1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

4.6 towing performance

Discussion in 'Site News' started by Guest, Apr 19, 2003.

  1. Guest

    Guest Guest

    I own a 99 Expy with a 4.6L and 3.55 gear ratio.
    Mainly city driving, thats why I opted for the 4.6.
    Looking at purchasing a 23 ft TT with a dry weight of 3700 lbs.

    I heard that upgrading the exhaust system can give better perf.
    any recommendations, etc, to increase towing power.

  2. Guest

    Guest Guest

    Change the rear end. Lower the final drive to 3.73 or more and you'll see a vast improvement in towing. But it won't be cheap, especially for 4x4.

  3. Guest

    Guest Guest

    thank-you, I do own a 4x4, and have considered that option.
    as you say, pricey.
    Any increased torque by changing out the stock exhaust to a
    cat back or something similar?
  4. abbyzdad

    abbyzdad Active Member

    Likes Received:
    Apr 6, 2003
    spokane, wa
    A cat back will help but you also need to let more air in. On my 97 4.6L I did exhaust first (cat back single in dual out) and noticed a little better performance. Installed a K & N drop in filter and that helped too. I also drilled 1 1/2 holes in my airbox so the airflow wasn't restricted to just what comes thru the snorkel in the fender. I didn't get any more mpg but did notice it pulled quicker off the line and seems to rev faster.

    good luck, Brian
  5. Guest

    Guest Guest

    Thanks for the info on air intake, Brian.

    I'll be taking it in soon for the exhaust upgrade.

  6. Guest

    Guest Guest

    Another thing is check into a non stock computer chip (Hypertech, Superchip, etc). If you go to the bother of modifying your exhaust and intake then you might as well optimize timing/air-fuel ratios, etc. in order to achive maximum "bolt on" gains.

    I must admit though I did this with my 2001 RAM 4x4. It has a 5.2 L with a 3.55 rear end. I modified the air intake to an AIRAID and the exhaust to a Dynomax catback system then added a modified PCM chip. The results were NOT stellar if even discernable.

    But the 3.90 rear end, though not cheap, was a HUGE leap in low end torque. The real problem here is the fact that the truck doesn't have a 5.9 (360) in it or a Hemi. But a 3.55 IMO is simply to high of a ratio for pulling anything significant with any engine IMO. Even guys that pull with F350 Powerstrokes, like my dad, use 4.11:1 rear ends to pull with.

    Good luck

  7. daoud elmassri

    daoud elmassri Full Access Members

    Likes Received:
    Sep 13, 2012
    Manchester ct
    Cody start at the junk yard for your rear end and front end it is alot cheaper u can get a use good used 3:73 from them . You might even be lucky and fine a K&N cold air intake like I did I got it for 20 bucks . I had also a 4.6 in my 2000 expedition it was a dog it had a hard time pulling my 24 ft Grady White I tryed a lot of difrent things and finaly bot a recked 2001 expedition it had the 5.4 with tow package W/R 100 transmission 3:55 possy rear end I took every thing out of that truck it was a good doner . I made some of my money back from some of the part I did not need good luck hope this was helpfull.

Share This Page