Strategies to keep cats from melting

[ProChargerTECH]

If you guys are using the "cat temp" that the computer is guessing at....

I can tell you PLEASE DON'T

The calculation is WAY off, once boost has been added. And the ONLY way to get a reading is by drilling a hole into the center of the cat, and measuring with a proper high speed EGT.

NOTE: I run cats on my daily beaten, 700hp car, never had an issue.
NOTE2: Not all cats are created equal.(wish we all had Hellcat kittys)

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[Torinate]

If you guys are using the "cat temp" that the computer is guessing at....

I can tell you PLEASE DON'T

The calculation is WAY off, once boost has been added. And the ONLY way to get a reading is by drilling a hole into the center of the cat, and measuring with a proper high speed EGT.

NOTE: I run cats on my daily beaten, 700hp car, never had an issue.
NOTE2: Not all cats are created equal.(wish we all had Hellcat kittys)

Appreciate that. That has come up before as far as accuracy etc.

Besides drilling and putting in a temp sensor, is there any other way to really tell?

Mike does have some good data on his COT etc. the question then becomes how off base the actual temp is. If the computer sees it as 1680 and turns COT on, that’s great! Unless the actual temp is a lot more.

@Procharger - any tips on how you’ve managed to keep your cats functioning fine and still beat on the car? I take it by your comments the Hellcat cats are primo...

If excessive heat is the enemy...

 

[markmurfie]

Stop looking at and thinking about the effect lambda has on egt alone, and look at the effect it has on catalyst efficiency . The reactions happening in the catalyst effect their temperature more than egt. You are not trying to cool the exhaust gases, you need to stop the catalyst from over working it's self.

 

[Torinate]

Stop looking at and thinking about the effect lambda has on egt alone, and look at the effect it has on catalyst effecientcy. The reactions happening in the catalyst effect their temperature more than egt. You are not trying to cool the exhaust gases, you need to stop the catalyst from over working it's self.

I can understand that. Any recommendations on how to achieve that though?

Thanks.

 

[engineermike]

@markmurfie the link I posted in post #46 and graph in post #68 reflect lambda’s effect on both EGT and the catalyst bed temperature.

 

[andrewtac]

If you guys are using the "cat temp" that the computer is guessing at....

I can tell you PLEASE DON'T

The calculation is WAY off, once boost has been added. And the ONLY way to get a reading is by drilling a hole into the center of the cat, and measuring with a proper high speed EGT.

NOTE: I run cats on my daily beaten, 700hp car, never had an issue.
NOTE2: Not all cats are created equal.(wish we all had Hellcat kittys)

which cats do you run?

 

[Supersolo]

Here is what I’ve found for the passenger side cats.

FR3Z-5E212-B
Passenger stock cat GT

KR3Z-5E212-C
GT500 stock cat

Interesting g to see the part numbers are almost the same. I’m wondering if the difference with letters is model year specific.

There are two differences in these numbers.
First change is in the prefix, from "F" to "K", I'll have to look that up, but I suspect it's a model differentiator.

The second change is to the suffix, from "B" to "C".
This is a revision indicator, where Ford have had to revise the item, via the engineering change request process (ECR).
Being a different model, the CAT spec for the GT500 could have been entirely different, from the start.
And now Ford are up to rev "C" for the CAT, typically suggesting they've gone through changes "A" & "B" already.

I have a stage 2 Whipple on my 2019 GT.
In my experience, Whipple don't support overseas customer much, if at all. So I ran the supplied tune, based on my stock tune.
The car did not drive very well and made too many pops & bangs.

I couldn't get the tune tweaked by Whipple, so I went to a U.S. tuner.
It was very messy at the beginning, but eventually, we seemed to smooth things out, until.....

Subsequently I was told I would need to remove the CATs, which in the U.K. include a GPF.
It seems from 2018MY onwards, the GPF CATs had wires running from them. I now suspect these link to a pressure sensor in the CAT assembly. Then when the CATs become congested, the internal pressure rises & this triggers the exhaust filter warning?

I've "modified" the CATs for now, but I need a longer term, emissions compliant solution.

Tuners need to prevent killing the CATs on their customers cars.

I am curious about the GT500 CATs.
Furthermore, I do wonder how manufacturers such as McLaren & Ferrari get 650+bhp from their V8s while complying with current U.K. / Euro / U.S. emissions regs.
It would seem to suggest not all CATs are created equal??

 

[Bandi]

Well, wasn’t the topic I was hoping to post, but here is where we are at.

I’ve been in the boat looking for a cat delete to ward off failure causing engine problems. However, with all the recent stuff going on, looks like I may be stuck with them. Good and bad though I guess...

What I’m hoping for in this thread is good information that may help us prolong the life of our cats and keep from catastrophic failure.

I’m not wanting the “just have a shop remove them” posts lol.

Certainly there are ways that would help prolong the lifespan. I’m also sure there are ways to make them fail faster.

What can we do help them live and what shouldn’t we do to make them fail faster.

Any ideas? What do the ZL1 and Demons do?

Does Seafoam help?

Are other brands of cats work better? Gesi?

Would running a meth injection system help as it brings temps down a bit?

Seriously, if this is the way of the future, then let’s help each other figure out ways to make it work!

If I have to conform, I still want my cake!

From what I have read online -- as credible as that sounds -- Hellcats and Demons also have issues with their factory cats. Simply put, making that much power, making WOT pulls, and expecting everything to be A.O.K. is simply a lot to ask for, even if it comes from the factory that way. The science is, in simple terms, boost and cats do not mix well.

A lot of the posts here are focusing on the science and intricacies of it all that I fully admit I don't completely understand, but from my own research and wanting to put a Whipple on my car there are a few things to consider:

- You will essentially have to limit your horsepower if you want the cats to last any substantial amount of time outside of shortening their life for simply putting the blower on and doing some inevitable WOT passes, whether in Mexico or on the drag strip.

- COT protection is a must for any plan of longevity, and it appears that most tuning companies can fiddle with this some to make it work but not work well. But, again, wanting to make a lot of power and trying to keep your cats intact is not going to bode well for the long term. It's basically either or.

- For guys like me who worry about emissions, headers are basically not an option as there are simply too many nuances with high flow cats, their location, readiness monitors, tuning, etc. I get that's the name of the game when you want to put aftermarket parts on a car and tune, but I'm not willing to go back and forth with my tuner, the tuning device, and the emissions tests to try to make it all work. I would rather just accept that I won't make as much horsepower as I wanted and be happy with it. Factory cats are going to do the best at keeping anything emissions related happy.

- Given that Whipple's tune is what keeps the whole kit CARB certified (from what I understand), you are drastically limiting your tuning options and that is also something I will have to live with since I'm not sure if a tuner is going to modify Whipple's tune to accommodate for a converter for example.

 

[engineermike]

...Does it go to a set value that you can determine or control to target an exhaust temp. ..

I think I finally have an answer to this. Check out the attached log data at WOT.

- Orange and yellow are inferred cat temperature.
- Red dotted line is the COT threshold setpoint in the tune.
- Blue and white are measured lambda from the WBO2s.
- White dotted line is the max enrichment to be used for COT, also set in the tune.
- Cursor is positioned where the fuel source toggled to "Exhaust Temp Enrich".

You see the cat temp rises rapidly until it reaches the red dotted line. Then you see the lambda goes to max enrichment and the cat temp curve starts come into control. The interesting part is that when the calculated cat temp falls under 1680, lambda starts to lean back out again, but not all the way up to power-enrichment levels, and the fuel source remains in "Exhaust Temp". What we are seeing here is the cat temp is being controlled by lambda in a feedback loop, rather than the typical stoichiometric or power-enrichment control values. Gas turbines are controlled similarly, in that fueling is commanded to control exhaust temp.

 

[Torinate]

Thank you for your knowledge and understanding of all this!! It really helps to have that base to help us understand what’s actually happening and figure ways to work around it.
Much appreciated!

 

[engineermike]

@Torinate I finally got the EGT logging going. This was more complicated than it sounds. I installed a Type K thermocouple just before and just after the 1st cat bed. I had to buy a couple of Rosemount transmitters and get an EE buddy to program them, then feed the signal into HPtuners ProLink for logging. I logged both temps along-side inferred cat temp from the PCM using the Whipple calibration (not really). The following snip is a short drive where I only went WOT shortly for 1.4 load and 5000 rpm max in 4th gear.

Orange is EGT in the collector just ahead of the 1st cat element, red is EGT just after the 1st element right next to the downstream O2. White and yellow are inferred cat temp logged from the PCM.

You can see the upstream EGT reacts very quickly and tracks relatively well with the cat temp, except the cat temp has some overshoot and a long cool-down. My guess is this is due to the exothermic catalyzing process. The downstream EGT is much slower to react, possibly due to the thermal mass of the cat element causing delayed heat-up of the downstream EGT. Now, the problematic part is where the downstream EGT is actually showing hotter than the cat temp after going WOT. This doesn't seem possible to me and might imply the temp overshoot is underestimated.

More to come on this.

 

[Torinate]

@Torinate I finally got the EGT logging going. This was more complicated than it sounds. I installed a Type K thermocouple just before and just after the 1st cat bed. I had to buy a couple of Rosemount transmitters and get an EE buddy to program them, then feed the signal into HPtuners ProLink for logging. I logged both temps along-side inferred cat temp from the PCM using the Whipple calibration (not really). The following snip is a short drive where I only went WOT shortly for 1.4 load and 5000 rpm max in 4th gear.

Orange is EGT in the collector just ahead of the 1st cat element, red is EGT just after the 1st element right next to the downstream O2. White and yellow are inferred cat temp logged from the PCM.

You can see the upstream EGT reacts very quickly and tracks relatively well with the cat temp, except the cat temp has some overshoot and a long cool-down. My guess is this is due to the exothermic catalyzing process. The downstream EGT is much slower to react, possibly due to the thermal mass of the cat element causing delayed heat-up of the downstream EGT. Now, the problematic part is where the downstream EGT is actually showing hotter than the cat temp after going WOT. This doesn't seem possible to me and might imply the temp overshoot is underestimated.

More to come on this.

Wow!

I will take your word on the complexities. So with your limited run, I see 1420* vs 1346* at the cat. Yea, not sure how it would be hotter after the cat.

I have the cat temp PID on my nGauge but haven’t really been able to drive it lately. Just got it out last weekend but weather has not been cooperating. I cannot remember the numbers after a pull. But, interestingly enough, the numbers go up and back down extremely quickly.

 

[engineermike]

Keep in mind this log was 5-6 minutes long so you’re looking at a full minute for the inferred cat temp to come back down from just a couple of seconds at wot. The “actual” cat temp (red) was much slower to come back down than the math model thought.

 

[sjmurphy34]

@Torinate I finally got the EGT logging going. This was more complicated than it sounds. I installed a Type K thermocouple just before and just after the 1st cat bed. I had to buy a couple of Rosemount transmitters and get an EE buddy to program them, then feed the signal into HPtuners ProLink for logging. I logged both temps along-side inferred cat temp from the PCM using the Whipple calibration (not really). The following snip is a short drive where I only went WOT shortly for 1.4 load and 5000 rpm max in 4th gear.

Orange is EGT in the collector just ahead of the 1st cat element, red is EGT just after the 1st element right next to the downstream O2. White and yellow are inferred cat temp logged from the PCM.

You can see the upstream EGT reacts very quickly and tracks relatively well with the cat temp, except the cat temp has some overshoot and a long cool-down. My guess is this is due to the exothermic catalyzing process. The downstream EGT is much slower to react, possibly due to the thermal mass of the cat element causing delayed heat-up of the downstream EGT. Now, the problematic part is where the downstream EGT is actually showing hotter than the cat temp after going WOT. This doesn't seem possible to me and might imply the temp overshoot is underestimated.

More to come on this.

The way Ford calibrates this feature is somewhat similar to what you have done. They place thermocouples throughout different locations in the exhaust and monitor temps during different speed/loads and drive cycles and put that into a tool that helps to calibrate the models. The model has inputs based on speed and load as well as lots of other variables like exh flow rate, spark, lambda, etc. One thing that obviously is troublesome is that the model doesn't know that there is a turbo or much higher loads from a supercharger so it really depends on how the model was calibrated.

However one difference is that there is a thermocouple placed in the midbed of the cats. Usually measured 1" post brick face(measured from front). The midbed temps are generally the hottest throughout the exhaust. There are reactions within the cats and they likely drive the higher temps you see post cats.

Depending on the materials used in the cats, above 900 or 950C midbed temps is the no go zone. So if you see temps above that, they can lead to burning the bricks.

Note: I haven't read through this whole thread so you might already know this info, apologies if this is nothing new.

 

[Torinate]

Eek!

That’s 1650-1740 Fahrenheit.

So depending on how accurate the PID is and the actual temp...

Can’t remember, but I’m pretty sure I’ve seen that.

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