I have a TL AWD and would like to know from anyone that has modified their exhaust as to whether this has helped with overall fuel economy.

This inlcudes cat back or complete replacement including headers.

Could people give an indication of improvement / decline in l/100km? What system? What cost?
I am hoping from what I have researched generally on this and other forums that there may actually be some benefit in "investing" in exhaust modifications :cool:

Thanks in advance

Tim

No, they might increase the Volumetric efficieny of the motor by a small amount, but it would be negledgable. Exhaust mods are purely for increase of torque and power, and they do it by allowing more air into the engine by removing the exhaust gasses quicker and easier. Exhaust mods would decrese fuel econ if anything.

I've picked up over 100km's to the tank since mu exhaust upgrade.

No, they might increase the Volumetric efficieny of the motor by a small amount, but it would be negledgable.

Look at his question!!!, you first say this



Exhaust mods would decrese fuel econ if anything.


Then you say this!!, isn't it a bit of a contradiction? :D

I've picked up over 100km's to the tank since mu exhaust upgrade.

Redav,

What did you have done? ( see edit) Do you have an average of the number of km's per tank / fuel effeciency figure I can work from?

I must admit that I am bit of a number cruncher :shock:

Edit. Call me dumb for not reading your profile........... :redface:

So how much did it cost? I also noticed you did not increase the pipe diameter through the entire length? Or was this included with the other exhaust modes? If so, what is your exhaust pipe diameter?

Phonic, i mean the gain in VE would be negledgable, the gain in right foot use will increase.

nelgedgable means existant but non measurable in my book.

redav did you have your cat replaced?

Phonic, i mean the gain in VE would be negledgable, the gain in right foot use will increase.

nelgedgable means existant but non measurable in my book.

redav did you have your cat replaced?

Actually, neither negledgable or nelgedgable mean anything at all :P negligible on the other hand means what you want it to :P

On a more serious note, I'm confused why an improvement in combustion efficiency would result in an increase in fuel consumption. Surely since you're getting more oomph per unit of fuel things are going to get better if they change at all. :confused:

In my own personal experience there has been no chance in fuel economy at all since I got my headers fitted.. but that's just because I give it even more stick now! :badgrin:

mainly because there would be less effort required by the motor to suck in the air with a greater VE ;)

Correct me if I am wrong.

Greater air flow through the cylinders allows for more efficient burning of existing fuel levels? yes? Hence why CAI also works by increasing the volume of air available at combustion.

Therefore you "should" be able to get greater economy (power/ torque for same fuel) if you don't change your right foot habits. Correct?

If so, HOW MUCH ? :rant: mumble... mumble...

Anecdotal evidence will also be accepted :)

Redav
Hi and welcome!


What did you have done? ( see edit) Do you have an average of the number of km's per tank / fuel effeciency figure I can work from?
Yeah, I've been driving the same pattern for the last 9 months and I've averaged 550 - 600km's per tank. If I drived conservatively I might hit 650 and that's with say 7 - 10l in the tank.

Since the headers and cat has been fitted, the least I've had has been 630km's. Now most,(probably 80%+), of my driving has been highway stuff but it's the same house -> work drive sitting on 100kph most of the way. The most I've had is 788 with 4l left and previous highest was 748 with 7l left.


Edit. Call me dumb for not reading your profile........... :redface:
Don't worry, no one else around he does that either.


I also noticed you did not increase the pipe diameter through the entire length? Or was this included with the other exhaust modes? If so, what is your exhaust pipe diameter?
The exhaust mods are the headers, high flow cat and straight through muffler. Factory piping is the 2.15 - 2.25 (whatever) inch stuff. Actually, I've had two tuners say that it's pointless going to 2.5 inch for the 3.0.


redav did you have your cat replaced?
Yes and I suspect that's had something to do with it. Mind you, my mileage wasn't much less than what it was doing 4 years ago with almost a third of the km's on it.


Hence why CAI also works by increasing the volume of air available at combustion.
It's the mass of air that an engine cares about but having a restrictive induction setup does stave an engine. Typically though any exhaust mods like headers that can allow more air in will be compensated by the ECU so it's still going to use more fuel than before.

I guess the other factor in the increase in economy is that the headers increase torque by about 8 - 10 percent across a reasonable range that's in use during every day driving.

should make no difference, unless your foot gets heavier to make it sound nice!!! think about it the injectors are still injecting the same amount of fuel

should make no difference, unless your foot gets heavier to make it sound nice!!! think about it the injectors are still injecting the same amount of fuel
Huh? If the injectors are injecting the same amount of fuel, why does it have a MAS sensor?

Add a 300kw turbo motor..

im now getting close to 800km highway cycle... or around 9.3 to 10.1L/100 :D

Well my exhuast seemed to chew up more fuel but after about a month things started to change. I think it was more to the fact that I was loving the sound of it... giving more acceleration just to hear how nice it sounds. Now I get more out of a tank then what I did before prob because its not as exciting as when I first had it put on. :)

No, they might increase the Volumetric efficieny of the motor by a small amount, but it would be negledgable. Exhaust mods are purely for increase of torque and power, and they do it by allowing more air into the engine by removing the exhaust gasses quicker and easier. Exhaust mods would decrese fuel econ if anything.I'm also thinking along the lines of Tsuro but, turbo, I thought torque and power improvements increase fuel economy - all things equal?

but the power and torque increase while in closed loop mode is only really because you are getting more air past the MAF sensor and the fueling is increased. you need less pedal to get the same amount of air into the motor now because the extractors aid airflow, so with the same amount of pedal your used to its flowing a tiny little bit more.

2 months back, put hi-performance exhaust system on my KR verada including a hi-flow cat.

i have noticed better fuel economy, using the full fuel tank method, works out at approx 0.5 to 1 litre / 100 km's better on average then old system.:)

but the power and torque increase while in closed loop mode is only really because you are getting more air past the MAF sensor and the fueling is increased. you need less pedal to get the same amount of air into the motor now because the extractors aid airflow, so with the same amount of pedal your used to its flowing a tiny little bit more.Ah yes, Fully Agree.

Guys, the point turbo's makes - for same throttle, more power comes more air & fuel going thru engine due to less resistance to flow. Fuel efficiency is increased if only driver throttle back to achieve same power. In reality, the action is somewhere in between, so fuel savings is sometimes negligarmeareable.

To me, for a reasonable cost, a more efficient engine is always a good thing.
lol

Well, whatever the excuse. Over 100km's per tank more and I'm not complaining. The headers should pay for themselves over the next 100ish weeks :bowrofl:

My AWD picked up torque with my cai, pod, exhaust and tb. My average comsumption dropped from 11.6 to 11.3 - but I have a section of road that I drive pretty hard each afternoon. I went a week without indulging myself on this stretch of road and the trip computer praised my effort with 10.6L/100km. I'd rather drive the other way thou :cool:

Before you ask, I do about 70% city:30% highway by distance and close too by time.

My effiencies also partially improved by a tranny cooler. See my profile for specifics.

BTW clocked my AWD 0-100km sprint at 8.3seconds. Not bad I say for what the car is.