with just intake and headers.... do you guys think i'd gain significant HP from running open header? because i'm planning aon a purchasing a cutout... part of the reason why is because i want loudass exhaust noise... but at my convenience... which is all the time except for when there's a cop... but ... any HP gains?

 

on the street - c'mon

 

daily driven? hahahahaha ya right!

 

on street.... hell yeah... i'm crazy like that... but like i said... it would just be a thing i do when i'm craving attention....

but really... what kind of gains should i expect?

 

Explain what you mean by an open header. any links?
Im curious.

 

you are alredy driving an ITR with a JDM front clip and you're talkin about running an open header to draw attention to yourself

 

Someone please explain what the hell an open header is?
Im no newbie but ive never heard of this before.

 

Do you mean unbolting the header from the catalyst?
I think you'll lose power actually. We have 0bd2 and u mess around
with the exhaust and you'll throw codes and so on.
Plus there needs to be some back pressure.

 

An open header is when all you run is the header. It's not the best for power. You will want to run a tailpipe and the length of the pipe must be tuned.

 

whatever. let him do it and find out what burnt exhaust valves from lack of backpressure cost... that is if the flames coming out of the header dosen't set the car on fire first...

 

so no exhaust?

 

wouldn't just running a straight pipe with no muffler be pretty much the same? i mean its not my style or anything, but if he wants to do it to his car and get ticketed thats him. at least with the straight pipe you won't smell tons of fumes.

 

I totally think he's asking for trouble. I recently had a problem with my distributor.
Relucter gear hit the magnetic pickup on the ICM and totally destroyed the gear.
It took me forever to figure out it was bad because it didnt go all at once.
Idle would go up and down eratically and so on. I knew somethign was wrong, but without codes couldn't pinpoint it. Anyway, the gear finally destroyed itself and it finally threw a code. code 4. which is for the crank position sensor. I know thats in the distributor so i took a look. Holy ****. Debris everywhere inside there.
The side effect is that the computer knew something was wrong and started dumping TONS of fuel. This fouled my plugs, 02 sensor (first), catalytic converter,
and made a total mess. Bottom line. Once the catalytic converter got messed up the car started acting up way too bad. My opinion... Dont go with a straight pipe or mess around with the exhaust unless you TOTALLY know what your doing and are prepared for what could happen. Our R's are highly tuned. Its not smart to mess with a perfect formula. Anything beyond header, intake, muffler, free flow cat, is probably asking for trouble unless its a complete cat back system.
Definately not smart running only a header or trying to use a straight pipe.
I dont think the gains are worth the potential headaches.
Just my 2 cents.

 

whoa whoa guys.... lets calm down here.... the reason why i posted this thread is to get more information!!! not to get flamed on... i understand the attention i'll get with the noise coming from an open header... but i think you guys are forgetting that i'm not just gonna disconnect the header from the cat... I'm actually utilizing a mechanical dump-valve cutout that's designed specifically for this purpose. It's made by McCord and allows me to control a butterfly valve which will determine all-out open-header, or closed running through the normal exhaust system. This device would be placed way after all of the o2 sensors and like SMSP said, after some length of piping to have it somewhat tuned. Yes... i'm expecting to lose all back pressure, and therefore lose some torque, and yes i'm expecting to gain high end because of the better flow. What i didn't know is that i could mess up my valves from lack of back pressure... thank you for that information... as far as getting tickets... i'm not gonna be driving like this all the time... i can control the butterfly valve from inside of the car...

if i am wrong in any way... please correct me.. don't flame... as of right now... i'm concerned with the valves getting messed up from no backpresure.... someone please explain... autocrossers run open-header on their R's...


[Modified by type rizzy, 7:56 PM 7/15/2001]

 

Yeah, I remember seeing something like that in the JCwhitney catalog. I'm not sure if lack of backpressure will mess anything up, but I would guess you would only gain 1 or 2 wheel hp.

 

rizzy, you should explain your intentions in the original post; the first post sounds like you want to be noise/smog polluting *******.

 

First off I agree with the fellas it is probably a bad idea. Second if you want the sound why not get a muffler that gives the sound like the Spoon N1 muffler that thing is so loud it is like running the straight header, but without the problems.....if noise is a problem put the valve before the axel and run a pipe to a second muffler to get the sound. Then you might get the attention of dual mufflers with the sound. This might be a crazy set up but like you said "i'm crazy like that".
My $0.02

 

I believe, at least in VA if you run cats, you don't have to run mufflers.

 

Yeah but he's talking about unhooking the header from the exhaust.
Thats just before the cat so there would be no muffler, cat, piping, etc.
It will make his o2 sensors freak out totally.
The car probably wont be drivable really is my guess.
but thats just a guess.
I cant see how he'll get away with it.

 

Read my thread up above a few msgs in this post.
I just went through a similar thing because too much fuel fouled the cat, 02 sensor,
and plugs. Car ran like ****!
When you get code 67 becuase your 02 sensors arent getting good readings,
the computer compensates by dumping tons of fuel. The rich mixture will foul plugs, the cat, and sensors fast. Not to mention the idle will be totally screwy because too much fuel is like throwing sawdust on a fire. More fuel can sometimes be as bad as not enough fuel. It messes things up pretty bad.

Trust me. I know alot about Type R's now mechanically.
If there is a possible problem I've been through it.
See my car http://www.targetplanet.com/venom

 

I gained 12 WHP with the JDM header out of a test pipe.

Removing the B-pipe and Muffler gained about 4 of those WHP.

You will get the wrong attention...its so loud the there wont have to be cops around, just in the city limits!!!

Either get a testpipe (for OBDII) or just put the dump past the CAT, then you wont throw codes.

FYI, I only use this setup on the track....I cant stand anymore that that!

 

type rizzy and itr-779 could you please explain how increasing back pressure helps torque?

Ben Tang could you explain why reducing back pressure will burn the valves?

 

Boba im not an engineer so my explanation will be fairly primitive.
Your engine works on the same principle as a pump. Or a siphon.
It is input/output.
Imagine sucking water down a hose when there is pressure there the water
flows freely. If there isnt as much or any pressure you have to prime.
Thats a really not solid answer but i think it is a semi good analogy.

 

I know it will be loud, but would it be ok to take off the pipe from the cat back and the muffler itself and drive for a couple of days maybe even a week or so. I am selling my cat back and am getting a new one, but the old one will be sold before the new one arrives. I am not worried about noise because their are no emisions requirements here, and every one and their mother drives around with straigt pipes( loud and annoying as hell) just wondering if it is safe for the moter.

 

I think you may have your reasoning off a little. If there is pressure in the header/exhaust, which is what you are calling back pressure, that can effect how well the exhaust flows from the cylinder.

Let's change the fluid that goes through the engine from air to water. Also assume the exhaust is full of water and the exhaust has zero flow losses due to bends or friction between the water and the inside of the tubing. Now we run the engine and the engine is pumping and exhausting water out of the engine and out of the tailpipe. Now lets put a 90 on the tailpipe and turn the exhaust straight up in the air. Every foot of water is equivalent to .43 psi so if you went swimming at a depth of 100 ft your body would feel 43 psi over its entire surface. So back to our vertical tail pipe, we'll make it 5 feet high (above the exhaust port) so we are now generating about 2 psi of back pressure on the engine. What happens to the pumping efficiency of the engine? It will decrease.

The reason that exhaust systems that are too big hurt performance is not because they reduce back pressure to 0, it's because the energy of the exhaust flow, which is function of velocity as well as other characteristics, deminishes greatly. Therefore, the exhaust system can't remove the exhaust from the header effectively and performance suffers. Everything is a compromise, you want sufficient velocities without generating extra work on the pump (your engine). This is also why stepped tubing is used in headers.

I hope that this helps to put to rest this back pressure myth. But, you could always have a case where a slight amount of back pressure may help things but that is by no means the norm. If it was, there would be no reason to sell a high flow cat.