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So I recently ordered FI LTH and I'm very excited to get them installed. However, I know that I'll need HFC to tone down the exhaust fumes.
The FI LTH ship without welded HFC and also include (optional) straight midpipes all the way to the resonator (I think).
My current setup has an H welded in the midpipes and then straight to the mufflers.
Here is a pic (please excuse my bad art skills):
I would like:
- Avoid cutting/welding the headers portion of the LTH
- HFC somewhere. Dont care about passing emissions, and EC can disable any CEL.
- Keep my H pipe
- Keep the straight pipes to the muffler
My questions are:
- Is having HFC well after the original primaries still functional? E.g having HFC after H pipe?
- Is there any reason I shouldnt cut/weld the headers? Or is this okay to do, and then just put the HFC in there and problem solved!?
- How many hours should a legit shop charge me for this LTH install work? A reputable Euro shop near me quoted 6 hours, while EC Canada told me 10 hours. Any possibility to ***** the install up with an inexperienced shop?
- Do I need O2 extensions? EC shop also told me I will need "gaskets and hardware" and said this will be $148.
Thank you guys so much for taking the time to read and answer the questions! Look forward to updating you guys with my hearing losses.
Last edited by NotABaller; 08-04-2017 at 09:56 AM.
Ideally you'll listen to a catted car w/o an H-pipe first. The H-pipe may or may not "improve" the tone to your taste. Cats w/o an H- or Y-pipe generally preserve the essential characteristics of the original exhaust tone, you just get less of it. Catted with LTH is still plenty loud so choose the right cats for your purpose.
Ideally you'll listen to a catted car w/o an H-pipe first. The H-pipe may or may not "improve" the tone to your taste. Cats w/o an H- or Y-pipe generally preserve the essential characteristics of the original exhaust tone, you just get less of it. Catted with LTH is still plenty loud so choose the right cats for your purpose.
The only reason I have an H pipe on the first place is because I replaced my resonator with straights. I read that the stock res contains an H. Therefore we should place an H upstream to maintain the stock sound/tone.
I think this may change with LTH and the H pipe will be too raspy, and I may need to drop an X in instead.
Thanks for the helpful responses so far everyone, especially to Bart, the nice gentleman who took the time to email me with a picture included too! The advice is very much appreciated
Cats must be hot to work. Mount them directly after the headers. You won't need to cut the headers.
You will need to cut the midpipes that are coming with the headers, and have an exhaust shop install cats for you.
If you are not worried about emissions, why bother with cats.
If you think it's too loud, then get a set of Valvetronic rear mufflers.
Cats must be hot to work. Mount them directly after the headers. You won't need to cut the headers.
You will need to cut the midpipes that are coming with the headers, and have an exhaust shop install cats for you.
If you are not worried about emissions, why bother with cats.
If you think it's too loud, then get a set of Valvetronic rear mufflers.
Im not worried with emissions, but I'd still like cats so that I can still personally enjoy my car (which should be loud) while being less of a dick to the public
Thanks for the suggestions. Putting bolt-on HFC after LTH before midpipes would be nice. Will probably try this method
Cats must be hot to work. Mount them directly after the headers. You won't need to cut the headers.
Mounted that way I've monitored cat temps of 1,000ºF or 540ºC on a fully warmed up C63. That's in the upper end of the ideal range so there's probably at least some flexibility with mounting options. I can't imagine more than a 50ºF drop over 12" of exhaust pipe.
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Originally Posted by Savage-wp
If you are not worried about emissions, why bother with cats. If you think it's too loud, then get a set of Valvetronic rear mufflers.
I actually think cats are a good way of tuning the sound and being a good citizen at the same time. By same day, same time dyno tests, I saw RWHP loss on a Dyno Dynamics (from least restrictive 100 cell cats to most restrictive CA-legal cats) range between 6-19 HP.
Do you have pics of your set up? I have plm hfc and made he mistake of installing them too far down stream. I've spoken to serge from benzworks and mike has also put together a custom mid H pipe for me. We are just concerned that the HFC won't fit immediately after the collector on the LtH due to the width. Which HFC and what was the width?
I may be able to give you a very qualified answer, but I am not sure how useful it would be:
So I have access to the fueling tables for a 2002 Subaru with oxygen sensor Before (upstream) of the main converter and a 2005 Japan market Subaru with oxygen sensor After (downstream) the converter. I can tell you what the differences are in the table, but then you'd have to take this teory ad adapt the table of the C63 for this.
For a rally car, the support team has of course no problem tuning for the sensor position.
I would say with having that C63 tuning software and maybe a bit of work on the right table, should be fine. I would say a Weistech or EC should have no problem adapting a tune for this.
Currently, EC has been working on my car for a few months now looking for the culprit of missing 60ish hp. Found a vaccum leak repaired it but my fuel trims are still >10% and apparently my timing is off over 4K Rpm.
so something else is going off.
My hfc are below my LTH but it seems too wide as I mentioned before. It has been suggested to me that it may be throwing off my fueling as my cats aren't
getting hot enough to kick on.
Getting back to the graph. Are these with the 200 cell nameless exhaust tips? I understand the general gist of the before and after graph. Is thus correlating to just the upstream o2 vs downstream o2? Or is the one above upstream stock and the second with the 200 cell nameless cats at the exhaust?
I'm sure I sound like an ignorant but I'm barely starting to pick up and have Im sorry if my question is confusing. Its hard to articulate clearly my question with my novice level of understanding. I understand AFR, fuel trims, and their relationship with o2s, temps and mafs. The pcm always fluctuating to be 1.47:1 but I don't quite understand the graph. If Y axis is RPM the X axis is load shouldn't it be between 0-100%.
No, the factory knows exactly how to change the tune in regard to the position of the oxygen sensor vs the converter, because they pay enough salaries and fund research.
For "civilians" like us, we have to have the right software and look at what they did and draw conclusions.
In order to start this, the perfect case is an "all things being equal" case.
That's what the above is.
One of them is the factory tune with oxygen sensor before converter and one with sensor after the converter.
The next step is to work on the two and overlay them and pinpoint the changes.
Then extrapolate from them to your particular situation and begin testing a tune with backup from a separate wideband that hopefully is loggable into the same logging software as the OEM one, to where you can compare and verify the readings of the OEM.
Edit:
Sorry what you're looking at above is not a graph, it's a 3D table that the ECU executes. It's a part of the tune.
So the ECU looks up the values of the afr based on reading the conditions on the x and y.
Changing the numbers and then uploading gets the ECU to look for a different afr.
The consequences of a mismatch are several, one of which are the trims.
Another thing that I need to explain is that our cars run in closed loop except under decel. The Subaru runs in open loop as soon as you become serious with the throttle.
This does not mean that the closed loop doesn't have correction tables (I don't know this for a fact, I have not seen Mercedes tables), and if they do have correction tables then that's where you implement the repositioning of the converter, in the form of corrections to afr readings (again I am guessing).
Currently, EC has been working on my car for a few months now looking for the culprit of missing 60ish hp. Found a vaccum leak repaired it but my fuel trims are still >10% and apparently my timing is off over 4K Rpm.
so something else is going off.
My hfc are below my LTH but it seems too wide as I mentioned before. It has been suggested to me that it may be throwing off my fueling as my cats aren't
getting hot enough to kick on.
Getting back to the graph. Are these with the 200 cell nameless exhaust tips? I understand the general gist of the before and after graph. Is thus correlating to just the upstream o2 vs downstream o2? Or is the one above upstream stock and the second with the 200 cell nameless cats at the exhaust?
I'm sure I sound like an ignorant but I'm barely starting to pick up and have Im sorry if my question is confusing. Its hard to articulate clearly my question with my novice level of understanding. I understand AFR, fuel trims, and their relationship with o2s, temps and mafs. The pcm always fluctuating to be 1.47:1 but I don't quite understand the graph. If Y axis is RPM the X axis is load shouldn't it be between 0-100%.
Cats should have zero affect on the air fuel because the primary O2 sensors that measure the gas for tuning are before the cats.
Did you install you primary O2 sensors after the cats?
IIRC 1350ºF or so is considered safe max temp. Your temps are crazy high.
Any idea what would make cars run that high? Cats going bad? They are 200 cell metallic core cats right after the last bend of the LTHabout 6" into the mid pipes.
Any idea what would make cars run that high? Cats going bad? They are 200 cell metallic core cats right after the last bend of the LTHabout 6" into the mid pipes.
Conventional wisdom re. higher than normal cat temps is that unburned gasses are entering the cat. Likely there are other possible causes but I'm no expert in this area. Like I said, I've seen this setup hold rock steady at 1,000ºF so I'm at a loss to offer anything definitive.
Any idea what would make cars run that high? Cats going bad? They are 200 cell metallic core cats right after the last bend of the LTHabout 6" into the mid pipes.
I was curious and searched this tonight. There's not a lot of info out there but this is a good general explanation.
Overheated Appearance
The chemical substrate inside the catalytic converter can melt, super-heated by an overly rich air-fuel condition, spark plug miss or other ignition malfunction. Generally converters that have a 200 degree F difference or more between the inlet and the outlet side of the converter at normal cruising speed show indications of interior overheating and can visibly turn the outside shell casing black, with a rainbow- colored hue. An infrared pyrometer or contact temperature probe is used to determine if the converter is working too hard to expel excessive heat.
Clogging
When the substrate within the converter melts either the platinum-palladium coating or the aluminum oxide honeycomb material, it forms an impenetrable slag, which blocks off the exhaust flow, clogging the passages. This creates a severe back pressure that affects engine performance. A clogged converter can cause rough idle, engine hesitation upon acceleration, weakened power, hard-starting and, in some cases, a no-start condition. Faulty components that cause overly rich fuel-air mixture, like cracked distributor caps, faulty EGR valves, incorrect timing or dirty fuel injectors can all cause melting. This symptom can be diagnosed by using a vacuum gauge on the intake manifold, or an exhaust back-pressure pressure gauge before and after the converter.
Fouling
Fouling results inside the catalytic converter when excess unburned fuel is present. The core temperature of the converter case does not have to reach excessive temperature, such as a meltdown of the substrate, but higher than normal temperatures will result, as well as some increased back pressure. When the substrate chemicals are diluted, raw gas frequently exits the exhaust pipe in a black cloud. The substrate can actually become wet, or fuel-fouled. Gas mileage suffers, as well as acceleration and overall power.
Getting my plumbing redone with Mikes power H pipe tomorrow
Imgur.com/a/wWMt2
I'm hoping to move my HFC to where the Collectors on my LTH end...and Mike fabricated a custom H pipe to a res delete to my agency power cat back. Do my cats look discolored? I know my headers have that rainbow hue but not my cats
I was curious and searched this tonight. There's not a lot of info out there but this is a good general explanation.
Overheated Appearance
The chemical substrate inside the catalytic converter can melt, super-heated by an overly rich air-fuel condition, spark plug miss or other ignition malfunction. Generally converters that have a 200 degree F difference or more between the inlet and the outlet side of the converter at normal cruising speed show indications of interior overheating and can visibly turn the outside shell casing black, with a rainbow- colored hue. An infrared pyrometer or contact temperature probe is used to determine if the converter is working too hard to expel excessive heat.
Clogging
When the substrate within the converter melts either the platinum-palladium coating or the aluminum oxide honeycomb material, it forms an impenetrable slag, which blocks off the exhaust flow, clogging the passages. This creates a severe back pressure that affects engine performance. A clogged converter can cause rough idle, engine hesitation upon acceleration, weakened power, hard-starting and, in some cases, a no-start condition. Faulty components that cause overly rich fuel-air mixture, like cracked distributor caps, faulty EGR valves, incorrect timing or dirty fuel injectors can all cause melting. This symptom can be diagnosed by using a vacuum gauge on the intake manifold, or an exhaust back-pressure pressure gauge before and after the converter.
Fouling
Fouling results inside the catalytic converter when excess unburned fuel is present. The core temperature of the converter case does not have to reach excessive temperature, such as a meltdown of the substrate, but higher than normal temperatures will result, as well as some increased back pressure. When the substrate chemicals are diluted, raw gas frequently exits the exhaust pipe in a black cloud. The substrate can actually become wet, or fuel-fouled. Gas mileage suffers, as well as acceleration and overall power.
Useful info...good to know
Retarded ignition timing can be a culprit for some of the symptoms above and generally an ECU will do this to control rpm when it senses a vacuum leak.
What I was trying to also tell you is that with indirect temperature measurement, a factor can be in place that skews the readings in an aftermarket rig.
It could be that not many with aftermarket converters were worried about reading converter temperature, so there is no knowledge base of what happens to the calculated temperature reading, when you change converter type from the normal ceramic to the metal substrate.
BTW, if I did this, I would hope to find a good tuner and get a tune that takes advantage of having metal substrate.
The metal substrate advantage IS that it tolerates higher temperatures.
Therefore when having it, you tune in such way as to have higher EGTs than stock, in order to materialize that in gains.
08-04-2017, 09:51 AM
