Best place for a Cat?

[johnc]

WOW! There are some really pompous people posting on my thread. Maybe I shouldn't be allowed to post here any more because of my ignorance. what kind of crap posts is that. for those of you that believe your are the end all be all of Z car information you can suck it! I've been posting her for years and I never come across such crap.

 

 

WTF? You start a thread that turns into one of the best technical threads regarding emission controls for our cars and you get your panties in a wad because you don't like someone's tone? It would be better if you just say thanks and go on your way with your cat install.

[BLOZ UP]

I'm still being told that modern 3-way cats are always operational, and need 14.7 to be most effective. Not just during transitions.

 

It's not like even brand new engines burn completely on every cylinder every time, right? So, that's what the cats for, right?

 

But I at least let Tony D and the like convince me to skip putting a cat on my new exhaust build. Even if I might be moving to California in a couple years--I will keep my main residence in TX. Ehem.

Edited February 22, 2011 by BLOZ UP

[rayaapp2]

I'm still being told that modern 3-way cats are always operational, and need 14.7 to be most effective. Not just during transitions.

 

It's not like even brand new engines burn completely on every cylinder every time, right? So, that's what the cats for, right?

 

But I at least let Tony D and the like convince me to skip putting a cat on my new exhaust build. Even if I might be moving to California in a couple years--I will keep my main residence in TX. Ehem.

 

Might I suggest a little more reading on the subject.

"Around" 14.7 is more accurate. To understand this more it would help if you read up on "Fuel Trim". That is a whole other subject though. Fuel trim will give you some of the answers you are searching for. There is a reason O2 sensors swing in voltage readings and it has nothing to do with the sensor. The sensor is simply a galvanic battery. Checking up on the fuel trim will give you more insight into this. The subject of fuel trim will eventually lead back to cat support. Modern and even not so modern ECU's are totally capable of keeping a rock solid 14.7 AFR at all times. Ask yourself why they dont. This will also fill in the operational and effective questions as well. Once you grasp fuel trim you can put the 2 together.

 

Dont let anyone convince you of anything over the internet. I and others are simply trying to give you the tools to figure it out on your own. Your totally welcome to try this on your own and possibly prove us wrong. There are a few guys out there that have tried. Some have failed, some have had success, and some dont know why either way. Treat this like a high school experiment and collect the data. I posted the info so that you and others would have an idea of the obstacles not to say it can never be done. Before doing something like this I feel that one should have an idea of how and why something works... a good idea. When re-engineering something of this caliber that is always a good idea. And when you fail find out why and try again until you have an answer. Isnt that how we learn?

 

Mixing and matching parts that weren't designed to work together isnt much of a logical way of approaching the situation. Learning about the parts and re-designing them to function together is a much more logical way to approach this, at least I think so. And if it doesnt work find out why and make corrections.

 

Another thing that should be read up on in depth is the word 'catalyst'. Understand what a catalyst is and how it works in the world of chemistry(not just cars). Then apply it to the cat we are talking about. Understand how a catalyst works, and how it fails. This should also bring insight on this topic.

Edited February 22, 2011 by rayaapp2

[Neverdone]

 

I'd try right there.

[Tony D]

I find in cold weather, that is about the desired placement for a cat on a vehicle. It seems like a universal fitment.

[zguy36]

WTF? You start a thread that turns into one of the best technical threads regarding emission controls for our cars and you get your panties in a wad because you don't like someone's tone? It would be better if you just say thanks and go on your way with your cat install.

 

 

I've been a member of this forum for quite a while, and have noticed that people with "knowledge" get away with a lot more "tone" than people without "knowledge". I agree that this thread has valuable information about vehicle emissions, but really struggle with the way that it is passed down.

Edited February 23, 2011 by zguy36

[BLOZ UP]

Might I suggest a little more reading on the subject.

"Around" 14.7 is more accurate. To understand this more it would help if you read up on "Fuel Trim". That is a whole other subject though. Fuel trim will give you some of the answers you are searching for. There is a reason O2 sensors swing in voltage readings and it has nothing to do with the sensor. The sensor is simply a galvanic battery. Checking up on the fuel trim will give you more insight into this. The subject of fuel trim will eventually lead back to cat support. Modern and even not so modern ECU's are totally capable of keeping a rock solid 14.7 AFR at all times. Ask yourself why they dont. This will also fill in the operational and effective questions as well. Once you grasp fuel trim you can put the 2 together.

 

“Fuel trim†is the amount of fuel added or subtracted by the PCM. The PCM starts out with a baseline fuel/air mixture that it believes will achieve a stoichiometric ratio. When the feedback from the HO2 sensors shows a deviation, the PCM adjusts the amount of fuel the injectors deliver, in an effort to hit the stoichiometric goal. It either adds or subtracts fuel from the baseline.

Is that not an accurate definition? I'm familiar with fuel trims, but they way you worded it makes it sound like something completely different...

[studioti]

I've been a member of this forum for quite a while, and have noticed that people with "knowledge" get away with a lot more "tone" than people without "knowledge". I agree that this thread has valuable information about vehicle emissions, but really struggle with the way that it is passed down.

 

100% Agreed. There is some very useful information on this thread and the majority of this forum, but sometimes people get blasted for questions only extensive searching would answer.

[Tony D]

"but sometimes people get blasted for questions only extensive searching would answer. "

 

Excuse me, but I need some clarification, who is 'getting blasted' in this thread? Someone asked a question, others answered it, there was clarification, and then further discussion and education on what is actually going on.

 

Where is the 'blasting' in the responses?

 

And god forbid someone 'search extensively'...

 

As to this comment:

"I've been a member of this forum for quite a while, and have noticed that people with "knowledge" get away with a lot more "tone" than people without "knowledge". I agree that this thread has valuable information about vehicle emissions, but really struggle with the way that it is passed down. "

 

If you want information, learn to be humble when asking for it, and when you get it THANK PEOPLE FOR IT! Putting on an attitude is NOT grattitude. Nobody HAS to answer anybody else's dumbarsed questions. If they do, consider yourself lucky. Some of us are easily happy without the internet and can get along just fine without ever 'sharing' what we know with someone who doesn't like the way information is presented to them FREE OF CHARGE AND ANY PAIN OR FINANCIAL OUTLAY. <edit> "Who is John Galt?"<edit>

 

Christ, if I was this picky about it when I was a kid, I would have gotten lugnuts and sparkplugs thrown at me and been scolded for not thinking before I asked "zuch a sthupid qvestion!"

 

Oh waitaminit, that DID happen to me when I asked questions where I didn't think about it first. Excuse me... did someone throw spark plugs or lugnuts at you in any of the responses?

 

I didn't think so...

Edited February 25, 2011 by Tony D

[rayaapp2]

Is that not an accurate definition? I'm familiar with fuel trims, but they way you worded it makes it sound like something completely different...

 

You will need to read up on Fuel Trim in depth, an abbreviated definition is not what your looking for. Fuel Trim "Strategies STFT" may yield better results. Ive never searched google for such things though. I had to take several courses in prep for my Ca Smog License that came with books that yielded the information.

FromFord Fuel Injection O2 info "A/F Biasing"

"OVERVIEW

 

The goals of the closed loop strategy are:

 

- add the capability of introducing A/F ratio biasing,

 

- maximize the feedback limit cycle frequency for all bias values, and

 

- maintain a simple calibration procedure to describe the closed loop limit

cycle.

 

The fuel flow is driven in a limit cycle manner about stoichiometry. Using

the EGO (Exhaust Gas Oxygen) sensor, the computer increases or decreases the

injector pulsewidths in a controlled manner. If the EGO reads rich, the

pulsewidths will be decreased (made leaner) at a calculated rate. If the EGO

reads lean, the pulsewidths will be increased (made richer) at a calculated

rate.

 

When an EGO switch occurs, an instantaneous change (or "jumpback") is made in

the A/F ratio back towards stoichiometry. The jump is made relative to the

A/F ratio (LAMBSE) value at the EGO switch.

 

The limit cycle can be biased to operate on the average richer or leaner of

stoichiometry.

 

An example of the closed loop limit cycle is shown on the next page. LIMIT CYCLE DESCRIPTION

 

{Text diagram here of the closed-loop limit cycle and relevant HEGO signal}

 

***** NOTE *****

 

The direction of the bias is controlled by the sign of the bias value. If

the bias term is negative, a rich bias is indicated. If the sign of the bias

term is positive, a lean bias is indicated."

 

 

This is all incorporated under fuel trim information usually because it is micro managed by the ecu under STFT(short term fuel trim) and it is called A/F Biasing. Though I cannot say how many sources on the internet will provide you with more of an answer than "the O2 simply swings in voltage".

Stay away from old GM fuel trim, unless your willing to take the time to learn their number system OR you understand Hexadecimal(though they were the Domestic forerunner). Manufactures all had their own types of fuel trim systems before OBDII Compliance.

 

LTFT should also be included for a full picture of the situation though. Its much more complicated than just ECU adding and subtracting fuel to hold stioch. Besides the fact that the ECU doesnt hold it at stioch at all. If you dont find a ton of Fuel trim stategy your looking in the wrong places. You may have to dig through manufacture literature for update courses to find the info your searching for. There is enough info on Fuel trim to teach a 6 hour day X 5 day course on it at least.

Edited February 25, 2011 by rayaapp2

[Tony D]

I have to say the explanations in the FSM for the 1994 Camaro were very informative. It really opened my eyes to how sophisticated the OEM's had become in response to the OBDII requirements.

It is this architecture that the next generation of 'self tuning' aftermarket ECUs is based. They use that short term and long term fuel trim logic to reprogram the flash memory or put it in NVRAM on the chip so that the more you drive the car, the closer you get to a 'perfect' tune for that specific engine---then when a sensor fails you drive on a FAR better curve 'limp home' than the factory could EVER put together in a generic form.

 

The OEM gets you close, the fuel trim and it's learning routines tailor the ECU to your specific engine.

 

The key is the sensor failure though---you end up not toasting a cat like on the old systems because the new ECU's give a far more complete map and don't necessarily go 'rich safe' any longer.

 

For us, the exciting thing is the aftermarket applications. After reading the GM FSM on the Camaro in preparation for using Tunercat on my buds 94 into 74 Camaro engine swap, I decided if I had a GM I'd keep the factory ECU and simply use a utility like Tunercat to tailor the GM ECU to what I needed it to do.

 

The focus on 'switching' though is the key. It's a digital signal that can be interpreted (though I understand the WBO2's may be considered analog due to the 1-5VDV output) using a NBO2 you had a switched signal which is very hard to correct for with a PID loop---you tailor it to watch for the switch and then set your gain, etc to compensate and keep the fuel control out of Hysterisis. With a 1-5VDC signal porportional offset from time integral is easier to gauge as you have a larger scale, more resolution. The more resolution you have to go to your set target point, the easier it is to set up the gain and resets to precisely track quick transients.

 

But this is more than I want to talk about when dealing with mixture control. I just spent four days on a system with no capacitance and a machine 4X as large as it needs to be with only a 30% turndown possiblity...and was tuning it's PID lopops to respond to demand swings AND keep it under a given MW/Day power consumption figure.

 

I kinda fell short. The loops could not be tuned fast enough given the hardware. Back to the drawing board. REV3 coming up... And I'll be on the plane again...

[rayaapp2]

WOW! There are some really pompous people posting on my thread. Maybe I shouldn't be allowed to post here any more because of my ignorance. what kind of crap posts is that. for those of you that believe your are the end all be all of Z car information you can suck it! I've been posting her for years and I never come across such crap.

 

None of you asked me if I had adjusted my carbs ... did you! None of you asked me if I replaced the hatch seals (yes even the antenna drain) did you!

 

Maybe I've adjusted the carbs to the point at which the care runs too lean and then adjusted it back to the point of proper afr's. Maybe I did but you'll never know ... because none of you asked. Oh yeah... my tail pipe is pointed at the ground.

 

There were a few good posts and I appreciate your CONSTRUCTIVE help and information. I always want to learn new things about my Z car but I want to learn it from people that aren't trying to prove how much smarter they are that the rest of the morons on the web site. Maybe follow what your mother told you ... if you don't have anything nice to say... DON'T SAY ANYTHING AT ALL!

 

Now, I understand that I might get busted by the mods for this post but at this point I don't care. I was going to post some pictures of my INSTALLED, WORKING catalytic converter, but now ... not so much. I'm just going to let people figure it out on their own.

 

The two or three people (and you know who you are) that messed up my thread with snotty comments are probably the kind of people that have a lot of good information but no one to give it to, because no one can stand be be around them. Please go to another Z web site or at least please don't comment on any threads that I start.

 

Sincerely, Matt A.K.A zeiss150 Just so you know who I am.

 

 

I've been a member of this forum for quite a while, and have noticed that people with "knowledge" get away with a lot more "tone" than people without "knowledge". I agree that this thread has valuable information about vehicle emissions, but really struggle with the way that it is passed down.

 

 

100% Agreed. There is some very useful information on this thread and the majority of this forum, but sometimes people get blasted for questions only extensive searching would answer.

 

 

I have PM'd several people about my comments. Half the people that responded said they viewed my comments as negative and half didnt have a problem with what I said.

Id like to say that I in no way intended my original comments to be viewed in a negative fashion, though I can see that they could be viewed that way now. I was joking around about a comment that was made that has been covered before and that I found entertaining. When the conversation became serious so did I with legitimate answers and no sarcasm. I think Bloz Up caught on to that and has been picking our brains ever since to satisfy his thoughts.

With that said I hope you guys can look past your bruised feelings as that was never my intention. My intention was to spark your thought process.

 

I am not the end all be all Z knowledge guy. Hardly. Do I know anything? Maybe, maybe not. I find that I am wrong to about things still as well. So dont take my word for it, find out for yourself. To be quite honest I dont think I approached this in a way that Id be unwilling to have anyone else approach one of my topics. In fact I could only hope someone would be so kind as to do me that favor!

 

I use the search feature for hours sometimes... Nothing wrong with "Extensive searching". In fact I dont limit myself to Hybridz.org when searching. I use search engines elsewhere as well. I also have books to reference. Your not searching extensively enough if you dont exhaust all options including asking your mechanic buddies, dig through as many books as you can muster, and search the entire internet. In this industry the old guys will tell you, If you dont know something STOP! Ask! Ask your fellow tech, make a phone call, or read! Ca BAR states that you may use any Industry Accepted literature for repairs.

 

 

 

So IF you still have issues with what I stated and think I was out to hurt everyone's feelings let me actually warrant your emotions.

 

I have NEVER had such problems with anyone face to face. Its pretty clear to those that have met me, and there are a good number of them on this board, that I am not a mean person and I strive to help others when I can. If you read into what I say as negative and your feelings are hurt still click on the image above, fill this report out, and send it to the Mods. (Yes, this means I AM BEING MEAN NOW!! See the difference?)

Edited February 25, 2011 by rayaapp2

[zguy36]

"but sometimes people get blasted for questions only extensive searching would answer. "

 

Excuse me, but I need some clarification, who is 'getting blasted' in this thread? Someone asked a question, others answered it, there was clarification, and then further discussion and education on what is actually going on.

 

Where is the 'blasting' in the responses?

 

And god forbid someone 'search extensively'...

 

As to this comment:

"I've been a member of this forum for quite a while, and have noticed that people with "knowledge" get away with a lot more "tone" than people without "knowledge". I agree that this thread has valuable information about vehicle emissions, but really struggle with the way that it is passed down. "

 

If you want information, learn to be humble when asking for it, and when you get it THANK PEOPLE FOR IT! Putting on an attitude is NOT grattitude. Nobody HAS to answer anybody else's dumbarsed questions. If they do, consider yourself lucky. Some of us are easily happy without the internet and can get along just fine without ever 'sharing' what we know with someone who doesn't like the way information is presented to them FREE OF CHARGE AND ANY PAIN OR FINANCIAL OUTLAY. <edit> "Who is John Galt?"<edit>

 

Christ, if I was this picky about it when I was a kid, I would have gotten lugnuts and sparkplugs thrown at me and been scolded for not thinking before I asked "zuch a sthupid qvestion!"

 

Oh waitaminit, that DID happen to me when I asked questions where I didn't think about it first. Excuse me... did someone throw spark plugs or lugnuts at you in any of the responses?

 

I didn't think so...

 

 

Tony,

 

I didn't want to single you out, because it will probably mean the end of my ability to post on this site, as I am not someone that posts a lot of great information, or has a lot of "worth" to this site and am breaking the site rules by posting this. I used to post quite a bit, but have mostly just enjoyed reading what everyone else has to say and applying it to my own Z.

 

You are the one with "knowledge" that I was writing about earlier, that gets away with anything you'd like to say on this site. You seem to know so much about so many topics, you are well versed and explain things very concisely, and of very great value to this site. What you lack though, is the very humility that you are expecting from everyone else. Your response to my post said a lot of things about how I should feel lucky that you answered some dumbarse's questions. If you look up the definition of "Pompous" as zeiss15 said some people are acting on this site, you'll find the definition to be: "having or exhibiting self-importance, arrogant."

 

I believe your actions meet this definition Tony. I may be alone; I may not, but still feel as though something should be said. I may not have had your experiences with people throwing spark plugs at me when I asked stupid questions, because I grew up with a great man who had extreme patience in answering my questions. My father taught auto shop at the local high school for 29 years before he retired last year. He is also a man with bounds of knowledge like you, but also is a man that will take any amount of time to explain something to someone who wants to learn. Every year he had a brand new class of dumbarse's that he took the time to transform into nearly every good auto tech working in a two hundred mile radius. Granted, many of those dumbarse's didn't learn, didn't want to learn, and remained a dumbarse. These are analogous to those that can't use the search feature and there isn't much anyone can do about them other than remind them that it actually takes work and motivation to learn things. I really think that the bulk of the people on this site aren't in that category though and want to learn and just need to be taught.

 

A man with knowledge can do many great things, but nothing as great as sharing. Learn to get off your high horse once in a while Tony. No one is forcing you to share what you know, you are choosing to volunteer your time and share what you know to those who don't know. Please remember that.

Edited February 26, 2011 by zguy36

[Tony D]

"No one is forcing you to share what you know, you are choosing to volunteer your time and share what you know to those who don't know. Please remember that."

 

Indeed, please DO remember that. For more extensive research on the subject of those with knowledge taking their ball and going home, I'd suggest reading "Atlas Shrugged" by Ayn Rand.

 

People will always have questions, to complain about the method in which someone taking the time to answer it (especially putting inference like 'high horsedeness' or malicious intent is the action of someone reading it. How such commentary relates to the thread in any constructive way is beyond my comprehension so maybe you can PM me for assistance with that, because such commentary doesn't belong in a thread where people are answering issues directly related to the question at hand.

 

And you're absolutely right, nobody forces me to give away free knowledge. Apparently they DO suggest that I give it to them in some format they demand as being inoffensive, on a given RGL, or complying with many other conditions.

 

Sorry, but to me, that smacks of terrible poor form. Either you are grateful for information provided, or you are not.

 

These types of posts are, IMO, in the 'are not' column. You have the same choice not to read them, or comment on them, or not participate at all.

 

When those without knowledge participate on a grand scale, without people with knowledge similarly participating, you have a situation like ZC.C. IF that is your intention...be careful what you wish for. At most, the people with knowledge will simply not respond. Then where is the O.P.? Or anybody else reading this thread?

 

SE\eriously, think about what you are saying in this regard. Take it to a logical conclusion. Where is (as asked before) any terrible transgression? Or is this just an example of someone complaining for some P.C. ideal because they don't want their feathers ruffled by discussion on a topic that may contradict what their original thoughts were.

 

The last several posts in this thread are totally useless, talking about people's sensitive feelings being hurt as opposed to the techincal discussion happening previously. That's how it started at ZC.C as well. You see how the moderation there turned out.

 

Nothing technical has been discussed here, as such this thread is ended IMO. It's now being dragged in to the mud with emotional baggage of posters with an agenda I can't understand. I've poorly done my part in proffering a response I should not have done...but like suggested "nobody is forcing me." I can survive without responding just fine.

[TimZ]

When those without knowledge participate on a grand scale, without people with knowledge similarly participating, you have a situation like ZC.C. IF that is your intention...be careful what you wish for. At most, the people with knowledge will simply not respond. Then where is the O.P.? Or anybody else reading this thread?

 

SE\eriously, think about what you are saying in this regard. Take it to a logical conclusion. Where is (as asked before) any terrible transgression? Or is this just an example of someone complaining for some P.C. ideal because they don't want their feathers ruffled by discussion on a topic that may contradict what their original thoughts were.

 

I guess maybe I should read every single post more thoroughly, but I fail to see anyplace where Tony or Ray said anything particularly offensive, AND the knowledge they shared was very valuable. The most offensive posts I saw came from those that were "offended".

 

WTF?

[johnc]

 

I guess maybe I should read every single post more thoroughly, but I fail to see anyplace where Tony or Ray said anything particularly offensive, AND the knowledge they shared was very valuable. The most offensive posts I saw came from those that were "offended".

 

WTF?

 

Ding, ding, ding, ding, ding! Winner, winner, chicken dinner!

 

There was nothing in this thread that I as an Admin here saw as offensive until people started complaining about offensive posts. Even those offended people didn't really post anything offensive, just a "feelings hurt" kind thing. Get over it.

 

EDIT: And yes, we do give those members who contribute buttloads of technical information to this site a bit more slack in their "tone" because of the value of their contributions. That's kind of how life works.

[ezzzzzzz]

Hilarious... Flaming (of sorts) is to be expected. What the original poster wanted was a simple answer which was place it where Nissan placed it on the 280ZX (just behind the transmission using a heat shield). What he didn't know was the can of worms he was opening up. As indicated by the extensive/exhaustive data shown there is a definative reason for using the cat. It isn't a band-aid to compensate for a multitude of other issues. While I agree that the language used is almost incenderary, at times, it is meant to open eyes to not blacken them. No one is trying to hurt anyone's feelings only enlighten and educate. The cool part is the sheer amount of information that came from the one 'simple' question. Thanks the all the wizards that chose to respond.

[Zmanco]

I too was considering adding a cat to my turbo motor to reduce fumes and emissions too - don't mind being a little green if it doesn't hurt But I was worried about how it would deal with sustained periods of WOT at AFR ~12 at the track, and this discussion confirms that it probably wouldn't have lived, if it didn't melt the undercarriage first.

 

Great discussion - simple questions often don't have simple answers.

 

One follow on question: I recall reading elsewhere that a typical NA engine makes max power in the 13:1 range. Yet that's likely to overheat/overwhelm the cats. So how do performance cars such as Corvette, Ferrari, and Porsche handle this? Do they still run close to stoich at WOT and sacrifice some power?

[Nigel]

I too was considering adding a cat to my turbo motor to reduce fumes and emissions too - don't mind being a little green if it doesn't hurt But I was worried about how it would deal with sustained periods of WOT at AFR ~12 at the track, and this discussion confirms that it probably wouldn't have lived, if it didn't melt the undercarriage first.

 

 

 

If there is an issue with this thread, it's that there appears to be an underlying tone of bias against using a cat that's based mostly on theory, but doesn't necessarily hold up in practice. Evidence of this can I think be seen from what I will argue is Zmanco's misinterpretation of the information provided. Based on my experience with actually having a converter installed in my turbocharged '73 240Z for the past 7 years, they do not fail due to running flat out on track days, and you're not going to melt the bottom of your car. I've had the exhaust off a few times over the years, and I can see the inlet to the converter. The last time I checked, the converter core was completely intact and showed no sign of damage. Also, the shop that did my exhaust installed the converter upside down, with the heat shield facing down. Nothing really bad has happened as a result. I have had an issue with leaking rear transmission seals, which are right above the cat, but that could be coincidental. Some day, I'll probably make up a heat shield, just in case. But, other than that, I haven't noticed any other ill effects.

 

I recently spoke with my two friends that I mentioned in an earlier post who had installed converters in their Z's. Just to recap, one has SU's and the other has triple Webbers. I thought that the fellow with the SU's hadn't noticed much of a reduction of exhaust fumes, but after talking with them both, they both noticed a significant reduction of exhaust fumes, and were glad they installed the converters.

 

Catalytic converters are not a solution for a poorly tuned engine, but there is evidence that if your goal is to reduce exhaust fumes in your Z, they can make a difference, with minimal impact on performance or your wallet.

 

Nigel

[BLOZ UP]

I too was considering adding a cat to my turbo motor to reduce fumes and emissions too - don't mind being a little green if it doesn't hurt But I was worried about how it would deal with sustained periods of WOT at AFR ~12 at the track, and this discussion confirms that it probably wouldn't have lived, if it didn't melt the undercarriage first.

 

Great discussion - simple questions often don't have simple answers.

 

One follow on question: I recall reading elsewhere that a typical NA engine makes max power in the 13:1 range. Yet that's likely to overheat/overwhelm the cats. So how do performance cars such as Corvette, Ferrari, and Porsche handle this? Do they still run close to stoich at WOT and sacrifice some power?

 

 

LS1s at least would go to whatever the stock tune is, but had a cat overtemp mode which (...) richened the mixture to cool the cats ().

Edited March 1, 2011 by BLOZ UP