straight pipes for 350

[350Z_LEE]

I went ahead and put straight pipes from the headers down. They put this cheesy canonthe end and it sounds very droney and ricey. I took it back today and i am going to have them take the can off. WIll that tone down that raspy noise and just give me the deep tone? I was thinking it was coming from that can.

[hazw8st]

With straight pipes you can run the risk of not having enough back pressure, which in turn hurts substantially performance.

[jEzTeR]

That is true...

where did you take it?

Did you buy a kit or just have them put straight pipes on?

[350Z_LEE]

I ended up taking it to a shop in town, but i pretty much learned a lesson. Their work is good, but i think i picked the wrong application. Now it so dam loud, that they gonna have to fab me another y pipe and connect it back into my stock can to tone it down. SO basically i wasted money experimenting. I am hopeing once i stick the stock can back on it will sound decent. Last time i try to cut corners!

[jEzTeR]

yeah the 350z is designed well. There are lots of aftermarket parts out there that have been proven to take power away for the car. We had a guy in our Z club who had several NA bolt-ons and he dynoed less than the stock #'s?

[350Z_LEE]

yeah i go tomorrow morning back there to have them fab a y pipe and hook backinto the stock can and tips. So i pretty much just got rid of the cats and ran new piping. Waste of money and time, but a lesson learned. From now on I will pay for already proven brand stuff. Hope it tones teh sound down. I am thinking it should since its back into the stock can.

[240 GTR]

i have Helix test pipes for my z. when i had the stock exhaust, it sounded pretty raspy between ~3000-3800. when i backed off the gas, it made another sound kind of like a BOV. then when i got a nismo exhaust, the raspyness went away completely.

i dont know if you have the stock exhaust or not, but i think the raspyness came from the gasses going from a large to small diameter....probably not too good for performance either.

when i got the nismo exhaust, i saw that the exhaust had been leaking between the test pipes and the exhaust. so i guess there was so much pressure that it forced the gas out from between the flanges.

[norikumiin]

With straight pipes you can run the risk of not having enough back pressure, which in turn hurts substantially performance.

I HATE it when someone says this... the loss of power with large diameter piping on N/A cars is because you are loosing velocity not back pressure

[350Z_LEE]

I will post pics of the install this week, or early next week. I just ordered the invidia true dual exhaust, and aps test pipes. Should fix my problem.

[Exar-Kun]

"I HATE it when someone says this... the loss of power with large diameter piping on N/A cars is because you are loosing velocity not back pressure"

...actually, this is also off-base. Getting positive cylinder fill requires some back pressure. Sure, too large a diameter wcan impede velocity, but typically not to the point of reducing the valume of exhaust that can be sent through the system. This works for intakes as well (larger throttle bodies, mani's, runners)....up to a point, you generally gain more valume of airflow because of the increased area than you lose from velocity.

N/A cars (unless their running high exhaust valume and very high revvs, typically) require some back pressure to ensure the combustion chamber fills with air correctly (positive fill).

So yeah, although some of the loss from mega-sized exhaust could be from velocity loss, that isn't the whole story either.

-Chet

[C-Kwik]

Not exactly. Backpressure will always hinder flow. Velocity (or lack there of) is a big culprit in decreased flow. The catch 22 here is that to increase velocity, you need to use smaller piping. The effect you want though is the high velocity as the momentum of the column of fast moving gas pulls trhe burnt mixture out of the cylinders. This is a bit simplified, but ultimately, this scavenging effect is what helps increase power. Generally for a street car, you want to increase the pipe sizes to a point where exhaust gas velocity can remain high at all RPM's. Most cars come from the OEM with exhaust pipe diameters that consider costs and noise reduction. The Z is probably freer flowing than you'ld find in most everyday cars so gains tend to be small or even detrimental with aftermarket systems as you've said.

[StricNyne]

i agree with c kwik about backpressure.

[MikeMurphy]

Not exactly. Backpressure will always hinder flow. Velocity (or lack there of) is a big culprit in decreased flow. The catch 22 here is that to increase velocity, you need to use smaller piping. The effect you want though is the high velocity as the momentum of the column of fast moving gas pulls trhe burnt mixture out of the cylinders. This is a bit simplified, but ultimately, this scavenging effect is what helps increase power. Generally for a street car, you want to increase the pipe sizes to a point where exhaust gas velocity can remain high at all RPM's. Most cars come from the OEM with exhaust pipe diameters that consider costs and noise reduction. The Z is probably freer flowing than you'ld find in most everyday cars so gains tend to be small or even detrimental with aftermarket systems as you've said.

^ He speaks the truth. I would like to add though that you will never find a perfect exhaust for all RPMs.

Drive safely.

[Exar-Kun]

I stand corrected. Thanks for the info.

[L33TZOR]

I ended up taking it to a shop in town, but i pretty much learned a lesson. Their work is good, but i think i picked the wrong application. Now it so dam loud, that they gonna have to fab me another y pipe and connect it back into my stock can to tone it down. SO basically i wasted money experimenting. I am hopeing once i stick the stock can back on it will sound decent. Last time i try to cut corners!

resonators sound like a good plan, dont make extra unnecessary bends, and adjustments, just get a good system thats proven!Sound doesnt mean power.