Flowmaster = Poor Gas Milage
Thread Starter
Drifting
Joined: Jul 2006
Posts: 1,840
Likes: 7
From: no. jersey Photo by Stro
St. Jude Donor '08
Flowmaster = Poor Gas Milage
Could this be my trouble? FM were put on and I was to busy enjoying my new sound. Now I have had a new clutch installed and i'm observing everything on the car. My gas milage has tanked. Before spirited driving milage was 19-21 mpg. After all above slight spirited driving 14mpg, easy pedal is 18-19mpg
Anyone have this or can explain this? I heard FM restrict flow after my purchased.
Anyone have this or can explain this? I heard FM restrict flow after my purchased.
Safety Car
Joined: Sep 2006
Posts: 4,759
Likes: 52
From: L.A. aka TooDamnManyPeopleville Ca.
No one has shown any proof that Flowmasters restrict flow.
The problem is that your car sounds so good now, that you wind it out more just to here it roar! I have them and suffer from this ailment myself!
Eventually you'll get use to them. Then you'll go out and spend more money on another mod!
The problem is that your car sounds so good now, that you wind it out more just to here it roar! I have them and suffer from this ailment myself!
Eventually you'll get use to them. Then you'll go out and spend more money on another mod!
Drifting
Joined: Jun 2007
Posts: 1,573
Likes: 295
From: Overland Park KS
Could this be my trouble? FM were put on and I was to busy enjoying my new sound. Now I have had a new clutch installed and i'm observing everything on the car. My gas milage has tanked. Before spirited driving milage was 19-21 mpg. After all above slight spirited driving 14mpg, easy pedal is 18-19mpg
Anyone have this or can explain this? I heard FM restrict flow after my purchased.
Anyone have this or can explain this? I heard FM restrict flow after my purchased.
Race Director
Joined: Oct 2005
Posts: 14,999
Likes: 200
From: Bay Area Ca.
You may be driving like an old lady but in the wrong gear! Along with a heavy right foot being in the wrong gear will contribute to poor fuel mileage. I'll drive in a 25 zone in 4th if I am looking for fuel economy. Hell if you put it in 6th your'll just about idle along at mid 30's per gallon.
Thread Starter
Drifting
Joined: Jul 2006
Posts: 1,840
Likes: 7
From: no. jersey Photo by Stro
St. Jude Donor '08
29k and sometimes driven like I stole it. 3rd gear is the one with the least amount of drone. Even highway I can't get it above 20 mpg.
Instructor
Joined: Jul 2006
Posts: 157
Likes: 0
From: Waterloo IL
There must be some other problems with your car. My mileage did not change at all after I installed Flowmasters. I can get 30-32 mpg on the highway. My overall is 19 and that includes 2 track days.
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Le Mans Master
Joined: Aug 2005
Posts: 5,335
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From: Eagle River AK
St. Jude Donor '06-'07-'08-'09-'10,'14
I had Flowmasters on my 07' and noticed no difference in fuel mileage. Have since changed to Corsa Sports and again, no change.
Last edited by MADinAK; Mar 8, 2008 at 11:45 PM.
Team Owner
Joined: Feb 2000
Posts: 45,199
Likes: 892
From: Texas
CI 1-4-5-8-9-10 Vet
St. Jude Donor '03 thru '10, '17
Your flowmasters may be causing your knock sensors to activate. The resultant retarded timing would definitely reduce your mileage. You may need to data log and see if timing is beening pulled.
Thread Starter
Drifting
Joined: Jul 2006
Posts: 1,840
Likes: 7
From: no. jersey Photo by Stro
St. Jude Donor '08
TIA
Team Owner
Joined: Feb 2000
Posts: 45,199
Likes: 892
From: Texas
CI 1-4-5-8-9-10 Vet
St. Jude Donor '03 thru '10, '17
Yes. In fact, that would tend to confirm my theory because the timing retard would affect your mileage AND performace. You could use a scan tool to check for knock retard. Or, if you are like me and don't have one - find a reputable tuner. They can fix it for you. It would be worth the price of a custom tune. From where you live, it looks like you are probably close to Cartek. If you don't know who to go to, go to the NE regional section and ask your local Corvette Forum frineds.. A custom tune will fix you up.
Team Owner
Joined: Jun 2005
Posts: 46,295
Likes: 2,596
From: Northern, VA
St. Jude Donor '15
"In honor of jpee"
Any particular reason the sensors would activate Mike? I didn't know that could happen.
Team Owner
Joined: Feb 2000
Posts: 45,199
Likes: 892
From: Texas
CI 1-4-5-8-9-10 Vet
St. Jude Donor '03 thru '10, '17
Bill, some of the louder aftermarket exhaust systems have been known to confuse the knock sensors, resulting in pulled timing and reduced performance. I don't know how common it is, but I have read of it in the C5 section. I believe one fix was to remove the sensors, wrap the threads with teflon tape, and re-install.
Last edited by need-for-speed; Mar 9, 2008 at 01:25 PM.
