after my engine was designed. The lack of lubricity from lower sulfur content caused extra noise and wear.

This is no different than the engines that did not have hardened valve seats when lead was used in gasoline. The engine either had to be modified to run on unleaded fuel without accelerating wear or an additive had to be used for the life of the engine.

NinerBikes wrote:
If your diesel engine is sounding noisy on straight D2, it's because it should, that's built into the design, and the motor was designed from the get go to run on the most common diesel fuel available, good old D2, not designer or boutique "greenie" fuel made out of animal fat or vegetable or plant oils from farmers or ranchers.

It is true, however, with newer Bosch HPFP's that a smidgeon of this biodiesel, 1/2% up to 2% does help tremendously with the wear scar factor of the diesel fuel on your precious and fragile Bosch CP4.X High Pressure Fuel Pump.

gulp! X2

atomization of Bio compared to regular diesel produce larger droplets (at the injector nozzle) the larger droplets result in lower HP, increase in emissions and reduced combustion. as one goes up in concentrations of Biodiesel the high the viscosity and cetane the lower the process of atomization decreases, making for a poor air/fuel ratio...