pop goes the 5.0

[BruceH]

Any feedback on safe mode with tunes for the 5.0? Are they not fixed to make a safe AFR if a sensor dies on a tuned car?

Sent from my NookColor using Tapatalk 2

A good tuner will have the load with failed maf tables correct....

 

[klaw]

Thanks for the info, Klaw. That's the first I've heard of a stocker failing, but I admit I'm not keeping a running tab on this. My comment was based on the threads at SVT dealing with this issue. Food for thought, though.

Here's another failed stock cat out of an '04 KB Termi:

 

[RED09GT]

Here's another failed stock cat out of an '04 KB Termi:

Care to name the tuner?

 

[klaw]

Care to name the tuner?

Per my comments earlier in this thread, in my opinion, the stock cats are not designed for the airflow and heat dissipation required to support 750HP (this termi is a pullied & tuned KB setup). The cat failure is only related to the tune in so far as the tune is designed to extract that level of performance (safely) out of the engine. If the cats then become the weak link, they need to be removed or the power dialed back (or larger/multiple cats installed).

 

[WytHorse]

Per my comments earlier in this thread, in my opinion, the stock cats are not designed for the airflow and heat dissipation required to support 750HP (this termi is a pullied & tuned KB setup). The cat failure is only related to the tune in so far as the tune is designed to extract that level of performance (safely) out of the engine. If the cats then become the weak link, they need to be removed or the power dialed back (or larger/multiple cats installed).

exactly! The tuner has NOTHING to do with it...just design limitations....

 

[klaw]

Part of the issue results from the way these cars are tuned. We measure the airflow and then add fuel to reach a target AFR (stoich at idle/cruise, somewhat richer at WOT). If the fuel system is under-designed, we know it right away because duty cycle maxes out and the AFR goes lean. No one would blame a tuner for that problem, the solution is obvious - add more fuel pump. In the case of the cats though, excess restriction etc from under-designed cats isn't particularly obvious. The airflow is assumed to be "what it is" and the fuel adjusted to match. Usually when the cats physically fail, the last "professional" to have touched the car is the tuner and it's easy to point the finger of blame in that direction. I think it's short-sighted to assume that one size cat fits all and that somehow the tuner fucked up because the stock cats you bought when your car was 300HP are now little shattered pieces when you tried to push 750HP through them.

 

[SS KILLR]

This is what my cat looked like with very few miles.

 

[RED09GT]

Too bad not enough of these will actually be driven as this would truly tell the truth as to whether it is the Horsepower that kills the cats.

http://www.roadandtrack.com/tests/drives/2012-shelby-1000
800+ at the wheels with stock exhaust manifolds and cats.