straight pipe

CumminsDriver

CumminsDriver

BAM BAM
Joined
Jul 16, 2006
Messages
397
Well i completely straight piped my buddys 6.7. Like redid the down pipe and punch'd out the cat, particulate filter and took out muffler. The stuff in the down pipe is not the stuff thats in the cat its a wire meshof some sort found out after pounding on it and it wasnt breaking up. But all n all its all down MPG went from 11.5 to 17.8 getting better too. My question is why is it still so quite? It was diffenitly louder but not like my 5.9 straight pipe. I didnt see anything on the back side of the turbo. What gives???
 
Did you do anything with the tuning from gutting the pipes ?
If not...you will be soon.
It ain't like the old days where gutting a cat was no big deal....gutting all that new stuff opens up a big as can of trouble.
 
Don't quote me on this but the reason it's so quiet is because it is basically the the 5.9 bored out. Longer stroke. During this longer stroke the fuel is not pumped in all at once but in smaller bursts. This is supposed to cause the quieter sound. Can't say I understand it completely but this is how it was explained by a neighbor.
 
You have to have a complete straight pipe with egr cooler delete to have it louder than hell. The cats (downpipe,egr,cat) have to be gone and the egr cooler that acts as a exhaust baffle has to be deleted too.
 
Well i intalled a egr delet and everthing from the turbo to the muffler right in front of the rear end is gone. And its still quiet. It actually sounds a little weired.
 
jktcummins said:
Well i intalled a egr delet and everthing from the turbo to the muffler right in front of the rear end is gone. And its still quiet. It actually sounds a little weired.
Click to expand...

have a buddy drive your truck while you are on the outside, thats what i did and it wasnt quiet to me anymore.
 
My 6.7 Has A 4" Straight Exhaust And Is Twice As Loud As My Fathers Stright 5.9. At 2000-2500 Rpm Its Freaking Unbelievable. Very Deep Sound And When E-brake Comes On At 2000rpm Or Above It Actually Pops Like An 18 Wheeler. No Egr Cooler And Egr Along With A Turbo Back Straight Exhaust Will Have The 6.7 Louder Than A 5.9.
 
a little quieter because of more injection pulses. But get rid of the EGR and EGR cooler like smoke said and you've got a different animal.
 
EGR Delete

When you say, "Different Animal", are you implying that it is more noisy or runs a lot better with better fuel economy?
 
be a friend to your truck and get rid of all the emissions control equipment and let it breath you will be pleased
 
when you did the EGR delete and cooler delete did it make it louder and did it lower your smoke?
 
Emission-less and still quiet and very little smoke. Variable geometry Turbo with e brake is part of the reason, but the engine has 5 ignition events per combustion stroke. 2 pre ignition, 2 main ignition and 1 post for cleaner burn. Unless you change that, you will still be pretty quiet.
Once you get used to the sound, (roll the passenger window down alot, lol) you get used to the throatier sound and with the e brake it sounds like a jet engine. :)
 
CumminsDriver said:
when you did the EGR delete and cooler delete did it make it louder and did it lower your smoke?
Click to expand...

you can see in my sig just about everything thati have done to my 6.7. All the deletes did make a noticable sound difference, but it does not sound like a 747 and it is not as loud as a straight piped 5.9. I would really like to hear sound bits from some of these peoples trucks, with the Holset VGT i dont know how they are making them this loud.
:ft:
 
You must log in or register to reply here.
Top