BAC Forum
General Boards => General Discussion => Topic started by: Robert Mielenz on December 16, 2018, 04:49:48 PM
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We are considering a newer coach, Am interested in the fuel MPG for this engine. We would appreciate any input from C 12 505 HP engine owners. Pluses and problems specific to this engine. Thank for your input.
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A good reference and background document was written by Cat a few years ago. I tried to find it in our BAC Coach Assist but didn't. Try it here:
http://prevostcommunity.com/PDF/Motor%20Home%20Fuel%20economy.pdf
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Robert, I set my trip meter to zero when I purchased our Beaver last year. According to Silver Leaf VMS our coach gets 8.5 MPG. I also checked it the old fashion way, noting the mileage at fill up and dividing the gallons into the miles driven following the next fill up and it was also right at 8.5 MPG. Ours is a C12, 455 HP with a side radiator with an internal water pump. The motor continues to operate normally (minus the alternator) even if you bust a belt.... which happened to me a few months ago. A CAT mechanic once told me the C12 was the best motor CAT ever made.... might get some debate from others on this forum on that LOL.
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The Aladdin system in our '05 Beaver says 5.5 mpg since new. C-13.
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A good reference and background document was written by Cat a few years ago. I tried to find it in our BAC Coach Assist but didn't. Try it here:
http://prevostcommunity.com/PDF/Motor%20Home%20Fuel%20economy.pdf
Great article!
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Robert, my C-12, with tag axle, will get 7-7.5 MPG depending on speed of 60MPH to 75MPH. Generator and Aqua Hot usage must be considered for accurate MPG. As far as pro's and cons of the C-12, the coolant filter hose location, being next to exhaust pipe can be a problem. That topic has been addressed on forum many times. For my money, the C-12 has better fuel efficiency than any of the big motors. For Beaver motorhomes, the C-12 was used thru 2004. The 2005-2007 mainly use the C13. There are some C-15's used in 2007 and up. If you are looking for fuel economy, the C-12 is your motor. If you are looking for HP and torque, the C-13 and C-15 would be my choice. Hope this helps.
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Mine gets an average of 7.0 using the Aladdin. I don't track it any closer than that. I just don't care a whole lot. As far as problems I haven't had any in five years and I hope this doesn'y jinx it! LOL
Jerry
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Bill,
The article you posted is also available in "Common Problems" (Technical section) of the BAC home page. It is titled "How to Improve Fuel Mileage From My CAT Engine".
Steve
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If you get Dave Atherton to do a diagnostic read out on your engine you will find the actual mileage it is getting, and numerous other things. That read out is specific to the mileage of the motor and you do not have any aqua hot or generator involvement to deduct.
Our C-12 505 in our 2004 Marquis on several over the years readouts stayed right at 7.75 mpg while towing a crew cab F-150 always fully loaded with firewood on trips from Michigan to Quartzsite. Numerous other items in the cab also. I drive most always on interstate from 68-75 mph as I like to get from A-B so you can start to enjoy camping in your Beaver even though I have been told you do not camp in a Beaver on this forum.
The C-12 is one of the last great diesels that CAT built prior to having to use DEF fluid. Just be sure you are getting Dave to do a diagnostics readout so you know what is going on in your motor. While you do not have a warranty it is a much bigger deal to know thru a diagnostics read out if you need to do maintenance on any part of that motor before it gets to a real expensive problem.
If you ever trade it or sell your coach that info printed on a CAT readout to the new Owner will seal the deal for the price you want. IMHO it doesnt get any better than that for piece of mind and $$$ value. A Beaver with an inoperable motor is not worth a whole lot.
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There is a fun to watch You Tube video by a CAT mechanic on the "Best CAT engine" -- if you just want to know the best hd CAT engine, jump to the 9:30 minute mark.
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https://www.youtube.com/watch?v=igDWcKX-a-4
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The C-12 is a good motor but the boss of the Cat truck big engines is the C 15 6NZ hands down the best truck engine cat made, it can be boosted to a 1000 hp and live running down the road. In that youtube video go the the 12:15 mark. This is the motor the O/O'ers use in their glider kits for a new trucks.
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Bill,
The article you posted is also available in "Common Problems" (Technical section) of the BAC home page. It is titled "How to Improve Fuel Mileage From My CAT Engine".
Steve
You are right. I didn't dig far enough.
Bill
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Gentleman, depending on how deep you food is pressed downward to the floor the Cat C-12
Provides a very easy 7 to 9 mpg have many 10 mph readings at 55 mph. There is always a
Question on mileage when doing a diagnostic readout of the engine ECM but facts are facts.
Information is retrieved from engine ECM via caterpillar service tool called Cat ET. and information
posted is correct. Second part of the question the Caterpillar C-12 is a very good engine but
caterpillar also several good models also. Mileage has many variable that can affect fuel milage
That may be better milage for some and less for others so there is not. Set number as per one
engine model to others model Gear ratio, tire size, air pressure in tires, transmission ratio wind
level travel or rolling grades etc. Dave Atherton Retired Cat Mechanic
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We get 7.7 mpg regularly in our 02' Marquis with the 505hp C-12. We drive at 65 towing a Honda CRV. If we slow to 55 we can get 8.3-8.7 mpg, but we seldom do that. All are correct that the C-12 is a super motor.
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I think Jerry has the right outlook on fuel mileage, dont pay much attention to it as we pull in and fill it when it gets ready to need fuel. Then on down the highway again. I dont ever remember checking our LP gas needed to run our brick & mortar house as to how many btu's we were using and so feel the same as going on down the road with the house on wheels. Just keep the tank full.
Only once and that was in the 70's when they were rationing fuel did we set out on a trip and figured if we could only get as far as the fuel we had we would camp there and figure out how to get back home later. Soon as we got out of Michigan we could get more than 5 gallons at a stop so it never was a real issue.
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Our coach has trouble averaging 5 mpg. Since we have no interest in knowing how much fuel goes through the generator, we simply figure the mileage by "gallons put in the tank divided by miles driven." We sit in Yuma all Winter using the diesel burner to make hot water and all that diesel usage without one mile driven makes our first fill after winter show awfully poor mileage. lol
We decided several years ago that if spending money on fuel is a concern, then don't own a Beaver... or any larger motorhome, for that matter.
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We don't mind spending money on diesel but I do like to optimize our mileage. One of the lines I choose to put on the silver leaf is rolling MPG. I find that being attentive of rolling MPG lets me find the sweet spot for mpg when in a windy area or on a long uphill grade, and when to kick off the cruise control. Also helps to control engine and tranny temps with my right foot. I drive in the 60-70 mph range, when on "good roads" when out of the mountains and light to no winds.
On our 6600 mile round trip last year from Spokane to New England in our '03 Country Coach Magna, C-12, 505hp, w/tag and towing our '97 Cherokee we averaged 8.4 mpg. That is according to the silver leaf and verifying by math, miles driven and gallons into the tank. We physically did that on around 6 fill ups on the trip.
On a 3k mile round trip this year from Spokane to SoCal we averaged 8.9mph into SoCal and an average of 8.4mpg into Spokane. It's a big advantage going downhill from Dillon, Mt into Vegas but you pay it back on the return trip climbing from Vegas into Montana.
The difference in the two trips was changing our toad from a Jeep to a 2014 Toyota FJ, the FJ is 400 lbs heavier.
In our previous 2000 Beaver Thunder C-12, 425hp, we typically saw mileage in the mid 9's. I used synthetics in the engine, tranny, and differential on both coaches, and a fuel additive that contains several points of Cetane. Tires are 6 Toyos on the rear and Michelins on the front.
Doing this keeps me awake....:)
Phil
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Robert,
Of course, your fuel mileage will vary depending on your driving habits (speed and acceleration rates), coach weight, wind resistance, and terrain (hills,mountains, or head winds), but the entire line of C 12 engines in Beaver coaches from the 425 HP to the 505 HP version will give better performance and fuel mileage than any other big block engine. I have been driving a C 12 powered Beaver for the last 15 years, a 425 HP 2000 Marquis a 505HP 2002 Solitaire, and I have averaged from 8 to 8.5 on the 39,000 lb. Marquis to 7.5 to 8 on the 50,000 lb. Solitaire that is 13.5 feet tall. Another comment about the C 12 is that in about 200,000 miles of driving one, I have found the engines to be almost bullet proof.
Gerald
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I wonder what CAT did, regarding engine design, that resulted in the C13 getting 2 mpg less (on a similar size/weight coach) than the C12? That's a 25% drop in fuel economy.
The engine displacement is only 5% different (732 cu-in versus 763 cu-in)
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Mike,
The C 12 would not meet the federal government upcoming emission standards, so the C 13 was built to meet those standards. The C 13 is a different engine design and not a slightly modified C 12. You can blame the 25% reduction in fuel mileage on the federal government. The biggest difference between the 2 engines is the redesigned cylinder head, dual turbo chargers, and operating program that uses different fuel mapping.
Gerald
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For those that may ever think of changing coach's you will possibly have to move out of the Beaver to some other brand if a newer coach. With that move you will almost always have to go to a Cummins in a Class A. That did not thrill us as we had the C-12 in our 2004 Marquis and I was sure a Cummins would not get the same performance.
To date we now have close to 30,000 miles on our 2017 Entegra Cornerstone with the 600 hp Cummins and we could not be happier. Its performance is excellent for a coach that weighs 58,000 lbs towing an F-150 pickup most always fully loaded with firewood and other items.
It's sweet spot is at 75 mph on the Interstate where it just seems to drive the best and run the smoothest. If it is windy it handles the road impeccably better at higher speeds than it does if you are in the 60 mph ranges.
The read out on mileage started at 6.5 miles per gallon and it is still at 6.5 so I have no idea if it is working or not. Just fill it when it needs it. A dream to drive.
It also has the Tag axle that turns and makes getting into and out of places we would never even consider with our Marquis. I have had the dear wife on numerous occasions say "you cannot get in there" and we did and back out again without bending anything, and its 45' long not 40'.
Yes it takes some green but all in all would do it over again. The Cummins has performed exceptionally well in all aspects from the flat land to the mountains back and forth across the US. It just likes a large drink every now and then.
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Hi Doug, I'm glad you are enjoying your Entegra. I don't want to rain on your parade but if you have the Cummins ISX engine, you should check out the discussion of Cummins ISX Broken Valve on the irv2. I think your engine is new enough that it has the updated parts (valves, heads, pistons, etc.).
(Note from admin; can't post links to other forum w/o original poster's permission).
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Mike, From all I have seen it is on motors I believe pre 2010 but in any regard the Spartan chassis info has a note that you should run your engine every month up until it gets fully to operating temperature for coachs that are sitting for long periods. Believe your info was answer to this situation that I did not know about.
However, as posted about Oil Analysis this is a critical very economical way to detect most all potential problems internally with an engine so that an owner can address them prior to the end result of a failure. Oil Analysis, dependent on miles driven a year, can be done yearly and give at first analysis a baseline for the engine, then it becomes a point to compare the next analysis against. You get a very clear look at what is going on internally. There is never a point that starting this baseline and then doing future analysis is not worthwhile to the Owner.
Because we have the 600 ISL Cummins we have already started oil analysis and have the report back form 1 lab. We are doing 3 different labs on each oil change. 1 with AMSOIL as we use their synthetic, 1 with CAT as they have an excellent lab that can determine what the metallurgy is should they find any metallic particles (CAT lab knows what all the metallic components are for the bolt on parts to their engines so they can pinpoint that part with the metallurgy analysis), 1 with a lab that Cummins recommends (We are still trying to get info from Cummins to see if they know like CAT does what the metallurgy is on all their bolt on parts).
At the worst it is about $75.00 to do 3 oil samples a year. With an engine worth somewhere north of $60,000 this sampling cost is a pittance compared to any other cost to keep this engine running. Even if you only do the CAT sampling on your used CAT engine at around $20.00 for the sample kit the piece of mind you get from knowing the health of your engine is very comforting. If it points to a future problem address it or make a decision on how to move to another coach. If you are going to sell and the tests indicates the engines good health that is a deal maker.
As most Forum comments will reflect there is much gnashing of teeth when you have a major warranty problem on a diesel engine. Any excuse will do to try and get out of that warranty either by the engine maker or an extended warranty company. That is the reason why we are using 3 lab reports to verify information on this 600 ISL Cummins.
Just because you have oil change receipts does not pass the final test to get either of them to take responsibility and do the necessary repairs.
By the way we are also having Dave Atherton run the Cummins Insite program as well as review all our oil samples. The BAC has the Diesel Diagnostics guy that numerous other clubs are trying to get, dont miss out on using this extremely valuable asset we have. I am not any smarter than any other coach owner and thanks to Dave I know a lot more than I ever used to about a diesel engine. You can too to protect your investment.
Merry Christmas to all.
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Mike,
Yes I agree Caterpillar engines are very good long life low maintenance cost engines with proper service. There are several models that stand out better than others and whose track records have been followed by Caterpillar Off Road and show long life and low operation cost. Many of these engines were sold to the R.V. industry prior to CAT's exit from the over the road business. However these engines are still in service and built today so we as R.V. owners have nothing to worry about. These engines or parts are available for your motorhome engine if needed.
I wanted to touch on why the C-13 engine had been chosen for on-road truck. The design of this engine can give a very broad range of engine horse power models where other models could not. As for one model Caterpillar engine that is stands out ahead of other models that I think it is down to owner preference and how he or she drives and maintains engine. When we get feedback about mileage in the high 200,000 mile range with little problems that is normal and expected for a diesel engine. You as an owner will not wear out your Caterpillar engine.
Wishing everyone a Merry Christmas and let’s look forward to happy travels.
Dave Atherton Retired Cat Mechanic