why 3 1/2 down pipe on 03 - 04?

[HAkers]

does anyone know the reason behind having a 3 1/2 inch down pipe exhuast on the 03 - 04 just to go into 4 " after the muffler? I'm wondering about it before I switch my '04 to 4" all the way. Is the ecm programmed for that back pressure for smog or something? just curious, everything has to have a reason... right?





QNTUMDC

2004 QC HO stock (in tdr pg 132 last issue)

 

[Parks]

????

The 2002 and earlier trucks had a 3" down pipe if I remember correctly and it went to a 4" as well.



That is a good question. I always thought they were just being contrary.

 

[Tomeygun]

does anyone know the reason behind having a 3 1/2 inch down pipe exhuast on the 03 - 04 just to go into 4 " after the muffler? I'm wondering about it before I switch my '04 to 4" all the way. Is the ecm programmed for that back pressure for smog or something? just curious, everything has to have a reason... right?





QNTUMDC

2004 QC HO stock (in tdr pg 132 last issue)

Maybe to increase torque - Sometimes too much flow to make torq lower...



I actaully did this mod back in 2004:

https://www.turbodieselregister.com/forums/showthread.php?t=114110



I figured 4inch is better than 3. 5, so why not?

 

[Prairie Dog]

It's because we dont have a cat. When they added the cat they increased the size of the exhaust to keep the overall flow up.

TG, because diesels fire after TDC, they dont bennefit from scavenging from backpressure like gassers do.



Scotty

 

[nickleinonen]

they dont bennefit from scavenging from backpressure like gassers do.

any turbo engine doesn't really benifit from exhaust scavanging near as much as a NA engine. . boost pressure does a good job of scavanging during overlap as long as drive pressures are not overly excessive

 

[J&LRam]

interesting article in TDR mag when they were testing the different fueling boxes shows the 3. 5 pipes on the '03/'04 were no problem with exhaut flow and EGTs. Guess Dodge engineers figured that was plenty of flow for that size turbo and power output.

JIM

 

[Benson]

I'd like to find one of the '4. 5, '05 exhaust flanges. Anyone know a source?

 

[100 Proof]

Don't forget that the pin wheel in that stock turbo is only about 1. 33 inches across. You can cover it with a silver dollar.



100 Proof

 

[DerekW]

Seriously why Does DC insist on choking HP and mpg. If I were them I would offer a "hotrod package" for those who like to play. They could even get away with more excuses on why not to repair the customers vehicle by saying "you bought the "hotrod package" you must like to play, and we only cover normal use not abuse". Why do we have to pay for something thats not what we want and have pay again to fix it to fit our needs?

 

[Rudity23]

Seriously why Does DC insist on choking HP and mpg. If I were them I would offer a "hotrod package" for those who like to play. They could even get away with more excuses on why not to repair the customers vehicle by saying "you bought the "hotrod package" you must like to play, and we only cover normal use not abuse". Why do we have to pay for something thats not what we want and have pay again to fix it to fit our needs?

Hot Rod?



One word... .



Emissions

 

[CPittman]

Well, that was worth my $35 right there... I never knew that diesels fired AFTER TDC. Never even thought about it... I, too, was uptight that my '04 has the 3. 5" downpipe - but I guess I'll just order my MBRP muffler, crank up the EZ and git on down the road!