Experience in towing with mid-sized SUV?

RockyMtnRay, our resident towing expert, now departed. Is he departed as in "passed away" or just doesn't show up here any more?

I agree with what Bill says above. Diesel engines produce a lot more torque because they, by definition, are a compression ignition engine. In layman's terms, they have to produce a lot more compression than a gasoline engine because the heat from that compressed air is what fires the fuel. (no spark plugs) Since they have a longer stroke (the distance the piston moves in the cylinder) they also have to have a longer "Throw" on the crankshaft. The longer the throw on a crank, the more mechanical advantage is available. Like a seesaw, the farther you move from the pivot (fulcrum) the more load you can lift. Gasoline engines are lower compression, so the throw is shorter and so they produce less torque. They have to rev to higher RPMs to produce the torque and that is usually accomplished in the gearing of the differential and transmission. If you had the same transmission and differential with a gasoline engine and a diesel, the Diesel would have more torque and the gasoline engine would have more speed. Speed and torque are an inverse proportion - in other words: as you raise the speed the torque goes down. That is how the big 18 wheelers can tow those big loads with their engine turning about 2100 RPM.

[Bill]

Originally Posted by Freedom

Is he departed as in "passed away" or just doesn't show up here any more?

Sorry, that wasn't very clear, was it? To the best of my knowledge, Ray is happy and healthy and still climbing the 14'ers based in his TM. But he found his time and knowledge to be much needed in the Toyota Tundra forum, so that's where he spends much of his forum time.

Bill

Good, I'm glad. I always like Ray and he always gave sound advise.

Originally Posted by Freedom

Gasoline engines are lower compression, so the throw is shorter and so they produce less torque. They have to rev to higher RPMs to produce the torque and that is usually accomplished in the gearing of the differential and transmission.

But it is my understanding, that you can still have a "torquey" engine or a higher horsepower engine, whenthe displacement is the same, even within the gasoline catergory? Generally speaking, if the stroke is more more than the bore, then you get a lower redline, lower horsepower engine, but it has more low end torque. If the bore is around the same or more than the stroke, you get lower torque, but a higher reving, higher horsepower engine. I am correct on these assumptions??

My 4 cylinder, low redline Jeep engine has all kinds of low end torque, but is sick going up the mountains around here. My wife's 4 cylinder, high redline car engine has all kinds of power going up the mountains, but it will stall in a heartbeat when you let the clutch out pulling from a stop. Of course, some of that might be due to the final drive ratios also, which I haven't compared.

Chap

Final drive ratios could have a lot to do with it, and also the ratios of the transmission gears. A lot of cars have real high differential gears to get the good gas mileage, but the low end torque to the wheels is lacking. The manufacturer is more concerned about advertising 35+ MPG than low end torque. This is partially due to government mandate. The same with transmissions. We had one car ('79 Subaru) that 4th and 5th were both overdriven gears - it didn't even have a "straight through" gear. Once again - you get speed at the expense of torque, and torque at the expense of speed.

Yes very true. The other problem being that a passenger car doesn't have a body or suspension designed for towing. On the other extreme is something like the 'mog which is indestructible. There are quite a few people here towing TMs with essentially unibody cars like the highlander which has a Camry drivetrain. Minivans too are unibody with sometimes good hp but not high torque output meaning the drivetrains don't need to be as strong. The Tribeca sounds like it is a pretty heavy vehicle meaning it has the mass not to get tossed around towing a TM. It is certainly within the realm of doing it. On flat ground at 60mph the TM is not very noticible back there.

[Mr. Adventure]

Guys, torque talk is cool, but the point of a Traillmanor is that you can tow it without being in the trucking business. If you' live in Colorado and are regularly towing above 5,000 feet you really have a different problem than most of us, who live below the 3000' level and just visit your higher elevations once every few years.

The RV "For Sale" ads are full of large parked hard-to-sell vehicles with lots of torque and prohibitive gas mileage. Lets use all this good towing experience among Trailmanor owners with smaller vehicles to distinguish Trailmanors from the rest of the industry.

[rickst29]

Originally Posted by Mr. Adventure

If you' live in Colorado and are regularly towing above 5,000 feet....

OK, the instant I pull it out of the garage I'm ALREADY at 6000 ft. And after dropping downhill to one of Reno's major highways for a short time, the trips nearly always go up from there.

But per above, I'm not making an "academic" argument. I've driven thousands of miles in a 2007 Tribeca, and the towing experience WOULD NOT be satisfactory where I live. On even mild hills of 5%, I'd almost certainly be running in second at over 6000 RPMs. On the 7% stretch of highway to my house, without a trailer and loaded only with my body, the Tribeca automatic chooses to run > 4000 RPMs . And if I force it to a lower gear manually, I can't hold speed-- it really does need to be spinning that fast, even unloaded. The 2008 is a totally new engine, and might work a lot better. But a V6 Highlander engine is definitely more capable of towing a TM, even though the vehicle body is slightly lighter and less strong. (We've got TM owners who are thrilled with Highlander towing of 2619/2720, even though I wouldn't do it.)

If you haven't actually driven the Tribeca, (and your post certainly seems to indicate that you haven't), you don't know it's idiosyncrasies. It's a very unusual car, and most of the weirdness is really loveable. But like a Ferrari F40, you have to make the RPMs "sing" like a swarm of killer bees before the engine's capabilities actually become useable. And yes, I have driven a Ferrari. But I don't like the idea of running at > 6000 RPMs for so many hours of the day. If you can't crawl into Yellowstone at more than 15MPH, I think that you need a better TV.

[Mr. Adventure]

Sorry, but my comments were more about this thread (towing experience with mid-sized SUV's) being diverted to truck talk. I don't know anything in particular about the Tribeca, and didn't intend to be commenting on one.

You lose a lot of horsepower at higher altitudes, and I'm sure 6000 feet & steep is very different than 2000 feet & steep. I guess my point is that living high in the mountains should be expected to require a different tow vehicle than the 98% of us who just visit there once in awhile.

Regards!

[Bill]

Mr. Adventure -

And probably without meaning to, you have hit upon the question that I have asked (and asked and asked and ASKED) of nearly everyone who asks "Can I tow a TM with my ...?"

That oft-repeated question has been "The issue is not so much WHAT will you tow, but WHERE will you tow?"

At some point I got tired of asking the question, so I quit. Somehow I was unable to convince anyone that it is one of the FIRST questions to be asked, not some afterthought that may (or may not) come up later.

Post #5 in this thread was not the first time I tried, but perhaps it was the wordiest. I tried to say what you just said, but I used far more words.
http://www.trailmanorowners.com/foru...ead.php?t=1477

Bill