Header Question!

[acidbug]

Well..My header has recently begun to make a weird rattle sound...I am not exactly sure where it's coming from..I checked the bolts on the header..and they seem good...

My best description of the noise..Is when i rev the engine (either while driving or in neutral)..The noise sounds like a slight rattle...but as i get into the higher rpm's the noise dissappears...

And as i let off the gass..approaching like 1500rpms..the noise returns..and sounds like even wierder..like exahust gas is escaping..

Also..I took off the silencer..to get an idea how the car would sounds w/ out it..and it sounds like a civic..very raspy sounding...

Not a deep tone at all!

Inother words..that rattlin sounds right out of the exhaust...

Could an exhaust leak cause that noise? Anyone experiencing these symptoms? People have told me that it's a new header and it takes time for it to break in..and the noise will go away on its own?

Also..my gas mileage has dropped considerably...I used to get a little over 200miles..on half a tank..now i am lucky to get 150miles...

Will this increase since i reset the ecu??

Chas:mad:

 

[Rism]

hmmmm
/me doesnt think he will get the obx header anymore

 

[L8R]

sell it and get a racing mazda header hehe. sorry i have no idea about your problem dude. good luck! - chris

 

[acidbug]

Easier said than done..

 

[MP3-Owner]

I thought the Racing Mazda header was the OBX header? They look exactly alike. I had a problem with my bolts backing out where the header bolts to itself. The connection where the 4 pipes goes into 2 you know. Anyway have you checked there?

 

[p5sundevil]

i would check the above mentioned spot, also what intake are you using?

it only rattles at low rpm makes me think it has to be a loose something because of the higher engine vibration then, i would go through from the head back and check all the bolts all the way to the muffler.

otherwise i dont know, i havent heard of the break in period but its possible.

 

[acidbug]

I thought the Racing Mazda header was the OBX header? They look exactly alike. I had a problem with my bolts backing out where the header bolts to itself. The connection where the 4 pipes goes into 2 you know. Anyway have you checked there?

Yeah...It is...

I have checked that location(where the 4 become 2)..actually cut my finger wide open..just trying to make sure they were tight..which they were...

The sound seems to be coming out of the midsection of the car...

I am planning to check all connections again..on monday!

Chas:mad:

 

[Installshield 2]

this could be a number of things...some can be delt with cheaply, some may be expensive...

First: What type of exhuast are you using...assuming since you have a removable silencer, it is something of the Apexi N1 style or 5Zigen Fireball (big fat cansiter for a muffler?, basically does it look like the HKS hyper exhuast?)...Is it a lightweight high performance exhuast, meaning huge diameter with very little tubing thickness?...

This is how it breaks down "generally"...Huge exhuast diameters kill low rpm pulse rate speed...These "pulses" that need to get the **** out of the exhaust pipes, tend to hang around and have jokes with each other at low/mid rpms, since the large diameter allows room for it. Some keep their speed up however, and slam off of each other into the pipes themselves...Think of all that happening very quickly, and things will vibrate...If you claim that this goes away at higher rpms, I hope this is your problem...At higher rpm the pulse rate is fast enough to have enough friction between the pulses to push everything out relatively quickly, thus great breathing and high rpm power, the benefit of a big exhuast all together...also the sound probably improves immensely, with much less vibration...Also thin pipes tend to have that "raspy" sound much worse than heavier thick pipes...

that is simply a brief description...hundreds of variables affect exhuast note...If you have a thicker exhuast it could be caused by internal engine damage such as compression issues, cylinder "leak-down" (think of higly boosted, poorly tuned engines that once sounded like an incredible blast furnace turning into a UPS truck), or other internal issues...

Also is your exhuast welded in place? or is it bolted onto a test pipe/secondary cat?...

Give me a little more info and I will give you all the info i have...

Also I doubt this is completely caused only by the Header...The problem may have been there before, but the addition of the header (which will keep the individual cylinder pulses seperated until the secondary cat or test pipe, which is the "mid section" of the car) may be causing massive turbulence within your current cat-back...

A friend of mine installed a lightwieght Apexi N1 cat-back with a Hot shot header on a Spec V...it is the raspiest exhaust I have ever encountered, and sounds like complete s***...Less pounds throughout the exhuast may save weight, but not exhuast note...

 

[perfworks]

many people have made good suggestions to your dilema
including installshield.
excuse the fact i am making this brief. i have alot of work to do. but it sounds a little like your cat may be the problem. Depending on many factors i have seen the insides of the cats break apart and rattle under light load. Then in higher rpms they cause a restriction and basically get pushed back into the componet housing.
you have been running nitrous for a while right? Well thats my suggestion.
its your second cat
hope this helps. Let me know how you make out.

 

[acidbug]

this could be a number of things...some can be delt with cheaply, some may be expensive...

First: What type of exhuast are you using...assuming since you have a removable silencer, it is something of the Apexi N1 style or 5Zigen Fireball (big fat cansiter for a muffler?, basically does it look like the HKS hyper exhuast?)...Is it a lightweight high performance exhuast, meaning huge diameter with very little tubing thickness?...

This is how it breaks down "generally"...Huge exhuast diameters kill low rpm pulse rate speed...These "pulses" that need to get the **** out of the exhaust pipes, tend to hang around and have jokes with each other at low/mid rpms, since the large diameter allows room for it. Some keep their speed up however, and slam off of each other into the pipes themselves...Think of all that happening very quickly, and things will vibrate...If you claim that this goes away at higher rpms, I hope this is your problem...At higher rpm the pulse rate is fast enough to have enough friction between the pulses to push everything out relatively quickly, thus great breathing and high rpm power, the benefit of a big exhuast all together...also the sound probably improves immensely, with much less vibration...Also thin pipes tend to have that "raspy" sound much worse than heavier thick pipes...

that is simply a brief description...hundreds of variables affect exhuast note...If you have a thicker exhuast it could be caused by internal engine damage such as compression issues, cylinder "leak-down" (think of higly boosted, poorly tuned engines that once sounded like an incredible blast furnace turning into a UPS truck), or other internal issues...

Also is your exhuast welded in place? or is it bolted onto a test pipe/secondary cat?...

Give me a little more info and I will give you all the info i have...

Also I doubt this is completely caused only by the Header...The problem may have been there before, but the addition of the header (which will keep the individual cylinder pulses seperated until the secondary cat or test pipe, which is the "mid section" of the car) may be causing massive turbulence within your current cat-back...

A friend of mine installed a lightwieght Apexi N1 cat-back with a Hot shot header on a Spec V...it is the raspiest exhaust I have ever encountered, and sounds like complete s***...Less pounds throughout the exhuast may save weight, but not exhuast note...

I am running a aerospeed muffler..w/ custom cat back...it defintely has a huge diameter..nearly 2.5inches..both ways..

I Have Not Cats on my Car

Basically the setup is..

header====2ndpart of header====testpipe====section where the 2ndcat usedtobe====resonator====axel backexhaust..

I will be taking pics tomm...hopefully the weather will hold..and get a upload on a sound file..to give people idea...

Also..When i take the silencer out...the noise from the exhaust(muffler)drounds out any sound..So i can't tell if its there..but raspy is a perfect word to describe it...

About compression loss..i don't believe so..the car is actually running better w/ the header..i figure if i had compression loss..i would feel atleast a loss in performace/hp!

Not sure what cylinder "leakdown"..

Chas

 

[perfworks]

no cats!
well scrap my suggestion.
ill see you at the meet. If it isnt taken care of by then

 

[Matthew]

ive been up for over 24 hours, but frankly it sounds like you havent tightened your silencer enough. i had the same problem when i first installed my silencer because i lost the screws that came with it. anyways i have screws with nuts on the inside now tightened so tight theyre in danger of bending the metal tip. but no more rattle..like i said, ive been up awhile and could not be reading your problem right, but i think thats your problem. the reason you cant hear it when you take off the silencer is because that in iteself is the problem. sorry for the ramble but im almost positive im right.

 

[Installshield 2]

The actual defanition of cylinder leak down can be different from person to person...Some refer to it as a loss in compression due to piston ring seal being lost and allowing a lot of excess oil to be burned, and "blow by" (I am unclear on what blow by is myself, some identify it as huge amounts of swirling oily air in the head which can be noticed by removing the oil cap?)...You would most likely notice that...some say "leak down" when the cylinder is completely ruined and refer to a "loss in compression" as normal high mileage engine wear...Some say leak down all the time with the use of percentages...

leak down is usually given as a percentage, the bigger the percentage the worse the leak-down...100% leak down in cylinder number 3 means absolutely no usuable compression at all, allowing unburned air/fuel mixtures to "fall" underneath piston crowns and ring lands and mix with the oil in that particular cylinder...not good, but that is also obvious...It takes either crazy boost levels or massive pinging to cause this, and it rarely will go from 0% (normal healthy engine) to 100% at once...it takes a lot of small pings over a long period...and the problem is usually noticed before the cylinder is deceased...piston engines are more tolerant of even big detonation than say a rotary engine, where one solitary ping can send it packing...

It is trickier than that though...with only low percentages of leak down you may not notice a loss in performance. That is why most claim that the first stages of leak-down can only be noticed by a very precise cyinder compression or "leak down" test, or by an off key or foul exhuast note...The compression changes (mostly compression being different from one cylinder to the next) will alter exhuast pulse rates, causing very inconsistent exhuast flow which will cause bad sounds...

This was just an opinion if all other exhuast problems checked out fine...You are running nitrous from what I remember, which can cause large amounts of detonation, but you seem to know what you are doing with it and not running too much...I sort of worded it wrong above...If you noticed poor sound right after exhuast mods, the exhuast in question is causing it...if you finished your exhaust and it sounded incredible for 2,000miles or something, and then it sounded like s***...the problem could be internal...

IMO you have a lot of matched pipe diameters from different places...Are any pieces stainless and other pieces not? pipe materials can also cause resonance that sounds raspy, and if they are not all the same one piece could be causing...

Let us know when you get under there...check all the bolts and flanges for warping...any leaks or missing gaskets, and make sure everything is torqued properly...i would put money on it that is something of that nature and not internal damage to the engine...

 

[acidbug]

Well Mathew was correct..The silencer..is loose..I took it off..and then put it back on and noticed the noise grew louder..turns out i didn't tighten it up enough...

Thanks for all the help guys..

And perf...I will definetly see ya at the meet..i wanna see your EVO 8!

Chas

P.S. Thanks install for the info!

 

[Matthew]

figured thats what it was

 

[glyph]

yeah, I knew it too...