Test pipe, do they really do you any good?

possible pop some flames to ;)

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Originally Posted by absolutR

if it didnt give u more power why would ppl take their cats out n put the test pipes in?

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they only make a difference on HIGH horsepower cars that make big power at the top and don't need the backpressure. People who do them on mildly modified cars don't really know why they do it... its coz their friends mums brothers dogs girlfriends auntys sons moms sister said its t3h h3ktic1!111!!!!

heres simple proof, on a bogstock B16a2, get a full 2.5in mandrel bent exhaust, you will notice a loss in low-mid range power and response for a MARGINAL gain in topend.....

a very effective high flow cat will actually give gains because:
- the catalyst is more effective while flowing more therefore...

- apart from burning like blow-by oil that went in the combustion chamber...

- it effectively ignites any unburnt fuel mixture also which may cause exhaust pop...

- and because exhaust cools down as soon as it leaves the head, the catalyst re-igniting them creates heat and accelerates exhaust velocity again, therefore...
- 'scavenging effect' is increased as increased exhaust velocity creates vacuum and pulls gases from the combustion chamber when the exhaust valves open, therefore...

- also scavenging more air on the intake side come the time the intake valves open....

I noticed the characteristics/power delivery of the motor changed but not worth the smell and pollution to justify it.

Just get a nice big hi flowing cat ;)

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Originally Posted by claymore

Test pipes work great averaging between 10-15 HP (sorry don't know the conversion for KW) BUT and it's a BIG but if you get caught on the street the fines are HUGE and just not worth taking the chance that the fine will be more than your car cost.

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are those figures from said drag cars or your average car?

coz i'm speaking from experience from a few years ago.. there was a 2-4wkw power loss before 5000rpm range and i think ~1.7wkw peak gain somewhere above 6800rpm.

annoying thing was that the exhaust shop didn't tell me about the legailities even though it was my choice.. i was going to keep it until another customer that day actually told me about the fines, etc... i think as an exhaust shop it should've been their job to inform customers of these things.

when your young and not many performance parts are available to you and don't know much about cars you end up buying stupid things like these... i was one of them, even bought hiclone, fuel line magnets, etc...

sometimes a test pipe is used to replace the cat when tuning. instead of tapping a 2nd bung into your headers the extra bung is on the test pipe for wideband O2 Usage.

for example

http://images.channeladvisor.com/Sel.../HC9600GSR.jpg

http://images.channeladvisor.com/Sel.../HC9600GSR.jpg

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Originally Posted by aaronng

You are better off using a straight through exhaust with no muffler and no resonators with a cat, then if you used an exhaust with mufflers but no cat.

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yes!! and it sounds so beautiful :thumbsup:

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Originally Posted by claymore

Yep another myth about needing back pressure.... ever look at Real drag racers or Nascar or SCCA or any racing series and see them using mufflers or ANYTHING to increase back pressure???

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real drag racers/circuit racers are running 600-8000 horespower and massive displacement engines with turbos and superchargers, or just big n/a motors, there is no need for backpressure.

on a street driven, N/A 1.6 litre 4banger, back pressure is needed.

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Originally Posted by claymore

Yep another myth about needing back pressure.... ever look at Real drag racers or Nascar or SCCA or any racing series and see them using mufflers or ANYTHING to increase back pressure???

Test pipes work great averaging between 10-15 HP (sorry don't know the conversion for KW) BUT and it's a BIG but if you get caught on the street the fines are HUGE and just not worth taking the chance that the fine will be more than your car cost.

Various car mags have done tests with brand name high flow cats Vs test pipes and the results show that a good high flow cat makes just as much HP as a test pipe in most systems or a minor decrease from a test pipe but still much better than normal Cat if you are set on doing something.

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i think u might be a little wrong, 10-15hp gains? these figure probably only apply on high powered vehicles or perhaps large displacement engines, i jus cant really see how u could gain that much power out of a 4cylinder, unless u can prove me wrong =]

also something interesting i found: you could probably say a high flow cat would give u the same gains as a test pipe and also making things legal

http://img503.imageshack.us/img503/9...stdynosqk2.jpg
http://img503.imageshack.us/img503/1...resultszu5.jpg

:thumbsup: cool post, good info

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Originally Posted by aaronng

You are better off using a straight through exhaust with no muffler and no resonators with a cat, then if you used an exhaust with mufflers but no cat.

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Standard cats are extremely restrictive, but I understand what you're saying. Upgrade your mufflers/delete them first, then if you're game, go for the cat (once you get off the public road ofcourse!).

I want to get a custom side-pipe from my J's racing headers for the track. I'm happy with the performance of my car, but when I'm on the circuit I love to have the sound of a race car (which mine sounds like with BC cams, quads etc.).

awsome find buddy, i wonder if that stock cat was a jdm one though?

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Originally Posted by EGJOE

awsome find buddy, i wonder if that stock cat was a jdm one though?

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I would think 90% are the same..

I have never heard a japanese cat giving more power than an aus cat