Max Trailering & Z71 Off-Road Packages (Silverado 1500)- Helpful for towing?

[dizzygti]

2 hours ago, RyanB said:

I’ve read this multiple times and am unsure what you’re saying. 

I think we're saying the same but slightly different things.   You're focusing on the power being there, I'm agreeing but saying it's going to take fuel to make it.   I was more talking about the 2.7 and higher rpms, not the 3.5.   A smaller engine is going to need boost or rpms to make the same power as the bigger engines, that's all.   The gas motors all have cam phasing and coil on plug hence variable ignition timing, they all make great torque, but do you want to putt along in the 5.0/3.5/5.3/6.2 or wind out a 2.7?   

My "tow" is either 3 miles (to a ramp that is dry now) or 8 miles (ramp is still useable with the lake down this time of year).   It's hilly, I don't go over 50mph, and I average 7.7mpg on while towing.   I have a relatively bigger boat, and the 3.5 EB often is over 4K on the hills.    The gas mileage in daily driving is awesome, right at 20mpg.   It goes to crap while towing.   That was my point I guess.   Seeing 1/3 of the rated mileage while towing seems like a huge drop off (and I am ok with it, I understand why), but do the NA engine's mpg drop off  2/3rds when towing?   Naturally, I'm speaking from zero experience with any of these motors other than 3.5, but I digress....

 

And we've taken this way off topic....apologies!  

Edited December 6, 2023 by dizzygti

[justgary]

59 minutes ago, dizzygti said:

My "tow" is either 3 miles (to a ramp that is dry now) or 8 miles (ramp is still useable with the lake down this time of year).   It's hilly, I don't go over 50mph, and I average 7.7mpg on while towing.   I have a relatively bigger boat, and the 3.5 EB often is over 4K on the hills.    The gas mileage in daily driving is awesome, right at 20mpg.   It goes to crap while towing.   That was my point I guess.   Seeing 1/3 of the rated mileage while towing seems like a huge drop off (and I am ok with it, I understand why), but do the NA engine's mpg drop off  2/3rds when towing?   Naturally, I'm speaking from zero experience with any of these motors other than 3.5, but I digress....

The hills are killing your mileage.  You pay a heavy penalty dragging more weight up a hill, and you don't get it all back going downhill (primarily due to wind drag and speed limits).  My 2005 F150 with the 5.4L V8 got about 7-9 MPG on the highway towing my toy hauler.  The 3.5EB gets 9-11 MPG or so with the same trailer.  I think the 10 speed transmission is responsible for some of that gain since it can easily get the engine into the best torque range.

If you look at the physics involved, towing means more mass to accelerate and more rolling and aerodynamic friction.  The recent gains in truck mileage are mostly about controlling the first two (aluminum body trucks and low oil viscosities, for example).  I pay about 1 MPG penalty for having 4WD (with it in 2WD) and another 1 MPG for towing mirrors due to drag at highway speeds.

[jjackkrash]

Towing my big 19-20k fiver I got around 11 MPG (almost 12) once on a long stretch of I5 drafting semis and not exceed 60 (mostly 55).  If I drive 70 and don't draft I am closer to 6 mpg than 7.  And I can kill even that on big hills.   Wind resistance and hills do absolutely kill milage when towing.  

[dizzygti]

37 minutes ago, justgary said:

The hills are killing your mileage. 

Yeah, well I can't exactly avoid them.    FYI I'm an automotive engineer, I'm well aware how it all "works."   

[RyanB]

I also don’t think it is wise to make any decisions on what someone will anecdotally state they get for MPGs. There are simply way too many variables there. 
 

If you want to figure out operating costs, take a look at fuelly. 

Figure 25 MPG overall in the 3.0 Duramax (impressive) and 17 in the EcoBoost. 
 

15,000 miles/year divide by 25 MPG is 600 x $4.17 (AAA national average for diesel) is $2502. 
 

15,000 miles/year divide by 17 MPG is 882 x $3.21 is $2832. 
 

So just in fuel there is a $330 savings which is basically a wash. The other operating costs for a diesel (like oil changes and fuel filters) will eat that away. 
 

so it boils down to which would you rather drive?

 

I think there is good reason that literally EVERY other manufacturer has gone away from diesel in their light duty vehicles. There simply isn’t a future for diesels in the light duty market. 

[justgary]

On 12/6/2023 at 10:00 AM, dizzygti said:

Seeing 1/3 of the rated mileage while towing seems like a huge drop off (and I am ok with it, I understand why), but do the NA engine's mpg drop off  2/3rds when towing?   Naturally, I'm speaking from zero experience with any of these motors other than 3.5, but I digress....

 

On 12/6/2023 at 11:56 AM, dizzygti said:

FYI I'm an automotive engineer, I'm well aware how it all "works." 

That wasn't clear at all from your question above.

But I'm only here to make sure the Chebby thread got fully converted to an F150 thread!

[dizzygti]

On 12/7/2023 at 7:31 PM, justgary said:

 

That wasn't clear at all from your question above.

I'm on my second truck (second is 3 weeks old and identical to first, 3.5EB F150) and first boat, so I'm not familiar with NA V8 gas mileage while towing other than obviously it'll go down.   I didn't realize you had to know the specific drop off mileage percentage during towing to be recognized as an automotive engineer...   I currently work for an ag/farm equipment maker, and guess what?  I didn't know squat about tractors when I took the job, but I'm posting this from our global R&D center in Japan. 

Ironically, no one answered the question.   

Edited December 13, 2023 by dizzygti

[Bozboat]

8 hours ago, dizzygti said:

I'm on my second truck (second is 3 weeks old and identical to first, 3.5EB F150) and first boat, so I'm not familiar with NA V8 gas mileage while towing other than obviously it'll go down.   I didn't realize you had to know the specific drop off mileage percentage during towing to be recognized as an automotive engineer...   I currently work for an ag/farm equipment maker, and guess what?  I didn't know squat about tractors when I took the job, but I'm posting this from our global R&D center in Japan. 

Ironically, no one answered the question.   

Q: …but do the NA gas engine’s MPGs drop off 2/3 when towing?

A: No. 

[justgary]

10 hours ago, dizzygti said:

Ironically, no one answered the question.   

Sorry, I thought I did answer it.  I tried to explain that the physics involved means that any engine has to create the power needed to do the job, and that power comes from fuel.

The fact that modern trucks get 20+MPG at highway speed is a result of a crazy amount of fine-tuning a lot of tiny things over the last forty years.  Aerodynamics is a big one, but rolling friction of tires on the road has also improved.  So has bearing drag of internal moving parts and internal air flow through the engine.  Just "leveling" a truck may cost a noticeable amount of mileage due to altered air flow.  4WD and towing mirrors both cost about 1 MPG each on the highway due to higher drag.

Towing ruins most of that fine tuning and takes us back to basic power needed to do the job.  An engine has to create a specific amount of power to pull more weight up a hill.  That power comes from the fuel, so the mileage will hit a limit for any specific job.  Adding gear sets to transmissions has helped a lot because more gears allows the engine to operate in its maximum torque band for a wider range of loads.  Towing means that an engine is no longer just at high idle cruising down the road.

As an example, it might take 30 HP to drive a truck down the highway unloaded, but 100 HP to tow a specific load at the same speed.  Headwinds and hills add to the power requirements.  Both a V8 NA engine and a V6 FI engine can easily create the power needed, and will generally need about the same amount of fuel to do it.  The FI V6 is more efficient because it creates more power per rotation, which means that the overall internal drag of moving engine parts is lower (e.g. 6 pistons moving instead of 8).  Producing power at lower RPM reduces engine drag, which is proportional to the square of velocity.  The FI V6 also has a wider torque peak, so it can deliver power more efficiently over a wider RPM range.  But overall, they both still need to make that 100 HP, which still takes a basic amount of fuel.

The bottom line is that towing efficiency is directly related to the power required to do the job.  We can't expect significant gains in efficiency when pulling random large masses that tend to have terrible aerodynamics.  Towing may also make the comparison between engines more equal because the extra power required gets the V8 operating in its best torque range.  With large loads, all similar-sized tow rigs get about the same mileage because they all have to produce about the same power to do the job.

The one place that forced induction will absolutely shine over a normally aspirated engine is at high altitude.  The NA engine will fall on its face much sooner due to lower atmospheric pressure, which means less oxygen available to burn fuel.  In that case it can no longer create the power needed, where the FI engine can.

[dizzygti]

6 hours ago, Bozboat said:

Q: …but do the NA gas engine’s MPGs drop off 2/3 when towing?

A: No. 

Thanks

[Bozboat]

10 hours ago, justgary said:

Sorry, I thought I did answer it.  I tried to explain that the physics involved means that any engine has to create the power needed to do the job, and that power comes from fuel.

The fact that modern trucks get 20+MPG at highway speed is a result of a crazy amount of fine-tuning a lot of tiny things over the last forty years.  Aerodynamics is a big one, but rolling friction of tires on the road has also improved.  So has bearing drag of internal moving parts and internal air flow through the engine.  Just "leveling" a truck may cost a noticeable amount of mileage due to altered air flow.  4WD and towing mirrors both cost about 1 MPG each on the highway due to higher drag.

Towing ruins most of that fine tuning and takes us back to basic power needed to do the job.  An engine has to create a specific amount of power to pull more weight up a hill.  That power comes from the fuel, so the mileage will hit a limit for any specific job.  Adding gear sets to transmissions has helped a lot because more gears allows the engine to operate in its maximum torque band for a wider range of loads.  Towing means that an engine is no longer just at high idle cruising down the road.

As an example, it might take 30 HP to drive a truck down the highway unloaded, but 100 HP to tow a specific load at the same speed.  Headwinds and hills add to the power requirements.  Both a V8 NA engine and a V6 FI engine can easily create the power needed, and will generally need about the same amount of fuel to do it.  The FI V6 is more efficient because it creates more power per rotation, which means that the overall internal drag of moving engine parts is lower (e.g. 6 pistons moving instead of 8).  Producing power at lower RPM reduces engine drag, which is proportional to the square of velocity.  The FI V6 also has a wider torque peak, so it can deliver power more efficiently over a wider RPM range.  But overall, they both still need to make that 100 HP, which still takes a basic amount of fuel.

The bottom line is that towing efficiency is directly related to the power required to do the job.  We can't expect significant gains in efficiency when pulling random large masses that tend to have terrible aerodynamics.  Towing may also make the comparison between engines more equal because the extra power required gets the V8 operating in its best torque range.  With large loads, all similar-sized tow rigs get about the same mileage because they all have to produce about the same power to do the job.

The one place that forced induction will absolutely shine over a normally aspirated engine is at high altitude.  The NA engine will fall on its face much sooner due to lower atmospheric pressure, which means less oxygen available to burn fuel.  In that case it can no longer create the power needed, where the FI engine can.

All that’s hard on my simple brain.  I do know that leaning on turbo power is like adding several cylinders.  It is amazing that a 3.5 V6 twin turbo can have so much power. My 2012 F150 ecoboost was faster and stronger at low rpms than my 2017 F150 5.0 but did average 9 mpg towing same boat at the same speed over same roads as the 12-13 mpg I got with the 5.0. I think they had different rear end ratios, and the 5.0 had the longer bed and wheelbase,  so that may have played into the equation. It would take the 5.0 much longer to recover 15 mph at freeway speeds than the ecoboost. Best I could do, the ecoboost got 1-2 mpg better overall not towing. Most likely because I have a heavy foot.

Edited December 14, 2023 by Bozboat

[justgary]

40 minutes ago, Bozboat said:

All that’s hard on my simple brain.  I do know that leaning on turbo power is like adding several cylinders.  It is amazing that a 3.5 V6 twin turbo can have so much power. My 2012 F150 ecoboost was faster and stronger at low rpms than my 2017 F150 5.0 but did average 9 mpg towing same boat at the same speed over same roads as the 12-13 mpg I got with the 5.0. I think they had different rear end ratios, and the 5.0 had the longer bed and wheelbase,  so that may have played into the equation. It would take the 5.0 much longer to recover 15 mph at freeway speeds than the ecoboost. Best I could do, the ecoboost got 1-2 mpg better overall not towing. Most likely because I have a heavy foot.

You bring up a very good point with axle gear ratio.  It behaves very similarly to prop pitch, so it probably does affect towing efficiency.

My 5.4L F150 towed the toy hauler about 1 MPG worse than the 3.5EB does.  I'm certainly sold on the 3.5L.

[RyanB]

15 hours ago, Bozboat said:

Q: …but do the NA gas engine’s MPGs drop off 2/3 when towing?

A: No. 

My experience isn't that dramatic of a change in MPG.  Towing my Malibu overall I feel like my Expedition gets about the same MPG as the Yukon Denali it replaced.  At least under the more flat highway towing.  Through the mountains I know it gets worse.  There have been times when it is in the 7 MPG range. That said, the Expedition can easily maintain or exceed the speed limit where the 6.2 Yukon simply could not (remember, elevation).

It does get a little worse MPG than the Yukon (or my Hemi GC) towing my 3500 pound Ranger.

I wish the app I tracked MPGs with on the Yukon was still available to back up my memory.

[JeffK]

Or just get one of these and call it a day - https://duramaxsuv.com/

 

https://www.facebook.com/duramaxspecialties/

Edited December 14, 2023 by JeffK

[granddaddy55]

15 hours ago, Bozboat said:

All that’s hard on my simple brain.  I do know that leaning on turbo power is like adding several cylinders.  It is amazing that a 3.5 V6 twin turbo can have so much power. My 2012 F150 ecoboost was faster and stronger at low rpms than my 2017 F150 5.0 but did average 9 mpg towing same boat at the same speed over same roads as the 12-13 mpg I got with the 5.0. I think they had different rear end ratios, and the 5.0 had the longer bed and wheelbase,  so that may have played into the equation. It would take the 5.0 much longer to recover 15 mph at freeway speeds than the ecoboost. Best I could do, the ecoboost got 1-2 mpg better overall not towing. Most likely because I have a heavy foot.

yep rear end gear ratio’s, the faster i go with my 3.73 the worse and worse it gets but that ability to nail it at highway speeds and pass is amazing on my 2.7 with that 3.73.   i literally zip around people so fast !  luv my 2.7 though as a commute vehicle the 3.73 is terrible.  to get rated hwy mileage (26)  i have to go 60 or less snd use cruise .  my in city mileage for true stop snd go is also pretty bad.  to get the rated city mileage (19)  i need to be on elevated hwys with extremely light traffic and drive 60 or less 

75+ with trailer is 6.7 mpg, i do have a massive 23 ft boat and that tower and windshield cant hide behind my 4x2 truck height.  it often cant get in 6th gear cause of wind drag

[granddaddy55]

4 hours ago, JeffK said:

Or just get one of these and call it a day - https://duramaxsuv.com/

 

https://www.facebook.com/duramaxspecialties/

only with airbags!!!!!!  nissan/infinity suv’s come with them (amazing how those engineers figured that out ) but not the american brands or is there a tow package that comes with them these days? i need bags for my 4x2 pickup , much worse sag on an suv!!

[JeffK]

1 minute ago, granddaddy55 said:

only with airbags!!!!!!  nissan/infinity suv’s come with them (amazing how those engineers figured that out ) but not the american brands or is there a tow package that comes with them these days? i need bags for my 4x2 pickup , much worse sag on an suv!!

These are retro-fitted suburban 2500's with the duramax drivetrain in them. This guy knows what he is doing with them. 

Here's an example build-out.

2009 Suburban 2500 4x4 w/Denali Truck Nose!!

109k miles on LMM Duramax Diesel & Allison 6sp!

-20” OE Replica polished wheels wrapped in 275/60 Nitto Recon Grappler A/T Tires

-Kryptonite UCA’s

-NEW (not reman) 3500 Suburban Steering box

-Air Dog Lift pump

-Pioneer In-dash DVD player & HiDef backup camera

-Boost POWER FOLDING tow mirrors (just released!)

-NEW Katzkin Tuscany series leather

-Full WeatherTech floormat pkg

-Denali 11-14 Truck front end-all OEM parts, both sides of unit repainted to ensure paint accuracy

Everything 100% functional and operating as designed!

As with all of our builds:

New GM Batteries

New GM Motor Mounts

New GM Glow Plugs

New Gm Fan Clutch

New GM Water Pump

New GM Pulleys & Tensioner

New Front & Rear Main seal

Up pipe Welded

3” Performance Downpipe

New AC Condensor & Dryer

New AC Suction Line

New hydraulic hose Transmission Cooler Lines

New Air Dog lift pump

New Power Steering Lines

New Brake pads, Rotors, Calipers & Steel Braided Flex line in place of rubber lines

New Moog HD inner & outer tie rods

New Kryptonite UCA’s

New Mevotech ATX lower ball joints

New Moog HD Idler & Pitman arm

New Bilstein 5100 Series Shocks and 5100 Steering Stabilizer

New GM Battery Tray

New GM Coolant Fittings at Firewall

New Allison Internal Wiring Harness & Output shaft seal

Entire frame & underbody acid bath’d & coated in POR 15 rust inhibitive paint

2” fill hose to both front & rear fuel tanks just like GM does with the pickup! (We are the ONLY company in the country that has done this- NO foaming/30min fill-ups!! 39 gal total fuel capacity/ 36 useable gallons)

[JeffK]

[granddaddy55]

2 minutes ago, JeffK said:

These are retro-fitted suburban 2500's with the duramax drivetrain in them. This guy knows what he is doing with them. 

Here's an example build-out.

2009 Suburban 2500 4x4 w/Denali Truck Nose!!

109k miles on LMM Duramax Diesel & Allison 6sp!

-20” OE Replica polished wheels wrapped in 275/60 Nitto Recon Grappler A/T Tires

-Kryptonite UCA’s

-NEW (not reman) 3500 Suburban Steering box

-Air Dog Lift pump

-Pioneer In-dash DVD player & HiDef backup camera

-Boost POWER FOLDING tow mirrors (just released!)

-NEW Katzkin Tuscany series leather

-Full WeatherTech floormat pkg

-Denali 11-14 Truck front end-all OEM parts, both sides of unit repainted to ensure paint accuracy

Everything 100% functional and operating as designed!

As with all of our builds:

New GM Batteries

New GM Motor Mounts

New GM Glow Plugs

New Gm Fan Clutch

New GM Water Pump

New GM Pulleys & Tensioner

New Front & Rear Main seal

Up pipe Welded

3” Performance Downpipe

New AC Condensor & Dryer

New AC Suction Line

New hydraulic hose Transmission Cooler Lines

New Air Dog lift pump

New Power Steering Lines

New Brake pads, Rotors, Calipers & Steel Braided Flex line in place of rubber lines

New Moog HD inner & outer tie rods

New Kryptonite UCA’s

New Mevotech ATX lower ball joints

New Moog HD Idler & Pitman arm

New Bilstein 5100 Series Shocks and 5100 Steering Stabilizer

New GM Battery Tray

New GM Coolant Fittings at Firewall

New Allison Internal Wiring Harness & Output shaft seal

Entire frame & underbody acid bath’d & coated in POR 15 rust inhibitive paint

2” fill hose to both front & rear fuel tanks just like GM does with the pickup! (We are the ONLY company in the country that has done this- NO foaming/30min fill-ups!! 39 gal total fuel capacity/ 36 useable gallons)

no thanks would rather have a daily driver gasser thats a modern vehicle. towed my boat with friends nissan armada suv snd it was a great tow vehicle 

[JeffK]

9 minutes ago, granddaddy55 said:

no thanks would rather have a daily driver gasser thats a modern vehicle. towed my boat with friends nissan armada suv snd it was a great tow vehicle 

He does them on the modern ones too.

Edited December 14, 2023 by JeffK

[Cole2001]

4 hours ago, granddaddy55 said:

only with airbags!!!!!!  nissan/infinity suv’s come with them (amazing how those engineers figured that out ) but not the american brands or is there a tow package that comes with them these days? i need bags for my 4x2 pickup , much worse sag on an suv!!

I have air in my ram 2500, only HD truck without leafs and keeps the truck perfectly level. Ram has had optional air suspension for a while now in 1500 and HD trucks. Gm has it as an option in the suburban's and tahoes. As well Land Rover and benz suv's

[Jordan22]

Just thought I'd share an update on my decision...

Thanks to this thread, I ended up going with the 3.0L Duramax Diesel w/ Max Trailering Package so I don't have any regrets at least from a towing capability perspective. This gives me Max torque (495 lb-ft) and max towing capacity (13,000 lbs) among Silverado 1500 builds. 

Now, I just have to wait for March until it arrives to the lot.

[redrooster]

On 12/14/2023 at 5:27 AM, JeffK said:

Or just get one of these and call it a day - https://duramaxsuv.com/

 

https://www.facebook.com/duramaxspecialties/

Those are amazing...except the dirty max engine. 

[JeffK]

37 minutes ago, redrooster said:

Those are amazing...except the dirty max engine. 

Beggars can't be choosers, unfortunately. This is really the only place I have seen something like this reputably done. I haven't seen anything like this for the ford platform, which I'm assuming is because they don't produce a 2500 excursion like Chevy does for the suburban. There's a lot of plug and play that I'm sure can be used this way. And let's be honest, any one of the big three diesels would get the job done. I have lots of brand loyalty to Chevy due to my childhood, but have been really impressed with what both Ford and Dodge have done over the years.

They used to do lots of conversions for the government too. 

[PrestigeLakeWide]

1 hour ago, JeffK said:

Beggars can't be choosers, unfortunately. This is really the only place I have seen something like this reputably done. I haven't seen anything like this for the ford platform, which I'm assuming is because they don't produce a 2500 excursion like Chevy does for the suburban. There's a lot of plug and play that I'm sure can be used this way. And let's be honest, any one of the big three diesels would get the job done. I have lots of brand loyalty to Chevy due to my childhood, but have been really impressed with what both Ford and Dodge have done over the years.

They used to do lots of conversions for the government too. 

Oh there are a few out there who do it, http://www.customautosbytim.com/

Way more expensive though due to needing old Excursion donor and 17+ 3/4 ton donor.

Relative has a modern 6 door.