Not big ones....but flames.

RARE Jaguar S type R Supercharged, Arden AJ 8 S9 550 HP - YouTube

 

Does that mean that all the snap/crackle/ pop is occurring before the cat? On an occasional basis I will get a bona fide backfire very obviously occurring at the back of the car, so a bunch of raw gas is making it past the cat.

 

 

That's what I thought.

 

that last video is no flames ... just smoke in the red tail lights ... can it happen sure ... but highly unlikely ....

and sure, Ihave seen flames in front engine cars like a GT-R but those are large diameter straight pipe cars ... never on a stock exhaust ...

 

Exactly, overrun combustion would have to be complete upon exiting the "red-hot" cats, and any residual flames would almost certainly be snuffed out in muffler.

 

Not much muffler in dynamic mode, but the cat is certainly a compelling argument.

 

I have not checked and looked into this, I do not know where the fuel is injected in the exhaust but I have a manifold back, high flow cat, large diameter, truly straight pipe from there back Capristo exhaust and nobody following me has mentioned flames.
Been now twice to the Blue Ridge mountains with relatively slow speed, high rev, constant braking and shifting drives up mountain roads for hours. Exhaust totally black from soot ... if I had backfires that make it out of the exhaust it would have been there and I am sure somebody would have caught it.

I think the fuel is injected before the CAT's, all bungs on the Capristo exhaust are for the O2 sensors alone. You can definitely tell that some of the crackles are further up or down the exhaust but I am no chemist and don't know what temp the exhaust reaches and if that is enough to ignite fuel alone.

no piping going through muffler when valves are open:



You can see the sooty outer tips here ... that is still a fairly rich situation when they are black like this ...

 

I think some people are getting confused.

There is no fuel being injected into the exhaust as such, it's coming out of the combustion chamber while the exhaust valve is open.

Direct injection engine, the injector fires directly into the combustion chamber, the ECU has a 2nd fuel table for the "controlled misfire" fuelling i.e the pops/crackles.

 

Here is one with a couple videos, but flames only on video 1. Video 2 is a cold start de-catted system.

Video #1

Video #2
https://www.instagram.com/p/BCqX9k-n...by=dub_customs