Look what the mazda guys have been up to...

[CHA54]

you would think a mod could post in the correct section in the first place ;)

[CAP]

Actually the comment was a reference to the fact that E-Gene only seems to appear around here sporadically these days. I wouldn't class it as an attack, I thought we were all a little more thick skinned around here?

Carlo, I thought mods were supposed to enforce the rules, not break them?

And who's broken them? Like I said - lets keep it on topic.

[Northy]

you would think a mod could post in the correct section in the first place ;)

thats the good part, I can get away with it

[CHA54]

you would think a mod could post in the correct section in the first place ;)

thats the good part, I can get away with it

looks like a bit of doubble standards going on here.....

well there you go :P

Edited March 5, 2007 by rollamods

[-JC-]

Actually the comment was a reference to the fact that E-Gene only seems to appear around here sporadically these days. I wouldn't class it as an attack, I thought we were all a little more thick skinned around here?

Carlo, I thought mods were supposed to enforce the rules, not break them?

And who's broken them? Like I said - lets keep it on topic.

Just because you edited your post to make yourself look better doesn't mean you didnt break the rules.

Dont you hate it when someone quotes you before you get a chance to edit . . . . . . .

[CAP]

What the bit about your stupidity? I still stand by it But I took it back for the good of the forum Like you said we all have thick skin :D so lets just leave it out there then

Now that we have that out of the way and off our chests lets get back to the original topic of discussion

[MR22ZZ]

Actually the comment was a reference to the fact that E-Gene only seems to appear around here sporadically these days. I wouldn't class it as an attack, I thought we were all a little more thick skinned around here?

Carlo, I thought mods were supposed to enforce the rules, not break them?

At the end of the day E-Gene has his cafe to run, having your own business saps time, plus there is also the fact that there may not have been anything worth posting at, which often seems the case lately.

[CHA54]

mmmmmmm, TuRD race headers... mmmmmmmmm, no backpressure :P

[MR22ZZ]

mmmmmmmmmmmmmm tuned lengths and optimised harmonics.

[CORZZA]

well that second large post does explain abit more.

Surely the pipe will not be healthy for the valves

[CHA54]

mmmmmmmmmm more of the same...

[MR22ZZ]

4A-GE Atlantic? I thing of beauty right there :D

[LordWorm]

mmmmmmmmmmmmmm tuned lengths and optimised harmonics.

Are you quite sure you know what you are on about when you refer to harmonics? cos saying tuned lengths and optimised harmonics is essentially the same thing.

the "harmonics" refer to the sound wave, and inverse pulse (reflection of the orignal soundwave generated by the combustion) through the headers.

to "tune" a set of headers correctly, they must be made to a length so that one pulse enters the collector (and fires its reflected wave back up the pipes) at the same time as the next exhaust stroke is completed at a given target RPM. Now you could tune them to 3000rpm, and as such the pipes would be quite long. Or you could tune them for 10 000rpm and you'd have short headers.

The harmonics mean diddly in the rest of the exhaust system...useful to know what they are purely to kill ugly noises in the exhaust.

so really, tuned lengths, and optimised harmonics are one in the same. You tune the headers to utilize that reflective pulse to your advantage when you want it to - you don't tune it for specific harmonics or whatever...tuning the length does this itself.

well that second large post does explain abit more.

Surely the pipe will not be healthy for the valves

not really an issue when i can control the fuel system entirely. Car runs no leaner with this pipe than it would with the standard exhaust attached, therefore the risk of burn through is negligable

[MR22ZZ]

The harmonics is associated with the length and ID and therefore the total free volume of the cylinder.

And yes the resonant effects of the exhaust after the headers can have an effect on the power and over all feel and driver comfort, via vibrations back through the engine block.

[LordWorm]

The harmonics is associated with the length and ID and therefore the total free volume of the cylinder.

the "harmonics" are harmonic reflections of the initial sound wave created by the explosion. And yes, ID has stuff to do with it. The formulas used to determine the lengths require ID of the pipe (usually limited to or determined by the ID of the exhaust port) is one of the values input and is part of the calculation used to determined what the "tuned" length for a given RPM. Headers designed to bring power on early are vastly different to headers designed to bring it on late.

And yes the resonant effects of the exhaust after the headers can have an effect on the power and over all feel and driver comfort, via vibrations back through the engine block.

here, unfortunatly, you've been slightly missinformed.

Consider an engine with the best possible header you can design for it attached. If you dyno it with NO EXHAUST SYSTEM behind the header, you get, for arguments sake, 100kW output.

now, go and put an open exhaust system on it..what happens? you lose power.

now add a muffler and a cat, what happens? you lose more power again.

unfortunatly we don't get the oppertunity to do it this way, we often go the other way... car with complete exhaust system on it...we replace the muffler with a higher flowing one and we "gain" power..but the gain would not be, cannot be, anywhere near what you'd get if you pulled the whole system off and ran with no exhaust what so ever.

to quote one source of valuable myth debunking exhaust theory:

"A muffler can no more "make" horsepower than Wile E. Coyote can catch roadrunners"

Ask anyone who tunes race cars..they'll tell you the best muffler for power is no muffler at all.

The determination of the size of the exhaust pipe is made based on how much power you want overall when all is said and done, and what pipe will flow that kind of power at a given RPM without disturbing velocity.. velocity vs volume. Its a trade off, and there is absolutely no perfect solution. Too big destroys bottom end, too small destroys top end.

The header and collector does all the work, after that, no amount of dicking around with the exhaust system can positively effect power. The car will ALWAYS make more peak power by removing the exhaust all together.

Megaphone mufflers (why they call them mufflers, i'll never know..they dont muffle squat!) seem to be the only exception, but i don't use, nore have i worked with a megaphone before, so I can't comment on how or why they do what they do.

Again, not trying to be a smartass and say you are full of it etc... just purely informing the miss informed.. We've all been there, and as long as there are exhaust shops there will be backpressure myths and claims about mufflers that are dyno proven to add power....

[CHA54]

for more reading see: http://www.burnsstainless.com/TechArticles/techarticles.html

and I really like these headers Burns made: http://www.honda-tech.com/zerothread?id=1780476&page=1

[SILVABULLIT]

Well I guess when Shao run his car on the dyno then took the rear muffler off and got the same reading from memory confuses all listed theories here.

Lordworm seems like a hell of a lot of time and money to gain that elusive 1/10 of a sec to qualify for drag meets with a 14.99 cut off from memory.

Buy a stock Sportivo and spend $1500 on intake and headers and run 14.3 hey Dylan

[MR22ZZ]

who needs to spend money on headers to get 14.3? :P

btw, why has the tread been moved

[CHA54]

because it had nothing to do with corolla's?

[LordWorm]

Buy a stock Sportivo and spend $1500 on intake and headers and run 14.3 hey Dylan

as i've said dozens of times to you before - i have absolutely no interest in purchasing or driving a sportivo. Viva la difference buddy... rollas just do not do it for me. Pushing the FSDE to the absolute ball breaking limit is what i'm out to do (post rebuild the engine will not last more then 50 000kms before it needs to be stripped back to nothing again and rebuilt...assuming i can source the FP crank and a few other odds and ends, i'll commence building hte spare engine up in the off season). For the same money i could get a second hand rexy, spend $1500 on it and run sub 14's....or i could get a 200sx...but i love the mazda...and building that is what i want to do.

Like i've said, i'm not posting here to upset anyone, or whatever..and the only thing i take issue with are the "these guys don't know what they are doing" garbage....I have posted what i've posted simply because the lions share of exhaust places wont tell you what they know, if they know, because they like to perpetuate the thought that designing exhausts is somewhat of a blackart (CES isn't like this, the times i've spoken to Trevor about this stuff, he's been very forthcoming even though he knows i'm not spending money with him, but there are certainly places around who will keep the information, if they know it, a carefully guarded secret.

cut off is 14.99 but is not being actively enforced by the sport compact group at this stage. i'm 15.5 before cams and dump pipe... with some SERIOUS dieting (as i'm entering all motor which lets me strip even more weight out) i hope to hit the qualifying time anyway, but its not a huge deal. - as for lots of time and money...pipe was spare pipe laying around from the turbo conversion of a mitsubishi L300... time, about 3 hours including cutting the flange and pipes, test fitting, removing the stock setup, wiring up the wideband and so forth... actual time to swap the parts over, 20 minutes tops.

as for removing the muffler and seeing no difference, says the muffler is having no effect on power. Which is a good thing. Free flowing open straight through muffler by the sounds of things. Other parts of the system would no doubt have an effect. Even the best high flow cats are a restriction. A muffler which makes no difference to performance when either on or off means someones made a very good choice of muffler. It also proves that the muffler isn't ADDING power.

[theDefiant1]

mmmmm

i read the beginning as gains all around, including low and mid range, not necessarily just high end.

Still stand by what i said though - it's how you use it (read: what you want to gain from said modification). That's really the be-all and end-all, ya?

[LordWorm]

mmmmm

i read the beginning as gains all around, including low and mid range, not necessarily just high end.

Still stand by what i said though - it's how you use it (read: what you want to gain from said modification). That's really the be-all and end-all, ya?

Thats right..this does what it is out to do...more peak power. The car is not being built for circuit work, or hill climbs or autocross...

The cams i have installed (custom billet tighe cams) are designed to make power above where the stock exhaust stops working... so the cams (which kill bottom end also), would be a hinderence rather than a help... less power in the low to midrange, no way of using the increased top end...as i said, with no time left to fabricate the headers, I had to do *something* to get use out of the cams.... and the spare 3in pipe laying around the garage was used.

[CORZZA]

4A-GE Atlantic? I thing of beauty right there :D

Rollamods its a race engine so the exhaust is understandable!

[SILVABULLIT]

Well it'll be interesting to see how you go against all my mates in the class dominated by the mighty VW's :)

[LordWorm]

Well it'll be interesting to see how you go against all my mates in the class dominated by the mighty VW's :)

you mean a class dominated by the Alcorn brothers and their 3rd gen civics, don't you? With the way those guys are going, and the way Online is going, they might as well start calling the class All Honda..

DYO racing ... and i'll doubtless be the slowest in the field..so i'll have no problems with consistency.