Ok guys, I need some hard evidence. I'm about ready to spend some money, so this is a serious question: Does a cold air intake and a free-flowing aftermarket muffler help mileage? Or, is just a claim from the manufacturers to get us to buy their wares?

Does anybody have first hand knowledge of before and after mileage tests on their vehicle using a cold air intake and a flowmaster, Magnaflow, etc. muffler???

Thanks, Jag
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54 F100
55 Fairlane
68 F100
55 Crown Victoria

 

Cold/cool air will provide a denser charge to the intake - Pure physics
An "Open" exhaust will provide better flow - Pure physics.

Note on the Exhaust - Engine builders design a certain amount of "Back Pressure" into the exhaust system to reduce "Pulse Wave" formation (Thats the effect of the exhaust from individual Cly traveling thru the headers/pipes)

So - The cold air system will improve performance (Unless it's hotter than your engine compartment) and I would ask for flow data from the various manf. on their mufflers and pick the best flowing one that you can afford.

 

What is this going on? I haven't seen a car that didn't have factory CAI since EFI came into being. (my '86 even has it) Most of the intake systems are designed to reduce intake noise, and really don't restrict air that much. Plus they use good filters, not K&N-type.

As far as improving mileage, I really doubt it, if it's an EFI car. Contrary to what Pep Boys and AutoZone advertise, even a clogged air filter doesn't affect mileage on an EFI car; the EFI system only provides as much gas as there is air flowing into the engine. How could flowing more air use less gas?

 

I put a k&n cold air induction with a throttle body spacer plus bought a tornado air flow thing that gives the air flow a vortex spin on my 03 fx4. I got about 1 or 2 mpg more and alittle more pep. Better air flow in and out is better SO I ALWAY HEARD.

 

I agree with F-1, with the mass air flow sensor I would think more air would mean more gas going to the engine. I have one on my 2000 F150 with full exhaust and a custume tune. I honestly never noticed a difference in mileage.

 

Jag, an internal combustion engine is a basic "air pump", the more air you let in and the more you let out then the more power you produce. That said...power does not necessarily equate to fuel efficiency, but if the engine does not have to work as hard moving the air then it does become more efficient. Dick C is right on the money.

 

It absolutely does not improve fuel economy, it improves power at a given throttle opening. But not much.

http://www.fueleconomy.gov/feg/pdfs/...02_26_2009.pdf

Engine & fuel engineering - air filter vs fuel economy - controlled test results

Engine & fuel engineering - air filter vs fuel economy (tricky question?)

 

Thanks for the responses everybody. I knew that the clogged air filter would not effect fuel mileage on an EFI engine. But the question of the upgraded muffler and the cold air intake was up in the air for fuel economy. I just prefer real life stories of before-and-after results rather than having to depend on the suppliers/manufacturers. Jag

 

Hey Jag,
I put in a CAI into my wife's Infiniti & it didn't do much for MPG but it did make one change that I appreciated. The sound coming from the engine/exhaust definitely changed - much more pronounced growl - very nice. I'd do it again just for that.

Ben in Austin