Muffler improving gas mileage?

[GranburyChuck]

Okay, this would have been a stupid question about a year ago. But now that I am paying $4.20/gallon for gas I thought I would go ahead and see what the response will be. Previously, I have had an Acura CL and BMW 328. On both cars I put cold air intakes and cat back exhaust. Each of these modifications netted me about 2 more mpg. For example on my daily, mostly wide open, highway drive of 42 miles each way I initially got 25 mpg in the BMW. Intake got me into 27 mpg. Adding the exhaust boosted that to 29 mpg. These were consistent numbers for my commute. Interestingly when I changed tires to an aggressive "chevron" pattern BG Goodrich F1 I lost 2 mpg. So my question goes out to those who have done these modifications. Do you notice a consistent increase in mpg? I know Izzy has posted on a muffler bypass pipe for $200. If it would net me a mile or so more per gallon that could add up quickly for me. By the way I pretty consistently get 22.5 mpg. I am not sure if the high flow factory replacement filters would gain much but the cold air kit from Evo Motorsport might. Although, both my Acura and BMW had fairly restrictive flow paths for the incoming air. The Porsche does not seem to be (2000 996 C2 Tiptronic with 95k miles).

Thanks for all input.

[skyloft1]

yo

Edited June 9, 2008 by skyloft1

[1999Porsche911]

Okay, this would have been a stupid question about a year ago. But now that I am paying $4.20/gallon for gas I thought I would go ahead and see what the response will be. Previously, I have had an Acura CL and BMW 328. On both cars I put cold air intakes and cat back exhaust. Each of these modifications netted me about 2 more mpg. For example on my daily, mostly wide open, highway drive of 42 miles each way I initially got 25 mpg in the BMW. Intake got me into 27 mpg. Adding the exhaust boosted that to 29 mpg. These were consistent numbers for my commute. Interestingly when I changed tires to an aggressive "chevron" pattern BG Goodrich F1 I lost 2 mpg. So my question goes out to those who have done these modifications. Do you notice a consistent increase in mpg? I know Izzy has posted on a muffler bypass pipe for $200. If it would net me a mile or so more per gallon that could add up quickly for me. By the way I pretty consistently get 22.5 mpg. I am not sure if the high flow factory replacement filters would gain much but the cold air kit from Evo Motorsport might. Although, both my Acura and BMW had fairly restrictive flow paths for the incoming air. The Porsche does not seem to be (2000 996 C2 Tiptronic with 95k miles).

Thanks for all input.

Even if you gained 2 mpg (which is unlikely), it would take you several years to recover the cost of the mods at today's prices. Makes no sense to me.

Edited May 28, 2008 by 1999Porsche911

[salayc]

Okay, this would have been a stupid question about a year ago. But now that I am paying $4.20/gallon for gas I thought I would go ahead and see what the response will be. Previously, I have had an Acura CL and BMW 328. On both cars I put cold air intakes and cat back exhaust. Each of these modifications netted me about 2 more mpg. For example on my daily, mostly wide open, highway drive of 42 miles each way I initially got 25 mpg in the BMW. Intake got me into 27 mpg. Adding the exhaust boosted that to 29 mpg. These were consistent numbers for my commute. Interestingly when I changed tires to an aggressive "chevron" pattern BG Goodrich F1 I lost 2 mpg. So my question goes out to those who have done these modifications. Do you notice a consistent increase in mpg? I know Izzy has posted on a muffler bypass pipe for $200. If it would net me a mile or so more per gallon that could add up quickly for me. By the way I pretty consistently get 22.5 mpg. I am not sure if the high flow factory replacement filters would gain much but the cold air kit from Evo Motorsport might. Although, both my Acura and BMW had fairly restrictive flow paths for the incoming air. The Porsche does not seem to be (2000 996 C2 Tiptronic with 95k miles).

Thanks for all input.

How did you determine you gained 2mpg with the previous mods?

Unless you have a banana in the tailpipe, I don't think you will gain anything from a muffler mod.

[GranburyChuck]

To calculate my mileage I used my odometer reading between fill ups and divided by the number of gallons at that fill up. The numbers were consistent over several fill ups since I do that 2.5 times in 2 weeks. Since I drive roughly 25000 miles per year doing the same daily drive plus a little extra and getting 22.5 miles per gallon with a gas price of $4 I spend $4444 on gas that year. (25000)*($4/22.5). Now if I do the same calculation and magically get my extra 2 mpg I have to spend $4082 (25000)*($4/24.5). So roughly a savings of $362. If the muffler bypass pipes Izzy uses cost $199 then within one year would easily pay for itself. Not to mention the fun factor. If you go to Fabspeeds website you will see how closed off the stock 996 muffler is. Anyway, I saw the results with my other cars so I assume some gains could be achieved on the 996. However, as 1999 mentions you must be frugal about the mods and see what achieves the best cost benefit ratio. However, we did not purchase this kind of car to just drive from point A to point B. So I assume we would all like to benefit from a little more fun.

[KevinMac]

To calculate my mileage I used my odometer reading between fill ups and divided by the number of gallons at that fill up. The numbers were consistent over several fill ups since I do that 2.5 times in 2 weeks. Since I drive roughly 25000 miles per year doing the same daily drive plus a little extra and getting 22.5 miles per gallon with a gas price of $4 I spend $4444 on gas that year. (25000)*($4/22.5). Now if I do the same calculation and magically get my extra 2 mpg I have to spend $4082 (25000)*($4/24.5). So roughly a savings of $362. If the muffler bypass pipes Izzy uses cost $199 then within one year would easily pay for itself. Not to mention the fun factor. If you go to Fabspeeds website you will see how closed off the stock 996 muffler is. Anyway, I saw the results with my other cars so I assume some gains could be achieved on the 996. However, as 1999 mentions you must be frugal about the mods and see what achieves the best cost benefit ratio. However, we did not purchase this kind of car to just drive from point A to point B. So I assume we would all like to benefit from a little more fun.

I agree at the price of the mods, and the price of gasoline, even at 4 mpg savings, it will take you some time to recoup your outlay of the mods! Need to look at the whole picture and not just the cost of gasoline.

[Izzy]

You should all consider that with the loud pipes, other motorists will be annoyed and will push you out of the way, therefore increasing your MPG.

Cheers

Izzy

[GranburyChuck]

You should all consider that with the loud pipes, other motorists will be annoyed and will push you out of the way, therefore increasing your MPG.

Cheers

Izzy

Thanks Izzy, gave me a nice laugh this morning. Was it really that loud though? I drive mostly highway at cruising speed in 5th (tiptronic). I assume it only gets louder when you accelerate.

[Izzy]

I think the sound is great in small doses. For example, driving 2:30 hours to VIR for a track day, the droning can get old and bothersome. However, on track and around the paddock, the scream of the engine is blissful. Then driving back another 2:30 home, by the time I get home I am ready do swap back to GHL.

I left them on for a week, driving to work is only 15 miles, and it was not bad at all. Until I had to dial in to a conference call. They are definitely sporty, and not great when you have to conduct business in the car.

Added bonus is my wife won't drive the car with loud pipes on, therefore reducing the number of door dings, etc.

Edited May 29, 2008 by Izzy