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What's the limiting factor?


Will

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Wind is the kicker. That's when you need horsepower. I had the same experience when I picked up a 14' x 7'wide enclosed motorcycle trailer for my dad. It has 7' of standing room inside and the front is just flat across. It isn't that heavy and my 4.0 Ranger did great in town--this was in Detroit and I was bringing it back an hour south of Indy. Anyway, fine in town. But when I started up the ramp and got to about 50 it just ran out of power. I drove it at 3,000rpm in 4th for 350 miles and it got about 12mpg. It's a lot more revs than I feel comfortable with and the semis going past have a low pressure area beside them that sucks the trailer toward them, which is fun. Sure you can do it.

Power is power. But let's compare a schoolbus with a Ranger. My 18,000 bus can pull a 6% grade at 45mph with the engine at 2,500rpm in 5th gear. It's 185hp with an engine that weighs 1,300# and a massive cooling system with like 3" radiator hoses.

A 4.0 SOHC Ranger pulling a 14,000# trailer will need 4,500rpm to make 185hp. You've only got 2 gears though. You take off in first (which might not be possible with a 14,000# trailer), shift it a redline and then it will be at 39mph and 3600rpm. If you hit the bottom of the hill at 4,500rpm it should be keeping up with the bus on the way up.

The main problem is that the 4.0 doesn't have enough gears if you are going to use it for that much weight. It has 2 gears to use on the hill and the bus has 5 with the first being 9.04-1 and a 4.78-axle. A 3.40 first and a 3.55-axle means your clutch is probably going to be on fire, and in reality, the bus will be long gone if they start together at the bottom. Next, both engines have to get rid of the waste of 185hp heat. The Ranger was in no way meant for that with it's little plastic radiator and tiny cooling system. You keep it at maximum torque for that long and the heads will wrinkle up and spit the gaskets out right before the pistons start swapping holes.

Old school buses did use passenger car engines. But they had upgraded cooling systems, very low and slow gearboxes and the engines were derated. Even the modern bus engines are derated. The 200hp 5.9 Cummins in a medium-duty truck/bus makes 300+hp in the Dodge pickup passenger car rating. If you wanted 300hp in a medium-duty truck you would put in a 10 liter engine.
 


downzero

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That's absolutely ridiculous. The same 5.9 in a marine application makes an ungodly amount of horsepower (more than in any pickup truck).

The reason school buses are detuned is for fuel economy, not because the cooling system cannot keep up.

I have a Dodge and even with a chip and 10,000 lbs behind it, you can bury it to the floor in overdrive up a steep grade and it will never overheat.

You are nuts if you think the factory would warranty a vehicle that cannot cool itself at maximum load and output.

The reason his truck is rated for such a low amount of weight is that it has no power. It is just not safe to try moving a heavy trailer in traffic with a 4 cylinder truck.

My Ranger won't even pull a small open trailer without struggling, and it has a 3.0!
 

Will

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A marine rating....hmmm. Is that Continous, Intermittent or Pleasure?

Then, you should know that a marine engine is connected to a propeller. The propeller is designed to absorb maximum horsepower--it cannot see maximum torque at a lower rpm--or anywhere. You know torque=heat--it's the maximum amount of fuel you can burn in one engine cycle that matters. With a wheeled vehicle the operator can use maximum torque whenever he feels like it.

Next, show me a commercial application of a 5.9 Cummins in anything approaching 300hp, or even 250, in a wheeled vehicle, besides a Dodge pickup.

Then I will admit to being ridiculous.

Fuel economy my ass. Why use an L10 for 300hp why the 5.9 can do it? For fuel economy?

Of course.

Motorhomes and firetrucks are also intermittent applications that get higher hp ratings because they don't see continous high outputs. And pickup trucks.
 
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85_Ranger4x4

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Next, show me a commercial application of a 5.9 Cummins in anything approaching 300hp, or even 250, in a wheeled vehicle, besides a Dodge pickup.

Then I will admit to being ridiculous.
Case used the 5.9 in tractors for awhile (they still might) I don't think they were ever rated over 150hp at the PTO. I don't know what the driveline drag is but I can't see it losing 100hp between the flywheel and PTO shaft to put it over your 250hp. Tractor engines get tortured probably more than in most other applications, so that says something.
 

Korrie

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A Casita is a relatively small trailer that is narrow with reduced frontal area than a typical travel trailer. I passed up a similar truck like yours because of the low tow rating. However if you are willing to take the risk of a void warrenty, tow what you want. I would try and keep the weight down by only taking what you need, don't haul water, etc. Be sure and use a weight distrubution hitch with a "light duty" torsion bar systems. Add a friction sway to the setup as well. And purchase a smart brake controller for the electic brakes it will do wonders to prevent trailer wheel lockup.

I serioulsy doubt a DOT officer on a bad day will ticket you for towing a Casita with a Ranger P/U. Most states require brakes on a 2000 lb trailer, towing mirrors, and working lights. That's about it.

Oh, and if the above setup feels unstable, some "cheap" upgrades would bigger sway bars, higher load range tires, stiffer shocks, and an extra rear leaf or helper springs.

Good Luck!
 

Will

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A DOT officer is paid to enforce commercial vehicle regulations. He's not going to fool with anything pulling an RV. I sold my Casita to a 90 year-old man with a Honda Accord--and I drove it to fill it up (at his insistance) before he would take the wheel. It was just fine.
 

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