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

[Northy]

stock cat/manifold removed

http://imagestore.ugbox.net/aview/Stockman...1b25ae6c81c1b30

engine bay with pipe fitted

http://imagestore.ugbox.net/aview/EngineBa...875916451c4c61e

pipe fitted

http://imagestore.ugbox.net/aview/Pipe01_e...1894a3353f6cde8

http://imagestore.ugbox.net/aview/Pipe02_0...d389a1f78427c79

the pipe

http://imagestore.ugbox.net/aview/Complete...9c35dbad81c15e7

Power lost? How?

It has a full after market fuel injection/ignition system, wild cams and a CAI system.

Short of tuned length headers (of which we are building), there's not much more to be done to the induction side of things.

Oh, and the stock exhaust simply doesn't flow enough over around 5000 RPM, so the dump pipe will increase the power output by allowing the engine to breath properly.

We'll just have to wait until MiniJam to get some time slips.

To elaborate, there is nothing you can do to GAIN power after the manifold/header whatever (with the exception of a megaphone muffler to help suck stuff out)... it can only be lost.

Now, 3inches through a full length exhaust system will lose power due to a massive reduction in exhaust velocity...but over about a 1m length, its not a problem. Now it may lose power down low, and the cams are helping it to lose power down low (theres fairly big overlap and a very wild exhaust cam which is helping to over aspirate the engine like nothing else. But on the quartermile, i launch at 4000rpm and then the car never gets below about 4600rpm. This pipe will greatly assist the top end....not as much as tuned headers, but i don't have the time to fab these up in time for Jam.

Theres nothing else in that pipe that can lose power. So i'm taking virgin exhaust gas out of the stock manifold when it as its highest velocity and dumping it out..instead of trying to squeeze it down a 2inch crush bent exhaust system, through 2 low flowing stock cats, and a restrictive muffler... therefore i've removed restriction, and am maintaining velocity, therefore it will make more power. Period.

Those that gain power by adding mufflers, cat backs, removing cats, removing resonators etc...are "gaining" by removing restriction....but they are still "losing" power potential created at the exhaust manifold...you need to take into account just how restrictive a stock exhaust is - free it up a bit, you get some power back...free it up alot by replacing it wholesale, and you really start to make big gains.

The shorter the pipe, the bigger you can go before velocity issues become an issue.

The whole "BIGGER LOSES POWER COS IT LOSES BACKPRESSURE" is the biggest and most false myth in mechanics ever perpetuated. An ideal exhaust system would have ZERO backpressure (yep, nada, none, zip.), coupled with the highest possible exhaust velocity as generated by the manifold through the use of tuned length pipes (optimum scavenging), merge collectors and the like. Once you've got that velocity you need the biggest pipe you can have that maintains that velocity or as much of that velocity through the system without creating backpressure (its a whole volume vs velocity thing).

For the record, once the custom tuned length headers are finished, i'll be running a full length 2.5in system - given a correctly designed set of headers, 2.5in can maintain velocity through a full system no worries.

Simply seeing 3inches and going "thats too big you'll lose power" is helping perpetuate a myth that exhaust shops use to keep their customers dumb, and sell them cheaper systems which require less effort on their part to assemble.

places to talk to if you don't believe me about backpressure: CES Racing in logan, Queensland. Burns Stainless in the USA....or do a bit of googling about backpressure and why its bad. The only people who seem to think its good are oldschool V8 hotrod heros and lazy/ill informed exhaust shops.

this is from another forum and i think this pretty much sums up the astina gt boys.....they havn't got a clue....

[MT]

WTF????

Oh yes im sure that will work... OMFG are they insane... im just in shock.

Please remove the words CES from that post as they are way too high quality to be mentioned with anything to do with what i just read.

[Northy]

http://b3motorsports.com/index.php?main_pa...;products_id=22

looks like you can actually pay money for this kind of stuff.....

[-JC-]

Will it fit on 1zz?

[LTS60]

Will it fit on 1zz?

LOL thats what i was gonna ask

LOL wtf these " c word" are off their guts.

:D

[sportiyo]

The whole "BIGGER LOSES POWER COS IT LOSES BACKPRESSURE" is the biggest and most false myth in mechanics ever perpetuated.

[GReddy_ES]

"Simply seeing 3inches and going "thats too big you'll lose power" is helping perpetuate a myth that exhaust shops use to keep their customers dumb, and sell them cheaper systems which require less effort on their part to assemble."

WTF..doesn't it depend wad capacity ur car's running that will determine how big a system u require..man what are these pple thinking..i know big is beautiful..but not in every case!:P

[theDefiant1]

**** it.

How many times have we heard::::::

It's not the size, it's how you use it!!!

'nuff said.

[MR22ZZ]

These guys obviously don't understand the harmonics of an exhaust which can play a greater role then the flow in some cases.

[theDefiant1]

I wonder what is next then?

Retrograde exhaust emissions (exhaust gases going the wrong way)?

(not taking the p1ss, just mildly amused)

[CORZZA]

Some peoples children!

[E-Gene]

what does this have to do with Corollas?

[-JC-]

what does this have to do with Corollas?

About as much as you do these days . . . . . . . .

[E-Gene]

what does this have to do with Corollas?

About as much as you do these days . . . . . . . .

What?

[shaohaok]

rudeness to a supermoderator around here, might cop a ban :P

[Azza]

As I read this for the first time, I notice Lordworm in here reading it too...

Whats your take Lordy....

[kelvin33]

hmm... wonder the exhaust on a trucker would fit on a rolla ..... :)

[LordWorm]

As I read this for the first time, I notice Lordworm in here reading it too...

Whats your take Lordy....

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.

Gases can flow at an average speed of over 350 ft/sec, but the pressure wave travels at the speed of sound (and is dependent on gas temperature). Expanding exhaust gases rush into the port and down the primary header pipe. At the end of the pipe, the gases and waves converge at the collector. In the collector, the gases expand quickly as the waves propagate into all of the available orifices including the other primary tubes. The gases and some of the wave energy flow into the collector outlet and out the tail pipe.

Based on the above visualization, two basic phenomenon are at work in the exhaust system: gas particle movement and pressure wave activity. The absolute pressure differential between the cylinder and the atmosphere determines gas particle speed. As the gases travel down the pipe and expand, the speed decreases. The pressure waves, on the other hand, base their speed on the speed of sound. While the wave speed also decreases as they travel down the pipe due to gas cooling, the speed will increase again as the wave is reflected back up the pipe towards the cylinder. At all times, the speed of the wave action is much greater than the speed of the gas particles. Waves behave much differently than gas particles when a junction is encountered in the pipe. When two or more pipes come together, as in a collector for example, the waves travel into all of the available pipes - backwards as well as forwards. Waves are also reflected back up the original pipe, but with a negative pressure. The strength of the wave reflection is based on the area change compared to the area of the originating pipe.

This reflecting, negative pulse energy is the basis of wave action tuning. The basic idea is to time the negative wave pulse reflection to coincide with the period of overlap - this low pressure helps to pull in a fresh intake charge as the intake valve is opening and helps to remove the residual exhaust gases before the exhaust valve closes.

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…

[CHA54]

Burns are brilliant with exhaust design.

[LordWorm]

Burns are brilliant with exhaust design.

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

[CAP]

what does this have to do with Corollas?

About as much as you do these days . . . . . . . .

Is there a reason for this comment ? <_< Don't make personal attacks especially for no good reason.

Personally I don't think this is such a bad idea. It's just another race-pipe for track to extract max top end power, obviously the lack of low end is acknowledged but not seen as a disadvantage for the purpose at hand (ie qtr mile drag - all high revs)

[KaZe-]

what does this have to do with Corollas?

About as much as you do these days . . . . . . . .

Is there a reason for this comment other then stupidity? <_<

watta smart *****...

[Northy]

what does this have to do with Corollas?

About as much as you do these days . . . . . . . .

Is there a reason for this comment other then stupidity? <_<

watta smart *****...

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

[CAP]

Guys don't turn this into another s@#t fight that's not even regarding the topic. Stay on topic and Lay off any personal attacks.

[-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?