Test Pipes And Downpipes?

[sethaiyaar]

I was looking through youtube, and came a cross lots of cars that had test pipes attached to them, mainly 350Zs and MPSs.

...now i know what it is and i know its illegal but i want to know if anyone in Australia has tried them or has info on them..performance, legality etc wise.

oh..and downpipes?...whats that same thing?

[Mr. Keets]

Test pipe = Decat

[rs73]

yes, legality wise? decat = huge EPA fines... think of $10k or above in fines and legal cost. You might as well hand your car to the EPA for free to pay your environmental debts....

[sethaiyaar]

i understand about the huge fines and all...i also understand that if its a huge risk why bother talking about it.

But i just wanna know what people think about them, eg if they give any performance gains,loss of low end power?, freer exhaust flow, noise levels, past or any experiences etc etc

[180 wanabe]

considoring where the cats are located on the V35 i doubt any cop would be able to tell if you had them in or not... however a polution test would catch you with your pants down

[rs73]

performance wise on turbo system it's probably more noticeable as there's less restriction...

not sure on N/A vehicles as some of the key points in keeping performance up on N/A engine is actually applying some exhaust restriction so the exhaust gas goes out at a controlled rate from one cylinder and another, creating what they call an alternating suction effect to help expelling the gas efficiently, that's because N/A engine do not have an assistance from turbo to create a positive pressure in the system to push the exhaust gas as quickly as it can...

but since I reckon N/A race cars don't use cat, there should be some extra HP gain, but probably not by much, at least less than those in turbo system

[sethaiyaar]

thanks for the info rs73, must applaud your knowledge in the field!...from what i have read from the research i did on G35driver (very limited), it does give you a increase in HP not much thou, the Fast Intentions website has dyno results to prove it, on a 350z but the gains were around 8-15HP, there was some loss in low end power but it was only within a 150rpm band (if that made sence).

oh and 180wanabe, ive heard the test pipes are hella loud, ive never seen a cop doing a test for emissions...has it happened to anyone?

lol, im kinda interested in them...hehe id love to tell a Prius driver about the set up.

[scathing]

There are some people who've run test pipes on their FM platform cars, that I'm aware of.

I don't know the exact power gain, but the exhaust gets a lot louder and raspier. Resonated test pipes will fix the latter.

It is extremely difficult to spot, since the cat doesn't really sit under the car and the car is so low. Actual power gains are minimal, being NA and all. Their main benefit over a high flow cat is that they'll be a shitload cheaper.

[180 wanabe]

Was talking to a guy @ work whos got a v35, he was saying he put on headers and test pipes and thew down 240rwhp about 179kw on the dyno in his 5 speed Auto

He did not have a before figure so thats a 9kw gain if most autos throw out around 170rwkw

[fcruz3r]

I've read about gains of about 20hp from a combination of CAI, plenum spacer, decat + exhaust, lightnened pulleys .....so 9kw from just a decat is really impressive.

the gains vs expense element on modifying a NA car has always been somewhat a turnoff. Biggest gains u can get for less dollars will always be to FI the car or use some laughing gas in a bottle. Nitrous oxide is illegal to use...but then again so is decat'n ur exhaust.

[xscape237]

Dont do it. Its not worth the fine if you get caught and prosecuted. Install some better flowing cats if you really think they are a restriction.

In any case I would be surprised if anyone here claims to feel a power increase after removing their cats. Why dont you just remove some dead weight (spare wheel, etc), its free and probably gonna have a better effect.

[fcruz3r]

Dont do it. Its not worth the fine if you get caught and prosecuted. Install some better flowing cats if you really think they are a restriction.

In any case I would be surprised if anyone here claims to feel a power increase after removing their cats. Why dont you just remove some dead weight (spare wheel, etc), its free and probably gonna have a better effect.

agreed. and in most cases removing the cat will slightly increase hp....but the reduction in backpressure will reduce low end torque

in day to day traffic, i reckon having more torque makes the car more fun to drive.

[180 wanabe]

Im keen to one day go down the NO2 path with a 75 wet shot, but in a way where I can have it pulled out/put in quickly/easialy

Im wondering if its possible to have the lines/filters hooked up but no bottel or controller... kind of as dangerous as a gun with no trigger or bullets

I know NO2 is illegal but seriously its not a bad thing like running no cats if anything it probaly reduces the nastys from the tail pipe by burning more of them

[scathing]

I know NO2 is illegal but seriously its not a bad thing like running no cats if anything it probaly reduces the nastys from the tail pipe by burning more of them

Actually, running no cats creates NO2. As a poisonous gas, it is a very bad thing.

Nitrogen dioxide (NO2) is a toxic pollutant generated by unleaded petrol engines during combustion. The catalytic converter helps speed a chemical reaction to break it back down to nitrogen and oxygen, the two most common molecules in air.

Happy gas is N2O.

If I ever go nitrous oxide, I plan on making it a full stealth setup. Delete the spare tyre and put all the infrastructure under the carpet. Have the purge fully stealth, venting in a very diffuse manner under the car. Run black plumbing under the bonnet, so hopefully no-one notices.

If the cops ever pull me over and ask to pop the bonnet, I'll hit a switch to purge the entire tank. By the time they notice the nitrous plumbing (if they notice it at all) and ask to see the tank, it will hopefully be empty (and therefore legal). Losing a couple of bucks worth of gas is better than the fine I'd cop for having it "loaded".

Hopefully breathing in all the happy gas will put them in a better mood for any other illegalities in the car.

[whtbox]

can put this on top of NOS Just say it's a Subwoofer lol

[siu_loong_bao]

Call me a "greenie", but I am 100% against those who decat their cars as a daily driver...apart from being illegal, there's a reason for the cat converters...just like there's a reason for condoms?

If you do it and are a member on this forum, you are an insult to the rest of us car enthusiasts out there...

If you want performance, go buy a turbo-charged car...

"If you decat and drive, you're a bloody idiot"....

***If professional racing is why you decat, then that's different***

I hope the message sinks into those who are looking to decat....

[180 wanabe]

Call me a "greenie", but I am 100% against those who decat their cars as a daily driver...apart from being illegal, there's a reason for the cat converters...just like there's a reason for condoms?

If you do it and are a member on this forum, you are an insult to the rest of us car enthusiasts out there...

If you want performance, go buy a turbo-charged car...

"If you decat and drive, you're a bloody idiot"....

***If professional racing is why you decat, then that's different***

I hope the message sinks into those who are looking to decat....

Good thing you never met my old 180sx, it ate a cat when the mixture was running too rich....

Personaly id leave my cats in as my V35 is a daily driver however im all for the stealth NOS system

[scathing]

Call me a "greenie", but I am 100% against those who decat their cars as a daily driver...apart from being illegal, there's a reason for the cat converters...just like there's a reason for condoms?

If you do it and are a member on this forum, you are an insult to the rest of us car enthusiasts out there...

If you want performance, go buy a turbo-charged car...

"If you decat and drive, you're a bloody idiot"....

***If professional racing is why you decat, then that's different***

I hope the message sinks into those who are looking to decat....

There's a reason for almost everything on the car. If having an environmental reason is why you shouldn't do a mod, you pretty much shouldn't touch any mechanical part of your car. Running big wheels is bad for handling as well as being bad for fuel efficiency.

You also shouldn't drive like this - hard acceleration is very fuel inefficient, and your car spewing out all that extra exhaust gas is bad for the environment. Tyres are made from crude oil as well, and so wearing them quickly by hard cornering will also contribute to the damage to our planet.

You should have also bought an old, locally delivered, car if this stuff truly matters to you. Shipping a car overseas goes through a lot of fuel, and it's not as if there weren't other 4 door auto cars available in Australia when you bought your car. It's very bad for the environment, and our local economy, to buy a modern low-volume import in terms of total footprint.

While a early 90's Falcodore may not be as fuel efficient as a V35 in itself, when you tally up the total fuel use with the ocean freighter that brought your Skyline here then the scales tip in favour of the local product.

[scathing]

FYI I don't believe that daily driven cars should be de-catted (or even HFC'ed, since almost every aftermarket cat will fail a modern emissions test), but only because of the "poisoning yourself and everyone around you" aspect and not some "effects on climate change" issue.

[xscape237]

oh snap