370z engine blown

red6spd

Does anyone else find it strange that Nissan apparently found that the aftermarket cats where the reason a several thousand dollar engine went boom and they are still gonna eat all that money?????????????? Something does not add up here, seems like the OP's mod according to Nissan directly resulted in the warranty issue.

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Fabsnoop

I'm glad they're covering the damages. I spoke to berk about the cats, and they said that a cat failing is usually directly due to problems with the engine. I have no idea if this is true.

gsxr750

B.S. ! There is no possible way parts from the exhaust can be sucked into the engine thru the exhaust ports.

The engine is a simple pump and the exhaust can only pump pressure out, it can't work as a vacuum and suck particles back into it.

Dirt or foreign objects can only enter thru the intake or other sources, oil, broken internal parts, broken head gasket etc.

Back pressure is only a term used to describe the amount of restriction to exhaust flow caused by a internal muffler, baffle or cat etc. Back pressure does not mean a reverse flow of exhaust gases.

This guys example is a good reason to show why is better to keep the car stock, dealers and manufactures are always looking for reasons to deny a waranty claim if possible.

Just be glad they covered your repair under waranty.

Most likely the ring damage was caused by the rings never really seating properly or a excessivly lean air fuel mixture and even engine timing could do it or bad engine mapping

Zenki370

Exactly what i was thinking. Ive found with most brands, its better to just modify the catback if youre going to touch the exhaust and leave it alone there after. Its the one and only mod Ive done on my Z and it will remain that way until the warranty runs out. I dont have extra cash to replace the engine nor the legal help it would take to fight a warranty denial.

Fabsnoop

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?

UNKNOWN_370

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.

Jordo!

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.

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ImportConvert

You're lucky he DIDN'T give you a "for sure answer". Shuffle back to the lobby and zip the lip, you just got a free engine even though the crap parts from Berk are what destroyed it. Go play the lotto.

onzedge

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Red__Zed

You know the exhaust ports stay open during the intake stroke, right? This is not a terribly uncommon occurrence (when cats go bad, that is)

gsxr750

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

Red__Zed

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.

ImportConvert

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

gsxr750

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.

Red__Zed

Dealer can expense it back to Nissan, Nissan knows OC is an issue and doesn't ask questions.

Dealer wins loyalty at nissan's expense. A single engine cost is trivial to Nissan. Pretty straightforward.