cutting out the cat

[rufrydrsc2]

I'm getting a test pipe made tomorrow, and I was just wondering how much hp should I get from that, or will it help much at all?

[X1nom3D]

considering it's a non-turbo, less restriction on the exhaust flow, you should gain more torque than horses, but it's still a gain... but if it's a turbo on the other hand, that's a definite gain in both areas!

[Halz]

Whats the point of asking this question if you're already set on doing it?

[twitchy]

1- your car will sound like ass, I wouldnt reccommend it

2- the power increase is so small it doesnt justify paying any money for it at all. Even when I cut mine off and made the plumbing all half an inch bigger than stock it was barely a difference

3-you cant gain torque and not horsepower on the same application

4-your already doing it anyways so...

[Sundi240]

I just got my H-Pipe and Flowmasters put on my Stang.

It will stink, it will be loud, you will gain some power, and it will sound SWEET.

[twitchy]

Originally posted by Sundi240
I just got my H-Pipe and Flowmasters put on my Stang.

It will stink, it will be loud, you will gain some power, and it will sound SWEET.

what year of stang? I love them.

[andrave]

misinformation:

1- your car will sound like ass, I wouldnt reccommend it

no it won't, wtf? I did it and my car sounds just fine.

2- the power increase is so small it doesnt justify paying any money for it at all. Even when I cut mine off and made the plumbing all half an inch bigger than stock it was barely a difference

but it consistantly makes more power on a dyno. So again, wtf?

3-you cant gain torque and not horsepower on the same application

Yes you can, der. again, what are you talking about?

4-your already doing it anyways so... so what?


:bs:

[prInce]

I put a testpipe on my '90 240sx. i liked the sound, it didn't stink like ppl said it would.
i didn't feel much increase in HP though. plus, not having a cat would kill the environment... get a high flow cat from random tech. it'll give you good power in both low and high rpm ranges. you need a little bit of back pressure at low rpm which will be diminished by the test pipe and you'll only feel increase in power above 3500 rpm (that's how it was for me)

[twitchy]

Originally posted by andrave
misinformation:

1- your car will sound like ass, I wouldnt reccommend it

no it won't, wtf? I did it and my car sounds just fine.

2- the power increase is so small it doesnt justify paying any money for it at all. Even when I cut mine off and made the plumbing all half an inch bigger than stock it was barely a difference

but it consistantly makes more power on a dyno. So again, wtf?

3-you cant gain torque and not horsepower on the same application

Yes you can, der. again, what are you talking about?

4-your already doing it anyways so... so what?


:bs:

let me rephrase this since some people take things the wrong way and get upset. MY car sounded like ass. It made ricey weed-whacker sounds and I personally MYSELF dont like my car sounding like my 2 stroke dirtbike. No offense if you like that sound, I dont. If I did Id buy a honda civic.

How much horsepower on a dyno? Cause my times werent any better on the track and it didnt feel noticeably faster in any sense. Lower end was a little slower, top end a little faster, all in all the same. Maybe it makes 2 or 3 horsepower on a dyno sure. Youd have that same effect from taking out your spare tire and subwoofer.

Would someone explain how you can increase torque without increasing horsepower in the same engine? Since its a mathematical equation and the two are dependent variables you cant change one and not the other, unless my studies in mechanical physics for the last 2 years were incorrect...



any other misinfo??

[prInce]

hehe... you're right twitchy... the car would start to backfire a lot and that pissed me off too. i called em car farts :D
you're also right about that torque 'n hp thing...

anyyyywaayyys, i've become kind of a nature freak and am against test pipes... high flow cats are the answer... i live in toronto and there's a ticket (upto $5000) for leavin your car idle for more than 3 minutes. removin the cat is just a big no no.. i believe they're pretty strict about it in all over North America.

anyways, i guess for the track a test pipe is allowed, but only if the car is turboed it really helps... otherwise, as twicthy said, just remove your spare tire & subwoofer... AND also remove a/c compressor, ps pump, relocate battery to the trunk or behind the pass seat :), carbon fibre hood, lightened lug nuts, 15" light racing wheels.. that will all add a few horses here 'n there ;)

[X1nom3D]

Originally posted by twitchy
let me rephrase this since some people take things the wrong way and get upset. MY car sounded like ass. It made ricey weed-whacker sounds and I personally MYSELF dont like my car sounding like my 2 stroke dirtbike. No offense if you like that sound, I dont. If I did Id buy a honda civic.

don't get me started, first of all, your car is the one that sounds like ass, mine doesn't, and if you knew better, which i know you don't, you can just change the sound of the exhaust by getting a different muffler, because DUH! that's what they're made for! and if that doesn't help you, get another resonator in it! this modification is for performance, not for sounding "good". which i'm sure some hondas probably sound better than your car anyway.

How much horsepower on a dyno? Cause my times werent any better on the track and it didnt feel noticeably faster in any sense. Lower end was a little slower, top end a little faster, all in all the same. Maybe it makes 2 or 3 horsepower on a dyno sure. Youd have that same effect from taking out your spare tire and subwoofer.

okay, if you have an aftermarket downpipe, or at least an aftermarket header for NA cars, you'll feel a difference. i don't think you've even done this modification before, that's why you have misleading information. and another thing, about taking out the spare tire and the subwoofer, true it is some weight reduction, but the only factor that really counts is that it lowers your center of gravity which makes it easier to accelerate. and believe me, with a little more power and torque, after taking out the spare and subs, you'll feel it even MORE!!

Would someone explain how you can increase torque without increasing horsepower in the same engine? Since its a mathematical equation and the two are dependent variables you cant change one and not the other, unless my studies in mechanical physics for the last 2 years were incorrect...

who the hell told you that it's a mathematical equation?!?! well okay, maybe AFTER the modification is DONE and you're reading it BY THE RPM RANGE! but you better believe it, I have seen modifications where a SUPRA TWIN TURBO actually gained a few horses, and LOSS some torque. yes, i said the supra twin turbo. only AFTER a modification is done, THEN you can apply that silly equation of your's. mechanical physics, hahaha LMFAO! 2 years!!! ROFLMFAO!!!!

any other misinfo??

nope, no more, I think we covered everything, thank you.

[twitchy]

-oh my car sounds like ass? Alright thanks then.

-Some Hondas do sound better than my car. The NSX is one 1 can think of.

-I didnt know having a lower center of gravity made it easier for your car to accelerate.Oh wait, I know, your one of those people that thinks their cars accelerate faster after they lower them, right? And that your moms Camry gains 10 horsepower every time you watch fast and furious? In fact, I was pretty sure acceleration was a unit increase in an objects velocity over a given distance. I was being sarcastic about the sub and tire as well. You wont feel a difference with them in or out.

-Wow, a supra twin turbo?are you serious? horsepower and torque are the same damn thing expressed a different way. You cant change one and not the other, at least as measured on an automobiles engine. Thats right, I said a supra twin turbo!!!


You probably shouldnt be arguing this point with a physics major.








To the original poster- My best advice would be to try it for yourself. Not everyones tastes and criteria are the same. Personally I want my car to come off as stock at all times and I didnt like the added sound effects when I cut my cat off. Save your cat in case you decide you would rather have it on.



well that was fun

[X1nom3D]

having a lower center of gravity does not necessarily mean that you've lowered a car. or did you already know that? and i didn't think you've read it enough times yet. I said "easier" to accelerate, which doesn't necessarily mean that you'll accelerate faster, BUT can mean that it's easier on the joints of the drive axles. or did you already know that? and I don't care what your damn textbook says about the definition of the word acceleration! screw your textbook AND your 2 years of mechanical physics! and actually, about the spare and subs, if you drive along a winding road, you'll feel a great difference. or wait, your car is too stock in order to feel anything. horsepower and torque is not the same damn thing. did you know that on some cars, by installing a CAI, you actually lose horsepower, but you gain more torque. and about arguing this point with a physics major, haha that's a bunch of BS. first of all, before you start going to school about physics, you need common sense. because physics IS common sense. I have more common sense than you do, which means I've studied physics long before you even knew the damn word. and also, might i add, you're the one acting like you're still in high school talking about fast and furious and bringing people's mom into an argument.

i don't need to go to school to learn physics like you do. there's nothing you can tell me, that i don't already know, common sense.
like, you throw a ball, it's gonna wanna keep on going, like no sh1t!

[720_datsun]

Originally posted by Sundi240
I just got my H-Pipe and Flowmasters put on my Stang.

It will stink, it will be loud, you will gain some power, and it will sound SWEET. fords = devil incarnate(sp*) if its american go chevy. only good thing ford makes is the 9in. read end.

[andrave]

anyone who doesn't believe that you can change HP without torque or vice versa just needs to flip through some dyno charts in a couple magazines to see that they are... um...
whats the word?
WRONG:boink:

[rufrydrsc2]

Got the cat cut out, car doesn't sound that great but then again I have no resonator either so it never did to begin with. I notice it is faster on highway runs which is where I play anyway. I have also noticed that it gets better gas mileage. It was just something to do, and it only cost $20 anyway so no damage there. I don't have to worry about the govt. b/c I live in SC and we don't have inspections down here and no smog control. We are actually allowed to modify our cars how we want. Thanks for all the help.

[GatorRX]

Sorry, got to agree, if you understand the relationship between torque and horsepower you know one cannot increase without the other increasing as well...

Horsepower is a measurement of work over a given unit of time, and torque is work applied over a distance (rotational force in the case of car engines) -- sorry if thats not clear, I'm no physics major... no offense meant by that either.

The two go together, if you know the torque at a given rpm you can figure out the horsepower, and vice versa......

[twitchy]

Originally posted by GatorRX
Sorry, got to agree, if you understand the relationship between torque and horsepower you know one cannot increase without the other increasing as well...

Horsepower is a measurement of work over a given unit of time, and torque is work applied over a distance (rotational force in the case of car engines) -- sorry if thats not clear, I'm no physics major... no offense meant by that either.

The two go together, if you know the torque at a given rpm you can figure out the horsepower, and vice versa......

Thank you!

You notice better mileage?? Mine got way worse, thats why I put one back on (one out of a 99 Pontiac GTP)

[andrave]

what a shame that holding a degree in physics, you can't apply it.
I'm telling you, look into dyno charts... I have seen first hand people put a product in that lowers torque and raises HP or vice versa...

[prInce]

my car also gave me excellent (better) mileage after installin the test pipe... :p

[X1nom3D]

Originally posted by GatorRX
Sorry, got to agree, if you understand the relationship between torque and horsepower you know one cannot increase without the other increasing as well...

Horsepower is a measurement of work over a given unit of time, and torque is work applied over a distance (rotational force in the case of car engines) -- sorry if thats not clear, I'm no physics major... no offense meant by that either.

The two go together, if you know the torque at a given rpm you can figure out the horsepower, and vice versa......

Gator; I know what you're trying to say, but that can ONLY be applied when comparing power levels at different RPM's. what we're trying to help you and twitchy understand is, a stock engine can have 300 HP and 325 ft-lbs torque at 5000 RPM. okay, if you measure the SAME STOCK engine at another RPM level, if the HP rises, the TORQUE SHOULD rise also... all right, you're following me? BUT when you MODIFY that engine, that modification MIGHT cause the engine to lose 5 HP, but gain 25 ft-lbs torque at 5000 RPM, so now the dyno would measure 295 HP and 350 ft-lbs torque at 5000 RPM. but you see, that's a measure at the same RPM level AFTER the modification. now AFTER it's been modified in such a way, you can THEN apply that idea to it once again. starting at 295 HP and 350 ft-lbs torque at 5000 RPM, if at 6000 RPM the horsepower increased by such and such, then the torque SHOULD also increase by such and such using a calculation. but still, sometimes, it's not true. why do you think some cars have the highest torque at low rpm, but also reads the highest hp at a higher rpm? i hope everyone understands this whole thing, after this post. I'm not trying to attack twitchy's 2 years' worth of education, but i'm only trying to help, open his eyes. maybe the professor doesn't explain it well enough?

[GatorRX]

what a shame that holding a degree in physics, you can't apply it.
I'm telling you, look into dyno charts... I have seen first hand people put a product in that lowers torque and raises HP or vice versa...

Here's where the communication is breaking down for everyone here. It is possible for PEAK torque to go down while PEAK horsepower goes up. Those are just numbers at points on the dyno graph, and are pretty useless in showing the real performance value for a modification, because car motors do not run at one RPM all the time.

What you want to see is an increase across the full rpm range of the motor. And if you do the calulations, at any RPM point on that graph if the torque value goes up, horsepower will go up as well. That's plain text-book physics. The calculation is:

HP = TORQUE x RPM ÷ 5252

if at 6000 RPM the horsepower increased by such and such, then the torque SHOULD also increase by such and such using a calculation. but still, sometimes, it's not true

Yes, it is true. ALWAYS. Feed "HP = TORQUE x RPM ÷ 5252" into Google and check the results if you don't believe this. This is the way it works, period. If a mod raises HP at a certain RPM point, then torque MUST ALSO INCREASE AS WELL at that RPM point, unless you live in a universe with different laws of physics.

The thing is you have to consider the values of torque and horsepower AT THE SAME RPM to see the relationship. Peak HP and peak torque VERY RARELY occur at the same RPM point.

To simplifiy, if you make a modification, and peak horsepower goes up at, say, 7000 rpm, you will see that the actual computed torque at 7000 rpm went up as well. However, peak torque could have been at 4000 rpm, and peak torque can go down at 4000 rpm while HP goes up at 7000 rpm.

Problem here is people throw around the words horsepower and torque without knowing how they work together. Putting on a mod, like on the Supra above, and seeing peak horsepower go up and peak torque go down is not a bad thing if, as an example, your car is running out of breath at the end of the drag strip or the back straight at the road course. On the opposite side, if you're getting beaten because your car can't pull out of the corners, you'll sacrifice peak hp for more peak torque. Worthwhile modifications are all about the area under the graph curve, NOT the peak numbers...

Here's a link that explains pretty well -
http://www.akamoto.co.uk/info/torque-vs-horsepower.htm

So you're both right, sort of.

[X1nom3D]

i guess i can settle with that one :)

[GatorRX]

COOL :bow:

[X1nom3D]

hey Gator, since you're in atlanta maybe you can tell me. is NOPI Nationals as great as they make it seem?? would you think it's worth the drive from wisconsin??? cause my buddy wants to go next year, so I just wanted to know from someone over there. do you even go to those events at all?

[Sundi240]

Originally posted by twitchy
what year of stang? I love them.

Its a 91 GT. Is there any way I can post a sound clip of my exhaust?