What is "normal" for pulling a TT?

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I know my subject is kind of cryptic, and I apologize. Let me give some more background: I have a 2001 Chevy Silverado Ext Cab with the 5.3L V8. I used to tow a
12' pop-up, and we recently moved up to a 23' hybrid (Jayco 23B). To prepare, I added a tranny cooler, changed the rear diff and coolant, and switched to synthetic oil.
I guess I was spoiled when I towed the pop-up. Cruising on the highway at 75mph was no problem. Towing the TT is of course a whole different story. It's UVW is right about 4000 pounds, and we specifically went with that to make it lighter and easier to tow.
I've towed it about three times, and I was wondering how much of the time I should spend in 3rd gear? How often does the cooling fan run (HOT here in Texas)? What is the recommended towing speed? What mpg should I expect?
Sorry for the questions - I'm kind of anal retentive about my truck. Although I'm sure everything is perfectly normal, I just don't know what to expect.
Thanks for sharing your experiences.
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snipped-for-privacy@gmail.com wrote:

With your 4L60E transmission always tow in 3rd gear. OD in that transmission is weak. Also, the frontal area of the new trailer will cause you to use more fuel so to get the best MPG slow down. Glenn
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wrote:

This is good advise but it is not because the 4L60 has a weak OD by design as it does not, it is because it has a OD ratio of .7 which is pretty tall (vs .75 for 4L80) and it is usally coupled with a 3.42 or sometimes a 3.73 which makes a a really tall final ratio in OD that is placing a lot of strain on tranny even keeping speed ( it requiwith a ooad. If you are fourtune enough to have a 4.10 axle ratio with stock tires then you can safely use OD sometime during easier pulls but otherwise stay out of it towing. When you do the math, the engine has to make to make about 43% more torque (and tranny clutch have to hold it too) in OD to deliver same output torque before interanl lasses are figured in with a .70 OD. (at first thought you think it should be 30% but it is not because if you are in drive and you have a 100 ft lbs in and out (not counting internal losses0, when you shift into OD the engine has to input 143 ftlbs of torque to make the same 100 ft lbs on output shaft. (143 x .7 equal 100) so you can se how much you can load tranny especaily with taller gears. ----------------- The SnoMan www.thesnoman.com
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This is exactly the reason I have a Dodge Ram Heavy Duty 3500 Dually Long Bed with a 600 Cummins Turbo Diesel. I donut have to write a paragraph justifying my piece o crap toy truck to do a real trucks job. Under power/over weight/over speed with get your ass killed.
That is all.
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On Thu, 22 Jun 2006 22:23:10 GMT, "MoParMaN"

It is all in the gearing of the engine to the load. With a 4.56 behind a good gas motor you can move some killer load effectively. It simply needs a differnet final drive ratio to match a gas engine power curve to load which detriot does not provide in most models to make diesel look better. Back in the later 70's I drove a C70 triaxle Chevy dump truck for a while with a 427 and a 20 speed (5 x 4) and it had no problems moving 30 tons GVW around (were it was legal at weight wise) and another 5 ton with a specail permit or about a 25 ton payload when hauling blacktop for big paving contracts. You modern Cummins or Dmax P/U would bust its nuts moving trying that weight which I could move through any terrain that could support the truck including soft grond that REALLY sucks the power down at 30 tons. I alos drove a C60 with a 366 and a 10 speed (5x2) and hauld a float with a backhoe or a dozer on it from time to time and that little gas motor did a credible job and never had trouble starting a load out. Durring that same time frame I knew a farmer that used to haul his grain from his silo to mill or a cincinati port 80 miles away with a 75 Chevy dually std cab with a 454, 4.10 gears and a SM465 granny gear tranny. His GCVW was around 30k and it did a fine job with it and did it for many years too. Yes there are oil burner P/U can pull but so can a gasser if properly geared. A lot of the diesel advantage is exagerated by the fact that most gas trucks today are poorly geared for their tow ratings. If you had say a 8.1 checy dualie with say a 4.56 and a 6 speed ally with double OD it would pull ANYTHING that a stock Dmax or Cummins would an with less fuss most of the time too and be a lot more fun to drive too. I recently went with a friend who owns a 05 Dmax cc and we drove a o6 CC with a new Dmax and one with a 8.1 and the 8.1 would run circles around the Dmax and was gone while the Dmax was still trying to build boost. He was very impressed over the responce difference compared to his Dmax and is considering getting one while there is still time. ----------------- The SnoMan www.thesnoman.com
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wrote:

ok this is fair comparing a 1 ton p/u to a triaxle dump truck. heck if we're comparing stuff like that then lets compare a festiva to a peterbuilt.
I alos drove a C60 with a

let me know how he likes the fuel bill when he figures that part out.

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I've given up with this guy... he just refuses to get passed his mental block.
I wave to him every time I pass him at a gas station :)
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i agree, most of the time....
you know i aviod most of the arguements here.
but............
but...........
but...........
but...........
a triaxle dump truck compaired to a 1 ton....
i mean get real!!!!!
ok im done.
anyways how's it goin tom?
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-Chris
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I think his point was the engine, a 460 , did all that work, because of transmission, gearing, etc. thats all.
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On Thu, 22 Jun 2006 21:49:35 -0400, "Christopher Thompson"

I am comparing a engine that is PROPERLY geared to the load not the vehicle. I am tired of people saying you need a diesel to move anything when all you need is proper gearing to do it and if you have it you can easily move a lot a weight with a gas motor. Heck if GM offered a 4.56 with a 6.0 and new 6sp ally (which you can get in a Chevy on specail order starting in 06) it would surprize you what that engine would pull effectively. The ally has a 3.1 first gear vs 2.48 in 4L80 and a reverse more than twice as deep too which give the Dmax a even bigger percived edge over a 6.0 with a 4.10 and a 4L80. They both make about the same horse power it is just that one is properly geared to load from factory and one is not. A 8.1 with a 4.56 and a 6 speed would be a incredable tow beast. ANd if you through in a mild 6 or 7 PSI boost with a super (about 1 third of Dmax's boost) it would get a bit "scary" at times bebeing able to make about 700 ft lbs of torque from about 1500 RPM to past 4000 RPM rather than a bit more torque on a boosted deisel over a much narrower RPM range. (not to mention that 700 FT lbs out of a 8.1 is not going to hurt tranny much (it is rated at 650 ft lbs) but 800 to 900 ft lbs out of a booste Dmax will shorten trannies life. I can drag a truck out of a mud hole with old 30 HP JD tractor that a Dmax truck would not be able to do in same conditons. It is all in the proper gearing for load and engine, not the engines type. ----------------- The SnoMan www.thesnoman.com
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wrote:

Yea, but the Dmax will get much better mileage and have a lot better ride than the 30 hp JD! You will also get to your destination before the end of the summer with the Dmax. <g>
Ron
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wrote:

That's right . . . you can also move a freight train with a 10Hp lawnmower engine if you can get it geared down enough just don't get in a race with a snail while doing it.
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Nahmie
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Your comparison has no merit when the question is about a pickup pulling a load, not about a tri-axle.

You can be tired all you like, but the facts are not in your favor. While true that you can move anything with a Briggs and Stratton if the gearing is correct, certain things make doing work easier. One of those is a diesel engine. A diesel has MANY benefits in doing work when compared to a gasoline engine. One of those is moving a heavy load at highway speeds without need for huge amounts of gearing and prohibitively large transmissions.

No, it would not surprise me. However, it might surprise YOU how much MORE fuel you burn and how much SLOWER a speed you go to do the work when compared with a diesel engine.

Why are we discussing the DMax? Its a POS engine to begine with. In your resistance to modern innovation, you ought to know a V8 isn't as efficient at pulling as an inline six like the Cummins.

I am sure (AGAIN, after all these years) that the engineers geared BOTH trucks properly for highways speeds here in the U.S. I think it is a betrayal of sorts to note that the DMAX needs more gearing than the gasoline motor; it speaks directly to the well known shortcomings of a V8 diesel with something other than low end torque as its strong suit.

Both of those engines in the modified form you describe would trash the transmission behind them without significant mods to the transmission. Stop deluding yourself.

Right and Wrong....... as in, yes, it IS all in the gearing for load and engine type. BUT..... Since JD tractors aren't geared for 65MPH pulling, you'll need to determine what would make the truck be able to pull the load at 65MPH, not 15MPH on a country road.
You are stuck on gearing without looking at the parameters of the job to be done.
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Max

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wrote:

If you want a gas engine to pull equivalent to a deisel, you will need a big six, not an eight. It will almost certainly need to be "boosted", and it will need to have the valve timing and intake/exhaust geometry optimized for producing torque at lower RPMs., A 292 Chevy six handily outpulled most 327s and 348s in the sixties. A 409 would toast it. A 300 inch Ford Six outpulled any 302 V8 and most 351s.A 460 would toast it. A deisel's advantage is higher average cyl pressures than a gas engine (which has higher instantaneous cyl pressures) and better thermal efficiency (which translates to using less gas). A properly geared gas engine can do a good job of towing a TT if properly set up for the job. A deisel , also set up properly for the job, will do a better job in many ways, on less fuel.
When towing, generally you want lots of grunt at low RPMs, you don't want to be winding 'em up and shifting, shifting, shifting to put the horsepower to the road. (671 anybody??) A 200 HP deisel that makes max power at 2400 RPM would be producing over 430 foot lbs of torque, and generally would produce that from about 1000 RPM (80 HP) or even lower.
The (today's) gasoline 200HP engine would generally produce max power at 4800 RPM, where it would produce 215 ft lbs of torque. At 2800 RPM it may produce 250 ft lbs and 133 HP, while at 1000 RPM it would possibly put out 200 ft lbs and 38 HP.
Some of the older gas engines, like the International 392 V8, put out 196 HP at 3600 RPM (just under 290 ft lb), and a peak torque of 316 ft lbs at 2200(132 HP). At 1000 RPM and roughly 280 ft lbs, it would develop 53? HP.
So the big old international 8 would need to be geared twice as deep as the deisel to pull away, and the currrent 200 HP engine would need to be roughly 3 times as deep.
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Max Dodge wrote:

It seems to me that the question is about power, engine vs. load, not truck design for ride and handling. In that case, his comparison does apply.
Has anybody noticed how this thread is posted to: alt.autos.dodge.trucks,alt.rv,rec.outdoors.rv-travel,rec.sport.football.college I haven't seen the OP, but I think it's obviously a.......wait for it......TROLL!
I've trimmed the newsfroup list so this only goes to appropriate newsfroups.
So, here's a technical question: Since buyers of diesel pickups choose them for low-end torque, why do they have turbochargers instead of superchargers?
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Turbochargers are generally more efficient than a mechanically driven supercharger, and are capable of much higher boost pressures.
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Max

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Try to actually answer his question. Mechanical superchargers do work better at low RPM. Turbo chargers are not capable of "much higher boost pressures." That's a function of the size of the supercharger and how fast it's driven.
Al
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Without getting inot a long drawn out technical paper, I did answer his question. THere are of course, many variables in the field.

"Work better??" True, turbo's have a lag time, dependant on size of turbo and engine to which its mated. However, this lag is not dependant on "RPM" as much as the two aforementioned variables. It is also notable that the lag time on a properly designed setup is minimal. Thus, since the turbo is capable of higher boost numbers, the lag time is acceptable in a trade off for more boost.

In general, your statement is INcorrect. A turbo will spin at much higher RPM relative to engine RPM than a supercharger will. True, superchargers can be set to a boost level with pulley/gear ratios, but this ALSO limits what a supercharger will be capable of. It may either boost "too little" at upper RPM's, or "not enough" at low RPM's.
A turbo, on the other hand, can be sized to boost according to engine LOAD rather than RPM, using a wastegate to regulate boost pressures. This is because one key factor is the expansion of the exhaust gasses. This expansion becomes (as a percentage) larger when more fuel is injected, even if RPM does not increase proportionally. Thus the turbo adapts to load while the supercharger will not.
http://www.superchargersonline.com/content.asp?ID 
More details can be found here. Note that the above link is a SUPERcharger sales outlet, so the info could be biased towards the superchargers, yet they play it straight.
http://www.ststurbo.com/turbo_vs__supercharger
Nifty graph shows exactly why the turbo is more popular: more usable HP. This is because of the higher percentage of efficiency from a turbo.
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Max

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Absolutely... but what you continue to fail to recognize, is that while your 8.1L gasser with a 4.56 gear (tell ya what - since this is a Dodge group, let's keep it Dodge-centric... 8.0L V10 with a 4.56 and an NV5600) - while that engine/tranny/gear combination will keep up with a Cummins 5.9L, a 3.73 gear, and the same transmission... it's going to get less than half the fuel economy doing so. It's not just about doing the job - it's about the cost-effectiveness of doing the job.
AND.... since we're talking about pick-ups here - vehicles that very often pull double duty as both load haulers and daily drivers - it's completely impractical to talk about a gasser with a 4.56 rear. You're looking at 8MPG tops (given that my 8.0L with a 4.10 gets about 10MPG, and those with a 3.54 get about 12MPG), compared to 18MPG with a Cummins. Yanking 10,000lbs. around, you're lucky to get 5-6MPG from the gas combination, whereas my Cummins gets about 14MPG pulling that weight.
Now... which vehicle would you choose? The one that gets 8MPG empty, and 6MPG towing, or the one that gets 18MPG empty, and 14MPG towing? This is not a difficult question...
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It is for me. Somehow I can't seem to relate it to carrots.
Denny
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