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Who Has Experience With Exhaust Cutouts?


SicShelby

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I ran dual QTP 2.5" on the Marauder. I never had an issue.

 

The Install was as follows: Stainless Works Long Tubes, Cutouts, The Stock Front Cats (Removed the Rears), Stock H-Pipe, Stock Mufflers, Stock Tips. The car was rather quite for the most part, and had a nice tone. But, once opened, LOUD AS HELL! The car picked up about 25+ RWHP and TQ with them if I recall ;)

 

:thumbup:

 

KillJoy

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I ran dual QTP 2.5" on the Marauder. I never had an issue.

 

The Install was as follows: Stainless Works Long Tubes, Cutouts, The Stock Front Cats (Removed the Rears), Stock H-Pipe, Stock Mufflers, Stock Tips. The car was rather quite for the most part, and had a nice tone. But, once opened, LOUD AS HELL! The car picked up about 25+ RWHP and TQ with them if I recall ;)

 

:thumbup:

 

KillJoy

 

Wth ARE you??

 

Anyways... Keep in mind the Shelby is in Cali now :( The emission laws in place there are relative to a frog's asshole.

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Wth ARE you??

 

Anyways... Keep in mind the Shelby is in Cali now :( The emission laws in place there are relative to a frog's asshole.

 

 

I believe most Cut-Outs are "For Off Road Use Only". I am not sure if that matters in CA or not. The nice thing about the Electric ones.... is you can Close them in a matter of seconds if you.... uhhhh.... are coming home late and don't want to wake up the neighborhood ;)

 

KillJoy

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I believe most Cut-Outs are "For Off Road Use Only". I am not sure if that matters in CA or not. The nice thing about the Electric ones.... is you can Close them in a matter of seconds if you.... uhhhh.... are coming home late and don't want to wake up the neighborhood ;)

 

KillJoy

 

I think that the cutouts will be fine, granted the inspection is done with them closed. What California kind of puts out of question, however, is high flow cats, long tube headers (I think there are some that pass on shorties, but not sure), etc.

 

Right now the cutouts are ideal because 1) I like LOUD, and 2) they are cheaper than axle backs and I can get my noise with a lot less $$$.

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I know CA is a PITA regarding to exhaust. IF you could do this.... it would be cool:

 

Stock Manifolds, Cutouts, All Stock Cats, Stock everything else...

 

You Front O2 would have to be far enough in front of the Cutout to not fuck the A/F with them open though.

 

You might also need another Tune for running wide open... I dunno....

 

:thumbup:

 

KillJoy

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I know CA is a PITA regarding to exhaust. IF you could do this.... it would be cool:

 

Stock Manifolds, Cutouts, All Stock Cats, Stock everything else...

 

You Front O2 would have to be far enough in front of the Cutout to not fuck the A/F with them open though.

 

You might also need another Tune for running wide open... I dunno....

 

:thumbup:

 

KillJoy

 

EXACTLY why I would want them post-cat...

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Also... I doubt it would do much for you.... but you could have the Stock Manifolds Ported, Polished and Extrude Honed..... I MIGHT help a little. It would not be cheap though (I imagine).

 

Although, your car is NOT common.... there is a chance you MIGHT be able to sneak a Header though :D

 

KillJoy

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Guest tbutera2112
Why in the world would I want them pre-cat?

 

why would you want them after the cats? that kinda defeats the point...you open them and youre still gonna have a quiet exhaust because those cats are going to choke it out...pre-cat and its going to scream, then close it and it will sound stock

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why would you want them after the cats? that kinda defeats the point...you open them and youre still gonna have a quiet exhaust because those cats are going to choke it out...pre-cat and its going to scream, then close it and it will sound stock

 

The sound quality is better with cutouts after the cats. The tone is a little deeper and far less Raspy. The cats do a good job at pulling out a lot of the rasp and increase the good noise. Besides, no dealing with tuning issues as with the pre-cat cutouts.

 

Putting the cutout after the cats means the sensors are receiving the signal. The computer can compensate and the motor is happy, and so is your wallet from the fuel you're saving (assuming you stay off the fun button). The computer reads the front and rear O2 sensor to do a check and make sure they're doing their job correctly by testing the exhaust straight out of the motor and again in/after the cat.

 

If the cat fails at cleaning the exhaust further the computer will throw a code, If the A/F can't get balanced because an 02 sensor is bad it'll throw the code, etc., etc.

 

Roger that?

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The sound quality is better with cutouts after the cats. The tone is a little deeper and far less Raspy. The cats do a good job at pulling out a lot of the rasp and increase the good noise. Besides, no dealing with tuning issues as with the pre-cat cutouts.

 

Putting the cutout after the cats means the sensors are receiving the signal. The computer can compensate and the motor is happy, and so is your wallet from the fuel you're saving (assuming you stay off the fun button). The computer reads the front and rear O2 sensor to do a check and make sure they're doing their job correctly by testing the exhaust straight out of the motor and again in/after the cat.

 

If the cat fails at cleaning the exhaust further the computer will throw a code, If the A/F can't get balanced because an 02 sensor is bad it'll throw the code, etc., etc.

 

Roger that?

 

I'm pretty sure the secondary o2 sensor isnt used in fuel trim calculations, its mostly there for see if the cat is working.

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The sound quality is better with cutouts after the cats. The tone is a little deeper and far less Raspy. The cats do a good job at pulling out a lot of the rasp and increase the good noise. Besides, no dealing with tuning issues as with the pre-cat cutouts.

 

Putting the cutout after the cats means the sensors are receiving the signal. The computer can compensate and the motor is happy, and so is your wallet from the fuel you're saving (assuming you stay off the fun button). The computer reads the front and rear O2 sensor to do a check and make sure they're doing their job correctly by testing the exhaust straight out of the motor and again in/after the cat.

 

If the cat fails at cleaning the exhaust further the computer will throw a code, If the A/F can't get balanced because an 02 sensor is bad it'll throw the code, etc., etc.

 

Roger that?

The computer won't have issues with emissions.

Nothing wrong at all with this idea. One way to do it.

I'm pretty sure the secondary o2 sensor isnt used in fuel trim calculations, its mostly there for see if the cat is working.

This is also true, but he'll have to reset the check engine light every time he opens them.

So are you doing this for the noise or the gain in power? I don't really understand...

 

When I talked to Gabe about this I got the impression that he didn't want to have issues with Cali's emissions and didn't want to detract from the original car much. I think he's on track for what he wants to do.

 

Don't forget that if you get manual cutouts and decide later that you want electric you can just bolt them on to the flange. It would be a simple upgrade.

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I'm pretty sure the secondary o2 sensor isnt used in fuel trim calculations, its mostly there for see if the cat is working.

 

The O2 sensor measures the amount of CO2 - obviously a byproduct from the magic happening in the engine. The O2 sensors are used to determine in real time your air to fuel ratio or A/F. Your A/F has a peak spot for performance, gas mileage, and emmissions. Granted when your stomping on the gas and hitting the track the feedback from the O2's mean fuck-all because it is running openloop. When your cruising down the highway or in town is when the system runs closed loop.

Closed loop means your computer is taking the air intake, ambient temprature, ambient pressure, and the O2 sensor readings to ascertain how much air and how much fuel to put into the motor at its current workload to keep bad gasses (like NOx for example) out of the atmosphere. It also helps with gas mileage, adds to the longevity to the motor because your not going to be running it too rich or worse lean.

Openloop is a set of predetermined fuel maps that are basically only used when your having fun in the car (i.e. flooring it or 100% throttle whichever term you want to use I care not). Putting the cutouts before the cats (o2 sensors) means your now robbing the information the cats receive from the exhaust, which means the computer isn't receiving the right signal, which also means its calculations for the A/F are now fucked.

 

Hence post-cat. I want to avoid the mixed signals that would be experienced with the whole pre-cat ordeal.

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The computer won't have issues with emissions.

Nothing wrong at all with this idea. One way to do it.

 

This is also true, but he'll have to reset the check engine light every time he opens them.

 

 

When I talked to Gabe about this I got the impression that he didn't want to have issues with Cali's emissions and didn't want to detract from the original car much. I think he's on track for what he wants to do.

 

Don't forget that if you get manual cutouts and decide later that you want electric you can just bolt them on to the flange. It would be a simple upgrade.

 

I think you summed it up better, lol. Honestly... I have a decent amount of horsepower - getting another 15 (more or less) from having them pre-cat isn't worth the tuning troubles to me. If I *did* elect to have them pre-cat, then like you said, I'm running a tune for them open, and one for them closed (if I wanted to be safe).

 

At this point... I just need it to "sound" like it his some amount of horsey power. :)

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The O2 sensor measures the amount of CO2 - obviously a byproduct from the magic happening in the engine. The O2 sensors are used to determine in real time your air to fuel ratio or A/F. Your A/F has a peak spot for performance, gas mileage, and emmissions. Granted when your stomping on the gas and hitting the track the feedback from the O2's mean fuck-all because it is running openloop. When your cruising down the highway or in town is when the system runs closed loop.

Closed loop means your computer is taking the air intake, ambient temprature, ambient pressure, and the O2 sensor readings to ascertain how much air and how much fuel to put into the motor at its current workload to keep bad gasses (like NOx for example) out of the atmosphere. It also helps with gas mileage, adds to the longevity to the motor because your not going to be running it too rich or worse lean.

Openloop is a set of predetermined fuel maps that are basically only used when your having fun in the car (i.e. flooring it or 100% throttle whichever term you want to use I care not). Putting the cutouts before the cats (o2 sensors) means your now robbing the information the cats receive from the exhaust, which means the computer isn't receiving the right signal, which also means its calculations for the A/F are now fucked.

 

Hence post-cat. I want to avoid the mixed signals that would be experienced with the whole pre-cat ordeal.

 

You have got the idea down when it comes to exactly what the first set of O2 sensors are there for. However the set of O2s after the cats have nothing to do with engine performance. They are there for emissions, and hence why most of use just delete them from the tune. I hope that clears it up, but I have to admit I don't think I'd ever do that good of a job explaining it.

 

A couple minor things though, O2s measure hydrocarbons (not exactly CO2), and I think of them as more of a real-time correction for closed loop operation. Any major differences between what the MAF reads and the O2s and it'll just kick a code and operate from the base maps, but now I'm just knitpicking. You've got the basic idea.

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You have got the idea down when it comes to exactly what the first set of O2 sensors are there for. However the set of O2s after the cats have nothing to do with engine performance. They are there for emissions, and hence why most of use just delete them from the tune. I hope that clears it up, but I have to admit I don't think I'd ever do that good of a job explaining it.

 

A couple minor things though, O2s measure hydrocarbons (not exactly CO2), and I think of them as more of a real-time correction for closed loop operation. Any major differences between what the MAF reads and the O2s and it'll just kick a code and operate from the base maps, but now I'm just knitpicking. You've got the basic idea.

 

You're right.

 

Lol my brain doesn't operate on little sleep.

 

But anything I think I got my answer - manual cutouts, weld them in. And... precat if I need an extra dash light.

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