dfontes1188

Having minimal backpressure is not about throwing on the biggest pipe, it's about maximizing exhaust velocity with the least restrictions The more restrictions you have, the more back pressure you have. People tend to think back pressure is all in the pipe diameter..

dfontes1188

I have read plenty of articles that prove otherwise..

I did not lose any low end torque/power when I went to a catless 3" exhaust system..

Ivory

iTrader: (3)

^you have back to back dynos to prove this? And changing setup to have less back pressure doesn't automatically mean you lose torque or power, the important part is not to over do it.

Ivory

iTrader: (3)

So in the grand scheme of things to create more back pressure would you 1. add more kinks to the pipe or 2 change the overall diameter of the setup? I still don't get the part where you claim no back pressure is the only good thing?

thepat

lol

dfontes1188

I have no idea.. ask the people who claim that your exhaust needs backpressure..

dfontes1188

Heres a thread from this site that proves backpressure for our engines is no good.

https://my350z.com/forum/intake-exha...k-for-n-a.html

gt20ir

iTrader: (1)

in the ideal world with a correctly designed header and exhaust system you will not need any backpressure. Most of the problems with almost every exhaust system out there is in the collector where the gasses merge. If you have a crappy collector, a formed one, or none at all, Then when the exhaust gasses flow from the primary tube into the collector, they dispurse and have no smooth transition causing a lot of turbulance... Mostly from the size transition being to great... I.E. (3) 1 3/4 tubes into a 3" formed collector. Not only do the gasses lose velocity, but they also lose their refractive wave pulse and pressure waves which effect scavenging and more...

Bottom line, a header/exhaust system that "needs" back pressure to work, and or make power, is a poorly designed system.

Now this is not to say that if you take this exhaust setup from a 2.25" exhaust to a 3" that he will not lose low end power due to the header design, but the power gains up top would be there if there is power loss due to reversion, or cam timing compensation due to reversion which will retard cam timing too fast and lose power, ( could lose power, depends on every setup).

Every header/exhaust size (the tube diameter them selves) is based mainly on the displacement of the engine and the VE of the motor ( the actual amount of air being "pumped" through it) and then how high of an RPM does the motor run... I.E. generally, speaking at higher RPMs the exhaust gas velocity will get too high on "x" size pipe and cause a restriction, so you will need to increase the pipe size for best higher RPM power.

Ivory

iTrader: (3)

If you posted this thread it wouldn't look as if you have no idea what you are saying. After reading the thread, it just looks like you are poorly translating what's being said in the thread and trying to act like you know what you saying.

What I gather from the thread is no different in concept except the terms being used, while "incorrect" the term back pressure has been equated by having a balance of restriction inside the exhaust system, thus creating the scavenging effect, by having completely eliminate said restrictions it would equate to having no back pressure and a open dump exhaust, which you said would be the best scenario, and this wasn't the case and definitely isn't what you should deduce from the thread.

What I gathered is this, your header to Y pipe choice in the upstream side of your exhaust is far more important than your downstream, that being said, yes even if you eliminate the exhaust completely after the Y pipe, there is minimal difference in power/torque, however the upstream pipe diameter is still crucial in creating proper "restrictions" previously termed "back pressure" to create more power via scavenging than simply going with the largest pipe.

going back on topic, the OP isn't changing an ordinary exhaust, he's also going with long tube headers, which would most definitely change how the overall system affects his power output whether positive or negative is yet to be seen.

kgkeen101

Whoever voted the 20-30WHP I like! haha. Nice showing, if I get a solid 10-15whp over the entire powerband I'd be very happy. Who knows though, given how terrible my exhaust was haha.

krazy4

Damn, I expected a lot more than 108mph.

kgkeen101

Yeah tune wasn't done or anything but oh well. Now since I know my exhaust was f*&ked too I am redoing a couple other things as well. Going to be better next time around.

kgkeen101

Freshened up the car with a couple new parts.



Engine back in its place though and ready to go.

Now our exhaust is all being completely custom made. I'm getting what I paid for back then for a "custom" setup which was just a bunch of crap bolted together that would fit. Nothing custom at all. This time not getting ripped off. This one truly is custom and to exact specification of what I wanted! I'm very excited to be turning it on soon and bringing her back to TPS to retune. Expect some good gains with what we freshened the motor up with =).

Exhaust shots!





That is right, check out the Borla tip, looks top notch and sleeper which is exactly what I'm going for. Just a clean look.







All the welding is top notch. Will take more pictures later, running 2 Magnaflow mufflers so she'll sound nice and smooth.

NiZMo1o1

iTrader: (13)

its been a long day hopefully tommorow we will finsh up , and also change that leaky seal, give concept Z a call and talk to them kevin , we need to start this bad boy up !

kgkeen101

I sent Coz an e-mail with the issues. His phones off I'll try again tomorrow.

thepat

its because i rock. but you knew that already

fully custom? did you ditch those ebay longish/short headers?

kgkeen101

exhaust completed, just sorting out a few issues and then we'll fire it up and dyno

kgkeen101

Gota love sneaking off with the wife's car for the day. =P

MIKERNM1990

...

kgkeen101

hang tight its almost done, redone with 3in exhaust and all.