What kind of hp gain with a testpipe?

[Camel]

How much hp gain with a testpipe on a stock ka w/ an apexi N1 catback? Didn't find anything on a search.

Thanks in advance.

[nolaws4evr]

heh, nice to see other people are thinking about doing this too. I see em on ebay all the time, 36 bucks aint bad at all. why dont you get one and let the rest of us know how it works out. or just wait for someone that has one to respnd...

[Machine]

not much, youll lose backpressure.

[Camel]

I figured you would lose alot of backpressure. How about this: use a resonator that has a turn in it and flange both ends to fit where the cat was placed. I figure that it will help a little with backpressure and deaden some of the noise while still freeing up the exhaust flow. Maybe I am crazy.

Someone with a testpipe, please report your experience...

[BuudWeizErr]

1HP

And 300% of the pollutants.

Leave your cat in.

[SHiFT]

camel, don't do it! you have a 98, the resonator is hollow. I found out the hard way. On the S14s the 2nd "cat" is actually just a resonator, the S13s have two cats. I have a test pipe in right now, just cause I didn't feel like taking it off and buying new gaskets again. The resonator keeps a little more low end torque and it sounds deeper. Theres a tinch more high end with the test pipe but the exhaust is more twangy sounding with the N1, I have the same setup. Not worth it, don't do it.

[Phax]

1HP

And 300% of the pollutants.

Leave your cat in.

:Werd

[Onizuka]

-2HP

And 350% of the pollutants.

Leave your cat in.

there i fixed it for yah buud.

[hadokenny]

dont do it unless u have a turboed engine. U dont gain much if your NA.

[Camel]

Killer, this is just the kind of advice I was looking for... Thanks guys. Looks like the opinion is unanomous. (spelling?) I am sticking with the N1 single until i figure out this supercharger thing. No turbo for me. I want a blown KA in a 240. And I probably have the cash to do it. (Might take a year to get the wife to agree tho...)

[tinted]

not much, youll lose backpressure.

You are misinformed. You lose power from backpressure. You gain power from no backpressure. 4 inch pipe on 2.5L engine, means more backpressure, not less.

[BuudWeizErr]

the S13s have two cats.

Since when do S13's have two cats? S13's are OBDI, not as stringent smog requirements (ECU) as post 95, OBDII cars.

As for the cat setup in S14's...

The real cat is in the header.The "cat" is a hollow piece that looks like a cat. Word is that Nissan did this so that the owners would not get harassed for not having a cat by uninformed people when in fact, they did have a cat.

I've also been told that the hollow cat was a real cat (making that two cats) for the Canadian market. I have yet to hear a concrete answer on that, so for now, that is hearsay.

And may I reiterate this once more.

I don't want to breathe in a ton more pollutants so you beat some ricer in your town by another fender. Leave your cat in, even if you live in BFE.

[Antyoo]

i cant stand the smell.

my dad has an aftermarket header on his 98 civic DX. we put in on because it was about 1/4 the cost of a replacement exhaust manifold(which includes the cat).

he has had the crack welded so now we just need some time to re install the stock manifold.

he gained a little bit of top end power(everything else is stock on the car) and about 2mpg

[Cyberkreig]

I want a blown KA in a 240.

heh Blown ka. I had one-a-those.

[Camel]

what is your definition of blown....hehe

[[Zero-S]]

Blown=what my engine is gonna be if I don't let up on the throttle.

[aleph1]

You are misinformed. You lose power from backpressure. You gain power from no backpressure. 4 inch pipe on 2.5L engine, means more backpressure, not less.

Nah man. For NA cars, backpressure (a reasonable amount) provides low end for driving around town. I have a 3" exhaust on my NA (going turbo) and I definitely noticed a lack of low end, and a bit of high end gain. I also had a test pipe on when I had my OEM exhaust and it does this: sounds cooler, smells worse, no noticable difference in power. Waste of money and environment, unless you go turbo, then its just environment =)

Well, on second thought, maybe I should replace backpressure with VELOCITY. A smaller diameter pipe increases exhaust velocity and adds power on NA setups. When your car is turboed, it puts out more exhaust thus you need a bigger pipe to match.

Nissan designed the 240SX with the cat in mind, it adds low end.

[Camel]

So by putting this big apexi n1 single on my na motor, i have actually lost horsepower? or it has shifted the powerband?

I did notice that when i put the silencer in on the second day, that i got a boatload more midrange power (3-4k).

[aleph1]

I believe you lost more low end than you gained high end. My personal seat of pants opinion. I have a 5Zigen Rocket 3" exhaust. Yes, keep the silencer in, it restores some low end. Beside my exhaust is soooo loud and bassy with out it, it deafens me in like 1 minute.

[Camel]

That sort of sucks, i probably would have kept the factory exhaust on until I turbo'd it had i known. So much for that 400 dollar catback system.