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Old 08-04-2015, 06:12 PM   #1
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Some Tow Vehicle specs to compare

I know that this may ruffle feathers but I am sharing what I did when recently selecting a new truck. I shopped the brands- Ram, Silverado, Tundra and F150. I had an F150 prior but wanted to really get what passed my test. I will share that I was hot on the aluminum truck but still prices and options played into it too. Here is the TOWING data I found using an online calculator on the published specs from the dealers. I posted more on Bob's 2014 F150 report thread but here is some info for you to chomp on. I did not figure the Tundra as they did not have a "tow capable" model at my dealer to consider so I moved on. PS. This does not apply to diesels! Yous guys with the big trucks are different. Those with vintage or smaller trailers may find other options but for those needing a tow for heft, consider this info.

According to the dealers of the respective brands I shopped, I am using their recommended configuration for pulling a 25' Airstream weighing 7000# gross with a tongue weight of 1000# with cargo in the truck bed as well. I have used @70 mph as the reference point since it is the most common hwy speed. Towing at 65 mph will grant some benefit but also lower some of the RPM figures such as torque on tap, etc. The Ford is the 3.5 Eco with 3.55/Silverado 6.2L with 3.75/Dodge with 5.7 3.92- all max towing models/most powerful options and calculated with 20" wheel option on all LTZ/Laramie/Lariat. The percentages indicate how much power/torque (actual) is available at speed:

F150@70 1806RPM 36%HP (139HP)/72% (302ft lbs)
Silverado@70 1788RPM 32%HP (139HP)/44% (202ft lbs)
Dodge@70 1936RPM 35% (138HP)/48% (197ft lbs)

As far as MPG goes the challenge with the Ecoboost is to not have to gear down or accelerate too much to keep blower usage down. The Silverado and Dodge use cylinder deactivation; however, it is unclear how much that may benefit while towing a heavy load. Additionally, the Dodge and Silverado are using an 8-speed transmission to keep the RPMs down to gain MPG; however, that also limits the torque/power on tap before gearing to attain more power/torque. The Chevy violates this the least but you can see the results. It is obvious that once gearing down, any cylinder deactivation is lost to increase power. My point is that these setups are less designed for towing and achieving better mpg. The amount of torque "on tap" is indicative of "pull available" without shifting or greatly altering engine RPM.
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Old 08-04-2015, 06:41 PM   #2
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I think I don't understand what you mean by "The percentages indicate how much power/torque (actual) is available at speed." Are the Torque, RPM, and HP all taken at the 70 mph operating point? There seems to be substantial differences in the above ratios. When I run the above numbers through a calculator (HORSEPOWER TO TORQUE CALCULATOR) the F-150 numbers agree. The other two don't, they are off by a factor of 2.

Thanks,

Al
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Old 08-04-2015, 06:47 PM   #3
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Question What am I missing.....

....the point being?

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Old 08-04-2015, 06:54 PM   #4
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Quote:
Originally Posted by ROBERT CROSS View Post
....the point being?

Bob
Not being facetious, Bob, but the point is that at a given torque and rpm, the HP is determined. When I take the RPM and torque posted above, only the F-150 HP comes out to be the same as listed in the post. I'm obviously not understanding the point of the OP, and I would like to.

Al
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Old 08-04-2015, 06:58 PM   #5
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Quote:
Originally Posted by Al and Missy View Post
Not being facetious, Bob, but the point is that at a given torque and rpm, the HP is determined. When I take the RPM and torque posted above, only the F-150 HP comes out to be the same as listed in the post. I'm obviously not understanding the point of the OP, and I would like to.

Al
Al,

No face taken........

I'm also missing the point

Bob
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Old 08-04-2015, 07:04 PM   #6
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Quote:
Originally Posted by ROBERT CROSS View Post
Al,

No face taken........

I'm also missing the point

Bob
Oops - I assumed (you know what they say about assuming) your "what's the point" was directed at me.....D.Oh!

Al
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Old 08-04-2015, 07:21 PM   #7
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I am often leery of the numbers, specs, claims, etc. of all these complex gas engines but forever faithful in a diesel engine.
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Old 08-04-2015, 07:22 PM   #8
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Yeah I'm seriously missing the point too. And I understand the numbers. The torque #'s don't really even seem relevant to me, since at 70mph pressing down on the peddle to speed up is going to resort in a down shift. Unless the point is the Ford has 302ft/lbs. Which makes sense since boost helps torque. (look at the turbo diesels)

Also, you ran the numbers at the crank, run it thru drivetrain loss.

And those numbers would be at speed under perfect conditions on a flat level surface. 70mph up a hill will put you somewhere else on the power band all together.

So .... what did you decide?
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Old 08-04-2015, 07:55 PM   #9
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I'm considering moving up to a 3/4T truck primarily for payload and nothing in the 1/2T market is close to 2000 lbs unless you buy the F150 Supercab XLT or can find the rare Chevy 1500 with 6.2L and Max Tow. The 2015 F150 promises of more payload haven't materialized since Ford downgraded the GVWR of 2015 models. Most models on the lots seem to be SuperCrews with short beds 7000 GVWR and never see any with towing mirrors. I can't tow without them now that I've got used to my Tundra's tow mirrors. They are expensive to purchase after market. Then when you think you've found something and look at the sticker it only has the 23 gallon tank.

The Chevy 6.2L is very hard to find and if found have top tier trims with high prices.

There are plenty of Ram 1500s around but their payload is weak about the same as my Tundra.

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Old 08-04-2015, 07:56 PM   #10
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I believe there is quite a bit of point being lost. I guess it was just clear to me. First the calculation tool:

Engine RPM Calculator

@Al and Missy, Utilize the third table to find RPM with final drive ratio, transmission final gear and tire/wheel diameter, in this case 31.9" for 20" which is what all models had I looked at and you will confirm the figures. The final trans gear of the Silverado is 0.65 and the Dodge is 0.67, the Ford 0.69.

@KJRItchie, We could not find the truck on the lot that I ended up purchasing (at first) there were 135 of them! It was inventoried as a Platinum model instead of a Lariat and other issues. I looked at several payloads BTW and there were several XLT models with 3.5 Ecoboosts over 2000# payload. One had 2300#.

@Boldadventure, all of them are going to have loss so in a sense it is equal. It is also based on highway cruising not accelerating. I got the F150. Cannot wait to tow with it though I now have a truck mortgage!

@TEdS I looked at the Dodge Ecodiesel but the 1400# payload would not work for me. The dealer mgr insisted that I would need the 5.7 with 3.92 to pull my weight without strain. Yeah, all engines are high tech and a gamble really. The high pressure injection systems alone are VERY expensive to replace. The cylinder deactivation thing has a history of problems and so does iterations of the turbo. Though I will say to you that I do not believe that today's diesels are the simple workhorses of the past. The tech on them now makes them less, well, reliable just by the added equipment LIKE the Bosch super high pressure fuel system, example. They are in the neigborhood of $10K if a problem. Ye old Mercedes just had a piston drip system pump and by today's standards (low tech) cheap to replace.

The percentages show that, at highway constant speed, the amount of torque available with the configured final drives, transmissions and wheels - at the road (wheels included) without any acceleration or gear down- on hand.

We know that torque is king with towing, not horsepower. AND the amount of torque "on tap" without any shifting (the percentage (actual)) will greatly reduce any gear reach of the engine needing to shift to get more power to pull up the hill. The percentages tell how much of the total torque is at hand at highway cruise. This SHOULD increase efficiency and reduce engine strain.
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Old 08-04-2015, 08:52 PM   #11
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I'll just say this, I traded my '03 Dmax for my 2012 F 150 SCREW 5.5 bed ecoboost 3.75 Max Tow, Platinum (yep a full bore sissy/poser truck- and I love it! esp. the air conditioned seats), last fall (2 years old, 23k miles, full warranty etc. etc. $20k less than a new one: do-the-math). I don't miss the Dmax, the F150 rolls out just fine. As a matter of fact it would smoke it in a non-towing drag race, heck it would smoke a lot of cars for that matter. Plus much better fit and finish, quieter, cheaper to maintain and my full mileage towing is within 1 or 2 MPG overall whether on trips with hills and mountains (around 10) or on the flats (around 12) . My non- towing mpg is better (it was around 17-18 with the dmax it's about 18-20 with the ecoboost - if I keep my foot out of it LOL) . BTW the 20" wheels are just fine. I air the Michelins up to 42lbs. and it's steady rolling. Much more enjoyable to drive when not towing (which for most of us is most of the time). That said, the newer diesels get a bit better gas mileage and certainly have more torque. Much needed for pulling that huge 5th wheel, or for high payloads, but not my 99' 27' Safari and what we carry. Of course with the newer diesels you also get the joy of dealing with DEF, which is one of the major reasons I didn't buy another diesel (maybe in 5-10 years, but I actually think gassers are going to be more common going down timeline). Not trying to start a flame thread, I dig the Chevy's and Dodges too, but with the whole package, the F150 did it for me. Just a real world experience, your mileage may vary....Whatever you get - enjoy!
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Old 08-04-2015, 09:35 PM   #12
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rodsterinfl:
I don't disagree with the output of your RPM calculator. The RPM numbers are reasonable given the difference in the final drive ratios. But you said:
F150@70 1806RPM 36%HP (139HP)/72% (302ft lbs)
Silverado@70 1788RPM 32%HP (139HP)/44% (202ft lbs)
Dodge@70 1936RPM 35% (138HP)/48% (197ft lbs)

When I put those RPM and Torque numbers into the Horsepower calculator I get:
F150 - 103.85 HP. Differs by 25%
Silverado - 68.77 HP Differs by 50%
Dodge - 72.62 HP Differs by 47%

I don't understand the difference. Are the torque numbers you listed the torque produced by the engine at the stated RPM, or the torque at the torque peak, regardless of RPM? I'm thinking the latter.

I guess that is the question I was really asking.

Al
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Old 08-05-2015, 05:53 AM   #13
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The figures are not the the total hp or torque of any of the engines but rather the actual HP and Torque that they have at the RPM the drive train allows at highway cruising speed, 70mph, without gearing down.Ex. The ecoboost actual torque is 420 ft lbs @ 2500 PM. How much of that is available at a typical highway cruising speed? Seventy-two percent or 302 ft lbs. It is a tell-tale of just how it tows. My old truck had very little torque while cruising and that showed up in West Virginia on the hills. The transmission shifted constantly and even then could not hold speed without shifting two gears down and sometimes not even then. That takes away from MPG, engine life and other things.

The concept is similar to those hybrid engine studies where they calculate the electric to combustion engine and calculate the mpg/assist at various speeds. That is where I got the idea because the same can be done with engine output, in this case torque. The more torque the engine has at a speed, the less likely it will struggle down to need a shift to gain more torque. We know that there is a relationship to RPM and MPG. With towing, which is set to ideally provide pulling torque while cruising? This will probably be a mute point when Ford switches to that new transmission which will lower the RPM like Chevy and Dodge have done BUT limit torque without a shift. We'll see.

No worries on my end. No one has to agree I just post my "geek" thoughts. I really get into it when I make decisions on things. Especially big ticket items. I've been the same on the Airstream and the add on stuff. Sometimes the decision is tempered with cost- the best on-class of something (like a Magnum inverter) may spec out best but it is out of reach for me $$$ so I go with second best. Other times I cough up the extra and live with it. This is just info for people looking at current truck models/brands. Brand loyalists don't really care about this and I understand. They will get what they want based on like or Z plan or experiences. Just an FYI
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Old 08-05-2015, 06:44 AM   #14
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Interesting info. Wish I could do calculations like that. When you can figure any of these trucks will do the job it's neat to know the differences between them. Thanks
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