Centrifugal Boost Question - Cats

[ApplesAndOranges]

I've been whipple from day 1 dealer install. Within 2,000 miles running stock whipple tune my cats were failing. Replaced woth kooks headers and their non green , regular high flow cats. Those lasted maybe 700-800 miles and failed quicker than the stock. This was just from daily driving on stock whipple 93 tune with the occasional merge ramp, bridge 3rd and 4th gear blast.

Ran free flow for a while but didnt like the raspy exhaust note or fumes from 93 fuel that would fumigate everything in trunk area.

Bit the $$$$ bullet and picked up GESI cats and have been trouble free for over 2 years now with plenty of 1/4 mile and roll racing days. My buddy runs GESI on his 1070whp hellcat and hasn't had any signs of failure either.

I made 786 whp SAE free flow on a dynapack and 819 whp STD on a dynojet with the GESI running same tune other than the COT protection related tables.

If you decide to go GESI cats, just be sure not to use a 2 step or no lift shift in order to keep them healthy. Also keep COT protection enabled.

You can always have them and lead pipes v banded to make swapping out of track days easier.

Did you notice any change in the volume of the exhaust with GESI cats vs the stock ones?

Sponsored

 

[stang17]

Did you notice any change in the volume of the exhaust with GESI cats vs the stock ones?

When my stock cats failed, I went Kooks 1 7/8 headers with the regular hi flow cats, then free flow, then the GESI. I will say adding the headers added a good amount of exhaust volume sound. The GESI definitely flow much more than stock and get rid of most of the rasp that had existed when free flow.

 

[Mikepol2]

I wonder what effect the amount of boost chosen has on cat life. Seems to make sense that the higher the boost, the higher the temperature. Remember pV=nRT from physics class?

 

[stang17]

So this data log is from this past Friday's test and tune. I run pcmtec canbus flex and had e74 in the tank and 3.375. I turned COT protection off for this run just to see how high cat temps would reach. Ambient air temp was 82 and IAT were 97 degrees at this point in the run. I have the standard heat exchanger and IC pump that came with gen 2 whipple stage 2 kit. I also have a custom supercharger blanket, MFP Phenolic spacers, and a Reische 170 T-Stat.

Cat temps (per the inferred logic) were approaching 1,700 by 7,000 rpm in 3rd gear. They reached peak temp of 1,790 by end of 4th gear run.

 

[engineermike]

@stang17 i actually installed thermocouples in my cats some years ago and found the cat temp actually rise when you let off. However, I’m 90% sure the degradation we are seeing isn’t due to peak temp. It’s due to thermal stress which is different. All of the tech articles on thermal degradation of catalyst have to do with molecular changes over long periods of time, not mechanical failure of the ceramic substrate. I believe it’s thermal shock causing failure, likely during DFCO.

 

[RiotfunK]

No matter the type of boost, centrifugal or roots. There will be a lot more heat. As for cats. It depends. I've seen some people kill them in a weekend and others are still on them, just like OPGs. I was running stock headers/cats for over 12K miles boosted and was told they were shot. Had some track time on them too. Picked up stainless works headers and have their exhaust and when the stock cats were pulled they were like new. Went gesi450 cats on SW headers. So far so good. I'm also not redlining my car daily. I've hit 7k rpm a handful of times since I've had the car. I'm not racing, is manual trans. Just a fun ride. Built for me, not dragy. I did it out of safety and was doing OPG/CS and things anyways.

Is def a lot louder than the stock setup. Constantly get the thumbs up and approval nods from people on the sound. I'm ok with that. The growl and the Kaachhhsssss afterwards is addictive AF.

 

[robvas]

@stang17 i actually installed thermocouples in my cats some years ago and found the cat temp actually rise when you let off. However, I’m 90% sure the degradation we are seeing isn’t due to peak temp. It’s due to thermal stress which is different. All of the tech articles on thermal degradation of catalyst have to do with molecular changes over long periods of time, not mechanical failure of the ceramic substrate. I believe it’s thermal shock causing failure, likely during DFCO.

This guy from GESI is saying something similar

 

[stang17]

I think dfso is actually what’s destroying cats. I’ve programmed mine to not enter dfso once the cats are over a certain temp. Mine have lasted several years at about 900 rwhp in both a Roush truck and Whipple car, but they are gt500 cats as well.

Speed density also does a better job of protecting the engine in the case of a cat failure.

What temperature setting do you use for not entering DFCO?

 

[MontiCristo]

best to just get rid of the cats, saves you the headache and thought in the back of your mind every time you make a pull.

Mine's got about 40k miles with a paxton centri kit with stock cats and they've held up fine. Mine is a daily and I don't do any track time however. Lots of freeway miles and pulls

see that's what i'm thinking. I'm not racing the car and it's my daily. I'd just like a little more scoot. thanks for commenting .

 

[engineermike]

What temperature setting do you use for not entering DFCO?

https://www.mustang6g.com/forums/threads/yet-another-how-do-we-make-cats-live-thread.218472/

1350 but choosing this wasn’t super scientific. Basically I erred on the low side.

Sponsored