Why is a tune required with header/hi-flow cat installation?

[justa25thTA]

Originally Posted by strych9

I agree with all that you've said in this post. I even agree that a tune is essential if you want to extract the maximum available power from your mods. The cost of the tune is irrelevant. If I can drop $1500 + on headers and cats, I can drop another $500 for the tune. Point is, I am not willing to devalue my Camaro's worth by programming the ECM. If I were to trade or sell it within the powertrain warranty period, I want the value-add that the warranty provides. That is the ONLY reason that I'm anti-tune.

The other point being, I could cam, heads, headers, CAI, exhaust, NOS, all day long with the Mustangs with no tune and no CEL and run high 11's all day long. So, I wanted to know why that couldn't be so with the Camaro. Thanks again.

I'm thinking those were the mustangs of old. Don't the new ones have similar issues?

[strych9]

Originally Posted by justa25thTA

I'm thinking those were the mustangs of old. Don't the new ones have similar issues?

To some degree, yes. The last Mustang I raced was a 2003 GT. However, the theories are still the same.

[Higgs Boson]

Originally Posted by strych9

To some degree, yes. The last Mustang I raced was a 2003 GT. However, the theories are still the same.

theories are the same but the logic in the ecu's has become so advanced and powerful (and specific to what is within range) that you almost have to tune it so it doesn't get wack.

emissions control is a huge priority these days and most of the advances in the computer side of things is geared to being able to hit requirements and still allowing power to be made. cars are so much cleaner than they used to be. i have a 1978 gmc 4x4 that is carb'd but tuned and jetted with my wideband and it is still so dirty vs new cars. the fuel control is so loose and approximated, it's just crazy.

[strych9]

Originally Posted by Higgs Boson

theories are the same but the logic in the ecu's has become so advanced and powerful (and specific to what is within range) that you almost have to tune it so it doesn't get wack.

emissions control is a huge priority these days and most of the advances in the computer side of things is geared to being able to hit requirements and still allowing power to be made. cars are so much cleaner than they used to be. i have a 1978 gmc 4x4 that is carb'd but tuned and jetted with my wideband and it is still so dirty vs new cars. the fuel control is so loose and approximated, it's just crazy.

Yeah, I can see this happening with all of the super-stringent EPA requirements. I've been out of the loop since 2005, so things have changed quite a bit. I feel like I've been sleeping for a few years.

[bucketobolts]

:troll:

I Smell BS...

[Higgs Boson]

Originally Posted by bucketobolts

:troll:

I Smell BS...

[bucketobolts]

Lets stop the boasting and start learning...

In the two catalyst system used on the SS, the front converter removes the Hydrocarbons and Carbon-monoxide while the rear takes care of the Oxides of Nitrogen, which by the way is the worst ecologically of the pollutants created during combustion. You know the stuff that causes acid rain and smog. The rear O2 monitors the function of only the front converter.

Now move that converter two feet further down stream and replace it with an "inefficient" emission wise HiFlow converter and your doing very little for the total emissions reduction. So with long tubes and HiFlow cats, you will get a CEL because the threshold window cannot be met.

The emissions system is not reducing the HCs or CO effectively and is by no way altering the NOx being produced. So why spend the extra money if they do not work?

You said previously that cats produced 15 more RWHP than cat-less. Pretend I'm from Missouri and show me, please.

[Higgs Boson]

Originally Posted by bucketobolts

Lets stop the boasting and start learning...

In the two catalyst system used on the SS, the front converter removes the Hydrocarbons and Carbon-monoxide while the rear takes care of the Oxides of Nitrogen, which by the way is the worst ecologically of the pollutants created during combustion. You know the stuff that causes acid rain and smog. The rear O2 monitors the function of only the front converter.

Now move that converter two feet further down stream and replace it with an "inefficient" emission wise HiFlow converter and your doing very little for the total emissions reduction. So with long tubes and HiFlow cats, you will get a CEL because the threshold window cannot be met.

The emissions system is not reducing the HCs or CO effectively and is by no way altering the NOx being produced. So why spend the extra money if they do not work?

You said previously that cats produced 15 more RWHP than cat-less. Pretend I'm from Missouri and show me, please.

no didn't. I said that high flow cats can provide 15 whp over stock cats. hf cats vs no cats is negligible.

no one here is talking about emissions. we are talking about the effects of a tune with headers/cats. however, you have merely restated what I already stated. the rear o2 sensor does not function properly when moved downstream, whether a cat is moved downstream or removed is moot. we aren't concerned with placement of stock cats.

I am glad you care about the environment and I am impressed by your understanding of the catalyst system. what I am not impressed with is your lack of understanding regarding the conversation.

after reading back, I see where your confusion is sourced. you said what's the point of high flow cats while commenting on factory cats. this means to me that you are arguing for stock and not changing it. what you are really saying is what's the point in cats, just go catless however you made no mention of catless in your comment.

[2SS45th]

The 15rwhp is regarding the tuned vs. untuned headers... not cats vs. catless

[Higgs Boson]

it is well documented that high flow cats are worth about 15 whp. it's documented that shorty headers are worth about 10whp. it's documented that long tubes provide a synergistic effect to both shorties and hi flows by providing a strong 30 whp. a tune will add another 10 - 15whp to any of these, including a stock car.

the better case for the tune is to make sure everything is RIGHT.

[Coyotekiller]

To the OP, what everyone else has failed to notice was that all you are really concerned with is sound. Am I correct in saying that?

If that is correct, don't bother with headers, just buy a axleback or catback exhaust. That's where most of your sound comes from. The headers do make the car louder also but not like a good axleback system.

Unless you are dead set on getting headers, I'd look at the back section of the exhaust first if warranty claims bother you.

[Higgs Boson]

Originally Posted by Coyotekiller

To the OP, what everyone else has failed to notice was that all you are really concerned with is sound. Am I correct in saying that?

If that is correct, don't bother with headers, just buy a axleback or catback exhaust. That's where most of your sound comes from. The headers do make the car louder also but not like a good axleback system.

Unless you are dead set on getting headers, I'd look at the back section of the exhaust first if warranty claims bother you.

that's a good observation ck.

[bucketobolts]

You are really showing your brilliance, just as in other threads.

The 02 is passive and just reports. It does not know where it is nor does positioning effect its readings.

It is the converters that are not working...plain and simple, and the 02 tells the PCM to turn on the light.

once I had a 350Z I denied a blown motor. it was stock except for a ratty ass catback. why did i deny it? not only were the rear fender linings melted from hot rubber on them, the dude left his time slips in the center console! dumbass.

I can also hijack if you would like to debate Constitutional Law. I bought and paid for my vehicle therefore it is my personal property. No one, especially you who has been contracted to work on my vehicle, has no right to rifle though my vehicle. I don't care who your daddy is or what he has bought you.

[2SS45th]

Originally Posted by bucketobolts

You are really showing your brilliance, just as in other threads.

Don't know who you are referring to here, but the 15whp gain in tuning is proven. If you are talking baout the guy moving the o2, I agree here. My o2 was moved back, and still threw the code.