| Author | Message | ||
| Scott Follows (Scottfollows)
Rating: N/A |
I’m starting to shop for my early 90’s MCI 102C3 shell and I’m trying to make a decision on the engine. What I want to do is compare the costs of various engine options with the costs of fuel over the long term. In other words, if I stepped up to a series 60 (I know they are rare on 102C’s), how many miles would I have to drive in order to break even on the higher engine cost. So can anyone tell me what the miles/gallon numbers are for the following engines with an automatic transmission? Engine: Miles/gallon: DD 6V92 DD 8V92T DD Series 60 (12.7L) Cummings L10 Thanks Scott | ||
| TWODOGS (Twodogs)
Rating: N/A |
all of them are going to be between 7 & 9 mpg...thats about what it costs to move 30,000 pounds down the highway...as far as the best engine...everybody has different opinions...I'd vote for the 12.7....fuel mileage is the least thing you need to be concerened with...condition & maintenance is what should be of concern... | ||
| TWODOGS (Twodogs)
Rating: N/A |
one thing to 'look out' for...most people will tell you it was overhauled 80,000 miles ago...(etc)...if it was...ask to see the paperwork on the rebuild....if they cannot produce it....be leary..... | ||
| Jim Stewart (H3jim)
Rating: N/A |
I have a 1995 Prevost H3-41 with the DD 12.7 series 60 rated at 425 hp and the Allison B-500 world tranny. On a 3,000 mile trip I did last summer, I averaged 8.5 mpg with the cruise control set at 65 mph. Gutted and mostly empty. I suspect that fuel mileage is strongly related to driving speed. I think I would get the best at 55 or 60, but I can't seem to drive that slowly. I guess I would get around 5 or 6 mpg if I did 75 or more. When I was looking to buy I looked at a bus with a 12.7 series 60 engine hooked to an HT740. The charter operator said no matter what he did, he usually averaged about 5.5 mpg with it. No more than 6 mpg. The world tranny has the same gearing as the the HT740, but with the addition of two overdrives. I speculated that the difference was that the older tranny was not able to make the most of the wide torque band of the 4 stroke, and kept the rpms higher than needed. While prices have fallen since I bought a year and a half ago, the series 60 / world combination commanded about $25k more than the two strokes. I think this was largely because I was competing with bus line operators and they were willing to pay that much more based on the number of miles they would drive and the spector of the pollution regs for the 2 strokes. I found that I couldn't come close to justifying the added expense based on my expected miles, even over the life of my bus project, but I bought it because of the way it drove and because I wanted it. had to beg borrow and steal, but it is a pleasure to drive. Also don't forget that the world tranny, I'm told, costs $25k for a rebuild, while the HT series is 1/4 to 1/3 of that. I'm not sure of engine longevity with RV usage, but I understand they have been getting 800,000 to 1,000,000 miles between rebuilds for the series 60 and 4 strokes in general vs 200,000 to 400,000 for the 2 strokes. Hope this helps, your mileage may vary. | ||
| Macgyver (91flyer)
Rating: N/A |
I have a 6v92... but, as anyone here knows me... I'm running around in a rig that's 60 feet long.  I got just a hair above 5mpg on a 1300 mile trip coming home last week. But, the gross weight of my bus is also 66120lb. I don't know what its actual weight is empty. -Mac | ||
| John that newguy Rating: N/A |
I think you'll find that your MPG will be highest when you can maintain a steady speed, rather than what that speed might be. Running 55mph and speeding to 70 and slowing to 55 then accelerating to 70, etc, will kill your mileage just as city traffic will.. | ||
| Henry R. Bergman, Jr. (Henryofcj)
Rating: N/A |
1974 Crown Super Coach 40-foot 10-wheeler with a Big Cam 250 Cummins (no turbo) right at 10.5 mpg at 60 to 65 mph. Sorry guys. | ||
| TWODOGS (Twodogs)
Rating: |
datsun 280 zx 25 mpg....but the question was about a MCI....this ain't a pissin' contest | ||
| WA David (Wacoastmci)
Rating: N/A |
MCI102D with 450 hp Series 60/Allison 4070HD 6 speed. MPG varies mostly whether towing Cherokee or not and whether hilly or not. Around high 8's mpg not towing around low 8's towing. Usually drive with cruise set to 63 mph. On the plus side, the Cherokee gets amazing mileage while being towed. | ||
| Ron Rutledgethundercoach
Rating: N/A |
'81 CROWN SUPER COACH,36',Big Cam,10.4 to 10.6 up here it Washington State...the road's will make the change, up or down hill | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
And since all us Crown guys LOVE to gloat, mee too.. 1962 Crown, 9 speed, roof raised a foot, Engine driven AC and two, count em two roof carbunkles... and a nice old Cummins 220 that gets me up to 75-80 no sweat...10.5MPG or 11 on a good day, no matter how hard I push her.. | ||
| Rob King
Rating: N/A |
Hi Scott I bought my bus, a 91 Prevost with an 8v92, in Jacksonville FA and drove to Missouri. I know it's not an MCI but it averaged 7.2 mpg over the 1500 miles at average of 65 mph. Have had a Newell with 8V92 that averaged 7 mpg with toad. Only real disadvantage to 2 cycle, in my opinion, and advantage to 4 cycle series 60 is the 2 cycle engine spitting out oil from slobber tubes that gets on everything from back of bus to tow vehicles. Series 60 advantage is overhaul times much longer but also, as post mentioned above, much more expensive and no slobber. Now for my opinion, on sound, I really like the gutsy sound of the 8V92, makes me feel like even though "I'm spitting oil, I'm toating power". Really boils down to personal preference and amount of money in the billfold. The trick is finding a happy balance that you can live with in your bus. Rob | ||
| FAST FRED Rating: N/A |
The bigest advantage (besided being a "million mile engine"whic hardly matters to an RV) is the slow RPM with the Big Buck bus tranny. The coach is quieter inside with loads of power avil from a tranny downshift. $25.000 extra could be easily offset with a grands worth of Soundown Noise controll goodies. If hillclimbing at higher speed is worth $25,000 to ya is a personal thing. Milage costs HP , the std 8V-71 will give about 16 hp for a gal of fuel at normal 1800 Cruise RPM The Ser 60 may be able to make 20hp/gal . at its more efficent lower RPM. Thats a POTENTIAL for a 20% lower fuel burn at cruise . Criuse controll would help. FAST FRED | ||
| Scott Follows (Scottfollows)
Rating: N/A |
Thanks for the information. Here are my calculations. I could almost justify a $10,000 premium for a series 60 given the additional benefits of that engine over the 8V92. However, I’d probably could be money ahead if I repowered with a Big Cam. I’m off to the Gathering at the Caverns next month so I’ll get a chance to get up close and personal with these beautiful machines. Assumptions: 8V92 7.5 mpg Series 60 8.5 mpg Big Cam 10.5 mpg Price/gallon $2.25 No rebuild needed in 10 years Scenario 1: Fuel savings based on 15,000 miles per year over 10 years Series 60 compared to 8V92 $5,300 Big Cam compared to 8V92 $12,860 Scenario 2: Fuel savings based on 10,000 miles per year over 10 years Series 60 compared to 8V92 $3,500 Big Cam compared to 8V92 $8,580 Scenario 3: Fuel savings based on 15,000 miles per year over 10 years Based on the price of gas in Canada (where I live) $2.85US/g Series 60 compared to 8V92 $6,700 Big Cam compared to 8V92 $16,310 Scenario 4: Fuel savings based on 10,000 miles per year over 10 years Based on the price of gas in Canada $2.85US/g Series 60 compared to 8V92 $4,480 Big Cam compared to 8V92 $10,860 | ||
| TWODOGS (Twodogs)
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yeah.....sure | ||
| Jim Bob Rating: N/A |
The sweet song of the two-stroke is worth 2 miles per gallon to me! (Hey I'm doin' this for FUN after all!) Jim-Bob | ||
| John that newguy Rating: N/A |
Tnx for the laugh, Scott! | ||
| niles steckbauer (Niles500)
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Scott - you may be able to bump those figures up if you figure in the Present Value of your $10k while factoring the future cost of fuel (at current inflation rate combined with fuel scarcity could easily climb to $5 plus per gal in 10 years) and estimating the future added resale value of your bus being already equiped w/ a Ser60 - its a lot of math, guesstimation and actuarials to get a real handle on the true return on investment - Niles | ||
| TWODOGS (Twodogs)
Rating: |
I think I know some guys that need to have their speedometer recalibrated | ||
| Scott Follows (Scottfollows)
Rating: N/A |
Ok, Ok,...I guess the rule is to buy the best bus you can afford, fill ‘er up and head out on the highway. My wife is the kind of person who would rather spend $10,000 up front for better mpg than be frequently spending slightly more at the pump. I think I can use this analysis to justify an increase in the bus conversion budget. Thanks for advice. Scott | ||
| niles steckbauer (Niles500)
Rating: N/A |
Scott - I almost forgot the most important factor - which you just pointed out - by all means do as the wife 'suggests' - when you compare the cost of mills and fuel to attorneys and alimony - there just ain't no comparison - you've made a wise choice - Niles | ||
| TWODOGS (Twodogs)
Rating: N/A |
THE WIFE...."NOW".....they are picking out heavy machinery.....THIS IS SCARY.....next thing ya' know...they are going to want to vote | ||
| RJ Long (Rjlong)
Rating: N/A |
Scott - A few more thoughts: ** Yes, buying the newest bus you can afford in the best possible condition up front will save you big time in the long run. ** Following the same logic, buying the powertrain you want up front will also save you big time, and keep Mama happy, too. ** The weight of your right shoe has a tremendous impact on fuel consumption. ** The closer you run your coach to the number 80 on the dash gauge marked MPH has as much effect on fuel consumption as the weight of your right shoe. ** Building the interior with granite countertops, marble floors, fully-tiled shower, multiple slide-outs (not recommended on pre "D" series MCIs) and other heavy components, as well as the amount of "stuff" on board, will have an impact on fuel consumption. ** A 40-foot GMC shell will get better fuel mileage than a 40-foot MCI shell with the same 8V71 engine: aluminum vs stainless steel construction. ** If you buy a coach with an 8V92 and decide to repower, doesn't matter which engine you shoehorn into the rear, the cost of re-powering will NEVER be recovered in added fuel savings over the life of the average RV usage. ** Regardless of which engine your coach has, you should plan on fuel stops every 500 miles as a precaution to the delightful task of repriming. ** The Big Cam Cummins mentioned by the Crown guys is a pancake motor laid over on it's side amidships in their application. The model Crowns mentioned are also extremely "slick" aerodynamically compared to a 102C3 MCI. ** 40-foot MCIs with a Series 60 installed OEM from the factory have a shorter wheelbase (translated: less room in rear-most baggage bin) and longer rear overhangs than those coaches using the 6V92 or 8V92s. This applies to late-production 102C3s and early production 102D3s. All current production models are engineered for the S-60, with appropriate wheelbases and rear overhangs. ** MUI 6V92 and 8V92 engines are simple to work on, everything's mechanical. DDEC engines are computer-controlled with correspondingly increased complexity and component cost. (Price an injector for an S-60 vs a MUI 8V92.) ** The two-stroke motors, besides having that distinct sound, also are smoother, especially at idle speeds. They do have less torque output than the four-strokes, so they don't climb Rocky Top quite as quickly - but then again, what's the rush?? ** Any coach you look at with an L-10 Cummins should be a candidate for a repower with an M-11 or ISM, thereby negating your fuel consumption savings over the life of the coach. The L-10s have not been a favorite when installed in the heavier highway coaches, with some driveability problems. The L-10s have been satisfactory in transit service, tho. ** Be sure to bring along a hankie to handle the drool as you peruse thru the coaches at the Caverns. . . HTH, RJ PD4106-2784 (8V71, 9.5 mpg @ 65 mph) Fresno CA | ||
| R.C.Bishop
Rating: N/A |
Crown Supercoach, 1964, 10 wheel, Cummins 220 (NH Series, Pancake style, amidships, Turbo,10 Speed Road Ranger, Jake, 38,500 GVR, air ride all 10, no engine driven A/C. As I was told by Northeren AZ University, who sold it to me,and verified....as Gary says, on a good day...scouts honor....12.0 to 12.5. All depends on the wind and.. and.. and.....Usually go comfortably 600 miles +- (Las Cruces to Dallas) before filling a 100 gallon tank....I 10 and I 20.( Flying J Anthony Tx to Flying J Garland (?). Have had it to 85 on the flat.....don't want to do more than that under any circumstance. 65 usually gives best ride, most comfortable driving and "feels good at that speed....roughly 1700 rpm. With these higher fuel prices, I prefer 1500, which cuts it down to 55/60 mph, again, depending on conditions. RJL drove these for a number of years...maybe he has more to add to this particular vintage. | ||
| R.C.Bishop
Rating: N/A |
Crown Supercoach, 1964, 10 wheel, Cummins 220 (NH Series, Pancake style, amidships, Turbo,10 Speed Road Ranger, Jake, 38,500 GVR, air ride all 10, no engine driven A/C. Full I beam frame under the coach. As I was told by Northeren AZ University, who sold it to me,and verified....as Gary says, on a good day...scouts honor....12.0 to 12.5. All depends on the wind and.. and.. and.....Usually go comfortably 600 miles +- (Las Cruces to Dallas) before filling a 100 gallon tank....I 10 and I 20.( Flying J Anthony Tx to Flying J Garland (?). Have had it to 85 on the flat.....don't want to do more than that under any circumstance. 65 usually gives best ride, most comfortable driving and "feels good at that speed....roughly 1700 rpm. With these higher fuel prices, I prefer 1500, which cuts it down to 55/60 mph, again, depending on conditions. RJL drove these for a number of years...maybe he has more to add to this particular vintage. A great coach with a few disadvantages, like under the floor bay space. (I have a trunk that will hold a double bed... width, not height)If you don't like 6'3" ceiling height, better raise the roof or forget it. Also curved roof style. We're short folks, so it is no problem for us. FWIW RCB '64 Crown Supercoach (HWC) | ||
| Stan Rating: N/A |
RC: Are you even remotely suggesting that TD could be wrong? | ||
| TWODOGS (Twodogs)
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lets run it out of diesel...I'll give you a gallon...& I'll meet you 10 miles down the road | ||
| R.C.Bishop
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Touche'...... Thanx anyway, TD. But I'll wave at you as I blow down (tailwind) I-40. .... RCB | ||
| TWODOGS (Twodogs)
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I wasn't going to wait anyway | ||
| Jerry W Campbell Rating: N/A |
I just filled up in Las Vegas and drove up 95 to 395 at Reno and from Susanville across the Sierras to Mt Shasta , up I 5 to Yreka, Ca. 676 Miles. I put in 70 gallons. 9.6 MPG That's cruising at 2000 RPM's. And there were quite a few hills as I remember. Jerry 1975 Crown Super Coach DD 671 Fuller 5 Speed | ||
| TWODOGS (Twodogs)
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what is the name of the truckstop on the east side of I-5 somewhere between Redding & Yreka,that has the coconut cream pie | ||
| Henry R. Bergman, Jr. (Henryofcj)
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Hey Scott....Their is no doubt that the Detroit Series 60 is probably a much better engine than the 30 year old Cummins Big Cam family. Also, the Cummins upright mill is pretty big physically and I do not know if would fit in your MCI. Some help here please. Yeah, Crown Super Coaches are cool, slick and have a good reputation, but actually they do not make that good of candidate for RV conversions. No baggage bins to speak of, and the headroom is only 75 inches, unless your raise the roof. We Crown owners did not mean to rain upon your parade. We were just giving you more info sooss you could make a good determination as to what kind of mill would WORK OUT FOR YOU. Not us. Actually, a hot 8V92TI would be OK for me. They sound sooosss cool. Forget the mileage...go for the fun of our hobby. Life is too short. | ||
| Jerry W Campbell Rating: N/A |
Dos Perros We remember the sign about the best coconut cream pie you've ever eaten or something like that, but we can't remember where we saw it. After 5750 miles it all starts to run together. It WILL be in the back of my mind for the next time we go by there. Jerry | ||
| Gary Carter Rating: N/A |
FYI: 8v92TA DD in 45,000 pound Newell. 6.5mpg over the past 11,000 + miles. Individual tanks and trips are almost meaningless. People don't include the low milage trips. I have a friend with a new 25,000 pound MH with a C-7. He has been keeping track since day one of ownership or about 15,000 miles now. Overall has been just shy of 8. go figure. |
