Anyone notice a MPG increase from Magnaflow catback? - NJFBOA - Home of New Jersey's Camaros and Firebirds

Mark42 · 02-13-2010, 07:15 PM

Anyone noticed a MPG increase from installing a Magnaflow cat back? Found the v6 2.5" w/3" tip Magnaflow 15693 at an affordable price and might just order it. I read about the hp increase, and if it gives a MPG increase too, that might just convince me to order one.

FlyingDutchman · 02-13-2010, 07:32 PM

I went from avg of 14ish mph to high 15s low 16s around town. Def a noticeable increase

Idk about highway, never bothered to check... this is with an LT1

**edit: i drove very easy though.

deadtrend1 · 02-13-2010, 07:46 PM

very unlikely that you will notice a difference in MPG, and I doubt the HP gain from it will be seat of the pants significant. MPG may probably be worse in the beginning since its hard to keep your foot out of it when you get a new exhaust. Probably plateau and be the same or slightly a tenth better.

maroman88 · 02-13-2010, 08:30 PM

Quote:

Originally Posted by deadtrend1

very unlikely that you will notice a difference in MPG, and I doubt the HP gain from it will be seat of the pants significant. MPG may probably be worse in the beginning since its hard to keep your foot out of it when you get a new exhaust. Probably plateau and be the same or slightly a tenth better.

agree lol... since i put the catback on my vette i went from 14.9 to 11.7 wen i checked this morning!

MyFirstZ · 02-13-2010, 09:42 PM

i dont wanna know. I just ask for 25$ 93oct when i go to the gas station. If i knew i probably would cry a little

JL8Jeff · 02-14-2010, 10:04 AM

What size is the stock I-pipe on the V6 cars? If it's less than the 2.5" then you will definitely see an increase in mpg. It might not be big but even a .5 mpg increase is nice. Winter is not the best time to compare mpg though, every vehicle drops a couple mpg during the winter. I average around 18-19 mpg daily driving in the summer with my LS1 and it drops to around 15.5-16 mpg in the winter. My old 4Runner would average 20 mpg in the summer and 17 in the winter. I picked up a solid 1 mpg with the 4Runner after installing a 2-1/4" cat-back which replaced the stock 1-3/4" exhaust. So bigger pipes will help mpg in the long run. The initial change in driving style may hurt as you enjoy the new sound and get on it more often.

Savage_Messiah · 02-14-2010, 01:48 PM

Quote:

Originally Posted by JL8Jeff

What size is the stock I-pipe on the V6 cars?

2.25"

Here, this is a great deal: http://www.fullthrottlev6.com/forums...ad.php?t=59092

sweetbmxrider · 02-14-2010, 03:42 PM

says the sale ended brah

i didn't notice any mpg increase, but i didn't have the proper equipment to measure for it so i guess this is really just an opinion.

ws6 jim · 02-14-2010, 04:02 PM

I agree with Jeff based on the sizing beforehand and the amount of back pressure a vehicle has to begin with.
Everyone buys a cat back for sound foremost, power and mpg is negligible and a fringe benefit.

Mark42 · 02-14-2010, 04:19 PM

Yeah, the pipes are 2.25 OD from the cat back on the single outlet system. So a 2.5" is a nice increase in area, but not too much for my stock v6.

All the other systems I had on other cars gave about 1-2 mpg increase on highway driving, but they were all custom systems.

I remember reading a doc from Magnaflow claiming 10hp and up to 3 mpg on the V6 cat back, but now I can't find it. The 3" version (same configuration) used on the V8's gives has a dyno sheet on their website showing 18hp and 15 torque gain. If the V6 does half of that, I would be impressed. They do claim:

Quote:

Question: How much horsepower can I expect to gain?

Answer: It's different for every car, but typically expected gains are in the average range of 10%.

Replacing the muffler/exhaust with a MagnaFlow will help your engine increase power by being able to expel exhaust gases quicker. This creates less workload for the engine, makes it run more efficient, and results in better power.

"Average Range" being the operative words......

I sent Magnaflow an email asking for the V6 dyno sheet(and any mpg info), seeing as they claim every design is dyno tested to ensure HP gains. We will see what they say.

They also had this interesting bit of info on pipe sizes:

I was surprised to read this on the Magnaflow site. Its classic "old school" exhaust sizing, where today it seems that many people think you can't get big enough pipes. Nice to see some rules stand the test of time.

sweetbmxrider · 02-14-2010, 05:13 PM

yeah if you research around, you will see its pretty well known. surprised you didn't find that out here

Mark42 · 02-14-2010, 05:58 PM

I'm surprised that no Magnaflow V6 owners have chimed in. Thought there were lots of them on this forum, especially after reading how many feel the Magnaflow is the best cat back for the V6.

Would be nice to hear from someone with the Magnaflow.

Savage_Messiah · 02-14-2010, 06:16 PM

I gained a couple mpg... I have the 3" though, not the 2.5

LTb1ow · 02-14-2010, 06:25 PM

Well if a good catback gains MPG, then NO catback means major MPG gains!

You should do headers too, I hear they can add MPG.

Mark42 · 02-14-2010, 08:09 PM

Quote:

Originally Posted by Savage_Messiah

I gained a couple mpg... I have the 3" though, not the 2.5

Something about the 3" system is confusing me. I've seen pics of Magnaflow 3" system that has two bullet mufflers and dual tips, but this system is not listed on the Magnaflow site. The 3" system listed is the same single muffler configuration as the 2.5" system.

Also read posts from 2006-2007 where people said the Magnaflow was loud and had a drone.

Was there an older 3" system with two bullet mufflers that is no longer offered?

Quote:

Originally Posted by LTs1ow

Well if a good catback gains MPG, then NO catback means major MPG gains!

CHRIS67 · 02-15-2010, 07:43 AM

I had a 4.3 Sonoma that had Magnaflow exhaust, a cold air intake, throttle body spacer, under drive pulleys, and a JET stage I chip. If anything my MPG went down because I drove more aggressively with the HP increase. More HP = more fun!! If you’re looking to save on gas the best thing you can do is keep those tires inflated to their recommended pressure, keep the car tuned, and keep a light right foot.

JL8Jeff · 02-15-2010, 11:16 AM

The 3" system would be more for trying to get maximum top end power which you're not looking to do. I think you would be better with the 2.5" system for your purpose. Even the V8 systems are necked down to 2-3/4" at the I-pipe connection so the rear portion of the system is most likely the same for both with just a different inlet size. My 2000 SS has the Random Tech cat-back and there is no drone or resonance at all. The muffler is a straight through with perforations to feed the passenger side tailpipe. You might want to look at actual muffler designs to help determine what might work best for you.

Mark42 · 02-15-2010, 11:42 AM

Quote:

Originally Posted by JL8Jeff

The 3" system would be more for trying to get maximum top end power which you're not looking to do. I think you would be better with the 2.5" system for your purpose. Even the V8 systems are necked down to 2-3/4" at the I-pipe connection so the rear portion of the system is most likely the same for both with just a different inlet size. My 2000 SS has the Random Tech cat-back and there is no drone or resonance at all. The muffler is a straight through with perforations to feed the passenger side tailpipe. You might want to look at actual muffler designs to help determine what might work best for you.

Hey Jeff! Thanks for the informative post. I have been looking at all the exhausts available and decided the 2.5" V6 cat back by Magnaflow is what fits the bill. The pipe size is perfect for a stock motor, and its all stainless so rust should not be an issue, and if the system fails, it is warranted for the life of the system. The muffler on this system is a straight through design, so it should be low restriction. I also like that all the packing is stainless steel too, so it should not burn, compress or blow out like fiberglass packing does over time.

I agree with your assessment on pipe sizes, way too often a system is fit to the car that is too big for the HP/CID, resulting in an actual loss of performance rather than the anticipated gain. From what I see on various forums, this system is perfect for my application.

Hopefully, this Maganaflow will not be too loud, or drone at highways speeds.

Thanks again.

Mike · 02-15-2010, 12:25 PM

the reason you aren't getting a ton of feedback from the magnaflow v6 owners, is because many of them don't care about mpg, or didn't pay attention to their previous mpg... i had a 3'' borla on my old 3.4 car, and while i never drove the car with stock exhaust, i do know that the car averaged 3-5 mpg more than the factory claims...

the 3.8 is obviously a more efficient motor than the 3.4 was, so you should be able to expect the same or better, but i don't know where your car is in comparison to the factory claims....

besides, it will sound good, gain a little power, and gain a little mpg, and the tips usually look better.... add all that together and its worth picking up.

Mark42 · 02-15-2010, 07:46 PM

Quote:

Originally Posted by cbrrmike

the reason you aren't getting a ton of feedback from the magnaflow v6 owners, is because many of them don't care about mpg, or didn't pay attention to their previous mpg... i had a 3'' borla on my old 3.4 car, and while i never drove the car with stock exhaust, i do know that the car averaged 3-5 mpg more than the factory claims...

the 3.8 is obviously a more efficient motor than the 3.4 was, so you should be able to expect the same or better, but i don't know where your car is in comparison to the factory claims....

besides, it will sound good, gain a little power, and gain a little mpg, and the tips usually look better.... add all that together and its worth picking up.

I suspect you hit the nail on the head!

Alright then, you guys forced my hand! It is becoming painfully obvious that I will have to find out if there is an MPG increase or not for myself. That requires procuring said exhaust system, so I have. It should be here Friday. After its installed, I will post my findings. This is all being done in the name of science, and no way reflects my desire to own a Magnaflow exhaust nor is the MPG issue being used as an excuse to purchase said exhaust......

sweetbmxrider · 02-15-2010, 08:22 PM

so what is your current mpg and will all conditions be replicated to ensure accurate data? just want to keep it factual.

Mark42 · 02-15-2010, 08:55 PM

I've been keeping record of fuel, miles and modifications since I bought the car this past summer. My driving is pretty much the same from week to week, so I will be able to post accurate results.

Mark42 · 02-18-2010, 04:03 PM

Oh man! Look what came today! This is sooooo much nicer than I had read or anticipated. I can't believe I got this for under $300 new.

The build quality of this system blows away anything I had bought from Flowmaster or Dynomax over the years.

Come on warm weather!

sweetbmxrider · 02-18-2010, 06:01 PM

weird how from what it looks, the outlets are on the same side. the magnaflows are nice though.

BonzoHansen · 02-18-2010, 06:05 PM

Looks good Mark. You'll love it.

Quote:

Originally Posted by sweetbmxrider

weird how from what it looks, the outlets are on the same side. the magnaflows are nice though.

The Banks Engineering 3" catback system on my 3rd gen had both outlets on one side. When I called Banks and asked they told me it flows better like that, not making the gas make additional turns. It also sounded awesome.