Subaru BRZ

[ScoobsMcGee]

Originally Posted by Clipdat

What about under throttle off vacuum deceleration? Also could it be perceivable then that there is a slight pulsing effect that draws a slight amount of exhaust gas back?

These are serious questions as I honestly don't know. It does however seem unlikely that the bits of the cat would make it all the way back up and into the engine.

It's hard to tell by looking at the photo, but the dislodged cat still seems to be mostly intact. So maybe those bits are from something else besides the failed cat?

I've heard many explanations as to why the pieces get sucked into the engine over the years, but can't say for certain.

What I can say is that engine failure from a precat collapse is a thing that happens, and is usually the result of unburnt fuel going into the exhaust system from a rich tune. It's a common problem with the Nissan QR25, which I had in a 2003 Sentra Spec V. In this case, if not a manufacturer defect, it could have either been from the engine relearning and dumping too much fuel into the engine, or a tune on the car which was intended to make pops and crackle noises (done by dumping fuel into the exhaust). Also plenty of other possibilities that my limited experience can't identify, since none of us seem to be mechanics around here.

https://www.b15sentra.net/forums/sho...d.php?t=135241

https://www.bobistheoilguy.com/forum...39188&page=all

https://www.maseratilife.com/threads...21/#post-23243

https://www.caradvice.com.au/687702/...p-crackle-pop/

Originally Posted by CrowsFeast

wth, it cracked the valve cover? That's rather extreme... I don't know that the cats are the things to blame on this one.. I know you said it happened right after the install but I've had enough secondary things pop up after I do an unrelated job on my car that I believe in coincidences now.

Also, doesn't that material look more like paper on the piston? Do you have a paper air filter?

I suppose it's possible that with a sufficient blockage; when the intake valve opens at the top, just before the exhaust closes (so during scavenging) that you could actually get back flow. It just seems so unlikely. My dad's truck years ago had the cat melt into a near solid blockage and it just had no power; no other damage (granted it's a truck engine).

*Also not a professional mechanic; just some guy on the internet.

As I wrote before it, me and a close friend had the same damages to our cars. In both cases the mechanic told us that the JDL Catalyzer was the cause. There’s a reason why they limited the warranty for track use and sc engines to only 90 days.

And both cars where using the HKS drop in airfilter, I think the damage was so big because of the combination of the catalyzer malfunction, low quality and the forced induction.

You see similar damages to Diesel engines when particle filter is blocked, the higher pressure causes often an turbo damage which often damages the engine when it’s late recognized.

Also both HKS SC Kits worked fine with ft86speedfactory catted UEL header. The engine of my friend was a fully build HKS 2.1 stroker engine and both supercharger kit have been installed by a professional company, so it was not an dyi.

[nikitopo]

Originally Posted by SugarBrz

As I wrote before it, me and a close friend had the same damages to our cars. In both cases the mechanic told us that the JDL Catalyzer was the cause. There’s a reason why they limited the warranty for track use and sc engines to only 90 days.

And both cars where using the HKS drop in airfilter, I think the damage was so big because of the combination of the catalyzer malfunction, low quality and the forced induction.

You see similar damages to Diesel engines when particle filter is blocked, the higher pressure causes often an turbo damage which often damages the engine when it’s late recognized.

Also both HKS SC Kits worked fine with ft86speedfactory catted UEL header. The engine of my friend was a fully build HKS 2.1 stroker engine and both supercharger kit have been installed by a professional company, so it was not an dyi.

Are you putting now back the ft86speedfactory catted header ?

[Irace86.2.0]

Originally Posted by SugarBrz

As I wrote before it, me and a close friend had the same damages to our cars. In both cases the mechanic told us that the JDL Catalyzer was the cause. There’s a reason why they limited the warranty for track use and sc engines to only 90 days.

And both cars where using the HKS drop in airfilter, I think the damage was so big because of the combination of the catalyzer malfunction, low quality and the forced induction.

You see similar damages to Diesel engines when particle filter is blocked, the higher pressure causes often an turbo damage which often damages the engine when it’s late recognized.

Also both HKS SC Kits worked fine with ft86speedfactory catted UEL header. The engine of my friend was a fully build HKS 2.1 stroker engine and both supercharger kit have been installed by a professional company, so it was not an dyi.

Who tuned the car?

The Car was tuned by GP Performance in Germany! It seems that they do their development on customer cars.

Originally Posted by nikitopo

Are you putting now back the ft86speedfactory catted header ?

Actually I was back to a modified stock header with an 100 cell HFC from HJS but then changed due more track use to an ACE 350 Header.

[botbs]

Originally Posted by SugarBrz

Actually I was back to a modified stock header with an 100 cell HFC from HJS but then changed due more track use to an ACE 350 Header.

Did you have any issue with stock header with stock cat?

Thanks