i'm interested in hearing thoughts, opinions, and especially first hand experience with towing trailers in excess of 10k lbs. i am considering an mc8 with an 8v71 and 4 speed manual. for most of my trips, i have the need to tow a trailer that's anywhere from 10-15k lbs. depending on what it's loaded with. mountain driving is a part of some of my travels as well.
i have read all of the debates about engine cradle strength, etc. so i'm not concerned with feedback on that. strictly on performance. how is power, cruising speeds, pulling grades, etc.
i am currently using a blue bird tc2000 with a 5.9 cummins/allison at545. for several reasons, a converted coach type bus will work better for me. my only concern is if it will tow at least as well as my blue bird.
that is really a subjective question.
1st it depends on the condition of your mill.
2nd the weight of your coach
etc etc
You are asking for a lot from an 8V71 non-turbo for the mountains.
In many mountains, I was only able to go 18 MPH (1st gear auto) with an 8V71 non-turbo. Bus was 34,000# towing 4000#. To me, this is unsatisfactory.
A friend with a 470 HP Series 60 pulled 18,000# trailer with his 44,000# bus. It was slow in the mountains - but useable.
I think you would be happier with an 8V92T or Series 60.
Ed Roelle
I can tell you from first hand experience that doing mountains takes a LOT of horsepower.
I pulled my cargo trailer ( 8,800 lbs ) with my MC9 with a good running 6V92TA / HT740 allison.
A 6% or greater grade will have you down to about 5 mph in First Gear. Not a pleasant situation.
If you plan on pulling something heavy, You absolutely need all the power that you can get. You also should have something with Jake Brakes or a Retarder. Getting up the mountain is one thing that wears you out but that downhill part will absolutely scare the heck out of you.
Bus brakes are good usually, But not good if you are trying to hold back a runaway freight train.
I don't care how good you say or think your trailer brakes are. They will fail to slow you down.
So that said.... Hmmmm.. 475 hp or better. Jakes or Retarder, Oversized Cooling system.
You would also need the right gearing and transmission. Most likely a 10 speed or Autoshift
that has enough ratios to let the engine keep the power poured to the ground.
Cummins M11 , Detroit Series 60 12.7 or Mack E-7 ( whatever the showhorn would allow. )
Were' talking about a TRUCK here, Not a normal Bus Conversion.
Seriously even of you could get that kind of power tucked into an MC8, The chassis might not be up to handing all that load or stress without adding about another 300 lbs of steel to strengthen it enough.
Me? If I had the time/energy and budget I would get all the power I could get. But alas I am stuck poor and nearly broke and what I got is all I got now....
I enjoy a challenging road, Hills, Mountains and Curves.. Just not all with white knuckle driving due to lack of power and too little brakes. Once you commit to climbing that mountain, You are hostage until it's over. Most places just don't have enough room to turn around when that feeling comes over you that "You really don't want to be here"......
Dave ( DrDave ) Now located in the Mountains of Tennessee.
I know I'm committing heresy here but you may want to consider a TRUCK conversion instead of a bus. I have seen some of them around and they really do a good job if you need to pull a heavy trailer. You can look at http://www.kingsleycoach.com/ to see what can be done. They are one of the high end converters and probably more money than you want to spend but it will give you some ideas. Also, most of the stuff on this board is applicable to trucks as well. At least you can get some alternative ideas.
Have fun!!
TOM
Quote from: oldmansax on September 29, 2007, 06:53:27 AM
I know I'm committing heresy here but you may want to consider a TRUCK conversion instead of a bus.
Tom,
That is exactly what I would do if I was hauling heavy trailers everywhere we went.
Select the platform based on need, not dream. :o
Cliff
TW,
I honestly think since you say your "considering using an 8 with an 8v71 and 4 speed manual. for most of my trips, i have the need to tow a trailer that's anywhere from 10-15k lbs. depending on what it's loaded with. mountain driving is a part of some of my travels as well."
That you'd be a lot better off finding a unit with more power from the start! That's asking alot from an already low power unit for mtn use! Back in the day when the 318 came out, it was a power house (compared to what they'd been using & every truck driver out there had them cranked up as far as they could too!) & it was coupled with transmissions that had more gears 13 spd was real common in those days!) in those old trks! But these days there are so many better options personally I'd look around for a MCI 102 W/O an engine and put in a take out from a wrecked truck like Brian Diehl did here;
MAK Publishing Bus and Coach Conversions Bulletin Board > Bus Discussion > All Topics ( click here for quick start! ) (Moderator: Nick Badame Refrig. Co.) > Going to get my new Motor/Tranny on Friday!
FWIW ;D BK ;D
Thanks everyone. Sounds like I'm probably better off with a dedicated toterhome or at least a smaller/lighter coach with equal power.
That kind of trailer weight is best handled by something designed for that - A TRUCK conversion. It will give you so many more benefits than a bus when it comes to road repairs too! ;D
A friend has a cover band & when they out grew their bus, he bought a Freightliner conventional sleeper cab truck & had the frame stretched to allow the fitment of a 28' box. He has the rear part of the box partitioned off for band equipment storage & the front part has the bunks, bathroom & lounge. He hung all the tanks & generator & etc under the box. Works well for him. He also has the 80,000# GCVWR ;D Kinda hard to overload that conversion.
I do not have proof but would think the 8/71 would match the 5.9, even in the heavier bus. I would think the 5.9 is a dog also. Tom Y
I don't know if'n it is the best idea but I towed a 10k # trailer with a gm 4106 standard 4 speed and natural 8v71 and did crawl up a lot of hills mostly in 2nd gear but some in 1st. The motor is designed to pull hard. The only problem i had was in Trail, B.C. where I missed a shift and had to unload the blazer to restart on the hill. It was I believe a 12 % grade. We are full timers out of Idaho and have pulled to AK twice with no problems.
I now have a MCI 8 with 8v71TA and Auto. It has pulled to AK also and all kinds of western state grades. I also have 3 friends doing the same. MCI5 with enclosed car trailer 6v92, MCI8 with 30 ft enclosed car trailer and is well above 10k #. and a Eagle 8V71 auto 10K# trailer.
Would something else be better? Sure but this is what I have. Might work for you too if'n you're not in a hurry.
I also had an MC8 with an 8v71 with no turbo and only weighed about 27,000 lbs. and towing a toyota pickup and I felt I was dangerously slow on the on ramps and hills. I now have an MC8 with an 8v92T at 36,500 lbs. and the same toyota and I feel much safer. But I bet with a large trailer like you want to tow and even an 8v92T will slow down. Then the problem is upgrading the cooling system to keep her cool on the hills. I would like to tow an 8,000 lb SUV, but I haven't got the cooling system to where I think I can use all my horsepower because of all the heat I have to dissipate doing it. For what it's worth.
QuoteI would think the 5.9 is a dog also.
it doesn't win any races for sure. it'll do solid 60-65 on the flats, but grades of any size knock it back to 40-50 and sometimes as low as 20 on steeper ones. i've got the pump turned up a little which helped some. 5.9's are so venerable to build up i feel like i could easily get all the power i want, but i'm still left with a lot of the bad OTR manners of a skoolie type bus.
this is what i'm looking at now. i'll sacrifice some interior over a coach, but it should be leaps and bounds ahead in towing ability/safety.
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fstatic.racingjunk.com%2F1%2Fui%2F4%2F1%2F2127506820232.jpg&hash=93938b2fa9b9315cfdb92ea03792a5ced5ddd452)
Highly recommend you NOT try to tow with a bus that has a non turbo 8V-71 with only a 4 speed trans. The bus was designed to just barely perform with the drivetrain it has now. If you put a 10-15,000lb trailer behind, I guarantee you that you won't be able to get it started on a mear 6% grade-of which is common on the Interstate system. As compared to trucks that at 80,000lb are required to be able to start on a 16% grade. You might be able to get away with starting if you have an Allison automatic. The non turbo 8V-71 is just not enough power. An engine with 13-1500lb/ft torque would work alright for you-not the 800lb/ft torque that the non turbo 8V-71 has-if with 65 injectors. Good Luck, TomC
Thanks. I've have almost completely averted my attention to totorhomes (truck conversions) now. like i said, they'll sacrifice some interior but the added towing power makes up for it. I was the high bidder on the mc8 I was looking at for $10k, but the reserve wasn't met which I guess is a good thing now that I've had a chance to really research further.
What about the 8v92t? i've seen it in a few older Peterbilt conversions.
Does anyone know good places to find used toterhomes? www.racingjunk.com has been great so far.
Anyone familiar with the Cummins 903? It's in a conversion I like, but I've never even heard of it.
The truck versions of the 903 were dogs. We have one in a tanker at my fire company. 57 MPH on a long flat.
The engines are capable of big power, I heard of marine applications at over 1000HP, but heat seems to be the problem. There is no way to dissipate the excess heat in a truck application.
FWIW, TOM
Would steer clear of the Cummins 903 engine. There's a real good reason why they are not used in anymore-just were not long lasting enough. Granted the military has some vehicles that were built around the 903 so Cummins is still building the 903 for the military. But remember-if the military gets 2000 hours out of an engine, that's all they require. I don't think 80-100,000 miles is enough miles for an engine to last, especially in this day and age of 1 million mile truck engines. Good Luck, TomC
yeah, it appears they're pretty widely used in bradley tanks and also marine/motoryacht applications. couldn't find much of anything on their use in the mdt/hdt truck industry.