CBE Fuel Economy

[Brownsound]

Had a look around and didn't really find anything conclusive, I recently had a catback installed (Custom job I bought from blackspeed3, it has a saber muffler with resonator) and had it installed at speedy about a week ago. I've noticed though that my fuel economy has dropped from about 400 per tank (98% city, 2.3L, Auto) to round about 370 before the light goes on. I was just wondering if this might be due to the ECU recalibrating itself or if it's something I should look into. I don't drive too heavy footed, the occasional spirited burst at lights but that's about it.

Thanks.

[gta_driver]

While it's not related to your case, I am experiencing worse fuel economy than I expected. If I managed to get to 400 km before the light went off, that was good. Mine is 2005 manual GT. I drive about 90% city (downtown).

In the winter, I can get as low as 300-320 km before the light shows up.

Abysmal fuel economy for a 4-cylinder 2900 lbs car...

[Iceman_F1]

While it's not related to your case, I am experiencing worse fuel economy than I expected. If I managed to get to 400 km before the light went off, that was good. Mine is 2005 manual GT. I drive about 90% city (downtown).

In the winter, I can get as low as 300-320 km before the light shows up.

Abysmal fuel economy for a 4-cylinder 2900 lbs car...

Well, the 90% city driving...downtown to boot would be a big cause for bad fuel economy. Not sure if it's because of CBE or not. I get almost 500km per tank (70% highway, 30% city) with a 2008.5 GT Auto Hatch. Kinda thinking about getting a CBE...not sure if it will affect my mileage though...

[gta_driver]

Well, the 90% city driving...downtown to boot would be a big cause for bad fuel economy. Not sure if it's because of CBE or not. I get almost 500km per tank (70% highway, 30% city) with a 2008.5 GT Auto Hatch. Kinda thinking about getting a CBE...not sure if it will affect my mileage though...

In theory, CBE should not affect your fuel economy. In all my experience, modifications like CAI and CBE had zero effect on the mileage - they neither improved it nor made it worse. And that's coming from 1996 Camaro Z28, 1991 Beretta GTZ (4-cylinder 180 HP). Some people claim that they even improve their mileage, although I did not witness it myself.

The one thing I experienced (and many others too) is that CBE on a small engine will open up the top end at the expense of the low end. Result: you get more horsepower at higher RPMs, and less torque at lower RPMs.

As for my mileage, I understand, my downtown driving is what kills it, but I was still hoping for little better than that :) - not the end of the world, by all means.

[Iceman_F1]

In theory, CBE should not affect your fuel economy. In all my experience, modifications like CAI and CBE had zero effect on the mileage - they neither improved it nor made it worse. And that's coming from 1996 Camaro Z28, 1991 Beretta GTZ (4-cylinder 180 HP). Some people claim that they even improve their mileage, although I did not witness it myself.

The one thing I experienced (and many others too) is that CBE on a small engine will open up the top end at the expense of the low end. Result: you get more horsepower at higher RPMs, and less torque at lower RPMs.

As for my mileage, I understand, my downtown driving is what kills it, but I was still hoping for little better than that :) - not the end of the world, by all means.

Yeah...Not sure how many litres you are filling up, but if it's a estimate of 50 litres at 320 km then that's 15L/100KM...which isn't great...but considering the higher idle that you likely do downtown, it kinda makes sense.

I've also heard that CBE and CAI don't REALLY affect the mileage either for or against...but I guess it all depends on your driving style. When I had the CAI on for a brief time, it SEEMED like better mileage...however it could have been me changing my driving style at the time. Who knows. I have a spread sheet with my fillups since about mid October and the mileage has been all over the place because of the different driving conditions and such.

Sometimes, it helps to do a spreadsheet for mileage like this to get a visual representation over a period of time on how the mileage has been doing.

[arnold22]

i have a 2009 2.0L mazda3 and I get about 425km (average since nov 19, 08) and that's 100% city driving. I have no mods on the car either.

I'm not sure why anyone would put an CAI or exhaust system on a daily driven car. You gain some high power at the expence of low end power which is what makes a fun city car.

[Hives]

i have a 2009 2.0L mazda3 and I get about 425km (average since nov 19, 08) and that's 100% city driving. I have no mods on the car either.

I'm not sure why anyone would put an CAI or exhaust system on a daily driven car. You gain some high power at the expence of low end power which is what makes a fun city car.

Agree!!!

[Gizzmo_jr]

It's transitive effect. In theory your exhaust is more 'free flowing' thus the engine should work easier and better fuel economy. But there is a catch...
Subconsciously like everyone who puts on a CBE for the first while, your stepping on the loud peddle to hear your investment. Killing your fuel economy.

Parallel to all this, at this time of year (winter) and especially with the rather low temperatures, all our cars are working harder so you'll always get worse fuel economy.

[SSmoked]

compared to last winter without my ms3 exhaust i got 430km +/-10km per tank with a 50/50 mix of hwy and city.
this winter with my ms3 cb exhaust im getting roughly the same 430 km +/-10km per tank while still doing 50/50 hwy/city driving.

however like others have mentioned when i first got my exhaust i had crappy millage as i was constantly driving agressivly. but after a couple weeks i calmed down and started to driving regular again with the often 5.5k rpms
my car is a 06 2.3l auto.

[Brownsound]

I don't think I've altered my driving style but I'll keep an eye on it now. Won't be driving my car for a little bit though, so it'd be interesting to see if the mileage will change once I go back to it.