Passat aftermarket exhaust

biged681985

Well-known member
Joined
Mar 19, 2013
Location
arkansas
TDI
09 Jetta

PickleRick

Veteran Member
Joined
Nov 29, 2017
Location
Greenville sc
TDI
05 GLS BHW sedan 5 speed conversion. BHW Carver SantaCruz in progress
You wont find much info on dyno tunes of small displacement turbo diesels on competing exhausts.

You will find info on dyno runs on small displacement turbo gassers like the Hondas B series engines.

Usually on a small engine (4 cyl) you put bigger exhaust on to increase top end power with a sacrifice of bottom end torque. Id be willing to bet without a better spooling/more efficient turbo swap plus tune youd end up with the same on your BHW.

As for the mandrel vs crush bend pipes usually the dyno results of say 2.5 tubing were not all that different. The biggest difference is in weight savings when comparing stainless to say titanium$$$$.

The turbo is essentially a muffler compared to a non turbo engine but with diesels I've noticed a drone at certian rpms which increases once a muffler is removed. The question is would you be happy with what little gains mit may or may not get you at the expense of a tractor sounding motor.
 

biged681985

Well-known member
Joined
Mar 19, 2013
Location
arkansas
TDI
09 Jetta
I’m currently running the buzzken Dow pipe, cat was bad, constantly smelled like rotten eggs when idling.

Main reason for wanting to replace is that they have 300k on the resonator and muffler. Figure with that many miles, they are probably a but clogged and restricting flow.

Coming from someone who drives nothing but diesels, the sound of a small diesel motor won’t bother me at all.
 

ruSSrt

Member
Joined
Dec 1, 2018
Location
Seattle WA
TDI
2001
Hey guys. I'm curious if it's worth for me buying a whole new exhaust or should I just do a muffler delete? I want to get a little more sound out of my B5.5 2.0 tdi wagon, but I drive a lot on freeway and don't want the drone (I do love my podcasts). Would deleting a muffler get me a better exhaust flow with little more turbo diesel sound. Or should I get resonator and cat out also to get any benefits?
 

50harleyrider

Top Post Dawg
Joined
Jun 16, 2007
Location
charleston,wv
TDI
2005 B5.5 TDI/geared BSM, BV43A turbo,stage 2 TDTUNING. 2005 5sp manual passat tdi stage 2 tdtuning,BSM delete. 2015 Passat TDI 6sp manual.
After market exhausts are always prone to annoying drone. I agree to avoid them unless your looking at mods to get over 200hp. The BHW does quite well with a bigger turbo and tune only. VW did a lot to keep exhaust noise low from the factory without being to prone to back pressure.
 

ruSSrt

Member
Joined
Dec 1, 2018
Location
Seattle WA
TDI
2001
After market exhausts are always prone to annoying drone. I agree to avoid them unless your looking at mods to get over 200hp. The BHW does quite well with a bigger turbo and tune only. VW did a lot to keep exhaust noise low from the factory without being to prone to back pressure.
Would you recommend just cutting of the muffler and leaving it like that? Would I get a little better tune out of exhaust? Skittles turbo whistle?
 

Mozambiquer

Vendor , w/Business number
Joined
Mar 21, 2015
Location
Versailles Missouri
TDI
2004 VW Touareg V10 TDI, 2012 Audi Q7 V6 TDI, 1998 VW Jetta TDI. 1982 VW Rabbit pickup, 2001 VW Jetta TDI, 2005 VW Passat wagon TDI X3, 2001 VW golf TDI, 1980 VW rabbit pickup,
I removed the catalytic converter on mine, it makes it whistle a lot more. It's still stock from the downpipe back. I've thought about going with something else, as I know it's not very noisy at all even with no muffler. I had the down pipe off and pulled it in and out of the shop, and it was actually still pretty quiet.
 

Mozambiquer

Vendor , w/Business number
Joined
Mar 21, 2015
Location
Versailles Missouri
TDI
2004 VW Touareg V10 TDI, 2012 Audi Q7 V6 TDI, 1998 VW Jetta TDI. 1982 VW Rabbit pickup, 2001 VW Jetta TDI, 2005 VW Passat wagon TDI X3, 2001 VW golf TDI, 1980 VW rabbit pickup,
Was it difficult to get to?? How does one take it off? Saws-all?
Yes, it was a bit difficult, but not the worse. Having the egr cooler already deleted helped. I pulled the flange off at the turbo, then the one below the catalytic converter. I pulled the exhaust apart at the junction below and had a lot of fun getting to the lower cat bolts. Then I wiggled that out and took it to the exhaust shop to get a piece bent that would fit in there. You could just gut the cat, but I wanted the extra space there, and didn't want the bottleneck.
 

tdiblair

Veteran Member
Joined
May 16, 2005
Location
CT Yankee
TDI
Passat 2005 silver Passat Sedan & 2005 Wagon Stone Henge Gray
So here i am Dec of 2020 - my 2005 PASSAT TDI throws a check engine light - shop claims a clogged Catylitic Converter... this is now an obsolete part - No Dealer has them. Can't find an aftermarket for this car either!

Next I applied to State of CT to get a ' Waiver' for emissions - told them there is no after market Cat's for this car or from a dealer. it's not made anymore.
So our Cat's have two Chambers. Coming off the exhaust is a small Chamber which is the first flow of exhaust that goes into the " Oxidation" Chamber and further down the pipe the exhaust then goes into the bigger chamber called the Reduction Chamber. Both the Oxidation Chamber and the Reduction Chamber have a O2 sensors right in the front of them. If I get the CT Emissions Waiver - i'm hoping to gut both Oxidation and Reduction chamber or hollow them out - but does anyone know if the sensors that are in front of each chamber will set off a Check Engine Light that never goes off? I'm up for suggestions on how do deal with a clogged CaT Converter with no after market replacment that I can find. Any suggestions here? Blair
 

Mozambiquer

Vendor , w/Business number
Joined
Mar 21, 2015
Location
Versailles Missouri
TDI
2004 VW Touareg V10 TDI, 2012 Audi Q7 V6 TDI, 1998 VW Jetta TDI. 1982 VW Rabbit pickup, 2001 VW Jetta TDI, 2005 VW Passat wagon TDI X3, 2001 VW golf TDI, 1980 VW rabbit pickup,
So here i am Dec of 2020 - my 2005 PASSAT TDI throws a check engine light - shop claims a clogged Catylitic Converter... this is now an obsolete part - No Dealer has them. Can't find an aftermarket for this car either!

Next I applied to State of CT to get a ' Waiver' for emissions - told them there is no after market Cat's for this car or from a dealer. it's not made anymore.
So our Cat's have two Chambers. Coming off the exhaust is a small Chamber which is the first flow of exhaust that goes into the " Oxidation" Chamber and further down the pipe the exhaust then goes into the bigger chamber called the Reduction Chamber. Both the Oxidation Chamber and the Reduction Chamber have a O2 sensors right in the front of them. If I get the CT Emissions Waiver - i'm hoping to gut both Oxidation and Reduction chamber or hollow them out - but does anyone know if the sensors that are in front of each chamber will set off a Check Engine Light that never goes off? I'm up for suggestions on how do deal with a clogged CaT Converter with no after market replacment that I can find. Any suggestions here? Blair
Yeah, not sure which car you're talking about. My 2005 only had one chamber with an oxygen sensor before it. No other catalytic converter. Cutting it out did not trigger a check engine light.
Is your car a TDI and are you sure it's a 2005?
 

tdiblair

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Joined
May 16, 2005
Location
CT Yankee
TDI
Passat 2005 silver Passat Sedan & 2005 Wagon Stone Henge Gray
Yours would be the first BHW catalyst that I have seen clogged. That said, there is no cat monitoring on a BHW. The only O2 sensor is upstream of the cat. You can remove it, but the car will stink. I have used a magnaflow universal cat for the Jeep liberty CRD as a replacement for one BHW cat that was rattling due to loose guts. Pipe size was a bit large but I swelled the ends of the downpipe to suit and tig welded it in.

Hi Quick TD.....Thank you for your reply - you are the ONLY one so far who knows if that upstream O2 Sensor will be monitored on a 2005 BHW's brain. As to this being the first BHW with a clogged Cat - I'm wondering too if the shop had the diagnosis right - more on that below.

I lost most of my power while going full throttle onto a highway - check engine light came on. The shop I took it too said it was either turbo related or clogged waste gate or a clogged cat....When the mechanic pulled out the O2 Sensor he is said the problem was solved when the back pressure was eliminated. So he said - clogged cat. We will order a new one from VW. I am not sure he actually test drove the car or would be familiar what full power was on my car.

So the shop was off to buy a new Cat from a VW dealer when they found out - VW has it listed as an obsolete part and no longer offered. So I'd appreciate your opinion on the next step as I have not been under my car - don't know what the cat looks like - only the shop has. You are giving me a much better understanding of a 2005 BHW Passat TDI Cat. So do I have what I write below - correct?

If there is only (1) single O2 Sensor that is -up stream of both the Oxidation & Reduction Chambers of the CAT .that single upstream sensor will never be able to monitor if there is either a Oxidation or Reduction Chamber down stream of it. There could be nothing downstream and that sensor will never care. As you said , remove it if I want, but car will stink.

That would be wonderful news not to have a Check Engine Light coming on. I'm assuming that Single Sensor would be the positioned in front of the first Chamber near the engine or what would be the "Oxidation Chamber and NO sensor further down on the the REDUCTION CHAMBER. Wonderful news.

There is a guy who makes a Straight Pipe (Techtonnic Tuning) to eliminate that First Chamber of the Cat or what I think is called the Oxidation Chamber - and he has a port for the O2 Sensor which I would have installed back in so the car does not stink. That gets me somewhere except for the Reduction Chamber that may also be clogged but no longer available....I assume just hollow it out would be your advice. Again, i have my suspicions too if this really is the first clogged Cat with only 66,000 miles on a 15 year old car.

So I'm wondering, like you , if it really is a clogged CAT ? Should I try the following to test the repair shop's diagnosis. First disconnect my battery for 10 seconds and reconnect the battery - to get rid of the Check Engine Light. Next with the O2 Sensor un-threaded from its port and the back pressure relieved as it streams out the hole for the removed O-2 Sensor - i should be able to drive the car for a few miles and experience full power again and no check engine light coming on ?

If that works then I should get what Techtonics Tuning offers which is a Turbo Down Pipe - it gets rid of the Oxidation Chamber and thread the un-monitored O2 sensor into that Techtonics down pipe. This alone might eliminate the back pressure - if not- hollow our the honeycomb inside the Reduction Chamber. I assume i'll hear more turbo spool up noise but i'm assume all is good if i do this - as i'm out of alternatives.

Lastly and a ray of hope if you run into this again at your end and don't want to do the Jeep Liberty CRD....Ebay is the only source in the world that shows it has a Cat for a 2005, 2.0 Liter Diesel Passat - it does Not say BHW.....it says " L4" and i don't know what ' L-4' mean unless it's the shape of the engine or ' in-Line - 4 cylinder?? It says Direct Fit. Amazing if true! Do you think that is , magically, the right Cat still made for a BHW or does the L-4 they post suggest something else llke a gas engine? Other than the missing BHW term it does say 2005 PASSAT 2.0 Liter Diesel. The 3 guys offering this newly made Cat that no one else today still makes ( not even VW) do show a diagram of the Cat if you are familiar with the shape. Do you think it's worth the $465 risk -yes I asked for a response from one of those guys on Ebay but no reply yet and no response from the State of CT for an Emissions Waiver - but I'm hoping that will come. If the Ebay item is real...i'd rather just do it right - even though Emission Stations can not monitor Emissions from a diesel - I hear rumored. The cost of Emissions Equipment for the low % of diesels is just cost prohibited - so they just look for Cells when testing a Diesel.

Hope to hear from you - Blair

Blair
 

tdiblair

Veteran Member
Joined
May 16, 2005
Location
CT Yankee
TDI
Passat 2005 silver Passat Sedan & 2005 Wagon Stone Henge Gray
Yeah, not sure which car you're talking about. My 2005 only had one chamber with an oxygen sensor before it. No other catalytic converter. Cutting it out did not trigger a check engine light.
Is your car a TDI and are you sure it's a 2005?

Hey Mozambiquer, I have not been under my car in 4 years since i did a Tranny Fluid Flush - can't remember what the Cat Converter looks like but yes it is a 2005 Passat TDI. BHW DIESEL.....What threw me off, as I have little knowledge of Cat Converter's is in my search for a new Cat - which no one makes anymore, is a post on Ebay when you search for a Cat Converter for this car.
Ebay show 3 different guys selling new - stainless - made in USA. Mfg AP Technologies Cats for about $470. The diagram shows Two Chambers - i assume the first Chamber to be the OXIDATION CHAMBER - the 2nd Chamber that is down stream about 3 feet the REDUCTION CHAMBER

 

tdiblair

Veteran Member
Joined
May 16, 2005
Location
CT Yankee
TDI
Passat 2005 silver Passat Sedan & 2005 Wagon Stone Henge Gray
Yeah, not sure which car you're talking about. My 2005 only had one chamber with an oxygen sensor before it. No other catalytic converter. Cutting it out did not trigger a check engine light.
Is your car a TDI and are you sure it's a 2005?
Hi Mozamgiquer, Yes it is a 2005 Passat TDI - BHW DIESEL....what screwed me up is my search of an aftermarket Cat for this car and the diagrams I see on Ebay . I have not been under my car in years except for a Tranny Fluid change out and paid no attention to the Cat . So on Ebay they show 3 vendors still selling the same AP Technologies newly manufactured Cat for this car. If so amazing since no other vendor will waste his time - not even VW will offer this Cat - it's obsolete they say. So in the diagram of this Ebay Cat - it shows two chambers (I assume oxidation and reduction chamber - with each chamber having a port for a O2 sensor. So right off the bat i'm thinking these guys have a miss print as to the details of the Cat they are offering - they won't reply to me. So if you are saying One Chamber - One O2 sensor.......Don't waste my time with the Ebay Cat Converter saying its for a 2005 Passat TDI...2.0 Liter Diesel ? ......the add does not say BHW either... it says ' L-4'.......I have no clue what L-4 means except maybe ' In-Line 4 Cyliner? Any thoughts on the best way to solve a clogged Cat when no one offers a replacement? Blair
 

Mozambiquer

Vendor , w/Business number
Joined
Mar 21, 2015
Location
Versailles Missouri
TDI
2004 VW Touareg V10 TDI, 2012 Audi Q7 V6 TDI, 1998 VW Jetta TDI. 1982 VW Rabbit pickup, 2001 VW Jetta TDI, 2005 VW Passat wagon TDI X3, 2001 VW golf TDI, 1980 VW rabbit pickup,
I'm going to call balogna on the mechanics diagnosis, it doesn't sound like your mechanic knows what he's talking about.
The aftermarket ones with two chambers would be for the gasoline powered vehicles, not for the BHW. Many times the fitment on the online places is off.
The catalytic converter on these cars is in the downpipe, just after the turbocharger.

But, what is the problems you're having with your car? Does it run poorly and with low power? With only 66k miles on the car? I highly doubt that the cat is plugged. Mine had 230k miles and still had plenty of flow. I would recommend bringing the car to a shop that specializes in vw TDIs or foreign diesels. You can find a list of shops here on this forum.
If the problem is the cat, the techtonics tuning downpipe would work very well to clear up the exhaust system.
 

50harleyrider

Top Post Dawg
Joined
Jun 16, 2007
Location
charleston,wv
TDI
2005 B5.5 TDI/geared BSM, BV43A turbo,stage 2 TDTUNING. 2005 5sp manual passat tdi stage 2 tdtuning,BSM delete. 2015 Passat TDI 6sp manual.
If you start meddling with the stock exhaust, welcome drone-guarantee it's coming and will annoy the heck out of you. The bigger pipe you use, the worse it will be.
 
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