exhaust saves fuel ?

[Simmo2302]

ok this is gunna be such a stupid noob question. but. you never know unless you ask, so...

we all know performance exhausts give your car more, power, torque and makes ur car more responsive,

but is there any evidence to say that it makes ur car more fuel efficient (ie tests done etc) other than peoples word that they feel like they are getting more mileage per tank?

[krogoth]

lol....

too many factors to consider

generally id say it makes u use more fuel coz u want to thrash ur engine to hear the sweet noise of the zorst, lol

but i highly dought u will notice any difference at all in terms of fuel consumption

[EG30]

it did for me.

On my eg si when it had the stock zc engine with stock ecu, i had a set of cheap mercury extractors fitted, with stock cat, and 2" free flow system installed ie resonator and rear stright thru lukey muffler.

def less throttle required to mantain a given speed on top of more response and power.

fuel economy improved in my case in the region of 0.2-0.3L/100km, not a huge amount but definately tangible.

[evoline]

If anything you should be using more fuel by having a full exhaust.
By increasing the flow of air, your car will automatically adjust how much fuel is mixed with the air to produce power. More air will result in using more fuel than desired to maintain a good Air:Fuel ratio. But there are many ways to diminish the effects of high fuel consumption... go clean your injectors or get a tune ;p

[misterandyle]

^^as above...i own a em1 and my brother owns a ej8....his is a y4 non vtec with full exhaust, mine is a b16a with vtec, he gets 450km on a good week w/o thrash, i get 500km doing the same both of us keeping it under 3000rpm. Correct me if im wrong but logically the way i see it is with an exhaust more air is allowed to escape quickly from the engine, hence allows more fuel to be eaten, u cant eat more fuel if its full of air...again correct me if im wrong, thats what i've always been lead to believe...

[Simmo2302]

wow all good points . lol

didnt think this topic would be so controversial.

can anyone find any tests, or dyno evidence to post to prove one way or the other. i do agree that there is probably too many variables to consider.

[misterandyle]

http://www.ozhonda.com/forum/showthread.php?t=41413

^^as i said

my point claymore as an example only is that the;
ej8 is non VTEC but is fitted with exhaust
em1 has a b16a2 engine which is VTEC

Yet based on rough ballpark figures the ej8 eats more petrol because more spent gas is leaving the engine. allowing more fuel to be produced from the air inside....

[krogoth]

Sure will increase fuel mileage IF YOU DRIVE THE SAME. Anything that makes the engine more efficient will increase mileage ALL OTHER FACTORS BEING THE SAME.

You guys are not thinking about it. If you increase the amount of fuel being put into the stream you are also increasing the engines power thus you need to push the gas petal LESS to have the same rate of acceleration so you actually end up relaxing on the pedal causing LESS fuel to be used.

although thats true, and it makes sense

i dont know if ull notice much difference really.....

[dahon]

you also have to consider diameters, im pretty sure honda made their stock exhaust sizing for optimum fuel/power.
especially around the low RPM range.

a stock diameter exhaust would allow exhaust pulses to pull each other along, in the low RPMs, this tight formation of pulses becomes an advantage as it keeps the them close together so they can pull each other through the exhaust reducing work the engine has to do to push it out. But as the RPMs rise, the pulses become closer and closer together, raising backpressure to restrict the piston in pushing out more exhaust gasses.
A larger diameter would increase the power you have in your midrange but in the end at the loss of some fuel economy in the lower RPMs (the pulses dont pull each other as much anymore as theres more of a gap) and considering you want fuel consumption youll be keeping it in the lower revs anyway. so all in all just keep it stock buddy if you want to save petrol.. if you want noise & some power, youll have to take out a tiny bit more out of your pocket a wk.

[autech]

If anything you should be using more fuel by having a full exhaust.
By increasing the flow of air, your car will automatically adjust how much fuel is mixed with the air to produce power. More air will result in using more fuel than desired to maintain a good Air:Fuel ratio. But there are many ways to diminish the effects of high fuel consumption... go clean your injectors or get a tune ;p


^^as above...i own a em1 and my brother owns a ej8....his is a y4 non vtec with full exhaust, mine is a b16a with vtec, he gets 450km on a good week w/o thrash, i get 500km doing the same both of us keeping it under 3000rpm. Correct me if im wrong but logically the way i see it is with an exhaust more air is allowed to escape quickly from the engine, hence allows more fuel to be eaten, u cant eat more fuel if its full of air...again correct me if im wrong, thats what i've always been lead to believe...


you also have to consider diameters, im pretty sure honda made their stock exhaust sizing for optimum fuel/power.
especially around the low RPM range.

a stock diameter exhaust would allow exhaust pulses to pull each other along, in the low RPMs, this tight formation of pulses becomes an advantage as it keeps the them close together so they can pull each other through the exhaust reducing work the engine has to do to push it out. But as the RPMs rise, the pulses become closer and closer together, raising backpressure to restrict the piston in pushing out more exhaust gasses.
A larger diameter would increase the power you have in your midrange but in the end at the loss of some fuel economy in the lower RPMs (the pulses dont pull each other as much anymore as theres more of a gap) and considering you want fuel consumption youll be keeping it in the lower revs anyway. so all in all just keep it stock buddy if you want to save petrol.. if you want noise & some power, youll have to take out a tiny bit more out of your pocket a wk.


Dahon is pretty close to the money.


Having a well suited exhaust system will increase engine efficiency - ie more torque/power for the same load.

Provided you drive it the same way you will see an increase.

[Crapdaz]

Dahon is pretty close to the money.


Having a well suited exhaust system will increase engine efficiency - ie more torque/power for the same load.

Provided you drive it the same way you will see an increase.

Which is not possible, as you grow to love the sound.

[henrygiang]

http://www.ozhonda.com/forum/showthread.php?t=41413

^^as i said

my point claymore as an example only is that the;
ej8 is non VTEC but is fitted with exhaust
em1 has a b16a2 engine which is VTEC

Yet based on rough ballpark figures the ej8 eats more petrol because more spent gas is leaving the engine. allowing more fuel to be produced from the air inside....

ej8 is a y8, not a y4. y8=SOHC vtec

[Limbo]

with my exhaust i ended up using more fuel all the time, always found that stock exhaust seem to be more fuel efficient

[AzKik-R]

if car manufacturers could produce more pony's for less fuel consumption they'd fit bigger exhaust's to all their cars, to counter the noise factor they would just fit silencer's

the answer is bigger exhaust = more fuel consumption.

[misterandyle]

ej8 is a y8, not a y4. y8=SOHC vtec

not all ej8's are y8 mate, some are y4.....including my brothers

[dahon]

ej8 badged the GLi Coupe = y4 engine
ej8 badged the VTi Coupe = y8 engine

thatll clear it up.

[55EXX]

the effect the exhaust would have would really only be minimal and only over a small rpm range. the smaller exhaust/ stock is more suited to daily driving as stated before due to the exhaust pulses increasing low rpm efficency. tho. during accelartion and higher rpm a good header and correctly tuned diameter exhaust not only wil increase flow and power but will move this greater efficency point higher creating more useable midrange power and top end. now this is where more people would skew the result by being more heavy footed but in theory the engine from being more efficent in these higher load conditions would save fuel.

[Simmo2302]

cool well since i usually travel at 100 on the highway everyday, a better exhaust sounds like it will do me some good.

[55EXX]

no it wont unless you like a droning baaahhhhhhhhh

now make sure you invest in quality mufflers. the rear muffler is what removes the higher pitched tones and the front removes the lower sounds.

i cut the rear muffler off one of my old cars and it screamed well but never stopped = headache

[Simmo2302]

no it wont unless you like a droning baaahhhhhhhhh

now make sure you invest in quality mufflers. the rear muffler is what removes the higher pitched tones and the front removes the lower sounds.

i cut the rear muffler off one of my old cars and it screamed well but never stopped = headache

lmao. lol

dont kno about baffel'd mufflers. allways liked thestraight thru (hot dog) type

[AzKik-R]

now make sure you invest in quality mufflers. the rear muffler is what removes the higher pitched tones and the front removes the lower sounds.

sooo, i'd actually like my car engine to sound a little like a motor bike / f1 kinda noise. anyone done this to their car?

from this statement, i'm guessing i'd just drop in a muffler at the front and remove the lower sounds, and only have the higher sounds?

[55EXX]

in theoy yeah but it will lower the overall sound output, restrict flow and make your car sound like that crappy raspy noise you hear from na stock 4cyl with just an el cheapo cannon. i would be more inclined to removing the rear muffler all together