Strategies to keep cats from melting

[Torinate]

That’s awesome! Who’s doing the install?

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[Grimreaper]

That's a very interesting piece of the puzzle. Have you been able to get the ex temp model to accurately match your probes?

Staged COT might be a doable option to limit the ramp rate. 2 points gives you a slope to play with. All the tunes I can recall always have the same temps in both stages. Would prob need to remove the mani and o2 sensor temp protection.

 

[engineermike]

That's a very interesting piece of the puzzle. Have you been able to get the ex temp model to accurately match your probes?

It's impossible with the tune parameters we have. I could if it were offset or proportional error, but there is a time component of the algorithm that can't be adjusted. The best I could do is keep the mid-bed temp below a desired number and find a good COT time/power balance.

Staged COT might be a doable option to limit the ramp rate. 2 points gives you a slope to play with. All the tunes I can recall always have the same temps in both stages. Would prob need to remove the mani and o2 sensor temp protection.

I've messed with the staged COT and not much changed in the behavior. And both are based on hard setpoints, not rate of change. I think the best we can do with the parameters we have available is to add fuel and enrichment rate at the right times.

 

[engineermike]

Since gt500 cats were brought up in post #2, I thought I would share what I learned today after purchasing some stock gt500 cats from another forum member.

The gt500 cats are the same diameter and length as stock cats. The rear o2, however, is fully exposed and doesn’t live inside a vented sleeve like coyote. Also of note is that the gt500 cats appear to be 400 cpi (20 x 20 cell in an inch) and the cells are square. The coyote cats are hexagonal cell 25 x 30, or 750 cpi, if my counting is correct. I can’t tell if the material is different.

For reference, in the attached pic the stock gt cat is on the right and it’s a failed one of mine. Gt500 is on the left and appears to be intact.

 

[Angrey]

Since gt500 cats were brought up in post #2, I thought I would share what I learned today after purchasing some stock gt500 cats from another forum member.

The gt500 cats are the same diameter and length as stock cats. The rear o2, however, is fully exposed and doesn’t live inside a vented sleeve like coyote. Also of note is that the gt500 cats appear to be 400 cpi (20 x 20 cell in an inch) and the cells are square. The coyote cats are hexagonal cell 25 x 30, or 750 cpi, if my counting is correct. I can’t tell if the material is different.

For reference, in the attached pic the stock gt cat is on the right and it’s a failed one of mine. Gt500 is on the left and appears to be intact.

Great work.

Would be interesting to see if the yield is different for the same flow.

Ostensibly, if they're the same material/catalyst, the denser array would not only oxidize more hydrocarbons, it would also be much more restrictive to flow and result in greater pressure delta.

Perhaps they're a different material and the less dense array is able to achieve better catalyzation while simultaneously reducing flow restrictions. Or perhaps Ford is allowed more pollutants as part of a fleet wide scoring. Does anyone know if the GT500 pays the "Gas Guzzler" tax? I wonder if said tax counts for not just economy, but pollutants as well.

 

[Dave2013M3]

A lot of is dictated by the kind of subtrate the cat has, not just the CPI. From the looks of the GT500 cat it looks to be of a much higher quality, and it probably needs to be as the GT500 with its boost.

 

[engineermike]

I’m such a dork…but @Dave2013M3 got me thinkin….attached pic is zoomed way in to both, approximately equally. Looks like the gt500 material is actually thicker; maybe even by double.

 

[Torinate]

Yes. Wow! Does loom a lot thinker. Would the square design also be inherently stronger than a hex design?

How many miles roughly on both these?

 

[engineermike]

Would the square design also be inherently stronger than a hex design?

My gut says the hex geometry is mechanically stronger for the same thickness and cell count, but that’s a huge difference in thickness.

How many miles roughly on both these?

The gt500 have 10k and was stock. The gt was a bad comparison; not sure the mileage but nowhere near stock setup.

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