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6.0 straight pipe?

  
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6.0 straight pipe?

 
CBOYER CBOYER
New User | Posts: 2 | Joined: 02/13
Posted: 02/26/13
06:16 PM

is straight piping a good or bad thing. i know it lowers your EGT's and that it make the motor breath easy. but i also hear that it turn the fuel mileage to *** and someone said something about back pressure. i pretty sure but could be wrong but i dont think the back pressure isnt an issue on diesel.  

jwentzel526 jwentzel526
New User | Posts: 36 | Joined: 08/11
Posted: 02/27/13
07:18 AM

It should I running pretty much a straight pipe set up but I kept the mbrp muffler in the system. With all I've done to my truck I get between 22-23 on the highway depending on what blend of fuel being used. Beside when you change your exhaust system from the factory to an aftermarket one the diameter of the pipe goes from about 3-3.5 inches crimp bent to a mandrel bent 4-5 inch diameter pipe so you are reducing the back pressure considerably. The reason why your mileage might drop is because your foot might be in the pedal more.  
07 Silverado Classic CC SB 4x4 LBZ LT3 mbrp downpipe upgrade 4 inch turbo back MBRP Cool Duals Quadzilla Stealth 2 at 90 hp, AFE hot pipe upgrade, AFE stage 2 cold air pro guard 7

5toMidnight 5toMidnight
User | Posts: 167 | Joined: 03/12
Posted: 02/28/13
06:08 AM

"someone said something about back pressure"
Those people know nothing about engines.

"but i also hear that it turn the fuel mileage to ***"
You heard incorrectly.  

idahobuckaroo idahobuckaroo
Guru | Posts: 1250 | Joined: 09/12
Posted: 03/02/13
01:19 PM

Straight piping is a good thing.

There is a lot of research to backup this claim.  Diesel pickups are great, but they are better if they are straight piped. One thing to consider is the local laws where you live. Some areas have noise ordinances that prohibit exhaust noise from modified vehicles.  Here in Idaho it is no big deal.

Diesel Exhaust as a free-flowing exhaust system performs two valuable functions on a diesel truck. First, it reduces back-pressure, scavenging exhaust gasses more efficiently and allowing the engine to pull in fresh air and fuel more quickly. That means more power.

Second, a free-flowing exhaust helps reduce exhaust gas temperatures—upwards of 200° F depending on the engine’s power level and exhaust system size (pipe diameter). For turbo diesels, the added exhaust flow helps the turbo spool quicker, increasing power in the low and midrange.

Another exhaust component that affects mileage is the catalytic converter on trucks so equipped. The converter’s primary function is to turn combustion byproducts into relatively harmless CO2 and water.

Over time, a converter’s core will plug up with contaminants or break apart from the intense heat. The resulting back-pressure and contaminant buildup in the exhaust will have a definite impact on engine efficiency. Straight pipe the exhaust from the turbo using the same factory diameter pipe.  

Note: if a catalytic converter is factory (2004 or later for Dodge Cummins), straight pipe from the catalytic converter back.  Install a 5 inch exhaust tip (stainless steel if you like to dress up the pipe).  
----------------

Towin' machine...  Joel

Cummins High Mileage Club Member
TDR Turbo Diesel Registry Member
SMARTY Tuners Performance King

5toMidnight 5toMidnight
User | Posts: 167 | Joined: 03/12
Posted: 03/03/13
06:45 AM

"Note: if a catalytic converter is factory (2004 or later for Dodge Cummins), straight pipe from the catalytic converter back."

That is a waste of time. The cat is the primary restriction in the system, as is the DPF in later models. Removing the muffler alone on them will do nothing for backpressure, just noise.  

idahobuckaroo idahobuckaroo
Guru | Posts: 1250 | Joined: 09/12
Posted: 03/03/13
07:20 PM

That is correct, and over a long period of time, catalytic convertors are prone to plug-up in gas engines and diesels.  I agree with you, and there is some back-pressure created from the catalytic convertor; however, the back-pressure from the catyalytic convertor is minimal.  There have been no issues with restrictions in my 3rd generation Cummins 5.9L by leaving the catalytic convertor in the system.

You bring up a good point regarding back-pressure which was more of an issue with my 2008 Cummins 6.7L engine due to not only a catalytic convertor, muffler, but the PVC and EGR valves, plus the particulate filter/after burner.  There have been no issues that I am aware from lack of engine performance by using a catalytic convertor since the 5.9L Cummins does not have a PVC or EGR valve which is more of a problem (than a 5.9L without PVC and EGR valves and leaving the catalytic convertor in the system).  The 6.7L Cummins does have back-pressure issues.

Straight piping after the catalytic convertor is still beneficial, and will improve the performance of openning up the engine.  It is a recommended by Cummins to keep the catalytic convertor on the system, especially if state emission laws require passing emission tests.  However, if I had my choice, it would be better to remove the catalytic convertor completely.

The other point worth noting is typically catalytic convertors will degrade in time and blow out the substrate material resulting in becoming less restrictive.  Thus, they will require replacement since they will be ineffective in reducing emmissions if that is the reason you choose to leave a catalytic convertor on your truck, as I did.  As noted, it is possible to blow out a catalytic convertor over time with extended high EGT's.

From my experience, leaving the catalytic convertor in place did not make a noticable difference on the truck's engine (2006 Cummins 5.9L) perforance, and my EGT's were reduced 150 degrees under a heavy load towing 10,000 lbs. GCWR (325 RWHP @610 ft-lbs torque).

The catalyst substrate is designed to last for the entire life span of the engine, and good engine maintenance is necessary to sustain the catalyst activity for a similar period of time. There are two major causes of catalyst deactivation: (1) high temperature and (2) poisoning. Source: Nett Technologies, Inc. Ontario, Canada

Catalytic convertor catalysts may suffer thermal degradation when exposed to temperatures above 1,200°F for prolonged periods of time. Diesel engines have intrinsically cool exhaust gases and thermal catalyst deterioration is not likely to take place under normal operating conditions. Catalyst overheating may occur only as a result of serious engine malfunction, such as leaking injectors, when unburned fuel is oxidized in the catalyst and excessive temperature rise is observed due to the exothermic reaction.

Several chemical elements have the ability to either selectively poison the catalyst or to mask the catalytic surface, thus, preventing the contact between exhaust gases and active catalyst sites. Substances to be avoided include phosphorus, zinc, heavy metals, lead,arsenic, vanadium and silicone. Some of these elements (e.g., phosphorus) may be contained as additives in the engine lube oil.

Low lube oil consumption and the use of low phosphorus oils are guidelines for extended catalyst life. Leaks of lube oil into the exhaust system are very detrimental and can irreversibly deactivate the catalyst within a few hours
or days.

I understand and appreciate your feedback; however, my only point was to be helpful, and if what I suggested is a total waste of time to you.  That's okay.

To each his own, it's your opinion, as is mine.
Best regards...  
----------------

Towin' machine...  Joel

Cummins High Mileage Club Member
TDR Turbo Diesel Registry Member
SMARTY Tuners Performance King

5toMidnight 5toMidnight
User | Posts: 167 | Joined: 03/12
Posted: 03/13/13
01:08 PM

"What I suggested is a total waste of time to you."
That is correct.

An extremely unprofessional moderator has been editing several of my posts to contain information I did not type so that it would appear I am saying something completely different from my original intent. I and Diesel Power's owners are aware of your actions and such malicious activities will not be tolerated.  

idahobuckaroo idahobuckaroo
Guru | Posts: 1250 | Joined: 09/12
Posted: 03/13/13
08:17 PM

Impressive... Most impressive.  
----------------

Towin' machine...  Joel

Cummins High Mileage Club Member
TDR Turbo Diesel Registry Member
SMARTY Tuners Performance King

MarineOne MarineOne
Addict | Posts: 2059 | Joined: 09/08
Posted: 03/14/13
02:47 AM

There was an article in one of the diesel mags about this, and they did prove that the difference in pressure with/without the cat in place was minimal.

The biggest restriction is the exhaust pipes themselves, and they did show there was about a 20% difference in flow with a mandrel bent system over stock.

Ideally since its diesels we're discussing, you really don't need a muffler since most of us already have a cat in place and this will silence most of the noise from the get-go.  Doing a muffler delete, especially if you have a stock unit rust out, is a nice cheap upgrade that adds just a bit of rumble.



-Kris  

2006 Dodge Ram 2500 QC 5.9L - Smarty CR S-06 on SW #5

2008 Dodge Ram 3500 QC 6.7L - H&S MiniMaxx on DPF tune for towing
Titan Fuel Tank
Aero Muffler 4040XL
Nathan AirChime K3LA

jwentzel526 jwentzel526
New User | Posts: 36 | Joined: 08/11
Posted: 03/14/13
08:42 PM

When I did most of my exhaust upgrades it started out as a cat back system then I changed the front pipe and the downpipe which made the motor breathe easier. And I noticed that my egt's dropped about 100 from what they were. The cat essential is resonator and it cancels a lot of the sound. I've noticed since I finished the exhaust a deeper tone all the way thru the entire powerband and the turbo whistle is more present which is a very nice sound if you don't have a problem with that.  
07 Silverado Classic CC SB 4x4 LBZ LT3 mbrp downpipe upgrade 4 inch turbo back MBRP Cool Duals Quadzilla Stealth 2 at 90 hp, AFE hot pipe upgrade, AFE stage 2 cold air pro guard 7

psa1sonic psa1sonic
New User | Posts: 3 | Joined: 03/13
Posted: 03/20/13
03:25 PM

Icon Quote5toMidnight:
"someone said something about back pressure"
Those people know nothing about engines.

"but i also hear that it turn the fuel mileage to ***"
You heard incorrectly.


some back pressure is required but the turbo provides ample enough. for scavenging, now for you vgt maby need a small amount for the sensor but if you keep it clean should work just fine  

5toMidnight 5toMidnight
User | Posts: 167 | Joined: 03/12
Posted: 03/21/13
12:55 AM

"some back pressure is required but the turbo provides ample enough"
That is false information.
Backpressure is never an advantage to an internal combustion engine.

"for scavenging, now for you vgt maby need a small amount for the sensor but if you keep it clean should work just fine"
That makes absolutely no sense.