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4" vs 5" Exhaust

bartf350bartf350 Member Posts: 2
edited August 2014 in Ford
I am looking at changing the exhaust on my '99 F350 Super Duty with the 7.3 Powerstroke. I have seen and read about 4" exhausts and 5" exhausts. Does anyone have any experience with either or both. Is one better than the other?

My truck is primarily used for too and from work during the week (when I am not in Iraq). I do pull a steel three horse trailer on weekends....about 9,000lbs. So, when I get back, I am looking for the best exhaust to put on the truck and potentially an exhaust break. Recommendations anyone?



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    ddf1ddf1 Member Posts: 18
    I understand diesel exhaust is alot like gas motors. Too big and you actually lose power. Unless you have got a motor pushing 1000 lbs of torque I would go with a 4" exhaust.
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    bartf350bartf350 Member Posts: 2
    Thanks! I am still researching. I do understand that changing the exhaust also means I should change the intake as well.....a whole package deal. I will keep the thread going as I find out more information. I am trying to find every article I can to find an answer.

    Thanks again and take care!
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    smokin03smokin03 Member Posts: 4
    I will clear up a misconception. A turbocharged diesel engine does not need backpressure to run. It is force-fed by the turbocharger, and the worse you will get with a free flowing exhaust system on your 99 is a lighter wallet. I owned a 99 with a 7.3 and installed a Magnaflow turbo-back kit. Got it for 400 bucks. With the exhaust system you will see quicker and better turbo spool up which results in more boost faster as well as lower exhaust gas temperatures. 5 inch exhaust will not get you any more power, it is mainly for cosmetics. The factory turbocharger outlet is only 3.5" so 4" is the most ideal size. It sounds like you have a daily driver and not a purpose built drag racing or sled pulling truck, so don't throw away money you don't have to. Also you do not have to change the intake, but on a 7.3 I would recommend it. It is pretty restrictive. Ford offers a Severe Duty kit, or you can spend the money on something like an AFE, or AEM Brute Force kit. Don't buy K&N for diesel. Get a good filtering kit, because you do not want anything getting into a high compression diesel engine! Join www.powerstrokeforum.com it is a forum specific to your truck. Look for me, my name is 99smokin73stroker. I will continue to watch this thread.
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    mscanmscan Member Posts: 1
    I have been reading the posts on exhaust systems but they seem to lean towards diesels. I have the 6.8 V-10 on my F550. I tow about 12,000 lbs up a hill that makes me gasp when I try to walk up it. I know my 5 will pull a house down (that's why I bought it) but I want to make it a little more efficient and sounding cool won't hurt either. I already have the K&N. How big should I go on the exhaust?
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    KCRamKCRam Member Posts: 3,516
    This particular discussion is in the Diesels forum, thus the emphasis. You may want to try the Ford F-Series Accessories and Modifications discussion or look for an exhaust discussion in the Speed Shop: Tuning & Modification Board.

    kcram - Pickups Host
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    fixindieselsfixindiesels Member Posts: 2
    Hey It won"t go in if it can't get out. 5" is the way to go. Yes a good cold air induction is recamended but you don't have too at the same time. Spend the money wisely. 5 Inch. Diesel.
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    outlawdieseloutlawdiesel Member Posts: 12
    well this is what I do all day long,diesel up grades. well for a stock power stroke, just do the 1-2-3s.Exhaust 4in-Intake and custom tuning. the 4in Exhaust is perfect for what your doing. make sure you get a 4inch turbo back.
    let me Explain why we reccomend these three products the stock exhaust system is so restricted with the Tight bends muffler and cat,when you install a aftermarket exhaust there straight through, the muffler is the same. so with no restrictions your motor can get the hot gas out as fast as the turbo & motor is pumping it out.and the result is lower egts
    better throttle response and more HP & torque. but first you got to get COOL Fresh air in the the motor,to really get the most out of your exhaust system. so with a free flow intake system. you will get more air in with out any restrictions at all,cooler air and as you know cooler air has more oxygen molecules so bigger and cleaner combustion adds up to more fuel mileage,cleaner burn and more POWER! so with more air going in more air going out. adds up to better,smoother running,more mpg,HP,torque
    now this is where the tuner comes into play.now we got air to her and we can get it out.
    it's time to custom tune the pcm to get the motor to run in the sweet spot.with alittle timing,fuel,pulse width,icp pressure and air to fuel mixture,with custom tuning we also tune the trans to hold the added hp and tq.so with these upgrades you should get 20 to 23 hwy and 16 to 18 city.more towing power,so you can get that big load up those hills with no problems and more performanced so you can play,4x4 driving,racing,sled pulling or what ever you what to do with your ford powerstroke.your truck will be a lot of fun to drive and not that old boring slug. the six postion chip is tuned only for you and the way you drive.
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    fixindieselsfixindiesels Member Posts: 2
    Hi. Truck runs great by itself but under a load, 5000 pounds is nothing for a powerstroke. No codes. 5" exhaust S&B cold air induction, 210.000 miles.. New fuel filter, Any help. Thanks guys.
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