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Aftermarket Intake Gas Millage Question

Aftermarket Intake Gas Millage Question

Aftermarket Intake Gas Millage Question

(OP)
Is it a myth that your cars fuel economy will be improved with an aftermarket intake system. I know in most cases it decreases due to the driver putting the pedal to the floor more due to the sound of the intake sucking in and the increased throttle response. But, I'm saying if your a conservative driver and you put an aftermarket intake on your car and remain a fairly conservative drive will your fuel economy increase like companies claim? And to be specific here I'm talking about a Short Ram and not a cold air.

RE: Aftermarket Intake Gas Millage Question

(OP)
I forgot to add that this is debate is on Fuel Injected vehicles (without getting the car remapped or retuned for the intake).

RE: Aftermarket Intake Gas Millage Question

Wouldn't you think that the manufacturer would have picked the intake that resulted in the best gas mileage to begin with?

TTFN

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RE: Aftermarket Intake Gas Millage Question

(OP)
With that point you could argue the fact that why don't manufactures make their cars faster? Theres standards and such that these cars are engineered to and requirements they must meet when they come of the assembly line that makes those types of things very hard for them in the first place. Which is why there is an aftermarket for this type of thing.

RE: Aftermarket Intake Gas Millage Question

No, there is no need for cars to go faster.  

However, there is a CAFE law that requires that cars achieve a certain mileage.  Because of all the smog controls and whatnot, corporate gas mileage is constantly under achieving, and if a simple intake change was all that was needed, all the car companies will jump at the change, just to bring up the average mileage so that they can easily meet the requirements of the law.

TTFN

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RE: Aftermarket Intake Gas Millage Question

If you use an after market inlet that is much more restrictive you will see a fuel economy increase that is somewhat proportional to the power decrease.

Otherwise, how can an after market inlet improve fuel economy. Do the people making the claim explian the mechanism by which it occurs.

Regards
Pat
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RE: Aftermarket Intake Gas Millage Question

"If you use an after market inlet that is much more restrictive you will see a fuel economy increase that is somewhat proportional to the power decrease."

I think this known as the "put a sock in it" argument.

If you think about the intake system as a long tube with various restrictions in it, it becomes remarkably hard to explain why any restriction in that tube will be better, or worse, than any other restriction, for fuel consumption. This does not apply at full throttle of course.





 

Cheers

Greg Locock


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RE: Aftermarket Intake Gas Millage Question

The stock airbox is designed with reduced acoustics in mind... since the aftermarket world is not restricted with this, there is power to be had.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Aftermarket Intake Gas Millage Question

Greg,

Would you agree that at the extremes, where the airbox provides the heaviest restriction to airflow, the aftermarket piece would provide for a better economy?

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Aftermarket Intake Gas Millage Question

only if you agree that you get better fuel economy at WOT than you do at part load! ha.
 

RE: Aftermarket Intake Gas Millage Question

Somehow, that doesn't make a whole lot of sense.  Wouldn't restricting airflow result in incomplete burning?  How is that good for fuel economy?

TTFN

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RE: Aftermarket Intake Gas Millage Question

The fuel injection system is calibrated to provide the correct amount of fuel for the air.

The throttle normally controls the air.

If the inlet is more restrictive than the throttle at WOT, the inlet controls the air rather than the throttle controlling it once the throttle goes past the point where inlet and throttle are equal, well to a point.

High flow or cold air induction adds power at WOT, not fuel economy. At cruise it makes no difference as the throttle is the real restriction.

Regards
Pat
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RE: Aftermarket Intake Gas Millage Question

With modern fuel injected vehicles you have sensors that take calculations on how much air and the temperature of that air is going into the engine. Along with how much fuel is not being used by the engine on the exhaust side. The computer will only ever send as much fuel to the engine as much air is being sent to keep the air-fuel ratio within its design. More air means more fuel. Very simple.

RE: Aftermarket Intake Gas Millage Question

For the same engine output power, if you could make the engine more efficient (less air restriction on the input), wouldn't the input power be less?

RE: Aftermarket Intake Gas Millage Question

generally speaking, for throttled port-injection reciprocating gasoline engines, engine output power (and by inference, input "power") is regulated by the intake restriction.  


 

RE: Aftermarket Intake Gas Millage Question

probably No economy impact, but I think in some cases air inlet (air box, air filter case, etc) tuning has been used to correct or at least minimize dips in the power curve, even of F-Injected engines.
http://www.calsci.com/motorcycleinfo/Airboxes.html
plus a few articles by Kevin Cameron of Cycle World.

Then there's the situation where the inlet "restriction" is a nice long intake runner of an appropriate size, whose positive inertia effects add more horsepressure than the few inches of water pressure drop cost compared to an oversized stub.   

RE: Aftermarket Intake Gas Millage Question

"For the same engine output power, if you could make the engine more efficient (less air restriction on the input), wouldn't the input power be less?"

No, because it takes a fixed amount of power and therefore a fixed amount of intake air to drive the car down the road under conditions that are identical with the only difference being your hypothetical low-restriction intake. Except at top speed or maximum hill-climb or acceleration - which ordinarily are a very small part of normal driving to the point of being insignificant - whatever intake restriction isn't achieved by the air intake ductwork, will be made up by closing the throttle a little more. Result ... No difference.

RE: Aftermarket Intake Gas Millage Question

So with the throttle closed a bit, wouldn't there be less air/fuel going into the engine?

RE: Aftermarket Intake Gas Millage Question

yes.

RE: Aftermarket Intake Gas Millage Question

banghead

- Steve

RE: Aftermarket Intake Gas Millage Question

Back to the original tenor of the OP, the OEM intake is designed to be the best piece of equipment that low bid can buy.  Manufacturers design cars to be able to produce them as cheaply as possible while meeting the mandated requirements such as CAFE, etc.

Notwithstanding some of the points made in recent posts which I have no quibble with, some engines benefit from more air, namely Diesels.  The amount of fuel added depends on your foot.

I put an aftermarket intake on a IDI diesel engine once and it improved the fuel mileage when I drove it decently, but hurt it when I mashed on it a lot.  And I did both at times.  It was up to me, but when I wanted to, I got better mileage than with the original restrictive manifold.  When I needed it, it was nice to have that extra power that the additonal air allowed me to put the fuel to.

rmw

RE: Aftermarket Intake Gas Millage Question

"So with the throttle closed a bit, wouldn't there be less air/fuel going into the engine?"

NOOOOOOO you are not getting it.

The total combination of the throttle restriction and whatever restriction exists upstream will total out to be 100.0000000% the same, such that exactly the same amount of air goes into the engine, such that the output power precisely matches what's demanded to run the car down the road. Since air/fuel ratio is held constant, so will the fuel delivery.

Do you understand that:

8 + 2 = 10
9 + 1 = 10
7 + 3 = 10

Same result different ways.

Stock restriction (call it "2" for argument's sake) requires throttle restriction "8" to get total restriction "10".

Less restriction (call it "1") means more throttle restriction (call it "9") but the total is still "10".

By the way, diesels are a different ball game because they are operating unthrottled.

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