i dont use any of jasma brand. the quality is really questionable..

the fact that they named their brand jasma makes me think they want to trick people into thinking that it is a japan brand when it is based somewhere in terengganu. what a corny marketing technique

works engineering crank pulley is more promising although its not really recommended to install LCP cos no harmonic damper like OEM to absorb torsion force acted on the crankshaft by piston movement

engine balancing also cant eliminate harmonic imbalance cos it reduces translational vibration, not torsional vibration

if u concern of longevity of the engine, not worth taking the risk on lightened crank pulley. race engine the odds dont matter cos it is rebuilt in short period anyway

but i agree it is strictly subjective cos the risk is different on different engine. just thot u should know what u dealing with

This post has been edited by upontheriversky: Jul 6 2011, 03:42 AM

please take some time to read about this

1. exhaust termination box - how to design a street compliant exhaust system that runs like tuned racing open header - by David Vizard

http://www.popularhotrodding.com/enginemas...exh/index1.html

summary:
- termination box should have minimum twice volume of engine displacement, but this strictly apply to WOT application. in practical 1.5 times engine displacement is sufficient for part throttle, city driving application
- this does not apply to sflow setup, only straight flow.
- since we dont have open chamber muffler here, fit the biggest straight bullet at the end of collector so it also acts like open atmosphere

to confirm that straight bullet can be used as exhaust termination box, this is my discussion in speedtalk.com forum:

http://speedtalk.com/forum/viewtopic.php?f=1&t=27535

this is why some enthusiast found that fitting a bullet gives better power overall than having straight pipe till the end and thought this is due to backpressure but its not, the bullet actually acts as exhaust termination box and make ur exhaust system seems shorter like those in open header and collector racing setup which contribute to the power gain

2. equal length header is not critical compared to secondary/collector length when it comes to header design, in practical it is more like polishing the port for bling factor so customer would think they are in the right step of buying high quality product and buying iridium spark plug supposedly for increased horsepower

http://www.sandersonheaders.com/Lets-Get-Technical.html

to summarize:
- these are the sequence of importance when it comes to exhaust tuning:
a) collector / downpipe length (until first bullet/resonator)
b) colector / downpipe diameter
c) header primary length
d) header primary diameter

this summary above is based on David Vizard's tuning 4 stroke book, google him up, he's a big shot in car tuning in the U.S. so in contrary, dont spend too much time on header because collector length is more sensitive to powerband curve than header itself

general rule for collector length:

18" - 24" for higher rev range (6k-7k peak), longer 30" - 40" for lower rev range (3k-4k peak) and if u wish to tune it further down slight higher than stock exhaust, use as long as 50"

a video of different collector length dyno test:

http://www.youtube.com/watch?v=1ywUEz5XtdE

if you are really into exhaust and intake tuning, pay ~rm200 for this PipeMax software and 90% chance says u will get the optimum result in real life. this should be worth for exhaust businesses. the software takes into account ur valve lift, intake port size, valve diameter etc so it is very specific and pretty accurate

it can also be used to calculate intake side

http://maxracesoftware.com/pipemax36xp2.htm

just to share some proven very useful info in exhaust tuning, especially for NA, i dont think this technique is applied anywhere in most exhaust shops here, most of us have only this in mind when modding exhaust system " how much and how fast the exhaust/ muffler/ pipe can flow".

nowadays, when u ask how to modify exhaust, u get typical answer like " manual use straight flow, auto use s-flow", "pickup use 4-1, top speed use 4-2-1". honestly, i think even auto can use straight flow which is better and get faster than stock pickup, achieve top speed easier than stock and the car is snappy. just swap to a smaller pipe and put straight flow in, definitely better than using large pipe than fit in 3 bullets to restrict it, waste of money on large pipe and the 3 bullets

fact is, the most important factor contributing to highest gain in exhaust system is " pressure wave tuning ", go to ur local exhaust shop and ask them this, im sure most of them will say its not related or dont have any idea. ive searched through all local auto forums, not one ever open this discussion so lets start now coz in exhaust modding scene in the states, they put extra effort on pressure wave tuning rather than having the highest flow coz its quite easy to figure out which is "when in doubt, always use smaller pipe size".

a quote that i really like in exhaust tuning:



there is more to this, search them up for more detailed info like determining collector length before terminate to resonator for ur engine. im just here to open some new perspective in exhaust tuning

guns for show, knife for pro, turbo for show, NA for pro

This post has been edited by upontheriversky: Jul 26 2011, 03:09 AM

search swirl bullet in this forum, u will find answer for spiral bullet there, same goes for straight bullet

straight bullet more performance than spiral for sure, FC depends on exhaust setup. if its custom to ur rpm habit then FC is lower, if it is set out of ur rpm habit then FC can be high

1 bullet is the best, 2 bullets just add up backpressure, if some people tell u to use 2 bullets for power, that means ur pipe is too big for ur engine or ur application. in that case, swap smaller pipe and remain 1 bullet, that is way better, no flow restriction, just faster flow velocity


12inch is better than 4 inch i suppose cause u have longer pipe length after bullet to build up exhaust velocity and aid scavenge out gas from the bullet before the gas enter ur midbox

why using bullet and midbox? for noise reduction or power improvement?

here is setup for race performance exhaust with street muffled system:


the resonator box (bullet) separates ur header and collector from the rest of exhaust system so header and collector length are kept tuned.

This post has been edited by upontheriversky: Sep 24 2011, 11:44 AM

what is ur current setup? best power curve is to use 1 midbox only, if its too noisy, better swap smaller pipe and get bigger body straight muffler at the back

mine is a straight flow setup but sounds like sflow. the back muffler has small piping and really big body.

i suppose ull get more power across certain rpm with 12" distance but no special peak. if u want some noticeable boost, use only one 3" midbox in the middle, everything else remain the same. this will fatten ur midrange, trust me

noise wise, if the drone is bothering u, custom a side branch resonator. this will confirm eliminate the drone. ill tell u how to do if u want




This post has been edited by upontheriversky: Sep 24 2011, 11:13 PM

can u describe the power from this setup?

my honest opinion for best city torque setup, keep ur 4-2-1, use 1 big diameter straight bullet, 1 big body straight muffler having same diameter as ur tailpipe. If u need a 3 restrictors (bullet, midbox, sflow) for ur engine to run good then ur piping size is more than big d, get a small diameter piping, NA is about flow velocity, turbo is about flow volume

1 big bullet is to separate ur 4-2-1 and downpipe tuned length, a straight muffler having same diameter as tailpipe and big body is to keep the straight flow noise to street friendly level

exhaust cools down and slows rapidly as it travels thru piping which induces backpressure so having big piping at the back does not make ur car torque-y, not that fun to drive IMO. Dont get confused with drag exhaust setup, those cars cant beat torque-y small engine small exhaust car in heavy traffic hehehe

i quote this from other site for side branch resonator, just read carefully and apply to ur scenario:




hehe touge spec engine is nice to drive across LDP/ MRR2 right? im having the same mindset too fast rpm climb at cornering exit, highest torque output across 2.5k - 4.5k for kelisa is what i need for non-track application. i dont bother with 5k power and above for a small engine, i keep tuning practical hehe

my usual place is torque gear and supercircuit in sunway, i like the workmanship but the price can be reasonably high. if small simple stuff i go to wai heng sunway instead coz its cheap. but if u know the design and spec, what u can do is go to cheap exhaust shop (wai heng, wei yip) and supervise them to do it. check welding finishing making sure no leaks after finish, basically be a b****y boss checking everything before u finally pay, i hate doing that coz seems disrespectful to the workers so judging by the work needs to be done, i select the desired shop

yes indeed bro, diameter tuning unlocks probly 40% of ur exhaust potential, its the length of ur header and downpipe to first bullet that makes the big difference

try this, if u r on 4-2-1, assuming extractor length is 15" like mine, then use 37" downpipe length and put ur bullet there. if header length is different, just makes sure header+downpipe length = 52". +- 1 inch is ok.

use 1.6" piping for downpipe, this will flow good up to 4500rpm on myvi engine. with myvi exhaust open BBDC at 30 degree, 52" of header+downpipe would give u boost at myvi peak torque 3200 rpm. for max boost effect, ur bullet internal pipe volume has to be minimum 2X engine cc i.e. 2.6L of bullet volume

if 4-1 then 52" starting from extractor flange to end of downpipe then put bullet there.

i tested this theory on kelisa, 34" downpipe to boost at 3500rpm, i felt boost at 3400rpm which made me happy coz it was really close to my approximation.

try this first and let me know the result, then i can propose something more to lengthen the boost duration

oh yeah, avoid openpodding ur intake, it does not do good for touge tuning, keep ur airbox, modify it to let airflow in easily up to ur rpm habit and call it a day. once air can flow easily thru ur airbox, there is no need for aftermarket drop in. use oem filter that was highly R&D-ed, designed and tested purposely for myvi

This post has been edited by upontheriversky: Sep 27 2011, 10:32 PM

yes, this technique applies to all conventional 4 stroke engine, the difference is the length of ur exhaust pipe depends on ur engine camshaft profile particularly the exhaust valve open BBDC. refer to ur manual for this data and i can help u approximate urs

it works even if u got engine with variable cam timing (vvti etc) coz i think only the intake cam is variable but exhaust cam has same profile across rpm

i actually stay quite far in desa petaling area hehe

the technique im practising is consistent with theory of using extractor for scavenging during valve overlap, except i study into details as how to approximate at what rpm u want this to happen at maximum by playing with pipe length

i referred to several tuning books, fluid dynamic students and race enthusiasts in U.S for months to fully get the concept, only now i apply coz budget not high so still got long way to go

i dont mind to meet up when got free time, then i'll share this technique so u understand better and can apply it urself

what im trying to say is there is no need for rigid stereotype like "if u r on auto, u lose power on straight flow", this gives wrong impression to first timer like i was when i was a total noob. i think auto can use straight flow provided that the piping size is small enough to keep flow velocity fast at low rpm. Since shift point for auto is around 2-3k rpm at lower speed, its hard to take benefit from big pipe big diameter muffler with stock auto gbox. same goes to manual, if its bad on auto it is also bad on manual coz given the same engine, power should be almost the same, only that manual can cope better coz it has more control over the rpm range, i can just shift gear at much higher rpm to take advantage of big pipe but its not gonna be fun to drive even in fast moving traffic.i remember someone quoted "true enthusiasts are really looking for fun, not just speed" which holds true IMO

2.6L can be equivalent of 3" diameter bullet having 22" length, the volume inside would give approx. 2.6L of air. u can use bullet/midbox if u got the space as long as after tuned downpipe, the piping change of area is significant and volume is close to 2.6L. if u can only have less volume, it will work too but not at its full potential but it will work, it worked for me on 2" bullet giving about 1L only where i need 2L minimum. this technique is derived from 4 stroke bike tuning where they use expansion chamber to increase horsepower

i forgot to mention the tuned part is only at the front (header+downpipe), once u terminate the tuned part with a midbox/bullet/expansion chamber, the piping after bullet to the back does not matter in terms of pressure wave tuning, what u need to do is make sure it flows well to not causing considerable backpressure

ive read experience from people using big bullet as expansion chamber is they tend to get drone so i cant promise u a super silent noise. custom a big body straight flow which has same diameter as ur tailpipe. big body muffles more noise, smaller pipe is even easier to muffle, thats the best i can say coz different people has different taste in exhaust sound. u can custom at supercircuit, i custom 1.6" big body straight flow and the noise is only as loud as typical 2" sflow but speed like a straight did mine there and it is reasonably priced.

A lot of racers in the U.S apply this technique to maintain their car horsepower while having street permitted noise. do a search on David Vizard, he's the one came up with this idea and people loved him for it

problem with my math is, i dont think it works that well with reverse flow muffler due to nature of it to break up the flow for noise reduction, i have confirmed it with some gurus so i dont really favor sflow, if i lose pickup from straight flow, get smaller pipe, thats it

ive bought 3" diameter 19" length oval bullet as expansion chamber but havent fit it yet coz no budget after bought that bullet haha so i cant tell my experience on the noise though..performance wise im quite confident

This post has been edited by upontheriversky: Sep 29 2011, 10:22 PM

in ur manual at engine mechanical section. usually there is a table showing engine cc, bore stroke, compression etc, there u will find intake/exhaust timing

dont get confused, 3" midbox and 3" bullet of same length has the same pipe volume, the body cant be counted coz its not free air, it has fibre packing so gas will not pass thru it, only sound waves are absorbed by the packing. what i did was the original bullet is 15" so i added 3" pipe extension at both ends to give 19"

thats the problem with termination box, it can be hard to fit especially for big engines, 2.6L has to fit 5.2L box volume to get full benefit of expansion chamber haha

yea i suggest u custom ur own muffler coz u cant find good quality 1.6" straight flow big body muffler anywhere, minimum size is 2" and since pricing for 2" and 1.6" are almost the same given same body size, better go for 1.6" coz has better silencing and power. supercircuit custom price is reasonable and quality is there

u can use 1.5" after bullet to keep the noise down. If u r using crush bent pipe, connection from bullet to rear muffler is best to make it in straight line as possible, too much bend can make 1.5" act like 1.2", re-do the oem route if u need.

the length of branch resonator is not fixed. u need to know at what rpm ur exhaust is giving the drone and start calculating from there because all cars can have different drone rpm

the progress sounds good

Piping size after bullet = same as downpipe? yes, if u have 2.6L, i think 1.5" should work well too if u want less noise
Distance to place rear muffler = not important. yes, if tuned pipe end is fully terminated, the part after does not matter to wave tuning, only need to make sure it flows well

stainless steel piping retain more heat and longer than aluminized steel if im not mistaken, so it keeps exhaust relatively faster than aluminized one but i suppose the gain difference is minimal

can whatsapp if u want, i havent use msn for ages haha

This post has been edited by upontheriversky: Sep 30 2011, 12:48 PM

yea, i could go with u whenever im free, weekend should be good. it depends on ur budget, supercircuit has higher charges than wai heng obviously but i wouldn doubt the workmanship, there is a chinese dude with glasses whom i can trust for touching my car hehe

but im not sure whether they stock normal pipe coz i think they only do stainless and i think they are the only one of many shops that owns a mandrel bend machine

bro, i need the exhaust open valve degree at BBDC to estimate, and would be good to let me know:
what setup u have on ur car now?
ur driving habit as in the rpm u usually drive in?
what kind of power u would expect?
do u prefer more straight line acceleration or faster speed recovery (torque-y)?

This post has been edited by upontheriversky: Sep 30 2011, 10:42 PM

Supercircuit in sunway, can ask for more steel wool than fibreglass so longer lasting for high heat application. can custom to ur specific dimension. price differs from car to car. I did mine there, paid deposit, waited 3 days for it and now very satisfied

oh how so?..every car manual usually states the cam timing degree, its ok, whats ur engine? i try look for the exhaust open BBDC for u. without it i cant do anything much really

i quote this from other site:


backpressure causes higher exhaust noise due to turbulence of slow moving gas from bigger pipe being collided by high speed gas behind it from exhaust port

if we want lowest possible noise, do piping as straight as possible, use biggest muffler canister/body, use smallest muffler pipe that flows enough for the engine. i believe if anyone is after pure exhaust performance, never use reverse flow / sflow / swirl unless one believe backpressure is needed to make power

there is a difference between sflow type and small pipe in terms of flow restriction:
- sflow system RESTRICT exhaust by blocking the path and forces the gas to change direction
- small pipe system CONSTRICT exhaust to smaller volume, therefore increasing its pressure and hence is forced to move faster, it does not forces gas to change direction
- downside of small pipe is, it does not allow power in big throttle difference in short time i.e. sudden wide open throttle will give u a holdback. it works very well with progressive increasing throttle, so driver is also accountable to make power in this case

just for fun, check this out, apprently straight thru muffler does not really act like straight pipe, it acts more like a megaphone:


yea thats the problem of fitting the box, space limitation, tune the downpipe length longer to fit the box and boosted rpm will be lowered

i dont really rely on exhaust shops for exhaust info anymore, i rely only on their outstanding welding skill. this technique has been practiced for decades in racing scenes in western countries, but i never encountered anyone who tried this yet here so lets prove it

This post has been edited by upontheriversky: Oct 1 2011, 09:01 PM

im just glad there is a shop actually custom make mufflers lol

yes, thats the reason why i custom in the first place, i needed the internal pipe to be straight 1.6" with sflow body muffler, there is none of this in the market ive gone to.

they cant weld alu to steel, only between steels. can try ur luck at velocity beside kin alignment, the shop custom make intake manifolds so could be the one u looking for

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Added on October 2, 2011, 4:14 ami will try find it, ill let u know when i do

This post has been edited by upontheriversky: Oct 2 2011, 04:14 AM

just ahead of kakimotor, opposite sunway college there are shoplots, its the one behind these lots

cost me rm380

that equation applies on pipe resonance, nice one the speed of sound determines the pressure wave speed and is the reason why we can have different result in real life from what we have calculated, speed of sound increases with temperature, different engines with different conditions at different climates will have different exhaust temperature, too many variables to get an exact answer haha

but one thing missing is we need it to resonate at rpm that we want during the valve overlap and valve timing for every engine could be different.

we want to have a pipe length so that the low pressure wave travelling back to the valves from reflection at bigger bullet mouth to arrive and enter the chamber when intake and exhaust valves are both open at overlap. note that this low pressure wave can be described as little area of vacuum travelling thru the pipe

as this vacuum approaches the exhaust valve at overlap, this adds up total vacuum at the exhaust valve area and therefore more exhaust will come out from the chamber willingly without any push from piston to fill that vacuum area and finally to the downpipe, and also at the same time, vacuum created from more exhaust going out will draw in more air from intake manifold due to increased pressure difference

basically the wave creates further vacuum so gasses can flow from high pressure at intake to low pressure at exhaust without much effort from piston movement, the extra power will go to ur wheel some tuner regards pressure wave tuning as the 5th stroke haha

there is also a term called over-scavenging where the intake drawn in are in fact pushed out the exhaust pipe, this can result from too long of a valve overlap usually associated with high cam but i have read that on stock cam, this will usually not happen as overlap is too short, my kelisa stock cam only have 9 degree of overlap out of 720 degree cam rotation hehehe

i could be wrong somewhere in my theory but i get the big picture, anyone got new stuff on exhaust mod please do share, lets make exhaust tuning not a dark art anymore haha

recently i have also read a remark from a header designer, jere stahl in which he said, the theory of scavenging might look neat and easy to us but what makes us think that gas only flow one way? it can flow both ways too, meaning how can we sure that when low pressure wave arrives at overlap, it will not make the exhaust gas to go backwards into the chamber and push intake out? because backpressure in exhaust header is generally higher than intake manifold, so if chamber is further "vacuum-ed", exhaust backpressure can push back exhaust into chamber, diluting mixture and air will be pushed back into manifold during valve overlap

something to think also..more research to come

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Added on October 4, 2011, 7:32 pmyea, ive asked long ago and i dont think its worth it. the design is good but not near perfect for that kind of price. i could use the extra money to custom a header to my calculated spec

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Added on October 4, 2011, 7:44 pmi have done multiple trial and error of open pod on my kelisa and i dont think there was a combo that can beat the power response from using airbox.

if i wanted to have intake pipe tuned to mid range, it will not fit straight in the bay unless i do a 90 degree turn coz it was really long so i gave it up and use airbox and modify it, serves me way better ever since

if want some boost on intake, read this out, it is called intake resonator. most people think it is simply used to reduce noise, i think its true on certain level. if the resonator located near snorkel, IMO it is used for noise reduction but if the resonator is located near TB then it is most likely for power boost

read this article about effects of removing resonator and lose power and how using resonator can boost intake charge

http://www.planetsoarer.com/resonator/resonator.html

my favourite facts from the above link:


multiple intake resonators to target boost at different rpms


most likely a low rpm boost intake resonator judging by the size of it


some aftermarket intake includes intake resonator to give boost for specific engine:


This post has been edited by upontheriversky: Oct 4 2011, 07:54 PM

using pressure wave speed as 1650 feet/s, i calculated header + downpipe length of 47.3".

if u know the needed runner length and diameter and the plenum volume needed to fit ur application best then can custom manifold, on the intake pipe side im not so sure how to apply pressure wave tuning to complement manifold and exhaust ones, need more time digging out hidden info on the net hehe

but u can refer to this article, he dyno-ed different open pod pipe length to see how length affects the powerband of the engine, and it seems that long pipe wins over short ram hands down:

http://autospeed.com/cms/title_Pipe-Dreams...49/article.html

i think k3ve2 cam profile is quite aggressive already for daily drive, overlap of 54, intake duration 260, exhaust duration 227, almost have trait of mild performance cam d, no need to reprofile unless higher power is needed

try:
- either straight flow muffler having same diameter as ur stock piping diameter with the biggest canister to muffle it, this would sound like sflow with added power
- or get a good quality s-flow muffler

i'll sum up my point of view to help u choose better

IMO, the pipe size is good enough for an auto so what u can do is swap that s-flow muffler to 1.6" big body straight flow muffler, dont use bullet style muffler as the noise could be unbearable, big body muffles a lot better. Also dont get 2" straight flow because its not efficient, people might say its ok but i dont think it is coz 1.6" expand to 2" will slow the exhaust down by a lot and cause turbulence thus backpressure, this disadvantage is more obvious at higher rpm / higher speed when everything in engine is moving really fast where 1% difference could be felt

also its good to know the primary pipe size and length of ur custom header so u could get the exhaust port / primary size ratio. most aftermarket header here will give u racing spec primary pipe size which does not work below 3k

before u decide on getting typhoon, compare the internal volume of typhoon intake and ur airbox, the one having most litres are the winner for ur auto and presumably a daily car, because more litres mean u'll have plenty of air reservoir stored for better take-off acceleration so if in any case the header lowers the low end torque, u got airbox to counter balance and boost it up, powerband is flatter and wider, not peaky and narrow

i have studied extensively enough to say that if the airbox design has a substantial restriction in the first place, no aftermarket drop in can help u gain noticeable power gain. basically decreasing airbox intake restriction will give a gain of approx. square root of pressure difference, in other word, decreasing intake restriction by 50% (making pressure difference bigger) will give u gain of 6-8% ponies.

Enlarge the snorkel pipe and airbox inlet if u feel there is a choke at higher rpm. typhoon might work on ur friend's car but does not mean it will work on yours. compare the rpm powerband between ur engine and his gti. usually high rev engines will benefit a lot more from open-pod style than low rev engines. open pod style on bigger engines will have more benefit than smaller engines because bigger engine has bigger torque to begin with so any low range power drop will not be as sufferable as small engine on open pod

i personally think using more expensive spark plug does not give u any noticeable gain in power except it will last longer for easier maintenance. Peugeot and all manufacturers must have "superior fuel efficiency" to meet the marketing target so i dont think they will cut a slack on combustion efficiency. Unlike exhaust and intake where noise regulation applies that engine efficiency has to be compromised. So the stock plug must have enough characteristics to give complete combustion on stock engine, anything more is not necessary unless u do something to the engine i.e. increasing the cc or something. Using expensive and higher quality engine oil will definitely increase hp and torque but not on the plug so no point using expensive plug if power is what u after.

no comment on unichip coz i havent got the chance to enter air fuel tuning world yet but an advice from old timers ive got is always try to get the best tuner to do it and saves cost and more worth it. dont cut budget on finding pro tuner.

he didnt do the exact calculation but when different pipe length was dyno tested, i reckon it is safe to conclude from the article that the length achieving highest hp is probably closest to the tuned length intake for that engine.

proof is he tested up to 100cm intake pipe length but 60cm pipe length wins the dyno so there has to be a reason why 60cm wins despite air travelling in 100cm pipe should be faster.

what we need to do is to find out how that length is derived with maths equation and generalise it to apply to all engines - reverse engineering

This post has been edited by upontheriversky: Oct 10 2011, 06:25 PM

same for me also.. if low end lost i couldn sleep at night hahaha

true also, i couldn get the take-off rush speeding after paying toll as fast as when i was on bigger pipe anymore haha but top speed sustain is much superior with smaller pipe, just need to open throttle gradually instead of floor it down right from beginning. i had problem sutaining power at high gear speed with bigger pipe

i guess kelisa stock gear ratio at higher gears are not meant for accelerating, more for cruising so its more difficult to spin the engine faster at higher gears to achieve high rpm, so more difficult to get high exhaust velocity. i think the same goes for most daily car stock gearboxes.

thats why 3-1 or bigger piping really good for pickup, at lower gears its easier to go i.e. 7-8k rpm and bigger pipe size can be used effectively in this case

ooh fark..lets do it hahaha

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Added on October 12, 2011, 2:57 amkeep the 4-2-1, keep stock piping, if midbox is straight and has larger diameter internal pipe than bullet, then keep it and remove the bullet, remove s-flow and replace with straight flow muffler that has same internal pipe size as ur stock piping or close enough. Make sure straight flow muffler at the back has diameter not more than 0.5" from ur stock pipe but if u can find same size is always the best, can use more than 0.5" but not efficient so best to avoid. most exhaust shop will say can use much bigger diameter muffler but does not say whether it is the best for ur car

midbox position plays a big role in the exhaust powerband so pay attention to the location in ur system. basically shorter distance between midbox and extractor will boost power at high rpm and longer for lower rpm.in general 12-18" for higher rpm, 18-30" for midrange and 30-42" for high torque at lower rpm, but anything shorter than 12" can lose out on potential power plus its not possible to fit a midbox at 12" after extractor, that would be near gearbox or crossmember d. i think for auto its best to use distance between low and mid range, something like 24-36" as gear shift point is usually in this rpm area

more specific distance i would need some info on ur engine.

noise wise, i like to think of the noise level of a muffler as a function of its body to pipe size ratio. when comparing 2 mufflers, i.e. given the same body dimension, the smaller internal pipe will sound much lower. so if u have a tight noise regulation rule, get the biggest body muffler u can fit under ur car having smallest internal pipe that flows enough for ur engine and application. plus silent and fast car looks more sophisticated hehehe

bottomline, never use sflow if power is what u want.

This post has been edited by upontheriversky: Oct 12 2011, 03:02 AM

im in desa petaling area, a bit far but no problem coming sunway


no havent done, poket still got holes to sew haha but if all wanna do i think i can stretch my budget a bit hehehe


mine is close to luqmanz result, with BBDC of 29 degree, these are the results:

tuned rpm - 3000 , exhaust port length+header + downpipe length before bullet = 59"
tuned to engine max torque rpm 4000, total length of 44.5"

i suggest u do it shorter by 2" because this length includes the port length inside ur engine head as well

im not sure whether im getting this right but since u can hold maximum of 3.5k rpm then shift gear, probably best to tune it to run at around 3k so during upshifting, the rpm will drop to around 3k which is near to the tuned setup rpm so hopefully torque can be sustained longer across gears and rpm without having engine to push extra to climb back to tuned rpm everytime gear changes

but ur engine has 4k and 6k for max torque and max hp respectively so makes me wonder should u tune the exhaust to these rpm? haha but come to think about it, no matter how powerful the engine is, the power delivered to the wheel is still governed by the gearbox so 3k is probably a good start

if u are willing to further trial and error, get the longer 59" one first so in case u need more power at higher rpm, just cut it shorter to the next tuned rpm and place the bullet there. if u start shorter then later u will need to add more length in case u need torque at lower rpm, welds will be all over the downpipe area and does not look nice especially these parts are where power is being unleashed the most hehe

when u look for the 4-2-1, pay attention to the primary pipe size, i have read that good ratio for primary size to port size is around 1.15, i.e. if port diameter is 1.2" then best primary pipe will have around 1.4" in diameter but generally u will see bigger than this so get whichever close enough. also there should be at least 2" of straight line at each primary pipe on the header in line with ur exhaust port, if they are bended down straight away after the flange then its not really good in design. both these features improve anti-reversion of the header design to prevent exhaust gases going back to the chamber especially at idle and low rpm when gases are moving slow

pay attention to the merge collectors too, look inside for casting marks and merge quality. good header will have long and smooth merge at every collector i.e. at 4-2 merge and 2-1 merge collectors. smooth long collector improves the flow easeness and most importantly, although pressure wave reflection is weaker but the reflection duration will be lengthened due to the long merge and powerband is wider. short collector will have narrower powerband but in return pressure reflection will be much stronger, good for high rpm take off, not really for speed recovery in city drive

so, to sum up:
-4-2-1,
-1.6" stock pipe
-4L bullet/midbox or if u cant fit them under the car, 2.5L or 3L will also do the job if u are not going for 5k and above. 4L makes sure that the tuned length is kept until ur max engine rpm, if u dont go that high, lower than 4L still ok. but make sure u keep at least 0.5" diameter difference between bullet and downpipe. say if u use 1.6" downpipe, try get something like 2.5" bullet which has 0.9" difference. if u use 2" bullet, at one point im afraid the bullet will be considered as extension to the downpipe , the length will go out of tune so efficiency is lost there.
- im not sure the stock muffler is capable of flowing the gas ur engine expelling due to manufacturer noise regulation. they always compromise exhaust efficiency for a lot quiter sound and low cost in muffler design but stick to the stock first and see how the new upgrade does to u, let us know the result and we come up with another proposal for u

sorry for long explaination but i just thought u deserve to know at least the essentials


depends on ur driving style and engine speed preference. 4-2-1 always good for torque sustain at high gear cruising and speed recovery from stopping and braking and 4-1 always good for low gear pickup and straight line acceleration to max rpm.

use sflow if u want cheap solution to noise issues and straight flow if u are after efficiency. power in straight flow setup is easier to predict, sflow can be hard to predict, sometimes u satisfied sometimes not. im always a fan of silent straight flow

best setup consists of either one midbox or one bullet only, if u need more than one to be satisfied, it simply means the piping is too big in diameter

generally keep at least 30-45" of pipe between extractor and bullet but this is not entirely accurate. need to know engine spec and cam timing to know for sure

This post has been edited by upontheriversky: Oct 13 2011, 12:47 AM

what engine is ur 1.0?

honestly 1.6" is too big, mine is kelisa and used to have 1.6" piping and sflow and it is not fast at all, pickup is fairly good but later on high gear felt like driving lorry, slow and no torque boost at higher rpm, FC becomes higher because i kept on pushing the car as it wont accelerate faster at high gear speed, it was worst than my stock piping, standard muffler with 3-1 extractor. i was very disappointed and that was when i start studying about all these exhaust stuff

it is a standard setup from every exhaust shop i went for 1.0, where they suggest 1.6" pipe and use sflow to increase backpressure from that 1.6" pipe

i have seen a kelisa 1.0 with stock 1.3"-1.4" piping, change extractor, straight bullet and straight flow muffler and the performance is really satisfying. the exhaust sounds fast and the feeling not like lorry at high gearing speed. definitely way faster than my last 1.6" and sflow setup

if u can have access to ur stock pipe again, i strongly suggest u get them back on, put straight bullet in the middle and custom a 1.5" straight flow muffler at supercircuit for rm350++. if budget does not allow, 2" straight flow is more readily available sometimes at cheaper price, but most importantly get smaller piping

trust me, u will gain much more power in ur driving at all rpm, guaranteed. 1.6" is superb on 1.3 myvi auto