Stock Headers MAX Power w/ Blower

[Performance nut]

Just to be clear, my cats failed on the base Whipple tune that comes with their Gen 2, stage 2 kit. Plugs were misgapped from the dealer which I chalked up to contributing to the issue the first time the stock cats failed.

Swapped out to Kooks and their cats failed while still on the Whipple tune.

Question is why. I have Kooks on my car for over a year now without a failure. Though I'm NA on the factory Ford tune, not FI on an aftermarket tune. Something tells me the tune is running your exhaust too hot causing cat failure.

Could be wrong, not an expert by any stretch. Just find it hard to believe strapping a SC on a car causes converter failures when there are SC cars from the factory that go years without destroying stock cats much less aftermarket cats.

Sponsored

 

[stang17]

Question is why. I have Kooks on my car for over a year now without a failure. Though I'm NA on the factory Ford tune, not FI on an aftermarket tune. Something tells me the tune is running your exhaust too hot causing cat failure.

Could be wrong, not an expert by any stretch. Just find it hard to believe strapping a SC on a car causes converter failures when there are SC cars from the factory that go years without destroying stock cats much less aftermarket cats.

I felt the same way. 2019 ZR1 corvettes come with 750 supercharged HP and have cats that can withstand it.

I called Kooks and they told me 700 hp NA is completely different from 700 hp boosted. The additional heat and pressure is what contributes to cat failure.

They did advise the GESI Green Cats are built differently to support high HP forced induction applications. I just didn't want to pony up the additional cash since I'm emissions exempt driving under 5,000 miles per year.

 

[EFI]

Just find it hard to believe strapping a SC on a car causes converter failures when there are SC cars from the factory that go years without destroying stock cats much less aftermarket cats.

It's a combination of the tune and cats not made to support such power.

As stang17 eluded to, there are high powered supercharged cars that have cats and maintain the 7/70 emissions warranty. It's that they have a better tune and the cats themselves are specifically engineered to survive in that scenario.

Ford did not engineer the MY15+ cats to support a boosted engine making twice the power. However I bet they made the GT500 cats differently to support that kind of power.

It's all about doing it right with the correct parts, not mismatching random stuff.

 

[SolarFlare]

Disagree to a certain point. Max performance and cats contradict, yes. High performance and cats contradicting, no.

Well, if you have such a good grasp then risk your motor. I won’t risk mine. I race a fair amount, I won’t risk a motor to run cats. I didn’t spend thousands on blower and supporting mods for mediocre performance.

 

[Jay-rod427]

Trying to understand something... why is everyone burning up cats? Are tunes running so lean that it is causing seriously high exhaust temps?

Quite the opposite, overly rich makes the cats burn off excess unburnt fuel which heats them up.

 

[ahl395]

Another piece of the puzzle is factory tunes usually have some kind of cat protection feature in them. Once the cats get to a certain temp it cuts power so they don't overheat. Aftermarket tunes usually remove this for the sake of more performance. With boost it doesn't take long for cat temps to rise.

 

[Performance nut]

Well, if you have such a good grasp then risk your motor. I won’t risk mine. I race a fair amount, I won’t risk a motor to run cats. I didn’t spend thousands on blower and supporting mods for mediocre performance.

Likely you are the far end of the spectrum looking for max performance. You don't care about anything but power, nothing wrong with that.

Mediocre performance is a relative term. Cats don't destroy cars though unless you do something really aggressive with parts or tune. And despite what the average garage mechanic believes, cats don't necessarily kill performance. It has been shown many times that they actually help performance in some street applications. Not saying all and definitely more rare in max effort situations. Just saying deleting cats doesn't always equate to a good thing.

It is something that is really annoying when people make this correlation. If you put 20lbs of boost on a stock block and blew your piston rings, would you say piston rings are bad for your car? I doubt it, just means you need the right rings for your application.

It's a combination of the tune and cats not made to support such power.

As stang17 eluded to, there are high powered supercharged cars that have cats and maintain the 7/70 emissions warranty. It's that they have a better tune and the cats themselves are specifically engineered to survive in that scenario.

Ford did not engineer the MY15+ cats to support a boosted engine making twice the power. However I bet they made the GT500 cats differently to support that kind of power.

It's all about doing it right with the correct parts, not mismatching random stuff.

Another piece of the puzzle is factory tunes usually have some kind of cat protection feature in them. Once the cats get to a certain temp it cuts power so they don't overheat. Aftermarket tunes usually remove this for the sake of more performance. With boost it doesn't take long for cat temps to rise.

Excellent points. This is why folks need to be more clear with expectations with their tuners. If the tuner gives you one of these :shrug:, they aren't your tuner. This is usually why I have a problem with most aftermarket tuners because I seriously doubt Ford left power on the table deliberately without good reason. Some of those reasons don't apply to all of us but some of them do.

Tuners change parameters. Good tuners know the cause and effect of everything and can protect the system and make power. Awesome tuners know what parts are needed to make the highest potential based on owners parameters (not talking canned part builds and tunes, talking specific combinations that yield specific results). With the right tuner, I'm willing to bet you could make our cars get 30+ MPG, 800HP with smog compliance, or turn a 9 second run with good street manners. All about goals and wallet sizes.

 

[Bartly]

I’m lower power than most, dyno said 582whpw, plus I’m at 4500 ft elevation, also never really get on it on long runs, usually 3rd gear is the highest gear I max the RPMs out. With that, I keep telling myself my factory cats will last being that I’m not pushing the power like some. When I finished installing the supercharger and loaded the tune I was seeing cat temps as high as 1950 deg. Sent the tuner logs showing this and they replied back that they accidentally left something turned off, can’t recall exactly what it was, but I think it had the word “enrichment” in it. Anyway they sent a new revision and I haven’t seen it go above 1650 since. Also another tuner told me that shutting the car off with really hot cats is hard on them, no clue if this is true, but I generally let mine cool down to 1150 before turning the car off after hearing that. I sometimes do wonder how accurate the CAT PID is being that it’s a calculated value. I am thinking next winter I’m going to pull them off to look at them to see if they are melting at all. Currently have about 12k miles on the supercharger, time will tell.

 

[SolarFlare]

Likely you are the far end of the spectrum looking for max performance. You don't care about anything but power, nothing wrong with that.

Mediocre performance is a relative term. Cats don't destroy cars though unless you do something really aggressive with parts or tune. And despite what the average garage mechanic believes, cats don't necessarily kill performance. It has been shown many times that they actually help performance in some street applications. Not saying all and definitely more rare in max effort situations. Just saying deleting cats doesn't always equate to a good thing.

It is something that is really annoying when people make this correlation. If you put 20lbs of boost on a stock block and blew your piston rings, would you say piston rings are bad for your car? I doubt it, just means you need the right rings for your application .

You’re not understanding what I’m saying.....are cats bad for cars? No. Does a high flow car really rob much power? No. Are cats a liability for a 650whp+ car that is raced? YES! In my opinion it’s a liability that’s close to say running a car that’s far beyond the capabilities of the fuel pump and uses a BAP to make up that deficit. Cats can fail, just like a fuel pump that’s pushed too hard.


Are there mitigating strategies? Yes, you run a softer tune to help keep both relatively safe/running a BAP that’s not full voltage 100% of the time. I saw my cats as a liability I could remove for $50 bucks so I did. To correct the other I need a $1000 fuel system. What do I do in the mean time? Send logs to tuner as often as I can and also review them on my own. I’ll never blame my tuner for anything that happens to my car, he understands what I ask of him and although I’m no tuner I can see his work in the logs. If anything happens it’s on me.

 

[smokinzx14r]

3rd pass at the track my cats went out the tail pipes :( I went with Mak cat deletes ...

 

[jgedde]

Seems like almost every car ive seen with a blower north of 680whp or so has LT headers and no cats, anyone make 700whp thru stock headers and cats?

How's 693 sound? Close... And thru stock exhaust.

J

 

[Ponderthis]

How's 693 sound? Close... And thru stock exhaust.

J

I wound up making 720whp 550TQ at one time thru stock headers n cats and old blower setup it eventually may of been almost 750 due to several tune changes over a few months anyway... Ditched the blower and now have twins and far more lol.. Hoping for 850whp minimum and at least mid 9s turned up @ 15psi.

 

[Brian Z.]

How hard is it to hollow out a cat? Any downside to hollowing them out as opposed to getting the MAK cat delete pipes? Not sure I really want to go with LT's right now, but would like to ditch the cats.

 

[stang17]

How hard is it to hollow out a cat? Any downside to hollowing them out as opposed to getting the MAK cat delete pipes? Not sure I really want to go with LT's right now, but would like to ditch the cats.

Full disclaimer, cough cough, this is for offroad use only.

Shop did it for about $100. How it was explained to me as that they removed the cats, then cut into the top of the cat and peeled back the top to expose the inside. They then scrapped/ removed all of the inside material and welded the top part they cut out back on. They then used a grinder/sander to smooth out all of the welds to make it look like the cats were never opened.

Since they went through the top that faces the underneath of the car, visual inspection would appear as though they were untouched cats.

I will tell you the car drives noticeably better without the cats, however it got a lot more raspy. I'm currently looking into ways to get the deep rumble sound back.

 

[Barrel]

My car was making something like 780 through SW high-flows and 788 without them. Not a big delta. Had to get rid of them once I stepped the boost up to where I'm at.

Sponsored