Upgrading Tow Vehicle And Tow Capability

[marpel]

Hello,

 

New to the forum and am looking for your experience and opinion.

 

Currently, I have a Sierra extended cab with 4.8 litre. I have towed three trailers over the years and currently tow a trailer with a total loaded weight of around 4500 lbs (trailer, contents and passengers). Although the weight is within the tow specs and, for the most part, tows OK (I live in hilly British Columbia but do a lot of towing through the Rockies as well as the US southwest and Denver Co.), I drive quite conservatively and restrict myself to the slow lane and under 60 mph on the flat (as everyone on the planet passes me).

 

I am about to purchase a new truck and am deciding between the 6.0L or 5.3L. I know both are well within the specs to tow the above set-up.

 

I realize that, regardless of engine size (within reason), towing a trailer up an incline will cause the engine to rev higher than a no load condition so am OK with higher revs under this situation (to a point, of course). However, with my current set-up, I cannot drive at over 60 on the flat unless the terrain is completely flat and/or going downhill and/or with a tail wind and/or drafting off a semi truck (as an aside, I was towing once in Wyoming on a flat straight road with a head wind and it felt like i was driving in molasses). Due to excessive shifting I don't use OD or Tow Haul but keep it in 3rd. The revs sit around 26-2700 RPMs however, which drives me nuts (my mechanic b-in-law says that rpm is no problem but I am anal and think it is too high for long term driving!!!). Sorry for the long intro, but my questions are these:

 

For those long flat drives through the southwest with speed limits at 70 or 75, is the 5.3L capable of towing the above in OD or at least in a gear where the revs are closer to 2000 or under?

 

If the answer is "No", is the gas consumption of the 5.3L at 70-75 mph, with a raised rpm, comparable to/less than/more than the 6.0L at the same speeds with, I presume, much less increase in rpm?

 

We go down to Denver often to visit the son and daughter-in-law, so am quite interested in your opinions on comparing the tow abilities and rpm, gas mileage on those long relatively flat drives. At around 60, the drives seem to take forever, so would like to maximize my speed in those areas that I can. I know the easy answer is to get the 6.0L but when not towing the gas consumption concerns me.

 

Again, sorry for the long post and thanks in advance.

 

Marv

[Stevens03]

Gas consumption isn't a whole lot worse with the 6.0 than the 5.3L. I've had the pleasure of owning both. The 6.0 is capable of getting 19 mpg and thats with 4.10 gears. Sounds like you drive conservatively and thats a good thing for the 6.0. If you keep the speeds under 65, you'll see 18-19 mpg unloaded Let me clairify too... thats a 1500 with the Vmax package 4L70e trans 4-speed with 4.10 gears. If you get a 2500, then the most you'll see is 16-17mpg highway due to the extra weight.

 

Are you looking at a 2011 or just a newer truck? The new 6-speed helps the 5.3L ALOT over the 4-speed for towing. You shouldn't have any trouble with the 5.3L towing that weight and maintaining the speeds. The new 6-speed has the gears close, so the motor won't need to rev as much unlike the 4-speed with a wider gear ratio. And if your looking at a new one, then make sure your looking for 3.42 gears at a min. The 3.08 gears won't tow as nice as the 3.42's will with the 6-speed.

 

If your looking at a used truck, and it comes with 4-speed, then again... the 5.3 is still very capable, but you need a taller gear like 3.73's or 4.10's to get the most out of it.

[fajitas21]

Steven is dead on, and your mechanic BIL is too.

 

2600 - 2700 RPM will not hurt a thing even longer term. I wouldn't sweat it if you maintain the vehicle.

 

I have a 5.3L - 6 speed and 3.42 gears (the setup mentioned above), and pull a 4100# Travel Trailer with awful wind aerodynamics around and it does a wonderful job.

 

Most trailer tires are rated not higher than 65 MPH, so that's as fast as I go, but I am running about 2000 RPM @ 65 MPH with my setup in 5th gear.

 

Unloaded, I average about 20 on the highway and about 15 - 16 town.

[wavery]

Both of the above replies are spot on..........

 

Running most trailer tires in excess of their maximum 65MPH rating is asking for a blow-out. I have Maxxis tires on my trailer and they say that you can do 70MPH if you over-inflate the tires by 10psi.

[music]

With regard to mpg when towing, you will get about the same whether using the 5.3 or the 6.0. If the 5.3 won't hold 4th, a 6.0 probably won't either (gearing difference from 4th to 3rd is much more than the power difference between the two). Towing in 3rd on the 5.3 is the best for your setup. You *may* lose 0.5 to 1 mpg vs using 4th, but you'll get better cooling and the transmission is stronger in 3rd. I don't fully agree with the 6-spd comparison for most towing conditions, simply because you are usually pulling in one gear for most highway conditions. Pulling 3rd on the 4spd has ~5% lower rpm than pulling 4th on the 6spd, and neither would pull my setup very well in the next gear (4spd/4th, or 6spd/5th). For the weight you have, you may well be able to pull in 5th on the 6spd w/ a 5.3/342 setup on flatter ground / low wind. As for mpg, you won't see much (if any) difference pulling 5th vs 4th either, and the noise won't be much different. Driving in 4th at low throttle is going to sound similar to 5th at heavier throttle, since both require approx. the same fuel consumption rate.

[fajitas21]

I pull in 5th on flats @ 2000 RPM, and a downshift to 4th is about 2700 RPM. Running either of these would be fine, and honestly uphill some moderate hills it downshifts, but overpasses and light hills it holds 5th very well.

 

People knock the 3.42 6 speed thinking it's a 3.42 4 speed.

 

Keep in mind that with the 5.3L you'll generate about 300 lbs of torque @ 2000 RPM, and about 340 lbs @ 4000 RPM. The torque curve flattens from 2000 - 3000 and then rises some to 4000 ish. The point being is that 2000 RPM is generating a good bit of useable power, and for my own experiences towing with it, it is plenty to toss my travel trailer around.

 

I do agree with Music's statement about the difference between the 5.3L and the 6.0L regarding power and gearing, but the 6 speed transmission is a much more significant upgrade than a larger engine in my opinion. (Clarification of my point is that it moves the load from a stop well and performs more like a higher numerically geared rear end).

 

Also, I can't remember where the chart is, but 5th gear in the 6 speeds is like a 0.89 ratio on the 3.42, so it's a little over 1:1, but not so much that it's not still a hard working gear. In addition, 4th gear is a little less than 1:1, something like 1.12 or something, so interestingly enough there's not a pure 1:1 gearing available.

 

As for mpg, you won't see much (if any) difference pulling 5th vs 4th either, and the noise won't be much different. Driving in 4th at low throttle is going to sound similar to 5th at heavier throttle, since both require approx. the same fuel consumption rate.

 

I also agree with this.

[wavery]

You can run that engine all-day-long @ 3500RPM (with a load).

 

General rule of thumb for pulling a grade is to try to run the engine ~or under 2/3 max RPM if climbing a long grade. That's where the 6-speed is so far superior. One can pick a gear to maximize performance while towing.

 

When I'm pulling a long 6% grade, I have to drop down to second and easily keep my RPM @ 3600 (around 65MPH). If I drop below that RPM, I don't have enough torque to sustain even 55MPH and will quickly drop to ~40MPH. It would sure be nice to have another gear to grab so that I didn't have to drive like a maniac while climbing long grades, trying to keep it ~ 65MPH.

[Stevens03]

If the 5.3 won't hold 4th, a 6.0 probably won't either (gearing difference from 4th to 3rd is much more than the power difference between the two).

 

I disagree. The power between the 2 motors it quite different. I've towed with both and both had the 4-speed and 4.10 gears.

 

 

You can run that engine all-day-long @ 3500RPM (with a load).

 

General rule of thumb for pulling a grade is to try to run the engine ~or under 2/3 max RPM if climbing a long grade. That's where the 6-speed is so far superior. One can pick a gear to maximize performance while towing.

 

When I'm pulling a long 6% grade, I have to drop down to second and easily keep my RPM @ 3600 (around 65MPH). If I drop below that RPM, I don't have enough torque to sustain even 55MPH and will quickly drop to ~40MPH. It would sure be nice to have another gear to grab so that I didn't have to drive like a maniac while climbing long grades, trying to keep it ~ 65MPH.

 

And I couldn't agree more. Having more gears allows you to climb grades without the engine screaming. Not that the high rev's hurt but it's quite a difference in my opinion.

[marpel]

Thanks everyone for the useful, and quick, replies.

 

Stevens11 - I will be buying new (and am deciding if I want to get the last of the 2011s or the first of the 2012s as I still have a couple months left to pay off my wife's vehicle first). If the 5.3L can properly pull my current set-up (just bought the trailer so don't see me upgrading for a number of years), I might lean towards that, however, when I posed my initial questions, I was referring to a 6.0L in the 2500HD. I was not aware that the 1500 came with a 6.0L option and can't find it on any GMC/Silverado site. Can you point me in the right direction or provide a link. As I don't need the extra weight capacity and am towing no more than 4500 lbs, I would like to investigate this option. Thanks.

 

Fajitas21 - Thanks, it seems like you pull a similar sized trailer to mine so your info about the 5.3L is quite encouraging. My mind tells me that 26-2700 rpms for extended periods is probably not a bad thing but I still have a hard time looking at the gauge as I blast down the highway (and even worse, try sitting in the cab with me when I'm pulling through the Rockies!!!). Excellent point about trailer tires!! I have towed three trailers over the years (albeit at less than 60 mph due to moderately powered towing vehicle), have talked to multiple trailer people/dealers and I never knew this. Seems the only benefit from a higher powered motor is the reduced rpm and better gas mileage but no real increase in speed, then. Very good to know.

 

Wavery - Thanks for the added info and the mention of Maxxis tires. I never thought about it before, but I guess the speed limitation to trailer tires is because of the smaller size??

 

Music - Thanks for the mpg info. Why, however, would towing in 3rd mean the temp is cooler than in 4th? Logic (at least my logic) suggests the higher gear the cooler things would be. Go figure.

 

And a closing comment - Jeez, thought all I had to do was buy a truck with a bigger engine, hook things up and go!!! You've got me thinking about gears, ratios, numbers, tires, safety......

 

Marv

[Stevens03]

Thanks everyone for the useful, and quick, replies.

 

Stevens11 - I will be buying new (and am deciding if I want to get the last of the 2011s or the first of the 2012s as I still have a couple months left to pay off my wife's vehicle first). If the 5.3L can properly pull my current set-up (just bought the trailer so don't see me upgrading for a number of years), I might lean towards that, however, when I posed my initial questions, I was referring to a 6.0L in the 2500HD. I was not aware that the 1500 came with a 6.0L option and can't find it on any GMC/Silverado site. Can you point me in the right direction or provide a link. As I don't need the extra weight capacity and am towing no more than 4500 lbs, I would like to investigate this option. Thanks.

 

Marv

 

Well If you were buying used, I was suggesting the Vmax since it was an HD 1500 and was built up thru 09. GM replaced the 6.0 in the 1500's with the 6.2L which is what I have now. It gets similar mileage as the 6.0 but WAY more power. I average 14-15 mpg city and 17-18 mpg highway with 3.73 gears. You can also get it with 3.42 gears which yield about 1mpg better. Since your buying new, I would consider the 6.2L because you plan on towing with it. The 5.3L will get the job done but the 6.2L will do it so much easier. Also the new trucks have an integrated brake controller that works really good.

[wurgs]

I agree with Stevens. The 6.2 1/2ton wil tow your trailer like a dream. The 2500 isn't needed for the weights you've mentioned and you will get less mileage and the ride is stiffer than the 1500. You might want to check your trailer tires as my rv has tires rated at 85mph so highway speeds aren't an issue.

[07 CC Sierra]

Like mentioned above, I'd go with the 1500 with the 6.2. Sometimes I wish I did. I get about 12 mpg around town with some highway driving no matter how I drive, and 8 mpg towing my trailer on the highway. My trailer is twice the weight of yours so that's not really a fair comparison. The ride is actually pretty smooth except when going over speed bumps or pot hole, then it'll knock some teeth loose.

[APT]

My mind tells me that 26-2700 rpms for extended periods is probably not a bad thing but I still have a hard time looking at the gauge as I blast down the highway (and even worse, try sitting in the cab with me when I'm pulling through the Rockies!!!).

 

Unless you buy something with forced induction, you''ll always have that "problem" above. 2700rpm is not high for any modern gasoline engine, even a V8. Yours can spin at over twice that safely. If it could not, GM would have made the rev limiter at 2500rpm. ;)

 

Anything with a 6-spd trans will help. The gear spacing will allow for smaller engine speed changes between gears. That helps optimize power vs. fuel consumption. The suspension of a 2500 will be noticeably better for towing, especially if you carry lots of stuff in the bed.

[fajitas21]

I'll share with you my thoughts on the 5.3L vs the 6.2L V8 Options.

 

When I tow, I sometimes wish I had the 6.2L, but that's about 5 - 10% of the time, and only when I'm pulling my TT.

 

When I tow utility trailers and 16 - 18ft lowboys, I honestly don't even notice them back there enough for me to wish I had a bigger motor.

 

When I'm driving (This is my daily driver), I'm glad I don't have it for the increased MPGs.

 

On a 70% hwy / 30% city tank I average 17.5 - 18MPGs. I'm really not sure I would get that with the 6.2L, cause that's the 3.42 gearing on my 5.3L, and there is NO WAY I'd buy the 6.2L engine and not spring for the 3.73s (if you're gonna pull, then PULL).

 

Consider when you do the most, and where you draw the line. I got a monster deal on a Texas Edition (I think it's All-Star in non-Texas states) with the 5.3L. It would have been about 2k more for the 6.2L, and I would have lost the leather I wanted as well (so 2k more to add that). I just couldn't justify it since I already knew I was good to go for what I was towing because before this truck, I towed this same TT with my Tacoma.

 

***Now on a different note....where did they put my 4.5L Duramax Silverado 1500.........then this discussion would just be null and void *****

[Blue2500CC]

Marpel,

 

How much do you load in the truck bed: firewood, bikes, generator, etc...? I think this is the only thing you may need to watch is the load in the bed of the 5.3 truck plus the tongue weight depending on your family size.

 

Our travel trailer is about 6300lbs, towed with a 2010 crewcab 5.3/6spd/3.42 Z71 4x4 and I have been very happy with it so far. Towing my utility trailer with a mower (total about 2600lbs) the truck barely breaks a sweat!

 

BUT, if you can control your right foot, get the 6.2! Lol

 

Wurgs,

 

Do you have LT tires on your trailer? If they are ST tires, everything I have read states the ST tires are only rated up to 65mph.

 

Chris