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Flowmaster And Cold Air Intake

Black04

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Black04 Enthusiast

Black04

Posted
Posted

Can I expect a 2 mpg increase by adding a flormaster system and then a K+N filter or perhaps a cold air intake kit?

 

2004 4x4 extended cab shortbed

5.3 with automatic

ws6_guy Senior Enthusiast

ws6_guy

Posted
Posted

expect a slight decrease in economy with flowmaster, for an intake it will make up for the Flowmaster and help a bit.

cmoore74 Enthusiast

cmoore74

Posted
Posted

Neither are worth the money if all you're looking for is mileage.

 

I observed the following on my 2006:

 

stock - 18-19 MPG highway

added AEM brute force intake - no change in mileage

then added Corsa cat-back - 0.5-1 MPG increase

 

Can't say it was all the Corsa or a combination of the exhaust and intake as I already had the intake on when I added the Corsa.

 

For me I love the sound and look which is why I did it. Seems to pull a little better, but without a dyno can't quote benefits.

fbachman Senior Enthusiast

fbachman

Posted
Posted

On my 07NBS 5.3 Sierra, the K&N replacement filter actually caused a 2mpg DECREASE in mpg. Upon further examination, I have come to the conclusion that the air box design on the Sierra is such that the K&N fits in "up-side-down". As the K&Ns ARE directional with respect to flow, I am assuming that, since it had to be installed "up-side-down" that it actually caused a performance decrement.

 

SO, to answer your question, no, the K&N will hurt to the tune of about 1-2mpg, based on my direct experience. I pulled it out after 1 tank of gas --- it was THAT noticable on performance DECREMENT and mpg.

 

Now, my experience on Flowmasters has been mixed. On a F__d F150 (5.4l) I owned in a previous life, it gave me a 1-2 mpg increase. On an F250SD (5.4l) the Flowmaster gave me no noticable improvement in gas mileage, though it didn't DECREASE it either.

 

Compared with "brand F" mufflers, it appears the NBS factory mufflers run pretty open, i.e. not as restrictive as the F__ds.

 

I have no specific experience with Flowmasters on GMs wrt gas mileage. My guess would be that, with the combination of a FM and K&N filter cartridge, you will, either, break even, or actually go down a bit in mpg, with the K&N being the bigger culprit.

 

Now, I have a GMPP CAI that gave me approximately a 1mpg increase. I would recommend a CAI rather than just the K&N filter. Some like GMPP, others prefer Volante, and still others like the K&N CAIs. Either way, a whole CAI system, I would guess, will help you out on the mpg side over the filter.

chevy6490 Enthusiast

chevy6490

Posted
Posted

CAI's are no help to fuel economy, big myth. More Air=More Fuel Added by computer to correct mixture, giving you either equal or less mpg. You get somewhat better performance, a better looking tube, and a louder engine.

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