Just went to the dealership to take a look at the broken HFC. The whole entire honey comb of the cat was broken off. It was just moving around freely. The tech at Nissan said "the only reason Nissan decided to replace the motor is because this motor is known for having oil consumption issues." I asked him if he was certain that the cat was the reason the engine failed..He said "it's one of the reasons.." I swear they'll never give you a for sure answer to anything. Should i go the test pipe route, have the hfc replaced (probably the worst idea since permanent viagra), or put the stock cats back on?

:iagree: Yezzzirrr. That's basically what I was saying earlier. Why lose a customer over a $9000 engine if he may buy a $40000+ car every 3 years or so?

There are only a couple of different cores being used.

Neither berk not FI make the cores, and it's worth checking into whether there is a material difference.

I am pretty sure the FI HFCs are 300 cell vs 200 for the berk.

:iagree: Yep, Nissan is full of shite.

Leave the cats stock. Just use a non-res exhaust. It will be the same difference in sound and hp. Either No resonators on the exhaust on a stock cat or test pipe on a resonated exhaust will still give similar gains. Unless you are changing everything from the intake, headers pipes and exhaust. The switcharoo won't make a big difference. The only true difference is forced induction.

It's not impossible that this happened, but the major damage was almost certainly due to inadequate lubing due to oil consumption.

To be fair, it can be difficult to figure out what caused what when two more more mechanical components fail at the same time -- all that matters is that they are covering it.

I'd look into a different set of HFC's or TP's.

exhaust valves are only open after the mixture has been ignited and the gases expelled out the exhaust after combustion, no air is ever sucked into the exhaust ports.

Vacuum is only created in the intake port , not the exhaust port

Cat material is fairly regularly sucked into the engine when they go bad. You should try searching these things before posting about them.

I think you misunderstand the way the valves are timed. Overlap is very common.

Indeed, especially with a high-revving NA motor. With boosted motors, overlap=power-loss and is kept to a minimum.

That's a really interesting idea -- I didn't think the resonators on an exhaust as restrictive at the core of a cat. If true, that's a good way to stay OEM and green, but pick up lost power. Would be neat to see a dyno comparison of the two set ups.

There is no exact proof in any of these online claims that broken cat material gets sucked back into the exhaust ports, from a reputable source.

Most of these claims are other online forums or ask the mechanic sites etc.

Resonators create no exhaust gas restrictions, cats do... HFCs paired with resonated or non-resonated exhausts will produce the same gains. Regular cats vs HFCs do change the restriction however. This has been tested by lots of different exhaust manufacturers.

+1 Happened to a friend of mines spec-v last year

Isn't a little bit of exhaust sucked back in as some sort of EGR? I read somewhere Nissan uses that technology but not very sure

Nissan dealers have been known to hire people. People post things on the Internet. People are highly unreliable.

Would love to see picture of said Berk cat. Evidence that cat material was found in combustion chamber or oil pan. Maintenance records of said 370z with accounting of people who did the work. Frequency and type of oil used. What kind of oil filters used for all oil changes. Any monkeying around with tune?

Yes some other motors have had issues with precats but haven't seen much evidence to regular cats located a ways down the system causing this on a VQ37. Not saying it can't happen but would like to see real evidence.

Otherwise this is just a bunch of pointless yapping and sensless product bashing.