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Old 05-21-2017, 06:42 PM   #1
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Bio Fuel mpg.

We are on a trip from LA Cal to Ny Ny then down to the Carolinas and back to LA. I have been tracking the mileage and conditions on my Prism 24m . We have been running 65 to 75 mph most of the way except for a wicked Snow Storm in Wyoming. I have had a high of 18.08 and a low of 13.8 which was a crawl in the storm at 35 mph. I got my first tank of Bio today and I was surprised it picked up a bit. 1/2 mpg. Same speeds and wind direction . I don't know how much since the sign said it could be anywhere from 5 to 20% . Do you guys notice much difference? This thing just impresses the heck out of me with the way it goes. We're in Iowa now and that was the first Bio tank I found labeled.
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Old 05-21-2017, 08:22 PM   #2
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Sprinter chassis are not designed to handle biodiesel concentrations higher than 5%. You run the risk of biodiesel getting into the crank case and causing an overfill condition and sludging. I has to do with the method the engine uses to recharge the diesel particulate filter. Read your manual , check your oil Level frequently, change oil and fuel filter early. I like most of the MBS forum members do our best to avoid biodiesel since problem related to its use may void the 100,000 mile warranty on the engine and emissions.
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Old 05-21-2017, 08:34 PM   #3
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Not much choice today. I've been trying to avoid it. But I'm here in Iowa right now.
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Old 05-21-2017, 08:38 PM   #4
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I posted on your other thread about the perils of bio-diesel as well. It might smell nice at the tail pipe but it's not nice inside your fuel system.

You need to slow down a bit too. It's not a car and the tires aren't designed for those speeds.

You are on 'vacation' not competing in an Indy Car race.
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Old 05-21-2017, 10:21 PM   #5
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You need to slow down a bit too. It's not a car and the tires aren't designed for those speeds.
The statement above is incorrect unless Forest River has changed tires. The tires on my 2015 Solera are
LT 215/85 R 16 115/112 Q
The "Q" on the end indicates that the tires have a speed rating of 99 mph, well in excess of any speeds mentioned here.

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Old 05-22-2017, 09:51 PM   #6
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On the hwys I've been on lately your speed limit is 80 and pretty much everybody is doing 85. I get passed by TTs and 5th wheels while I'm doing 75. I'm pretty use to high speed racing and I make sure it's safe. When the wind kicks up or it gets too crowded I slow way down.
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Old 05-23-2017, 05:47 AM   #7
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A note on speed...
Our Sprinter 3500's are powered by a 3 L motor that develops 188 hp and 325 ft. lbs. of torque, and 2800 rpm is the sweet spot for max torque. We drive our SunSeeker between 55 and 62, and in 5th gear the rpm's are 2250 @ 55, and about 2550 @ 62... on medium and steeper hills, the turbo kicks in, and the LOD (engine loading) maxes out at 99% (maximum power) on my ScanGuage. A lot of folks over at the Sprinter Forum, who use these vehicles commercially, recommend keeping the LOD at 80% as much as possible to get the best service from the motor (fuel mileage and longevity). I have never driven at 75, but I imagine the rpm's in 5th are at or higher than 2800, with the turbo at maximum 99% load... the engine is maxed out. It is a fine engine, but for how long? Keep in mind that all those folks passing you with 5h wheels and motor homes are running engines at least twice as big as ours with 600-1000 ft. lbs. torque numbers. And passing you doesn't make them smart.

Regarding speed in general, we have gotten over feeling bad about being passed... on controlled access highways we stay right, and on secondary roads we usually do the 55 mph limit, and try pull over to let the "flies" buzz by. Where do you drive where the limit is 80? I am certain that Iowa is 70. We have been all over, and have only seen maximums of 65-75. Sure, everybody speeds, but that is another topic.

Take it easy... it a Recreational Vehicle!
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Old 05-23-2017, 06:06 AM   #8
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"A lot of folks over at the Sprinter Forum, who use these vehicles commercially, recommend keeping the LOD at 80% as much as possible to get the best service from the motor (fuel mileage and longevity)."

Most of the commercials are interested in going past 250,000 miles , which at the usual 10,000 miles for an RV is way more years than most are driven.

The MB computer is very very smart , there are no "high loads" in 5th gear as the tranny would shift down.

Remember the same engine is in some euro cars , rated 100HP higher.

The lower Sprinter HP rating is the protection against "too high a load" .

Leave the unit to cruise in 5th and enjoy the next 250,000 miles.
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Old 05-23-2017, 09:30 AM   #9
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I only went that fast because we were being rushed. I do have to learn the RV life style and slow down. Even my Jeep 4 door Rock Crawler was set up for high speeds in the dirt. It's hard for me to slow down but believe me we are trying. Both the wife and I raced cars and love the speed. 80 seems so tame after 200, but now that we're here the rest of the trip is at no more than 65. I am going to order a scan gage when I get home. I want to monitor this thing. That would be fun too. Trying to squeeze the last mpg out of it instead of the last mph.
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Old 05-23-2017, 03:41 PM   #10
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Hey Ffred...

The 5 speed tranny in our Sprinters is not so smart... it notoriously lets the RPMs drop too low when climbing... the load will max and hold until they get down into the 1500's, causing it to "lug", which is not good in many ways for this motor.

I don't know about you, but we plan to run our baby awhile... in our first year we covered almost 19000 miles, and will do that again this year, planning about 180 days on the road.

Bobgeri, I hope we meet on the road sometime! It sounds like some interesting stories around the fire. It is pretty common to rush around at the start of this lifestyle... we sure have, but not @ 75 MPH in the SunSeeker.

Happy travels!
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Old 05-23-2017, 03:49 PM   #11
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Bob your rolling house gets better MPG than my 2dr Jeep !

Enjoy your adventure !
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Old 05-24-2017, 06:16 AM   #12
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.." it notoriously lets the RPMs drop too low when climbing... the load will max and hold until they get down into the 1500's, causing it to "lug", which is not good in many ways for this motor."

In old non turbo diesels, keeping the rpm up was how to have the power to climb a hill.

Today the turbo creates the maximum HP at far lower RPM.

This is how better fuel mileage is done with modern computer controlled turbo engines.

If more power is required to maintain speed on a grade , the tranny does shift down well before an engine "overload" could occur.
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Old 05-24-2017, 07:13 AM   #13
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Quote:
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.." it notoriously lets the RPMs drop too low when climbing... the load will max and hold until they get down into the 1500's, causing it to "lug", which is not good in many ways for this motor."

In old non turbo diesels, keeping the rpm up was how to have the power to climb a hill.

Today the turbo creates the maximum HP at far lower RPM.

This is how better fuel mileage is done with modern computer controlled turbo engines.

If more power is required to maintain speed on a grade , the tranny does shift down well before an engine "overload" could occur.


If the engine loading is monitored using a device such as a ScanGuage II, you will see that the motor gets to maximum load and holds there, not shifting until the RPM's drop to the 1500's, while the motor develops its highest torque around 2800. More to the point, we are driving a 5.5 ton non-aerodynamic box using a relatively small 3 L motor. Running it at maximum load constantly (what you would be doing at 75 mph) will shorten the engine's life, IMHO.

Believe it or not, the Sprinter van comes standard with a 2.1 liter 4 cyl engine mated to a 7 speed tranny... this set-up has proven more reliable than the 3 L 6, because the 7 speed shifts when it is supposed to.

Happy travels!
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Old 05-24-2017, 08:56 AM   #14
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Let me clear up some misconceptions...

First off, modern diesels are designed to produce maximum (useable) power at a lower rpm than diesels of yesteryear through devices like adjustable pitch turbochargers and / or compound turbocharging. Fuel management systems (computer controlled injection timing) and interaction between the transmission and the engine ECM are common place today.

Diesels today produce their power at a much lower rpm to mitigate emissions related issues as well. They also run much hotter because of EGR so internal components have changed as well, Things like ceramic followers in the valve train, filled valve stems and ceramics in the exhaust tract are used.

Builders design their engines to run slow and numerically specify final drive ratio's to achieve that. The transmissions are usually interacting with the engine ECM to achieve the most efficient shift points in relation to the power band (curve) of the motor.

Forcing an engine to run at a higher rpm or manually controlling downshifts and upshifts just impacts fuel mileage negatively and can shorten engine life because you force the engine to operate out of it's normal (factor designed) operating range.

The first Class 8 emissions diesel truck I ever drove (Detroit Series 60 DDEC), I had to reprogram my brain to up shift and down shift the 13 speed Roadranger at a much different (lower) rpm that what I was accustomed to with a non-emission engine. Prior to emissions controlled diesels (Prier Tier 3), useable power was typically produced between 1800 rpm and 2100 rpm (855 Cubic Inch Cummins I-6 turbocharged engine). Not the 1200 to 1500 rpm of an emissions engine.

Let the (automatic) trans decide the optimum up shift and down shift points. It's been calibrated and mated to the engine ECM and emissions software by engineers that know a lot more about the characteristics and operating parameters of the engine and transmission than you do.

I realize you bought it and I don't care if you are going 65 and throw it in reverse because you will pay the repair bill, not me, but for the sake of longevity and fuel mileage (because the price of fuel is already going up and will continue to do so), it's advantageous for you to extract the best mileage from your vehicle, unless of course you have steel hinges on your wallet and don't give a darn about what it costs to fill it up...
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Old 05-24-2017, 09:29 AM   #15
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"2.1 liter 4 cyl engine mated to a 7 speed tranny... this set-up has proven more reliable than the 3 L 6, because the 7 speed shifts when it is supposed to."

Most of what I read about the 4 banger seemed to be more reliable because it had better equippment for the Air Police and did not lock down into 10 starts you're dead mode.

The ScanGuage II is a great tool, but the dist. told me it is not yet setup to do my 2016 Isata 3 FWS with a 2015 chassis as it is still under warentee.

Using A borrowed Scan II with a CEL light could not find a transient fault in the DEF , or reset he check engine light light. Had to go to Freightliner.

It was interesting to use , but I will wait for the upgrade to read the latest codes , and the ability to reset any faults.

The new large truck and bus engines are indeed torque monsters, although the DD latest innovation is the GPS talks to the engine computer and will shift down at the start of a huge grade , rather than having the tranny do the shift in mid grade.

200HP in a 11,000lb MH vs 600HP on an 80,000lb truck ,
about 3 x the HP vs 7 x the weight,the truck needs the RPM.

Of course that's for newer 80,000 trucks ,

my 1956 Flxible VL 100 Bus conversion with a DD SER 40 and ZF 5 speed with OD, would not shift into 5th till 68mph ,
and never found a hill that it couldn't master in OD., at 1500RPM, but it was only 30,000lbs.
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Old 05-24-2017, 12:07 PM   #16
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Quote:
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"2.1 liter 4 cyl engine mated to a 7 speed tranny... this set-up has proven more reliable than the 3 L 6, because the 7 speed shifts when it is supposed to."

Most of what I read about the 4 banger seemed to be more reliable because it had better equippment for the Air Police and did not lock down into 10 starts you're dead mode.

The ScanGuage II is a great tool, but the dist. told me it is not yet setup to do my 2016 Isata 3 FWS with a 2015 chassis as it is still under warentee.

Using A borrowed Scan II with a CEL light could not find a transient fault in the DEF , or reset he check engine light light. Had to go to Freightliner.

It was interesting to use , but I will wait for the upgrade to read the latest codes , and the ability to reset any faults.

The new large truck and bus engines are indeed torque monsters, although the DD latest innovation is the GPS talks to the engine computer and will shift down at the start of a huge grade , rather than having the tranny do the shift in mid grade.

200HP in a 11,000lb MH vs 600HP on an 80,000lb truck ,
about 3 x the HP vs 7 x the weight,the truck needs the RPM.

Of course that's for newer 80,000 trucks ,

my 1956 Flxible VL 100 Bus conversion with a DD SER 40 and ZF 5 speed with OD, would not shift into 5th till 68mph ,
and never found a hill that it couldn't master in OD., at 1500RPM, but it was only 30,000lbs.


For the record, my mileage generally improves with the downshifts.
We have a 2016 chassis, and the ScanGuage ll works for me... aside from engine load, it also monitors coolant temp (along with a lot of other stuff) which is good to know. I do not use it as a diagnostic tool (many do) and I would not want to reset problem codes (which is possible) as I will not be servicing it myself, and messing with the codes makes diagnosing problems at MB or Freightliner problematic, and might effect warranty issues.

Regarding comparing performance to over-the-road trucks or '56 buses, in my first post I was referring to 5th wheels being pulled by large pick-ups and class A's on Freightliner chassis's, all of which have pretty strong torque to weight ratios compared to our Sprinters.

Note to the OP... My intention was not to highjack your post to get into the above conversation, but to make a case for not running that little 3L V6 at full bore , 70-75 mph speeds for extended periods of time. I am not convinced that doing so will lead to a long, trouble free engine life. But only time will tell... let's all hope we have plenty of that!

As you probably have surmised, there is not much feedback out there regarding mileage with biodiesel, as its use above 5% is frowned upon by MB.
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Old 05-24-2017, 12:35 PM   #17
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"............As you probably have surmised, there is not much feedback out there regarding mileage with biodiesel, as its use above 5% is frowned upon by MB........."

It's 'frowned upon because it screws with the SCR system (Selective Catalytic Reduction) system aka: emissions hardware.

MB or Diamler also owns DDEC Detroit Diesel Engine Company.

As an aside, don't get in a collision with your Sprinter based Moho. Because the chassis is monocoque construction, fixing any chassis related damage is a costly nightmare.

The dealership I worked for (Freightliner) had a couple Sprinter parts vans and one got in a wreck and I observed the body shop repairing it. It's all cut and weld in new parts. Nothing is bolted, everything is spot welded and it's mostly formed sheet metal. Got rid of them all and went to Ford E350 diesel parts vans. They have a real box frame seperate chassis.
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