LordWorm

I didn't see any of the VW's qualifying runs cos i was stuck in the lanes...just going off the seeding chart, where i was listed as second last...with a vee doule-ya behind me. Yeh Dave's gotten a bit sick of being beaten - smartest race i've ever seen dave run, normally he just goes for PB's and national records and doesn't care about breaking out. Bit of a risky tactic - he had to beat Andy's light (which he did) then hope like crazy Andy didn't break out (otherwise he would have broken out further)... paid off though Definantly cheeky, but thats racing so alls fair i guess. Can't wait to see what the alcorns get upto next (i had a word to them through the day...) - that red rocket will definantly go buttloads quicker...they are only launching it as 2000rpm - and even at that engine speed have to preload the axles lest they get snapped - they've broken about a half dozen sets since they put the K20 in. If they can sort out breakage, get a harder launch, keep the car glued to the track and make a shade more power - skys the limit for that thing.

3 tenths of a second improvement in time, but that could be down to a lack of exhaust system (bit of weight there). Definantly definantly DEFINANTLY more power though, engine required about 4% increase in fuel across the entire tune to burn in the right air fuel range, which is an indication that more exhaust gas is being evacuated in a more effecient way, thus more space for air in the cylinder, thus a requirement for more fuel...and so more power. Car also wasn't "retuned" as such for the pipe, all we did was adjust MIX_TRM by +4%, so there was a flat spot around 4500rpm that was quite noticable MPH is also one of the biggest indications of increased power, and that was up by nearly 3mph. so yes, considerable improvement to top end, and allowed me to run the car upto a revised rev limit (600rpm over stock) without it starving itself for air (again, something i can't do on the standard pipe, it just runs out of legs at about 6300rpm normally) - i do normally drive it to the revised rev limit on the track, but mainly for gearing advantage on the next change, but this time i was definantly making more power up there, and was getting a benifit out of a slightly bigger top end. didn't see anyone giggling, not that i'd give a **** if they were.

second to last qualifier...there was a dub according to the seeding chart (not sure if it was one of your lot) that went slower than me, but not sure if he hung around for the racing (assuming he broke something or was just out there for sh!ts and giggles) none of the cut off times are being enforced this season - appart from the front mod cut off, which if you go over you get bumped to street front and have to pull off your slicks....combined class tho so it doesn't really matter, hence why i entered in the first place. Jamboree saw 40 odd cars in street rear, the slowest being some volvo at over 20 seconds, and it was allowed to race.....its all well and good to have cut offs, but until ray gets a decent following, he's not gunna turn entrants away. I wouldn't have put it in if i wasn't going to be allowed to race it. Was a good day out... i was taken out in the quarters because i redlit against that insane alcorn red rocket (if that thing doesn't end up with the national record in the near future i'll eat my hat...they havn't even really begun to touch that K20A - still on standard cams, with a head that'll flow happilly with far more lift and duration - still standard compression, still standard redline...in a car that when wringing wet is only 25kg short of the weight break with driver....that thing will move) I'm hunting anyone who happened to video my car at all...apparently the insane pipe was blowing blue fireballs while i rattled it off the rev limited on a burnout. was a great day out... big thanks to the vee dub boys for loaning me an air compressor and being good fellas all day, cheers to Brenndan for the chat, cheers to ray for a good event, and to the willowbank guys for a brilliant track....

if its the transmission motor mount, i'd hazard a guess (without looking into it) that he's gone for AWR mounts....they are known to cause problems on the SP23 due to not having nearly enough "give" in them.

Correct, you can say its a "gain" over standard. But the exhaust system isn't "doing" anything to give you that gain. The doing is happening in the headers. Yes you "gain" power over stock, but you gain it by, as you say, robbing less of the power away after the collector. and my point of view is very much slanted towards racing.. Perhaps a more eliquent way of putting it, but its essentially exactly the same explaination as was copied from the burns stainless website. and yes that is how scavenging works. the vacuum from each exhaust pulse helps pull the next pulse out, as well as draw the next intake charge in. The gas "expands" to fill its container, being the collector, and the exhaust pipe. This expansion slows the gas down, and cools it. Yes you get explosive expansion inside the cylinder when it goes bang. It will also expand to fill its container as it leaves the combustion chamber. Puff a small bit of smoke (or a visible gas of some sort) into container, and seal the lid... what happens? the smoke eventually expands to fill the container. Same thing happens in the exhaust system. I'm reaching back a bit to my junior science classes, but from memory, a gas will always expand to fill its container. container gets bigger (so going from 1.25in primarys to a 2.5in collector), gas expands. Oh and I didn't say it, again, quote from Burns Stainless website. You're game - not only to drive essentially an open exhaust system on a public road, but to drive it hard enough to listen to the majority of the rev range :P

Yeah not gunna put it on the "road" so to speak... the damned thing is loud (like hear it from the next suburb loud)...ear splitting, gut wrenchingly loud.... Looks like we'll be renting out archie's dyno soonish though - got a few cars that need a tune and i'm chasing a horrible timing gremlin...so i'll be sure to back to back it vs stocko system. another point which hasn't been made, this pipe is lighter than the standard exhaust system. So it might only make me another handful of kW at peak power, but its going to save me quite a few kg as well. Lighter hey? The first exhaust made from cardboard..... Be sure to bring it to the next CES Dyno day won't ya.... Alsso, you want loud...did you ever hear the terrorist pipe, Shao can tell ya about it Yes lighter than stock stock's first cat is inside some big cast iron piece, weighs an absolute tonne I never heard the terrorist pipe.... but yes, my pipe is loud..there is absolutely nothing muffling the sound... just like any open exhaust i guess.

Yeah not gunna put it on the "road" so to speak... the damned thing is loud (like hear it from the next suburb loud)...ear splitting, gut wrenchingly loud.... Looks like we'll be renting out archie's dyno soonish though - got a few cars that need a tune and i'm chasing a horrible timing gremlin...so i'll be sure to back to back it vs stocko system. another point which hasn't been made, this pipe is lighter than the standard exhaust system. So it might only make me another handful of kW at peak power, but its going to save me quite a few kg as well.

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.

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.

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.

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. 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....

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. 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

that they are... I remember seeing a spaghetti header they made, for a rover or something, because the customer wanted optimum tuned length (which meant long long primaries), but stock fitment was a must... When we design headers we use 3D graphics to get around the difficult design processes and get our pipes within 5mm tollerences - but even with this kind of tool, I'd have no idea where to begin on such a design. you pay through the nose for burns gear though..easilly thousands apon thousands for a set of headers

Well, Azza, I do have a take on this, seeing as its my car, and my business, my post on another forum, and my work that’s being attacked by people who seem to not really understand what they are on about. And I don’t mean that in an offensive way. 90% of people running around don’t have a clue about exhaust systems – that includes exhaust shops themselves…So heres some theory. An undisputable fact is that the job of the exhaust system is to evacuate exhaust gas from the combustion chamber as quickly as possible. A stock exhaust system however, has a very different job. Its job is to be cheap, and quiet. This is why we all go out and spend big cash on fancy exhaust systems. Unfortunatly for us, adding anything after the header or manifold cannot and will not ever gain any potential. The gains you get by putting on a fancy cat back, or a free flowing muffler are gains created by removing restrictions developed in the stock exhaust system. Ok that sounds a bit confusing, but it will become clearer as you read on. A bit about header theory – Exhaust gas leaves the combustion chamber at a constant speed, calculated with complex equations using things such as cylinder bore, and compression to come up with a figure in feet per second. When this pulse of exhaust gas leaves the exhaust port with explosive force, it is followed by a pressure wave which moves at the speed of sound. The reflection of this pressure wave (the negative, or vacuum pulse) in the collector is what is used in race designed headers to gain tremendous amounts of velocity and help the exhaust system breathe correctly. Heres a bit of an explaination from the most highly sought after, and well reknowned exhaust shops on the planet (sort of a US version of CES I guess), Burns Stainless. Ok so what does this tell us about backpressure? Not much..but its an interesting read, and shows the lengths high end exhaust shops will go to to create velocity in the exhaust system. Now, velocity DOES have a bit to do with backpressure. Backpressure is the enemy of velocity. As the name implies, backpressure is pressure build up in the exhaust pipe, caused by a) a pipe that is not large enough – this sustains velocity but does not allow enough exhaust to flow out, therefore it backs up the system – or B) a pipe is too large – this reduces velocity as exhaust gas expands into the larger pipe and cools, therefore gas is not completely evacuated and before long it too backs up the system as gas lingers and isn’t being “sucked out”, or c) restrictive exhaust components which through poor design back up the system. When most exhaust shops talk about backpressure, they are infact talking about velocity. The requirements for backpressure date back to the good old days of carberated motors, which were not correctly “tuned” for a free flowing engine, thus the engine was prone to leaning out. This caused valve burn through. Backpressure would act like a fire extinguisher, cooling the explosion by taking up valuable combustion chamber realestate. Another interesting point is the sheer amount of expansion that goes on in the combustion chamber. Calculating the volume of air/fuel mix entering the engine at each revolution is quite simple (1/4 displacement * rpm gives you a rough amount in cubic cm per minute)… but the amount of exhaust gas that is generated is much more, due to expansion under extreme heat, and the conversion of chemicals as they burn. As a rule of thumb, 13x the volume of the intake charge is generated at combustion. This further emphasises why backpressure is bad. If just 1/13th of the exhaust gas remains in the combustion chamber following combustion, then you have absolutely no room to squirt fuel and air. Now it is true that a large exhaust pipe, such as my dump pipe, can have a negative effect on velocity at low rpm, HOWEVER, baring in mind that I am already behind the eight ball using a stock manifold (the stock FSDE manifold is nothing short of the worst possible design ever), and the 3in pipe is extremely short (about 1m), the size of the pipe isn’t really an issue as exhaust pulses travelling at circa 350ft/s, the exhaust is completely evacuated before it becomes a problem. Also, the 3in pipe is larger than the collection part of the manifold. After that point, not much really happens. Bare in mind this pipe is PURELY a temporary thing for racing purposes. We have a delay on the flange plate required to build the tune 4-1 racing header for the car, and as such I needed to do something about my exhaust to take advantage of my larger cams (the engine would not breathe past 5000rpm with the standard exhaust, and that’s about where the cams “come on” – by removing ALL the restriction after the manifold, I am at least giving them half a chance to do some good before the manifold exceeds its efficiency potential. The side exit dump pipe that will be added to the header when the complete system is finished, will be a mere 2.5in, but the run up to the dump pipe will be longer, and the entire system will be designed to operate with pipes of 2.5in. There are plenty of resources on the net which explain more reasons why backpressure is bad, and backpressures effect on outright power. Yes backpressure CAN artificially create torque by increasing combustion chamber pressure, but there are other ways to keep this pressure up so your “big” exhaust doesn’t have a negative effect on torque. One such way is dialing in overlap on the cams, so that there is more time for the negative exhaust pulse to suck the next intake charge in. This adds more air + fuel rather than air + fuel + unflamable exhaust gas. In summing up, yes you can go too big, but in the case of my dump pipe, it does add a considerable improvement over the stock system for my purposes. Yes I will lose a considerable amount of bottom end but over the quartermile I’m never ever under 4500rpm. The point of this pipe is purely to get give me a slight (even if its just 1/10th of a second) gain and help me meet the minimum qualifying time, even though it is not a requirement at mini-jam. Its also a bit of promotional carry on, as the car is very very loud, and therefore will get noticed more than if I had the standard (i.e. dead silent) system on. Anyway, I hope this clears a few things up for everyone, and I apologise if anything I’ve said here has offended… that is not my aim at all. Yes we do know what we are doing. We do have quite a bit of knowledge in this field, backed by a solid understanding of the physics involved, as well as listening to those in the know. If anyone has any questions regarding this sort of stuff, I’d only be too happy to answer them for you. Cya’s…

Qld highway patrol also have a fleet of unmarked Honda Accord Euros...few of the mazda boys have been bitten by these....patrolling the freeway to the gold coast, as well as a few roads to the sunny coast..