Whats your engine Max HP and the RPM at Max HP ? (ok i found it)

4-2-1 header
Total length from exhaust port till the bullet = 51 inch (for RPM 3000) or 44 inch (for RPM 3500)
Bullet volume ... 4 lt ...
Can use Stock muffler if the flow rate is 305 Cubic feet per min ..
Remove the cat
Stock 1.6" piping should suffice ..

Just a suggestion lol ...

This post has been edited by luqmanz: Oct 12 2011, 04:35 PM

well..with the newer higher compression... the exhaust is supposed to be louder

imagine before this it was already very loud... wonder how loud the new setup is gonna be... this is gonna be.........interesting hehehhe


lucky i dont have high cams... otherwise.... brap brap brap brap brap brap

This post has been edited by mADmAN: Oct 12 2011, 04:11 PM

beli sudah..wei u still go for B20?

hi luqmanz,

140hp (103kW) at 6000rpm. I think the cutoff is around 6.5k rpm. never tried these though

not sure if stock muffler is a straight flow. currently stock exhaust setup is as such


I measured the length from header outlet (6.exhaust front tube) to bullet (10.exhaust center tube) is about 55".

As such, I just need to get
1) 4-2-1 extractor
2) get new pipping from exhaust outlet to bullet at 44" lenght
2) remove cat
3) get a 4L bullet
4) stay with stock muffler

did i get this right?

thanks.

This post has been edited by caarzee: Oct 12 2011, 04:45 PM

Ok ... I amended the calculation above LOL ...

Wanna ask some sifu here, which header is better for auto car??? 4-2-1 or 4-1? And also S-flow or Straight flow muffler better ?

yup....need torque

I want to ask ... Which distance is best for auto 1.0 from bullet tO the midbox and then to the tip?

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

QUOTE(kokhing520 @ Oct 12 2011, 06:06 PM)
I want to ask ... Which distance is best for auto 1.0 from bullet tO the midbox and then to the tip?




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
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currently my setup is..
- 3-1
- straight flow with modify bullet (to increase backpressure)
- big S-flow muffler
- piping 1.6"

this 1 need confirm wit king amir lo.. if he really wanna do dyno, then wait for him lo... i lately burnt a hole in d pocket as well... somemore this end of month goin holiday at langkawi...lucky this month salary comes out at 2Xhb

I want dyno as well...Where is ur preference place for dyno????

GT-Auto ok???

it's a good start. thanks for providing the estimates for this.

the same engine runs on sentra manual transmission models, and there are sporty versions of it (ie Spec V models but not available here). hence they're able to hold it at 6k rpm. mine is AT but I guess, if i wanted to hold it at 6k, i'll need to enable the overdrive button and keep my foot on the pedal and hope i dont hit anything along the way. haha. nonetheless, this is more of a family car, haha, I'm less incline to do so especially with our traffic here in KL/PJ.

yea, agreed. i'll probably go with your suggestion

the 1.15" / 1.2" port diameter size that you're refering to is the engine manifold exhaust outlets, did I get this right? this then best fitted with 1.4" primary pipes (ie cyclinders), this will be the extractor head/header that goes to the engine manifold exhaust. is this correct? then it should be 2" in length horizontally on the primary before a curve bend downwards. hope i get this right. I read here that a good design, the diameters of the extractor to be slightly increased/decrease as it goes to the collector. a bad design is where the exhaust port and engine manifold port diameters the same.

this is good stuff info! powerband means, the ability to expand/hold the torque?

actually the 1.6" stock pipe is my own guessing. it could as well be a 2" pipe. as such, i'll need a bullet of 3" diameter. how do you go about calculating the bullet volume? say if it's 15" in length and has 3" diameter? I read earlier at one of your suggestions is to add some pipe of 3" length before and after the bullet if the bullet volume is insufficient. 4L is hard to find for a bullet. as one of the guys found out, the longest length for the bullet is 15".

will try with stock muffler first and if not that good, save some $$ and get a better one. some reviews of matola seems promising.

i've got to ask this, and this maybe silly noob question. why not use the cat convertor as termination box? what are the downside besides noise suppression? how about placing a catcon after the midbox bullet, although logically this is restrictive setup but it's better to have the cat before the midbox.

hey, no need to be sorry. in fact, i should say thank you for taking time to put this together. i am quite happy with the lengthy notes. these explaination helps me to understand more. now i know why the collector's length is important because it also helps to create a vacuum for the gas to be pushed out as the BBDC cycle goes, types of collectors layouts, cylinder firing sequence and how it relates to the header non-sequential paring. before this, i know nuts about exhaust system! truly good stuff and it's science at work.

This post has been edited by caarzee: Oct 13 2011, 11:50 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

Let say .. exhaust open 30 BBDC intake open 30 BTDC
One question... what happen if we tune the length so that the wave arrives back at the exhaust port only 180 degree after its released ? (the same exhaust cycle)

Is this good or bad ?

Really appreciate on your explanation bro!!
currently engine if not mistaken..should be EJ-VE..
so...wat is the size of the piping u recommanded?

Just use the high-school math formula to calculate ........ Volume = PI x radius x radius x Length = PI x 1.5 x 1.5 x 15



A termination box is used to "fool" the pressure wave into thinking that the pipe has ended. So this TB needs to have a big volume to "mimick" atmosphere. Cat-con is just a narrow pipe with filters.
When it thinks the pipe has ended, the wave will later be reflected back to the exhaust port in an upside-down manner.

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Added on October 13, 2011, 10:58 pmupontheriversky...

Did u notice that .. if u tune the exhaust at 4000 RPM ... you can also gain the same effect at 2000 RPM ... the same thing if you tuned for 6K RPM .. you can get the same effect at 3K RPM ... is this normal ?

This post has been edited by luqmanz: Oct 13 2011, 10:58 PM

hi luqmanz,

pardon my ignorance, haha.

ok ok, i googled around. first get the vol jisim, and then convert it to litres

so, to get 4L, with 3"diameter bullet, this translation that I need the length of 35.4" for a bullet haha.

( a ) therefore, if there is a length of 15" bullet, i'll need to join two bullets to make it 30" and adds two 3" length of 3"diameter pipes before and after these two bullets to make it somewhat total length of 36" (ie eq to 4L), or
( b ) should I go with one bullet of 15" length, and extend the pipping of 3" diameter after the bullet to make it 36" in total length (ie 4L), before it reaches the stock muffler, or
( c ) since I have a muffler (and it's not a straight flow), just leave it as one 15" bullet

what would be the logical and economical option?

and thanks for replying in the termination box

thanks.

This post has been edited by caarzee: Oct 14 2011, 10:06 AM

hahaha,
this is what i am thinking too. the TB box is such a headache to make up the volume.

ok anytime u guys wanna do around next month count me in, never been on dyno before


how much GT auto charging?

if its ej-ve, get 1.5" piping since thats the smallest ive found so far, stock piping size is hard to find in kl area, i got a friend in penang says got 1.4" if u want to travel all the way there


actually the cat-con can be used as termination box as it does expand the gas to a bigger volume, its just that the boost strength wont be as high as using a bigger volume termination box. i suspect honda use catcon as part of their exhaust tuning on their new models, some of my friends on new honda jazz complaints after changing to 4-2-1 extractor and losing power they used to have but got gain in higher end, i guess the power loss is due to removal of the catcon. the tuned exhaust must have been sync-ed with oem airfuel tuning so removing it tempers with oem air/fuel ratio as well

to play safe so that we wont temper the oem exhaust tuning if there is any, can use cherry bomb bullet to replace catcon, its still an expansion chamber only its free-er flowing of course than the cat

yea, i always thought of that but i cant be sure for now, i have to do dyno on my car and study it. there is also one thing to consider, if it resonates at 4000rpm, there has to be some rpm where anti-resonation occurs in which we will have a torque dip so i guess best to consider all this when choosing rpm to tuned for