exhaust system

[marcus]

hi bros
wats the diff between mandel bend?crush bend? and straight thru in terms of power. straight thru as i know is the best but its illegal..wats the nxt best thing to it??or able to get as much power as straight thru but nt illegal

cheers

[SLOWEGG]

Mandrel bend, cause the pipes are all welded so its the same size all the way throught. Unlike press bend, they bend the pipe making it smaller at the bends.

[dudeling7]

straight through is not illegal in an exhaust system, the reason why many people get defected is that straight thugh systems tend to be very niosy, and way over the legal limit.

a stock exhaust system is only just under the legal limit so most aftermarket exhaust systems which are bigger in size will actually be over the legal noise limit, how far over depends on the size of piping, number of resonators and the muffler you use mainly.

[stephen8512]

straight through is not illegal in an exhaust system, the reason why many people get defected is that straight thugh systems tend to be very niosy, and way over the legal limit.

if its a defect, technically doesnt that mean that its illegal anyway?

[marcus]

so a piping of 2.5 suitable for teg vtir?

[barefootbonzai]

yes it's fine, man you have so many questions.

[dudeling7]

if its a defect, technically doesnt that mean that its illegal anyway?

haha yeh i guess, but my point was that upgrading your exhaust system to a straight through one is not actually illegal - its the noise of having the straight through system that can deem your car unroadworthy.

[Tobster]

"Straight-through" tends to refer to the muffler (as opposed to baffled or turbo mufflers (note "turbo muffler" merely means the way the gases are moved -- nothing to do with a turbo car).

Any exhaust piping will needs bends in it somewhere. Mandrel bends maintain the same overall pipe diameter so there is no constriction -- but they're expensive.

Press bends mean they just bend the pipe -- so there's a bit of constriction. However, it's worth noting that unless the bend goes more than 90 degrees, there's really very little (real world) difference in the flow rate of the mandrel and the press bend -- and the press bend is cheaper.

It all depends on how your exhaust needs to be set up -- and a good exhaust shop will be able to suggest what's going to be best for you.

[marcus]

thanks bros

[aimre]

Mandrel Vs press Bent:

http://www.warpspeedperformance.com/huth7.jpg

Press Bent at the top, mandrell at the bottom, both same diamater pipe, but notice how much thinner it get in the press bend.

Muffler
http://www.studiodino.com/studiodino/images/muffler.jpg

Thats something like a stock muffler, notice how easy gas flow is comprimised for sound deadening

http://e30m3performance.com/installs/installs-2/exhaust/magnaflow_inside.jpg


Notice how this straight through oval muffler doesnt compramise gas flow.


Theres some more info for you

[Twincam16]

straight through is not illegal in an exhaust system, the reason why many people get defected is that straight thugh systems tend to be very niosy, and way over the legal limit.

a stock exhaust system is only just under the legal limit so most aftermarket exhaust systems which are bigger in size will actually be over the legal noise limit, how far over depends on the size of piping, number of resonators and the muffler you use mainly.

Dont give false information. Straight through is actually one of the most illegal modifications somebody can do to their car, and can result in up to $10,000 fine for not having sufficient catalytic converters hooked up. The sound isnt the only thing wrong, its the pollution and police are very strict about this.

(-) Rep point for you. Dont post unless you have the right information, and dont condone something like that.

[Tobster]

A straight through exhaust doesn't necessarily mean you don't have a catalytic converter (which is absolutely necessary). A straight-through exhaust sytem can still have resonators and a catalytic converter -- it just means the gas flows straight through a smooth path without being shifted from its straight path to other chambers (like in the muffler pictured above).

Dudeling7 is quite right -- many straight through exhaust sytems are defected on noise levels because they tend to increase noise levels. It's not false information. (Give him back his rep point! ;))

A straight-through exhaust system can be legal if it has a cat-converter and meets noise regulations.

I think there is some confusion about what actually is a "straight-through exhaust" -- which, as I said earlier, generally means an exhaust system which uses straight-through mufflers or resonators.

[xtercii]

your aftermarket system is also meant to match the number of mufflers your original exhaust has, otherwise even if your muffler is making no sound, it's still a defect. I had a tuff time with EPA.

[DreadAngel]

I always thought straight through meant no Cat, no resonator hence why its called straight through, which means with no Cat its illegal (something to do with emissions for sure) and with no resonator the sound is definately past the legal limit meaning straight through systems are in fact illegal

[dsp26]

straight through is not illegal in an exhaust system, the reason why many people get defected is that straight thugh systems tend to be very niosy, and way over the legal limit.

a stock exhaust system is only just under the legal limit so most aftermarket exhaust systems which are bigger in size will actually be over the legal noise limit, how far over depends on the size of piping, number of resonators and the muffler you use mainly.

yeah dude don't give false info but i'll make a slight corerction...

Straight through systems are ilelgal as it solely refers to a cat-less sytem. A straight through design muffler in other words a cannon does not fall under the same category.

it is a AU$10k fine per cylinder or litre of displacement.. i can't remember which... if you have a straight through system meaning you don't have a cat. All the high performance track cars you read about in Hot4s and shit with "straight throughs" are exactly that.. Track cars. The only alternative is to use a "Test Pipe" to replace the cat AT THE TRACK.

Though it is true what you say about noise decibel limits of stock exhaust systems being just under limit, however that isn't what concerns the EPA or ADRs... its more the emissions emmitted.

^^ That is the reason Corolla Sportivos are no longer available as APPARENTLY Toyota lied about power and emmisions. It is also the reason the 350z just barely passed ADRs to be allowed delivery in to Australia... they had to have 2 cats and a very restrictive twin exhaust sytem... hence why most jap cars especially turbo ones get such massive gains from just changing the exhaust

[dsp26]

actually in terms of quitening down the exhuast a bit... anyone here have a connon with the N1 silencer installed??

wrap a shitload of industrial steel wool (not the thick woolies dishwashing ones), the really thin dense ones around the pipe of the silencer and shove it back in... someone on another forum did it and lost 3dB

[dudeling7]

sorry my mistake, i was thinking of a straight through system with a cat, i was going to comment on this but thought that he/she would know it was illegal running the car without one.

Twincam16 - calm down man, i should have explained that i was reffering to a system that included a cat. and then straight through from the cat back. in this case the act of installing a straight through system is not actually illegal its the result of installing it which will make it illegal if its too noisy etc. but yes i think there is some confusion on what actually is a straight through system the topic starter was reffering too.

[nigs]

Ever heard a B series motor with 2.5 system, no CAT and a straight through muffler hit Vtec?
Makes me almost want to own a Honda......oh wait :(