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03:14:07 - 12/29/2024
Dakota Performance
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Biff
Dodge Dakota
6/01/2001
13:24:40
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 Subject: Gibson catback exhaust = increased MPG?
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Hello,
I've noticed the Gibson exhaust group buy is quickly coming to an end. I plan on keeping my truck for a while (2001 QC 4.7L 3.55LSD auto) and was doing some math to try and justify the cost of adding a catback exhaust.
With gas at $1.70 per gallon, if I increase my MPG by 1, It would save me $50 for every 10,000 miles driven. Thus the catback exhaust would pay for itself in about 72,000 miles.
Is it likely that getting the Gibson catback exhaust on my 2001 4.7L will increase my gas mileage by 1 MPG? What have been your experiences?
Thanks in advance!
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Dan Gruber
Gen III
6/01/2001
20:48:49
|  RE: Gibson catback exhaust = increased MPG?
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I didn't notice any change in gas mileage when I put on my Gibson, nor when I put on the airaid. But then again, I didn't buy either one for gas mileage...I just liked the sound. As an added benefit, they appear to have added a few ponies.
Maybe it's just me, but trying to justify buying an exhaust by saying that it will pay for itself in 72,000 miles is a bit of a reach. Are you really going to notice the $350 or so over 5 years? Probably not.
If I were looking for gas mileage, I'd go get me a Honda Insight and be banished to the slow lane forever. Of course, that'd be worth some laughs at the dragstrip...
Dan
2000 CC SLT 4.7 4X4 Auto 3.55 LSD
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Doug McCoach
Dodge Dakota
6/02/2001
12:18:43
| RE: Gibson catback exhaust = increased MPG?
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Message:
Dan, I have the same setup. An Airaid intake with a Gibson 3" sept side cat-back exhaust. I too like the sound the combination makes & noticed more performance gains with the intake than with the exhaust.
Biffster, I noticed no improvement in mpg driving locally but did see an improvement of about 1/2 mpg on the highway. This makes sense since most of these mods are aimed at improving the ability of the engine to breathe/exhale & the available outside colder air is flowing pretty good @ 70mph. If you are looking to improve performance/mpg you may want to try the 70mm TB by F&B when it comes out, it is supposed to be the best performance mod we've seen. Looking at the costs of the other F&B TB's I wouldn't be surprised if it costs $400 - $500 or more. I am waiting to find out about an "oring" issue with Mopar that is supposedly not available for the 68mm TB if I wanted to upgrade from my stock 65mm TB. I have another post discussing this in more detail. The trouble with the F&B 70mm TB is that it sounds like the current air intake systems won't be compatible(fit) with the 70mm TB so we would have to wait for them to come out too. All this waiting drives me crazy!!!
2000 QC 4x4 Auto 4.7L V8 3.55's
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biff
Dodge Dakota
6/04/2001
10:47:14
| RE: Gibson catback exhaust = increased MPG?
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Message:
Thanks for the info Doug! It's always good to here from a third party about the performance & mileage gains of the products we're interested in. Since most of my driving is on the highway, it sounds like I would see a slight gain in MPG. However, not as much as I would like to see. At .5 MPG, it would take 145,000 miles in driving for the gas mileage improvement to pay for the exhaust. However, you bring up an interesting point that the gains occurred at 70 mph because the engine was receiving a ram-air effect. Maybe adding a TB and an exhaust together would compliment each other both in performance and MPG? I have a drop in K&N filter in the original airbox (Based on previous cars I've owned, the airbox looks quite small for a rev-happy 4.7L V8). I'm waiting for the K&N FIPK because it eliminates the airhat and is made from plastic (not metal) which should keep the intake charge cooler. Since it sounds like a future hot setup would be the exhaust + F&B TB + K&N FIPK, I to am interested in hereing about the TB and K&N fitting each other. Waiting on go-fast goodies does suck! But that's the price we pay for having a truck motor that has a rush to the redline and a smooth refinement to boot! Happy motoring,
Biff - 2001 Silver QC 4.7L 3.55LSD Auto, PaceEdwards Roll Top, K&N Drop in (for now)
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Doug McCoach
Dodge Dakota
6/05/2001
03:07:27
| RE: Gibson catback exhaust = increased MPG?
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Message:
Biff, I forgot to mention, I removed the rubber flap from the passenger side of the radiator & took out the stock funnel of the bottom half of the air filter box & cut it down a few inches so it points straight toward the front of the hood & is in clear air/eye shot of the newly opened up space. It gets real good air flow with that setup, especially @ 70mph. Also, in the cooler months of the year, I think the Airaid is as good as any air intake system. However, in the summer months when it gets real hot, I'm a little concerned about it sucking hot air from the engine/hood since the rubber seal that is supplied doesn't seal that well at all. I've been thinking of ways to improve the seal but it hurts my head too much. I was thinking of either using just the stock air box with a K&N air filter, or switching to something like the Z-tube when it gets real hot outside. The z-tube removes all restrictions including the air hat & from what I hear, it performs as well as it sounds. I think the only way to tell which works better is to have more than one air intake on hand & see for yourself. I know its more money spent but what the hell. I don't think you'll find any modification that will actually pay for itself, except maybe for the non-performance ones. We are all doing it for kicks & giggles, a few more ponies/ft-lbs of torque, & a sound that makes people look twice when you let her rip.......
2000 QC 4x4 Auto 3.55's 4.7L V8
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