# Custom Exhaust Work



## Snipe656 (Oct 22, 2009)

I have always been led to believe it is the fuel itself and not just some component of the fuel.


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## Snipe656 (Oct 22, 2009)

I just got back from looking at a car for sale by a local biodesel reseller. Oil contamination came up and he said in the newer vehicles the issue is when the regen process happens that the fuel itself seeps into the oil due to the flash point of biodiesel being twice that of diesel. That is from someone who obviously should be biased to the biodiesel side of things, so take it for what it is worth.


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## wxmanCCM (Feb 17, 2010)

There was a study conducted by NREL recently on the oil dilution from use of biodiesel blends (M.J. Thornton, T.L. Alleman, J. Luecke, and R.L. McCormick, "Impacts of Biodiesel Fuel Blends - Oil Dilution on Light-Duty Diesel Engine Operation." Presented at the 2009 SAE International Powertrains, Fuels, and Lubricants Meeting, Florence, Italy, June 15-17, 2009 - http://www.nrel.gov/vehiclesandfuels/npbf/pdfs/44833.pdf).

Direct quote from the paper...



> ...For the SCR system (which used a urea solution as a reductant and required only late in-cylinder fuel injection for DPF regeneration), biodiesel oil dilution ranged from 4% - 8% for oil samples ranging in age from ~50 to ~75 hours [with B20]....


Just for reference, VW says that oil dilution up to 50% is tolerable (http://www.biodieselmagazine.com/articles/2290/understanding-the-post-injection-problem).


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## 62Lincoln (Sep 26, 2004)

Dilution of oil in the sump is only half the story:



> Oil additive packages, which may constitute up to 25 percent of the total lubricant, contain dispersants to suspend soot in the oil, viscosity improvers, over-base detergent used to neutralize any acids built up and zinc dialkyldithiophosphate (ZDDP) as an anti-wear agent. "Look at all of these additives," Fang says. "They are all bipolar molecules-one side of these molecules is very polar while the other is nonpolar. The nonpolar tail is used to sustain the polar head and make it suspended in the oil, which is largely nonpolar." So the additives are relatively polar compounds compared with the base oil, and methyl esters are polar as well. *Polar molecules are attracted to polar molecules, so biodiesel in the oil is attracted to the likewise polar additives. "We used spectroscopy to quantify this," Fang says.The more polar the additives, the more they interact with the biodiesel. And if the biodiesel gets degraded, or experiences thermal or oxidative aging or whatever, the biodiesel will absorb more oxygen and become even more polar, which will generate even more interaction with the additives." *
> 
> It didn't take long for Fang to discover the adverse effect aged biodiesel has on ZDDP, the anti-wear additive. *ZDDP is chemically designed to be attracted to the metal surface of the cylinder walls and to form a protective layer.But if you've got biodiesel in your oil, and the biodiesel likes to go to the metal surface too because the metal surface is polar, the biodiesel competes with the additive over the metal surface," Fang says. Although there are complex interactions between the biodiesel and additives affecting the functionality of the additive, Fang suggests the mere fact that biodiesel and ZDDP compete for surface area on the cylinder walls is troublesome enough.* The effectiveness of detergents is also mitigated by the presence of biodiesel in the oil.


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## pql (Oct 9, 2011)

Biodiesel has detergent properties in and of itself. It is known to clean engines that have used petroleum diesel previously. Biodiesel also has greater lubriosity (sp?) than petroleum diesel, especially the ultra low sulfur that is specced these days. I have good experience. I know others who have good experience. I believe that biodiesel burns clean enough that a vehicle can pass an emission test without a DPF, UREA injection, or catalytic converter. That is how I am hoping to move my X5. Where I live there is no emissions test required. I will be responsible for my own choices. If it breaks, I will fix it. Others must choose their own paths. I am happy with mine so far.


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## Snipe656 (Oct 22, 2009)

pql said:


> Biodiesel has detergent properties in and of itself. It is known to clean engines that have used petroleum diesel previously.


When I was at the biodiesel place today someone came in and bought 300 gallons of B100. Not to run though, they use it for cleaning things at some plant around here.


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## floydarogers (Oct 11, 2010)

pql said:


> ... I believe that biodiesel burns clean enough that a vehicle can pass an emission test without a DPF, UREA injection, or catalytic converter. ...


No, it will not. You will have unavoidably high NOx emissions - that's what the catalyst removes in the reduction reaction.


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## pql (Oct 9, 2011)

Fair enough. How about the soot issue that the DPF is for. Biodiesel does not produce soot that I can observe.


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## Snipe656 (Oct 22, 2009)

pql said:


> Fair enough. How about the soot issue that the DPF is for. Biodiesel does not produce soot that I can observe.


It sure was producing it yesterday in the old 240D I looked at but probably not the best of cars to judge the fuel with. Then looking at the back of their cars up there they too had a fair amount of soot. One was a BMW, no idea what engine was in it though since was a year I know diesels were not sold here. The other looked like a mid to late 90s S class Mercedes. Perhaps in all three cases it was just how the cars were setup. The BMW did look rough, the 240D was rough, but the S class actually looked like a well kept up car.


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## floydarogers (Oct 11, 2010)

pql said:


> Fair enough. How about the soot issue that the DPF is for. Biodiesel does not produce soot that I can observe.


As mentioned, soot does occur from biodiesel burning. Soot is unburned or incompletely burned carbon. Biodiesel is a hydrocarbon, just like regular diesel. There will always be some soot, since the combustion cycle is never 100% efficient.

The answers and background to all this stuff is in the "ST810 - Advanced diesel..." and "Introduction to diesel tech..." pdf files that were posted in this forum. They're not in the DIY so you have to search for them. Very informative.


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## Sharks06lly (Oct 1, 2011)

Would you even be interested? yes very interested
What would you want out of a custom exhaust? louder exhaust tone, dpf removal along with cat and def( pretty much entire emissions system)
Would removing the DPF and Cats be a requirement, or something you could live without? requirement
What is the most important thing you'd like to see out of a custom exhaust? having options of actually being able to get straight pipe or one with a muffler
What would you be willing to pay for one? eh price isnt a factor as much as quality and availability


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## cssnms (Jan 24, 2011)

Going to see the guys at Benchmade Proper http://benchmadeproper.com/ tomorrow so they can put the car up on a lift to see what they are dealing with at which point they will let me know what our options are. They seem pretty optimistic they can do something for our d's.

That said, after further research I suspect without the coding to do a dpf and or urea delete exhaust options will be limited. Given where the DPF is located DP's appear out of the question without dpf tuning delete. Not sure exactly if the urea injection occurs down stream or up stream or where the nitrogen gas sensor is in the exhaust stream, which would then determine if we would be limited to just a midpipe or midpipe and back exhaust. Hope to find out more tomorrow.

That BIG can in the lower left corner is the DPF.


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## pql (Oct 9, 2011)

I'm very interested to see what you find out even though I'm an X5D owner. Sorry but what's a DP?

Peter


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## cssnms (Jan 24, 2011)

pql said:


> I'm very interested to see what you find out even though I'm an X5D owner. Sorry but what's a DP?
> 
> Peter


Downpipe.


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## floydarogers (Oct 11, 2010)

cssnms said:


> ...Not sure exactly if the urea injection occurs down stream or up stream or where the nitrogen gas sensor is in the exhaust stream, which would then determine if we would be limited to just a midpipe or midpipe and back exhaust....


The DEF injector is in the outstream of the DPF, upstream of the NOx sensor.

But the DPF is *also* the oxidation catalyst, which reduces HC, CO, NO. So, removing the DPF essentially eliminates all the emissions system (other than the EGR.)


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## cssnms (Jan 24, 2011)

floydarogers said:


> The DEF injector is in the outstream of the DPF, upstream of the NOx sensor.
> 
> But the DPF is *also* the oxidation catalyst, which reduces HC, CO, NO. So, removing the DPF essentially eliminates all the emissions system (other than the EGR.)


It's good to know that the injection occurs more upstream and near the DPF. Next I need to determine where the NO sensor is located along the exhaust system stream. This will ultimatly dictate how much can be done. I think my goal is to see what the options are while leaving both the DPF and urea injection system intact.


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## julesandtrish (Mar 2, 2006)

Good luck. Please keep us posted.


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## Snipe656 (Oct 22, 2009)

cssnms said:


> It's good to know that the injection occurs more upstream and near the DPF. Next I need to determine where the NO sensor is located along the exhaust system stream. This will ultimatly dictate how much can be done. I think my goal is to see what the options are while leaving both the DPF and urea injection system intact.


Unless the sensor just screws into a bung within the exhaust then just a matter of putting a bung in the new exhaust for that.


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## floydarogers (Oct 11, 2010)

cssnms said:


> It's good to know that the injection occurs more upstream and near the DPF. Next I need to determine where the NO sensor is located along the exhaust system stream. This will ultimatly dictate how much can be done. I think my goal is to see what the options are while leaving both the DPF and urea injection system intact.


According to the diagrams in the "ST810..." and "Advanced Diesel ..." pdf files (search), the sensors are immediately before and after the catalyst, which is under the driveshaft where a resonator goes on the gas models.


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## cssnms (Jan 24, 2011)

Had a good meeting with the guys at Benchmade today. Let's just say it looks VERY promising. Will report back with photos/video within the next 2 weeks, followed by some dyno comparisons.


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