CAI or short ram? save gas?
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CAI or short ram? save gas?
yea well just wondering. gas prices are rediculous now. i was wondering if having a cold air intake save you gas or have a short ram intake. does it make a difference? personally i think short ram gives you more mpg because is doesnt give you more hp than a cai. and more hp=less mpg. any thoughts or suggestions.
Last edited by civic05acer; Jun 1, 2006 at 02:04 AM.
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Rep Power: 0 How much more gas do you want to save in a civic. Honda have done their best already getting the best MPG out of it. As far as intakes some people have supposedly got 2mpg better with CAI. And the neutral part you were talking about. Thats the most absurd thing I have ever heard of. Just drive your car normally
Dain Bramaged.
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Rep Power: 0 In all actuality, it's not "absurd" in the least. I have heard something like that. I seriously doubt it would save gas, as at idle fuel consumption is negligible. I have heard that it's good for the transmission/torque converter to not be sitting at a light engaged, but that was on a much older car. The technology has probably, and I say probably, progressed to the point where such actions are not necessary nor effective.
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idk, i got the best mileage now with intake and exhaust, 42mpg. before i could never get more than 34 all highway when the car was stock. there are other mods and stuff too but still... and the putting in neutral at a light actually will use more gas because the idle goes up slightly from drive to neutral. its good for the tranny tho cause the fluid cools down. put it in neutral for long lights in the summer
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From my understanding. For automatic transmissions, coasting on neutral will not save gas because the engine will need fuel to maintain idle where as coasting the engine is being spun by the cars speed. At a red light, if you put it in neutral it will disconect the engine from the drivetrain as we know. However, in drive the engine is still linked to the drivetrain, which happens to be not moving, putting load on the engine. Also, neutral should help keep the transmission cooler at a red light.
Dain Bramaged.
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Originally Posted by gearbox
=and the putting in neutral at a light actually will use more gas because the idle goes up slightly from drive to neutral. its good for the tranny tho cause the fluid cools down. put it in neutral for long lights in the summer
And on the subject of an intake improving mileage, there is some substance to that proposition. The thing you must take into consideration is that an intake is a passive performance modification, not an active one. (An example of an active performance mod would be something like a turbo, nitrous oxide, etc that physicall adds or force-feeds more oxygen into the engine. Basically any kind of boost.) All passive modifications do is make the engine more efficient.
I can't remember what the rule is called, but there's some law of physics that states that energy can not be created or destroyed. How is that relevant? Here's how: a certain amount of energy enters the engine, which in this case can be viewed as a basic machine that converts chemical and electrical energy into mechanical and thermal energy. This energy enters the engine as chemical energy (fuel and oxygen) along with electrical (ignition) and leaves as mechanical (whp) and thermal (exhaust gasses).
While all this may be a bit excessive, it is still relevant. An intake (either cold air or short ram) provides less resistance for air to enter the engine by either providing colder air, a smoother path, a shorter path, or a combination of the three. This means that the oxygen entering the engine can move much move freely thus allowing the engine to produce more power.
What's the point of cold air? Cold air is denser than warmer air. Denser air contains more oxygen, which equals more power. I think a rough formula goes something like this:
G=.01(P((B-O)/11)),
G=.01(P((B-O)/11)),
where G is the horsepower gains, P is the present horsepower, B is the temperature inside the engine bay, and O is the outside air temperature. For every eleven degrees fahrenheit of difference between the outside air temperature and the air inside the engine bay, there is a 1% horsepower increase. While this may not sound like much, it can be substantial iunder certain circumstances. Say the temperature outside is a cool 67 degrees fahrenheit. You've been driving for a while, so the temperature under the hood is about 200 degrees. Your engine isn't incredibly powerful, but let's say it gives off 100 bhp with your short ram intake. Using the formula given above, that equates to about 12 bhp over what the engine would be producing if it were drawing hot air directly from the engine bay (like from a short ram intake). While that's not an astronomical figure, it is at least impressive for just a piece of metal pipe.
Allow me to clarify exactly how all this is related to better mileage. When the engine is not having to work as hard to ingest air, that energy that was previously used for respiration goes elsewhere, such as the drivetrain. And when the engine's not having to work as hard to maintain a certain speed, it doesn't use as much fuel. It will still turn as fast, but it won't require as much throttle to hold that speed.
(The formula provided is for a rough estimate. It is intended for clarification purposes only. Please, someone correct me if I'm wrong. I welcome any advice and/or criticism)
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Rep Power: 812 good info, but in regards to rpm and gas mileage, i think you went a bit off topic. the reason has to do more with acceleration than with rpm. if you accelerate to 3k rpm 10 times over and over while stopping after each time, you will use a ton more gas than accelerating to 3k rpm once and cruising at that speed for the same amount of time. its more that acceleration uses more gas. but yeah i dont really have proof nor does 500rpm difference between drive gear and neutral prolly even matter. but the engine does use up alot more fuel at idle than when cruising at a constant speed, even if the rpm is higher.
Dain Bramaged.
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Rep Power: 0 Haha yeah, I did go a little but overboard, but better too much than too little. As far as acceleration goes, I agree completely. It's not the actual revolutions that determine fuel usage, it's the load on the engine combined with the engine speed.
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Rep Power: 0 i floor mine way to much to even care about gas mileage. Only thing i compare my car to is the trucks that hear my car pull up and try to race. I figure that idoling he will have already wasted the gas i will spend kicking his @$$. I would think it doesnt matter which you get for gas mileage, only if your trying to gain some power from it because ive had both also. didnt like the cai because i didnt want to hydro lock whenever it rains here
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Rep Power: 269 Gas mileage is more about your throttle position, the more the throttle is open the more air that is getting in and the more fuel you'll use. I remember when I first drove a BMW with the MPG indicator I noticed how it always went lower with more throttle, however I could be sitting at 4.5k rev/min on the highway with the throttle open just enough to maintain speed and get 30-35 mpg according to the gauge.
About the the mpg difference between CAI and SRI, it really won't make any difference maybe 1-2mpg and that's if you drive the same way that you did before. If you stomp on the throttle more (which most people do after getting an intake, it just sounds so damn good) then your mpg will be worse. I will say though, I think a CAI will give you a little better mpg than the SRI but like others have said, there's also added risk/inconviences such as hydrolock and more frequent filter cleanings with the filter in a hard to get to spot in most cases.
About the the mpg difference between CAI and SRI, it really won't make any difference maybe 1-2mpg and that's if you drive the same way that you did before. If you stomp on the throttle more (which most people do after getting an intake, it just sounds so damn good) then your mpg will be worse. I will say though, I think a CAI will give you a little better mpg than the SRI but like others have said, there's also added risk/inconviences such as hydrolock and more frequent filter cleanings with the filter in a hard to get to spot in most cases.
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