Considering engine swap for towing purposes

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by XS ive, Jul 23, 2013.

  1. XS ive

    XS ive Rockstar 100 Posts

    Hey guys, on a tablet so this will be short. Doing a significant amount of towing with my truck. Trailer is a 7x12 v nose with a usual total wt of 5k. It seems to be working very hard on some of the longer pocono grades. Even though it pulls them at 55 65 I dont like seeing the rpms at 2750 and engine temp creep to 235. Even though I can average 10.8mpg towing so I am thinking upgrade. Looking at a 14 2500hd/duramax. A lot of $$$$$ so need some input. Ie Real world mpg on the duramax and normal op temps/mpg for a 5.3.
    Thanks in abvance
  2. stchman

    stchman Active Member 2 Years 1000 Posts

    If you are going to tow with your 2008 a lot (it sounds like you do), I would highly recommend getting a bigger transmission cooler and an external oil cooler. They will help keep your temps down.

    Also, it looks like your put bigger tires on your 2008, while big tires look great, they take their toll on fuel economy and significantly reduce towing ability. When you put those big tires on the truck, did you re-program the ECM to tell it the new tire height? If no, your transmission thinks it has the stock tire size and shifts the transmission in that manner.

    As far as getting a 2500HD with a Duramax, if you can afford the truck and can justify the cost, go for it.

    The Duramax/Allision combo is one of the most capable powerplants in a 2500 or 3500 truck on the market.

    For a 2014, you're looking at ~$50K and a lot more if you want the LTZ trim.
  3. XS ive

    XS ive Rockstar 100 Posts

    Thanks for quick reply. On a real keyboard now and I can get more specific.
    My truck is a Southern Comfort edition which came from Chevy as is. It has the OEM tow package with an external oil cooler, was re programmed for the 35's, and also has a dual exhaust. I added a Volant intake, and a High capacity True Cool Tranny cooler which keeps my trans temp at around 175* on the longest steepest grades. I also recently added a Roadmaster Active Suspension system. The truck pulls the trailer great, just seems like it is working too hard to do so. I think 2750 is a bit high for RPMs on the highway to crest some grades, and it usually cruises at 2100RPMs at 67-70 mph on flats in "D", it will pull in OD, but shifts in/out too much. It only has 38k miles on it and I am still under warranty. I love my truck and really didn't think I'd be towing every weekend.
    I guess what I am looking for is validation to consider a 2500HD with the 6.6 Duramax/Allison. It would likely be overkill for my situation but I would really enjoy stress free driving home after a weekend of Motocross racing.

    Does anyone know if the beds of an 08 1500, and 14 2500 are the same size?
  4. j cat

    j cat Epic Member 5+ Years 1000 Posts

    Since you tow in that area with those large long grades you will need tow in 3rd gear and be at the higher rpm of about 2700 RPM @ 55MPH. the other problem you created as mentioned is larger tires. what this does is reduce the gear ratio meaning the engine load is increased. If you put on the OEM sized tires you will have more torque available for the tow load.

    If I had this type use in this area I would not use those sized tires .

    Diesel is not cheap. however you will have the torque to pull the load up the long steep grade.
  5. stchman

    stchman Active Member 2 Years 1000 Posts

    FYI, the OEM towing package does not have an external oil cooler. If your truck has an external oil cooler, the Southern Comfort people added it.

    Those 35" tires are killing your towing ability. When you get the "Max Trailering Pack" on a Silverado, they limit you to 17" rims with 265/70/17 tires.

    Your 08 crew cab has a 5'8" bed, the 2500HD has only a 6'6" or an 8' bed options.

    As I said, if you can afford a 2500HD with a Duramax, get it. It will be cheaper to put smaller tires on your 08 and re-program the ECM. The truck may look dumb with small tires and a 3" lift.

    One thing you could do is change the differential gears to say a 4.10. This will help you achieve better torque.
    Last edited: Jul 23, 2013
  6. mfleetwood

    mfleetwood Epic Member 5+ Years ROTM Winner 5000 Posts

    ***Thread title changed from "need some help" to match thread topic***
  7. XS ive

    XS ive Rockstar 100 Posts

    I triple checked the Chevy specs on the 2014 2500HD and the standard bed size is the same as the 08 1500. Actually, they have the length of the 2500HD as 78.8" and the 1500 78.7" all the rest are identical. I will have to take a tape measure and measure myself to be sure. I just can't put smaller tires on the truck. It's part of the look and I wouldn't like it. I got some nice numbers from my dealer so if the tape measure works in my favor, I may have to go to the bank....
    I hate to see my XS ive truck go, but I'd rather trade it in then kill it.
  8. stchman

    stchman Active Member 2 Years 1000 Posts

    For Chevrolet 1500 trucks(2008 - 2013):

    Regular cab - 6'6" or 8' bed
    Extended cab 6'6" or 8' bed
    Crew cab - 5'8" bed only

    Now with that being said, in 2008, you could get an extended cab 1500 with a 5'8" bed, but they are somewhat rare. IIRC GM stopped offering the extended cab short bed in 2009 and later.

    In 2014 GM is offering the ability for a crew cab to have a 5'8" or 6'6" bed in a 1500.

    For Chevrolet 2500HD trucks (2014):

    Regular cab - 8' bed only
    No extended cabs made
    Crew cab - 6'6" or 8' bed

    For Chevrolet 3500HD trucks(2014):

    Regular cab - 8' bed only
    No extended cabs made
    Crew cab - 6'6" or 8' bed (Note, dually is 8' bed ONLY)

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