[svsantosh]

Purpose of this experiment

1) How to Decat? Time and Money?

2) PUC shops in India - are they equipped to trap the decat cars with their pants... err, catcon out?

3) What is the engine-head-backpressure that everyone is speaking of? Is it a truth or a myth? (Solved - Read on...!!)

4) Decat with Stock Remap, what changes - Fuel Efficiency, Power, driveability, smells, PUC?

Before I go straight to DeCat, let me clank my plates/spoons for my gurus & their experiences and also my own.

My alma-mater for learning the ropes about EGR

https://www.team-bhp.com/forum/diy-d...-turbo-di.html (DIY: How to Block the EGR Valve on a Turbo DI)

This thread by a4anurag was an eye opener for me...

https://www.team-bhp.com/forum/diy-d...-ddis-mjd.html (DIY: EGR Valve Cleaning (1.3L DDiS / MJD))

...which led me to do this, with confidence

https://www.team-bhp.com/forum/diy-d...-blanking.html (DIY : Chevrolet Sail UVA 1.3 TDCI - EGR blanking)

Its been 40,000+Kms since I blanked the EGR. No issues till date and definetly a marginal 5-7% increase in power and fuel efficiency. I would not go back to the original state now that I have tasted the benefits of EGR blank (in my case its a Free-Flow-EGR, I didnt want to choke up the EGR component, it now works BAU but doesnt let anything inside the inlet manifold)

Recently I happened to read a lot about DECAT, pros and cons, Remap or not, etc...

https://www.team-bhp.com/forum/techn...its-worth.html (Removing a Catalytic Converter (Cat Con) - Do you guys think its worth it?)

Ideally I wanted to post this (thread's) content in above thread, but I wanted to keep the DIY part and PUC-Shop's Outdated equipment for a different topic of discussion if possible.

And Sankar's post made me take the final call/plunge

https://www.team-bhp.com/forum/techn...ml#post4149961 (Removing a Catalytic Converter (Cat Con) - Do you guys think its worth it?)

Side Note about *REMAP*

I am sticking to stock map for now, really not interested to push a "1.4LacKms/6yrs/1.3DDiS" daily 'bread and butter' car to its limits. Intent of all my efforts is do minimalistic mods/unmods to better the tiny diesel burners capabilities. Many thanks to various threads on TBhp (Doc Narens SCross, Tharians Figo Aspire, Sankar's Swift & so many other Bangalore boys and their threads on bangalore remap stories, but I will avoid Remap now)

[svsantosh]

This is the easy part.

Make two flanges identical to the ones on your cars catcon.







Get some 1mm to 1.5mm thick SS bends and pipe lengths.









You need basic welding knowledge and a welding machine and presto - the cat is out of the car.

[svsantosh]

What does your 100-150Rs tell you and the government every 180 days? That you driving your car daily on public roads is equal to planting a sapling along the road side? Or that your car is within the stipulated pollutant limits & norms, provided is is tested in accordance to the procedures laid down by some department in the Honb'le Govt of your respective state or the overall National MVA?

I wonder what exactly is the engineering, policies, decisions behind the PUC shops, their machines, equipments, processes, etc etc. See my cars history of emission certs from last two times. (Third was taken recently to disprove Catcon is essential).



Case 1 - EGR bypassed, catcon was cleaned recently, PUC pass

Case 2 - EGR bypassed, catcon was driven 6 months, HSU% slightly on higherside

Case 3 - Decat (recently) - CLEANEST EMISSION CERT IN A LONG TIME

I was thinking to myself, "Who is making a bigger fool of whom here?"

What is HSU? What role does the catcon play in reacting with the exhuast gases, becoming red hot and letting out smoke as a byproduct of cat-conv process? And how is the smoke (color? density?) a indicator of how clean your car is? I feel its stupid to have HSU% as a indicator to check the pollution levels of your diesel engine, because without a catcon your car is running the cleanest... I am not telling it, the govt approved process/equipments are telling so.

[svsantosh]

Before talking about pressure, let me share some basic observations made during the course of this experiment.

Catcon surface temp outside the fat bottle area, at full RPM (similar car, 1.3MJD Punto, similar age and odo)



My Cars exhaust manifold junction (where the input turbo spools) at full RPM



Same time as above, full RPM, my Decat downpipe surface temp



One should know the Catcons 1st level filter in principle is a barrier to fluid flow (exhaust gases) and it creates a high pressure zone between the engine's manifold and catcons 1st filter.

Basic design criteria for any turbine is "Pressure, Temperature & Flow". The automobile turbo AKA turbine, is designed according to the pressure inside the impeller housing area (the casting housing which draws from the exhaust of engine), temperature of exhaust gases (I think the downstream catalyst reaction should not have any bearing on the gases upstream at the turbo wheel) and finally flow - the volume of exhaust gases hitting the vanes/blades.

Decat & Backpressure issue

In effect a turbo's performance is guaranteed only if all its design parameters are adhered to. This is even more a problem in FGT which has a narrow band of operation. Now in a DeCat the backpressure, or inlet vanes pressure is drastically reduced, while the exhaust gases temp & flow are more or less similar. This WILL CREATE a BIG PROBLEM in driveability, especially if you know your car too well and can sense all minor changes in its behavior. You will notice a immediate drop in so-called power, but ideally is the lack of boost in low range that will make your head crave for the power but it kicks in, albeit a fraction of second slower.

Not a deal breaker, but a ReMap can overcome this issue by bringing back the original pressure values, I am assuming by burning a tad more fuel to make up the pressure. There is nothing else left to control I guess.

I have driven the car for a little over 1000Kms after the Decat, I have got used to the low-pressure/no-boost phenomenon and have adjusted my throttle inputs to make up for the extra gas and mentally adjusted my gear change pattern. It is a pain for first few 100kms, but none the less its not something impossible.

So, I hope this clarifies the everlasting controversy of backpressure in engines and especially the turbo'd ones. Ways to overcome this include force feed input air or a bigger turbo, or a VGT, or a REMAP. Its ones choice.

[Jeroen]

How does this work in India? Is it legal to take the cat out?
I know in most of Europe, the basic rule is if the car was factory equipped with a cat, you can’t take it out legally.

Jeroen

[svsantosh]

Decat with Stock Map, what changes - Fuel Efficiency, Power, driveability, smells, sounds, PUC

To begin with the driveability changes permanently. There are many ways to overcome this, but please begin with a Remap.

Smells - It does smell like my old CJ340 or Armada Grand, say a old 407 or a sumo (old diesel people movers, but only if you got some tail wind) its not that pronounced.

Sounds - There is very minor turbo whistle audible, but very hardly noticeable

Power - Low end torque is missing because of the altered turbo behavior, mid range and top end remains the same, not a very noticeable difference. (Again, a Remap can do wonders I suppose)

PUC - Duh, its a Farce! I am on the lookout for a industrial gases testing lab, I am ready to volunteer my car for a 'real' test of effects of Decat on our environment. I am sure its belching out unacceptable level of heavy metals without being caught by the current PUC Standards.
Time to upgrade and overhaul our PUC industry inside out.

Fuel Efficiency - It was not a surprise, it increased by a good ~7%, I am yet to complete the tests, may be a bit more close to ~10%. Only contributor is gases are flowing freely and there is lesser resistance on the pistons to push out the exhaust gases.



Side Observations - I noticed the coolant was running hotter at 90'C, but that was on a very hot day last week in Bangalore, 34-35'C in peak of noon with AC in full blast. The radiator fan was constantly working, got the SS down pipe wrapped in glass wool belt from a local enfield bullet spare shop. I was suspecting the engine block taking in a lot of temp from the surface of the nearby SS pipe, or even the radiator taking in heat from the SS Pipe.



Coolant is staying at 70-75'C, need to clean the intercooler & radiator surface with a pressure wash to see if there is dirt built up.

After one or two tankfuls, I will shelve this experiment and once I find a fully equipped gas analysis lab I will refit this decat pipe.

Project costing :
Flanges - 600Rs
SS Pipes/Bends - 500Rs
SS Welding - 500Rs
PUC to prove a point - 125Rs
Silencer Wrap - 350Rs
Total - 2075Rs

Thanks to a bunch of good friends who are fellow TBhp'ians and assisted in the DIY.

[Reinhard]

Originally Posted by Jeroen

How does this work in India? Is it legal to take the cat out?
I know in most of Europe, the basic rule is if the car was factory equipped with a cat, you can’t take it out legally.
Jeroen

It is illegal in India too. Any changes to stock exhaust system are actually illegal on paper at least. But then enforcement of this rule is a different thing altogether. For now - they have started coming down hard on motor-cyclists with modified exhausts. Not much attention on the cars other than the standard emission tests every 6 months.

[svsantosh]

As much as I dont want to post 'Illegal' contents on Tbhp, I am more concerned about the incorrect method that the entire country is testing its cars, bikes, autos, trucks, vans, etc. Who knows, if done correctly, more than 70-80% may need some repairs to stop polluting.

[Reinhard]

Originally Posted by svsantosh

As much as I dont want to post 'Illegal' contents on Tbhp, I am more concerned about the incorrect method that the entire country is testing its cars, bikes, autos, trucks, vans, etc. Who knows, if done correctly, more than 70-80% may need some repairs to stop polluting.

Indeed your test results are quite eye opening. A car without cat-con is giving the cleanest emission test result! Wicked. Not a huge surprise for me, looking at the devices being used since decades for these tests & the level to which our fellow Indians go to rig scanning devices / meters for commercial gains. I don't have a huge hope that the "online" PUC tests will make a big difference to this either.

Anyway - don't want to deviate too much from the main topic, there are other threads already discussing plenty about weak emission test practices in many parts of the country.

Thanks for posting the test results. Food for thought if taken in the right spirit indeed. (I don't personally agree with removing a cat-con from a vehicle of course.)

[Kosfactor]

Originally Posted by svsantosh

Side Observations - I noticed the coolant was running hotter at 90'C, but that was on a very hot day last week in Bangalore, 34-35'C in peak of noon with AC in full blast. The radiator fan was constantly working, got the SS down pipe wrapped in glass wool belt from a local enfield bullet spare shop. I was suspecting the engine block taking in a lot of temp from the surface of the nearby SS pipe, or even the radiator taking in heat from the SS Pipe.

Attachment 1982953

Coolant is staying at 70-75'C, need to clean the intercooler & radiator surface with a pressure wash to see if there is dirt built up.

It requires quite a bit of courage to do what you are doing, tinkering with CRDI - Turbo - EGR engines

How hot is the coolant supposed to run? The old vehicle`s that had temperature gauge and used to display it as 40-80-120 IIRC, usually hovering around 80 mark.

I would not worry about the legal aspects of it , because any mod can be deemed illegal, from stickers to sunfilms to crash guards to roof racks to tuning box to headlamp upgrade to even writing something cool on your windshield.

Unfortunately we do not have a Gale banks here in India for performance diesel products that stay within the legal system.

[svsantosh]

Originally Posted by Kosfactor

2. OP`s car runs hot since the EGR cooled exhaust is no longer available to deal with all that fresh air, the exhaust temp goes up , piston is not cooled properly, turbo is getting roasted and gives up the project (just scenarios)....

Refer to my other EGR thread (in opening post), my EGR is not only blanked but is functioning albeit it's letting out the pre-cooled exhaust gases directly outside of the engine. I am also constantly monitoring and intake air temp and that's not changed a bit.

Originally Posted by Reinhard

Indeed your test results are quite eye opening. A car without cat-con is giving the cleanest emission test result! Wicked. Not a huge surprise for me, looking at the devices being used since decades for these tests & the level to which our fellow Indians go to rig scanning devices / meters for commercial gains. I don't have a huge hope that the "online" PUC tests will make a big difference to this either

Actually you got me wrong here. I am saying that what the government is checking in the name of PUC (what ever that HSU% means) is actually cleaner without a Catcon. I know I may sound very stupid here, but my hunch is government is looking for the wrong component in emissions and I want this thread to be an eye opener. I can vouch for the 2 emission centers I frequent, they dont fudge as long as I know. But there is something very wrong that our current PUC norms are checking for.

[GTO]

Mod Note: No more posts please on whether the thread should be allowed or not. We will allow it, just as we do with so many others on free-flow exhausts, engine swaps, remaps etc. Thanks for the support & understanding

[Motard_Blr]

A lot of performance-seeking car owners do this modification with the objective of reducing exhaust back pressure to improve engine power. But there are some misconceptions about catalytic converters and 2 in particular come to mind:

Catalytic converters limit power: the truth is that yes, but only in some vehicles. Some car manufacturers try to save money by using smaller catalytic converters and those do cause higher back pressure. But this is not a rule. Many cars run equally well without a catalytic converter and this proves that the cat has no negative effect on exhaust back pressure.

Catalytic converters reduce or eliminate smoke: this is not true. Catalytic converters are mainly used to reduce carbon monoxide and unburnt hydrocarbons (fuel) in exhaust gas. Smoke is actually composed of very fine particles of carbon and ash that are so small that they stay suspended in gases (air or exhaust gas). Though they are very small, they don't spend enough time inside the converter to be burnt off to carbon dioxide. To reduce or eliminate diesel smoke, a diesel particulate filter (DPF) is required.


The exhaust emission readings only show smoke measurements, not HC or CO. Maybe there would have been a difference if these, too, were measured before and after de-cat.


BTW, a known limitation of infrared thermometers is that they measure different temperatures depending on the reflectivity of the surface being measured. A highly reflective surface, such as polished stainless steel, will cause an IR thermometer to display a lower temperature. So this means that manifold temperature as seen in the photo cannot be trusted. The correct way to measure the temperature would be with a contact-type thermocouple.

[hserus]

Originally Posted by svsantosh

Coolant is staying at 70-75'C, need to clean the intercooler & radiator surface with a pressure wash to see if there is dirt built up.

God no. Don't pressure wash your intercooler unless you like the fins bent due to too high a pressure. Once you've disconnected it and drained the oil as much as you can, spray wd40 inside and outside it and let it soak in, drain to let that wash away the stuck oil residues. Then wash it with kerosene after you have let the wd40 + oil drain out.

The same with the radiator, good old scotch brite will take care of it for minor deposits. If you've been filling tap water in your coolant reservoir for a while, or the original coolant was mixed with tap instead of distilled water, you'll need caustic chemicals to clean the residue out, leave that to a specialist.

[Dr.Naren]

Thanks for the detailed thread

Originally Posted by svsantosh

Project costing :
Flanges - 600Rs
SS Pipes/Bends - 500Rs
SS Welding - 500Rs

This is very interesting, never knew one could DIY a decat downpipe for just 1.6k