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Discussion Starter #1
Someone on another board told me the Injen straight tip exhaust had built in silencers, (unlike the angled tip that has removables), I did not believe them. How could Injen be "Dyno Proven" and have restrictors in there.

Being the mad scientist that I am, I decided to see what they were made of. I am a bit lazy, so I figured, I would just see how far I could go from the back end in.

So I got a cheap web cam ($12) and a USB LED light ($5) hot glued them to a big bolt I stuck into a length of heater hose. Added some electrical tape and I was good to go. This is what I found

http://www.hypersprite.com/auto/video-z-00...jen_str_tip.wmv
(sorry mac folk, it's windows media but that is what I had time for)

It might be a little hard to see but basically half way down the back muffler there is a silencer. I can't tell what size he choke tube is in the middle but it seems like it is about 1.75 or so. So at low RPM, exhaust flow is low enough it will go right through. As the motor revs higher. this blockage will force exhaust through the packing.

This is not a performance piece in my book and I am downright mad about it.
It also explains why the system seems louder at 2k rpm than 5k. Further, it explains why so many people have fiberglass all over the back of their Zs. The exhaust is trying to escape and it is being forced through the packing. Why couldn't they just use a spiral perf tube like Greddy?

Chris

PS. Just so there is no confusion, there is an edit splice from going in to going out as I spent a good minute trying to get the camera past the obstruction, I could not. The splice just saves a minute worth of useless download for everybody.
 

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Shame on you for not using vaseline or some kind of lube! :lmfao: :rolf2:

Good work, Mr. Watson! Now what?
 

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Discussion Starter #6
[/quote]

I have not decided what to do yet.

The earlier angled tip had removable silencers that are illegal here in CA (maybe other places too) and they also had a reputation for being to loud, something the newer system has not lived down even though they are not as loud.

Further, it makes me question the dyno numbers claimed by Injen because they are using the early numbers for the later system.

The system design is flawed from the start, if they are running the exhaust through a 1.5 or 1.75 inch choke, it would have been better to go with smaller diameter mufflers (say a reduction of a quarter of half inch) but they probably use this same can on multiple systems and just incorporated it with the 350Z. This can might be acceptably quite for a single outlet system, but not for a dual system with only 3 cylinders (1.9L) feeding it. So the only real way to fix the problem and remain under the sound limits would be to design an entirely new set of back mufflers, something I don't think they are going to do.

Another solution for them might have been to add resonated tips (like ANSA used to sell back before they went all rice), I have seen these take the edge off a system and get it to respectable levels and still allow for free flow.

As for fixing it myself the big problem there is that it's stainless and I don't know anyone that can weld stainless with stainless. Because the back can has a bend on both ends, there does not seem to be a way to get at the choke without disassembling the cans.

Another thought I have been contemplating is selling it and getting something else, what, I have no idea.

Chris
 
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