Advise needed: Whats the best exhaust setup for 1.8 litre mivec

Sapeqlaa

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Sapeqlaa

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Dear guys,

Apologies if there is already a thread on this..but out of curiosity as the titles goes..:adore:

Am currently using a 2.3 inch diametre piping from the extractor straight out towards the muffler with no bullet..and have been using this setup for the past 2 years..but i noticed there's a slight decline in throttle response compared to a 2 inch piping setup that i used to have earlier...

Is it normal?..or is my current diameter is too big?..some of my colleague with similar engine setup recommended using 2.3 diameter for a 1.8 mivec..

And at the same time, while browsing other forums and blogs..there are several different setup combination that used 2.3 and 2 inch diameter simultaneously (where the 2 inch starts just after the extractor and 2.3 inch will continues after the bullet extension)...:hmmmm:

Simply put, which is the suitable exhaust diameter combination for a 1.8 liter mivec with moderate modification (ie: no high cam, standard throttle body, intake and etc)..2 inch or 2.3 inch?.. :biggrin:
 

mADmAN

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mADmAN

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2.3" n ur asking if its too big??

and here i am thinking that u should use 2.5". a friend of mine is running a mivec 1.8 with 2.5" pipings
 

Sapeqlaa

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Sapeqlaa

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what type of muffler u use now

using a straight flow, HKS hi-power taken from a neo vvl..

---------- Post added at 08:45 AM ---------- 6 hour anti-bump limit - Previous post was at 08:38 AM ----------

2.3" n ur asking if its too big??

and here i am thinking that u should use 2.5". a friend of mine is running a mivec 1.8 with 2.5" pipings
thats the thing, couple of them using 2" , theres another with 2.3", and some with 2.5"..but i've heard for a 2.5" u need to have a more elaborate modification as the low end will suffer a bit, is it thru?..correct me if im wrong..:adore:

just looking for a setup with justification on it, coz im doing my exhaust setup based on what i heard rather than what shud it be..again, im just seeking for an opinion..:biggrin:
 

Sapeqlaa

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Sapeqlaa

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I'm using 2.5" on my 1.8 mivec rs, no mods, only made the compression higher, throttle response declined but what you get on the top end really counts.
ic sir..mind telling me ur current piping setup, do u use any bullet in between or just straight up piping until the muffler end? have u tried a smaller diameter earlier, if do, care to share me ur experience as a comparison.. :adore:
 

mADmAN

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mADmAN

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my friend's MIVEC 1.8 is stock 4g93p block with stock pistons etc... everything stock....but gearbox 1.3 hahahhaha

still, he travels daily with that car from shah alam to cyberjaya via highways and he still gets about 500km per full tank even with his walbro.

his setup if not mistaken is a 4-1, 1 bullet, 1 muffler...2.5" pipes
 

Sapeqlaa

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Sapeqlaa

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my friend's MIVEC 1.8 is stock 4g93p block with stock pistons etc... everything stock....but gearbox 1.3 hahahhaha

still, he travels daily with that car from shah alam to cyberjaya via highways and he still gets about 500km per full tank even with his walbro.

his setup if not mistaken is a 4-1, 1 bullet, 1 muffler...2.5" pipes
thats a pretty good fuel consumption for a 1.8..maybe due to the 1.3 gearbox haha...im thinking of finding an extractor that is worth the money and the performance oso..tonnka comes in mind, but damn expensive..

aside from that, R3's oso sounds good..any contact for aftermarket extractors sir?
 

upontheriversky

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upontheriversky

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diameter is not a big concern as compared to the length when it comes to power. smaller pipe gives u faster response as velocity is kept high while bigger will have sluggish response but it shines once u got the momentum. in general 2" supports up to 144hp and 2.3" up to 185hp so its pretty easy to figure what diameter ur engine needs

current collector length is considered too long since no bullet (change of piping area) in the middle to separate ur header & collector from tailpipe side. the long downpipe to back muffler is considered as "one system" which is not good for high rpm power.

fit biggest straight bullet u can fit after 18" to 24" of downpipe to make ur exhaust appear "shorter" to the engine and u wil gain really fat midrange torque. give me ur engine exhaust BBDC degree, header length and rpm u want to tune and ill calculate ballpark figure for ur collector length

And at the same time, while browsing other forums and blogs..there are several different setup combination that used 2.3 and 2 inch diameter simultaneously (where the 2 inch starts just after the extractor and 2.3 inch will continues after the bullet extension)...
it should be other way around, 2.3" front and 2" at the back. exhaust cools down rapidly as it goes to the back so it slows down, smaller pipe at the end keeps the velocity up. bigger pipe at the end slows it further and cause backpressure at high rpm
 
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Sapeqlaa

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Sapeqlaa

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diameter is not a big concern as compared to the length when it comes to power. smaller pipe gives u faster response as velocity is kept high while bigger will have sluggish response but it shines once u got the momentum. in general 2" supports up to 144hp and 2.3" up to 185hp so its pretty easy to figure what diameter ur engine needs

current collector length is considered too long since no bullet (change of piping area) in the middle to separate ur header & collector from tailpipe side. the long downpipe to back muffler is considered as "one system" which is not good for high rpm power.

fit biggest straight bullet u can fit after 18" to 24" of downpipe to make ur exhaust appear "shorter" to the engine and u wil gain really fat midrange torque. give me ur engine exhaust BBDC degree, header length and rpm u want to tune and ill calculate ballpark figure for ur collector length



it should be other way around, 2.3" front and 2" at the back. exhaust cools down rapidly as it goes to the back so it slows down, smaller pipe at the end keeps the velocity up. bigger pipe at the end slows it further and cause backpressure at high rpm

tq sir for these comprehensive input, now i got a bigger idea on what to contemplate when deciding for my exhaust setup..

a. 1st thing im gonna do is to retain my current piping diameter..

b. 2nd step is to fit in a bullet (btw, went to the exhaust shop..they got two specs..one with a 2.3" diameter and another with a bigger 2.5" inch diameter..as u say go for the biggest, shud i go with the 2.5" diameter sir?)...

c. 3rd step: get input for BBDC degree (forgotten the exhaust in and out cam degree..need to check) plus my header degree..btw, what do u mean by "rpm that i want to tune"?..sorry for d lame question..not much in the technical department :biggrin:

all in all, tq sir for this feedbacks...:biggrin:
 

mADmAN

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mADmAN

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it should be other way around, 2.3" front and 2" at the back.
u sure about this? coz my setup is somewhat similar...but with an exhaust cutout...

my pipes are 2.5" all the way to the cutout with 1 bullet. so when the cutout is open its a 2.5" exhaust.

but when the cutout is closed, exhaust gets routed from the 2.5" pipes to a 2.3" pipe into a Spoon Street S-flow muffler. so when its closed...the car may be quiet but damn the car feels heavy and choked.. at ALL RPMs.
 

zac

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zac

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im not expert in mivec or exhaust, but sharing is caring^^
my engine spec ori mivec rs + 1.8block, use back mivec piston
hotbits 4-2-1 for satria r3 + 2" ori route piping + bullet + perdana-like twin tip s-flow exhaust
dynoed 190hp/21kgm... fuel consumption 10km/ltr
i do feel suffocated during hi rev, but lazy to change...
 

upontheriversky

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upontheriversky

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tq sir for these comprehensive input, now i got a bigger idea on what to contemplate when deciding for my exhaust setup..

a. 1st thing im gonna do is to retain my current piping diameter..

b. 2nd step is to fit in a bullet (btw, went to the exhaust shop..they got two specs..one with a 2.3" diameter and another with a bigger 2.5" inch diameter..as u say go for the biggest, shud i go with the 2.5" diameter sir?)...

c. 3rd step: get input for BBDC degree (forgotten the exhaust in and out cam degree..need to check) plus my header degree..btw, what do u mean by "rpm that i want to tune"?..sorry for d lame question..not much in the technical department :biggrin:

all in all, tq sir for this feedbacks...:biggrin:
its good to have at least 0.5" difference between downpipe and bullet diameter for strong low pressure pulse reflection for higher exhaust scavenging effect, the bigger the diameter difference, the stronger the reflection pulse but trade off is, the higher the drone and boomy noise from big bullet.

u can also think of the bigger bullet as temporary exhaust dump, if its really big enough compared to downpipe, the engine does not have to increase pumping power to get rid of exhaust all the way to tailpipe, it can use less energy by dumping exhaust into the bullet and let pressure difference between bullet outlet and atmosphere drives and extract gases from bullet to tailpipe and finally to atmosphere, less pumping losses by the engine. This might not be significant at low rpm but as u go to much higher rpm, any pumping losses reduced can be significant, so it is important :)

in pressure wave tuning point of view, the really big bullet will act like the atmosphere, it will appear as if engine is dumping exhaust to the atmosphere. so instead of length tuning exhaust all the way to the tailpipe which is impossible for high rpm benefit due to long piping system, u can just tune the length until that bullet and its done, the header and collector will be kept tuned without the back system spoiling any tuned length, provided the bullet size is big enough to replicate atmosphere. This will maintain power if ur header is already tuned length by the aftermarket for ur engine

hehe its ok, exhaust valve open BBDC can be found in the manual, if u swapped aftermarket high cam then u need to ask them what is the new exhaust open BBDC degree, without that degree, i cant do any estimation on the length. header length u can simply estimate or go to shops that sell exact header and measure it hehe

the rpm u want to tune at is the rpm where u want the most scavenging effect to happen, u can use this to cure torque dip rpm in ur dyno to boost it and have a wider powerband or tune it to coincide with peak torque rpm for good speed recovery at corners/street use or tune it to coincide with peak hp rpm for good straight line acceleration /race use.

the downside of length tuning is, if u tune the exhaust to resonate at one rpm, about half that rpm, u will experience power loss / torque dip, that is the trade off.

Usually tuner will use intake manifold to tune it to resonate/boost at high rpm while the losses at half that rpm will be recovered by tuning exhaust to resonate at that torque dip rpm, raising that dip so can end up with flatter torque curve

u sure about this? coz my setup is somewhat similar...but with an exhaust cutout...

my pipes are 2.5" all the way to the cutout with 1 bullet. so when the cutout is open its a 2.5" exhaust.

but when the cutout is closed, exhaust gets routed from the 2.5" pipes to a 2.3" pipe into a Spoon Street S-flow muffler. so when its closed...the car may be quiet but damn the car feels heavy and choked.. at ALL RPMs.
what is a cutout? from what u said, u seem to have 2 systems in ur car now, isn it? thats nice :)

it is due to the Sflow muffler, small pipe does not restrict gas flow, it CONSTRICTS gas into smaller volume so the gas pressure is increased and is forced to go faster, the faster exhaust will automatically drag exhaust behind it as well, therefore can be used to reduce pumping losses by the engine for better power efficiency

while Sflow RESTRICTS gas flow by blocking the path and forcing the gas to change in direction, pumping losses is increased everywhere because engine now has to work extra to pump that gas out the blocked muffler. while of course the trade off of smaller pipe is at one point at higher rpm, friction losses is increased therefore inducing backpressure. trust me, if 2.3" is suitable for ur engine at rpm that u want, swap sflow to 2.3" straight flow muffler and u will release the choke at all rpm

and say if ur exhaust header is bought to be "tuned length", it will be spoiled by the reverse flow since length tuning/pressure wave tuning works effectively on straight system, not so on blocked system so the power loss can result from there too.

OEM only have the intake manifold wave tuned but not the exhaust due to noise regulation, wave tuning is how japanese can manage to come up with smaller engine while having a lot of power these days

on latest engine like new honda i-vtec, they come up with "torque boost resonator" on new accord and jazz, its the same concept of wave tuning with more complicated modelling. even the cat converter are nowadays acts like expansion chamber for exhaust tuning, explains why some newer model suffers high FC from removing catcon alone supposedly to ease gas flow but was ignorance of that fact

im not expert in mivec or exhaust, but sharing is caring^^
my engine spec ori mivec rs + 1.8block, use back mivec piston
hotbits 4-2-1 for satria r3 + 2" ori route piping + bullet + perdana-like twin tip s-flow exhaust
dynoed 190hp/21kgm... fuel consumption 10km/ltr
i do feel suffocated during hi rev, but lazy to change...
its the sflow bro :) never use reverse flow muffler type if performance is what u after. ive used 1.6" piping with 2" sflow and car is choked like crazy

now using 1.5" smaller pipe with 1.6" straight big body muffler and it works wonder, noise is same as 1.6" with 2" sflow but speed like a straight. straight flow can be as silent as sflow if the internal pipe is much smaller than the body in ratio
 

deanengson

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deanengson

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ic sir..mind telling me ur current piping setup, do u use any bullet in between or just straight up piping until the muffler end? have u tried a smaller diameter earlier, if do, care to share me ur experience as a comparison.. :adore:
My current setup has no bullets or resonators or whatsoever, just a straight pipe from the flexible to the muffler. Having a bullet is suitable since it will retain some backpressure for daily driving.

And yes, I have used 2 inch piping when it was a 1.6 and the response was superb, while I was still using a 2 inch S-flow muffler too. Fuel consumption was very low.
Now the 2.5 inch straight piping is killing me, a full tank only gets me around 200kms town driving.

While my Mivec was still 1.6 + 2" piping nothing in between + S-flow exhaust = I could get around 400kms++ town driving. No highways in my area :D

Still, its up to you, whether you want response or top end power.. (Gotta get the engine revving around 4-5K rpm to feel the power :driver: