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

where to get the data? I mean which section..

swirl bullet can scrap la
if wanted to use swirl bullet better use back ur cataliac converter

you are a true enthusiast
now I've found someone that's willing to go that far for R&D and yet willing to share i'm happy seriously XD
Thank you.

i actually stayed in klang, just that i work around subang area.

i'm actually also that kind of person when it comes to car tuning, is just that i never got the correct material and ability to give me that sort of understanding becoz i dun practice reading books hahahaha and i have bad maths.
so far I only did my suspension and stopped there coz don't know much about it and did not achieve result I wanted. theres even more trail error,knowledge, know-how to have when it comes to suspension.

sorry oot. i think more have to personal chat liao, mind to give me an add on msn or anything?

regarding the 2.6L bullet, in/out 3" 22" length then it would look quite monstrous right? the biggest i've seen on kweng84 fb is also about 15" length, i wonder if that sort of size is available, if its 3" its still able to fit to 1.6" piping right.
will midbox easier to be found if its at that capacity since midbox is larger/oval.

so basically my whole piping should be 1.6" from downpipe till end of tail pipe? or after bullet onward make it smaller like 1.5" if i scared about the loud noise?

rear mufller wise, i think i should really go for custom like you reccomended @ supercircuit. big body small holes(1.6"?)
but how big exactly on the body, you mention is biggest ever that can fit behind right.

if is still too loud, then your side branch resonator method can be used right, 97cm/2 about 19" would cancel 50% noise and 97cm/4 about 10" would cancel about 25%

Progress;

4-1 Extractor --> Downpipe 1.6" --> [52"] Bullet 2.6L --> 1.6" pipe till end tip? --> custom big body straight flow muffler with small hole

Piping size after bullet = same as downpipe?
Distance to place rear muffler = not important.

p/s : btw, does stainless piping and galvanize steel/white steel piping makes different on sound and performance?


LOL got it.

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

I wish we could go together when I'm going to do it. Since you have experience wit supercircuit, isit good to do whole thing there or do everything else where and only custom rear muffler there afterwards.

Engine model: S4PE-2-FDM
Total displacement (mm): 1332
Bore (mm): 76.0
Stroke (mm): 73.4
Compression ratio: 10.0
Firing order: 1-3-4-2
Max output (DIN) kw/rpm: 70/6000
Max torque (DIN) nm/rpm: 120/4000

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

anyone knows a place in PJ/Subang/Shah Alam that custom make a muffler?

as in the muffler itself..the internals etc... places ive went to so far dont do it.

not stated in the manual...

My exhaust current setup: 4-2-1 header - midbox - straight muffler. Engine still original, only change spark plug.
Shift gear between 3k-4k rpm
faster speed recovery

just went back from supercircuit to enquire about the system setup and the custom made rear muffler.

he(tommy, i guess is the guy u mention, w/ glasses) commented that the setup is abit too much backpressure from the 3" diameter 22" bullet, and the piping size of 1.6" is already big, stock is 1.5"
(when he says alot backpressure does it also means low noise? i guess not.) he's friendly enough to give suggestion and offer me to take in my car for further measurement and talks.

he says if pair this together with the custom small in/out 1.6" big body rear muffler probably will ruin the whole air fuel ratio and gain high fuel consumption. and mention if wanted to properly tune the mid powerband, solely from this setup wont work unless with emanage to retune the afr to match it.

also if wanted to fit the 22" bullet, the position would not allow since theres where the shifter is located.

they have ready made 2.5" diameter 26" bullet.


i'm starting to think, is the setup we are trying to do is something weird here in our local modification field. instead he suggest using 2, 1.6" about 6 - 9" length straight bullet and have a rear straight flow muffler which i think this is the usual setup that everyone will get.


btw, the custom rear muffler pricing i get, seems to be abit high, what do you think if its at 5+80.

This post has been edited by [ r u g a ]: Oct 1 2011, 03:55 PM

Just get a another muffler, what's the point of repairing one?

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

engine model - S4PE

i didnt say anything about repairing...i wanna make one from scratch with my specifications of the internals and dimensions etc...

and if i were to repair....the main point is that mine is ohlee spoon


u seem to be a supporter of them eh?? heheheh....

anyway, any idea if they can custom make the pipes INSIDE the muffler based on my specifications? not too worried about the wool or fiber thingy....that one can settle later...main issue is the pipes inside and also if they can weld aluminium to steel.

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

---

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

is it possible make the exhaust noise quite loud since my midbox and bullet distance onli 4inch,somemore i use s flow muffler?is it will reduce noise after i change the distance to 12inch?is it back pressure will reduce the pick up or top speed?i plan to remove my bullet and use midbox onli..it will make my car exhaust noise more louder or remain same?how about performance?

thanks for the info... will drop by supercircuit when its time...how much did ur muffler cost anyway?.... and where in sunway they at? any landmarks etc? never been to their place before

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

cost me rm380

rm380 for ur muffler? hhhmmmm... looks like mine is gonna cost significantly more..

ok... thanks for the info