does ram air affect economy?

[fcm42000]

just thinking, wouldn't it lower the vacuum at highway speed, lowering the amount of vacuum advance?

Is there a way to monitor timing degrees while driving, someone must have thought of something by now?

 

[autopar3000]

Some people would say that ram air saves gas at highway speeds because your engine doesn't have to do as much work to pull in the air. I'm not so convinced, though.

 

[fcm42000]

I am referring to a non computer controlled engine

 

[RustyRatRod]

If the engine is TUNED to take advantage of the ram air, the economy will go down.

 

[dustoff440]

click on this [ame="http://www.google.com/search?q=msd+8680+timing+control&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-USfficial&client=firefox-a#q=msd+8680+timing+control&hl=en&client=firefox-a&hs=uTs&rls=org.mozilla:en-USfficial&prmd=ivnsfd&source=univ&tbm=shop&tbo=u&ei=JffiTfC6CMq_0AG_9ZWNBw&sa=X&oi=product_result_group&ct=image&resnum=3&ved=0CD8QzAMwAg&fp=affca57603ff195e&biw=1280&bih=885"]msd 8680 timing control - Google Search[/ame]

 

[demon seed]

just thinking, wouldn't it lower the vacuum at highway speed, lowering the amount of vacuum advance?

Is there a way to monitor timing degrees while driving, someone must have thought of something by now?

IMHO, I can't imagine that the factory ram air effect is going to equate into more than the equivalent of a pound of boost, remember that the air coming through the scoops runs into an air filter upstream of the carb. This all goes out the window if the filter element is pulled and you're giving her over 100MPH. Where the ram air does help to generate a few extra HP is by drawing outside, hopefully cool, air that will be denser than the hot air under the hood. I wouldn't be worrying about the advance at this point cuss I doubt that the signal below the butterflies will be impacted unless of course you're running a racecar in which case the vacuum line is disconnected anyway.

 

[fcm42000]

I would be curious to see what a vacuum gage would do at cruise with and with out ram air, you know, the difference.

Lets say it does make a pound of pressure (hypothetically) Then there wouldn't be any vacuum for the distributor.

 

[oldkimmer]

................There's no difference, i've tried 6 ways from sunday...............kim.......................

 

[dodgetkboy78]

Colder air in the intake will make more power and MPG, no matter what Kim says.... Sorry, facts are but facts, might not be much, but it is a difference.

Not so sure you would get much measurable boost at cruise throttle/mph though, but the air temperature difference would make a slight difference in power output potential, thus RAISING vacuum.....

As far as lowering vacuum from just a small amount of boost you may get from the stock ram airs? Nah...... But, if in fact you could put a big enough air trap to actually make boost, then yeah, the vacuum in the intake would lower from the boost...

 

[fcm42000]

"boost will raise vacuum" WTF?

do you understand the difference between negative and positive pressure

Colder air is denser, so a given volume of air at a colder temp will use more fuel to maintain a/f.

"Colder air makes mpgs better" WTF?

 

[RustyRatRod]

Actually, the FACT is like I stated. IF the engine is tuned to the extra incoming air being rammed into the intake, then that means it has been richened up to match the increased COLD air coming into the engine. Cold air means dense air. that means more air and fuel packed into the engine. More air + more fuel = LESS MPG. Always has, always will. I don't give a **** what anybody says.

 

[67Dart273]

The facts:

COLD air (ram air) may at some point LOWER economy because it can cause carb icing problems. When I say cold, I don't mean all that cold. A 43*F day in, say, 80% rel. humidity in Portland may cause you problems. Even if the carb is not icing, vaporization of the fuel may deteriorate.

"BOOST" will NOT affect economy. All any perceived boost is going to do is "ease" the engine's pumping effect, but you are not using any horsepower to accomplish this.

You will not "lower the vacuum" because any boost effect will result in LESS throttle

 

[fcm42000]

click on this msd 8680 timing control - Google Search

Thats pretty cool, but I was thinking of like a digital or analog read out that displayed, real time, timing, probably would need a crank sensor at a minimum

 

[67Dart273]

Colder air is denser, so a given volume of air at a colder temp will use more fuel to maintain a/f.

I assumed we were referring to carb equipped engines. A carb will not compensate with a richer mixture.

 

[RustyRatRod]

I assumed we were referring to carb equipped engines. A carb will not compensate with a richer mixture.

It will if you physically tune it to match the functional fresh air scoop.

 

[fcm42000]

It has been established that a lot of advance at cruise helps fuel economy, you get a lot of advance from the engine vacuum, engine vacuum is a component of a few variables, ambient pressure being one. When you floor it you loose most of your vacuum because the throttle blades aren't in the way. Vacuum advance doesn't work without vacuum.

 

[fcm42000]

I assumed we were referring to carb equipped engines. A carb will not compensate with a richer mixture.

I am not asking about the a/f, just the effects on timing, thats all

 

[72bluNblu]

All of the factory ram air scoops are too short to make ANY kind of significant "boost". Unless you're getting more than about 4" above the level of the hood, you're still going to be in the boundary layer for the airflow going over most cars. Which means you're not going to see any significant velocities inside the scoop. The scoops also do not have enough surface area to really create a significant amount of pressure. If you don't believe me, take a look at any auto racing format. The hood scoops that are used are huge, and are elevated significantly over the level of the hood. Most of the cold air induction systems in racing are set up to take air from ducts in the nose of the car (where the air is coming straight in), or from somewhere other than the surface of the hood.

They do provide for cooler air into the engine. With proper tuning, this will make more power, and use more fuel if you're taking advantage of the cooler air by upping the fuel. But, the cooler air also should improve the thermal efficiency of the engine. Whether or not that saves you any fuel would depend on the specific temperature of the air, temperature of the engine, atmospheric pressure and air density, all at a given time, and are some pretty involved equations if you really want to get into it.

As far as the vacuum advance being significantly altered, in a word, unlikely. And of course, you're assuming that your vacuum advance and timing are already dialed in to be perfect for maximum fuel mileage. But if you really think you're onto something no one else here understands, you don't need some fancy computer or ignition module. Just hook up a plain old vacuum gauge and drive down the road at 60 mph with a nice steady throttle, once with the ram air open, once with it closed. Taa-daa. If they're significantly different, you may be able to assume that your vacuum advance is ever so slightly different. And if you've really got a lot of time on your hands, you could try more speed variations to figure out EXACTLY where the best/worst mileage occurs. Or, at least, where you think it occurs, since vacuum is only one variable out of a whole ton of variables that effect fuel mileage.

 

[inkjunkie]

Staying out of the arguement of the op's question, but one thing I do know is both of our vehicles (EFI, 1 diesel & 1 gas) get better fuel mileage here in the cooler climate than they did down in AZ. And yes, that is with both the a/c on & off. The Exploder was getting a touch under 20 in AZ. In the Pacific North West it is getting almost 21......

 

[moper]

Anything that makes it easier for the engine to breath will increase efficiency. It's more a question of is it enough to measure or feel. Anythig that is cooler and more dense, or reduces trubulence while helping the air enter the carb, "should" give the benefit of better economy.

 

[dodgetkboy78]

"boost will raise vacuum" WTF?

Read again, cooler intake charge will raise vacuum..... WTF!

do you understand the difference between negative and positive pressure

More than you ever will..... thinking in terms of manifold pressure/mixture/EGT's in aircraft. (Same deal)

Colder air is denser, so a given volume of air at a colder temp will use more fuel to maintain a/f.

LOL, well, no, it may need a bigger jet, but the fuel needs will be the same power produced.

Also, think, a cooler air charge can run leaner. (In economy circumstances) Even more if the fuel is HOT and the intake charge s cool.

"Colder air makes mpgs better" WTF?

Yes sir.... Sorry it doesn't make sense to you......So maybe you should do some research, forget automotive, try piston aircraft engines, and all will be clear.

 

[fcm42000]

Without ram air the area forward of the throttle blades is a given negative pressure, period. With ram air it may not be enough to make positive pressure, but there will be a difference in pressures (negative) on both sides of the throttle blades. Now what happens when there is a pressure difference in two areas and a non sealed wall between them (throttle blades), hmmmm, well naturally they want to equal them selves out, if you argue with that you just plain don't get it.

Just to clarify, I am not asking in reference to air fuel ration, ok, get it? Just if anyone KNOWS if the lower vacuum (closer to zero/ambient) will affect how much the distributor advances at cruise because the affects of a higher pressure from ram air.

 

[fcm42000]

You will not "lower the vacuum" because any boost effect will result in LESS throttle

That makes sense

 

[green1]

You don't get boost, you get cooler air.

 

[dodgedifferent2]

I drive a 03 dakota year round with the shaker hood. Its a 4.7l ... i do notice a slight difference in mpg in the winter. I usually run around the 17-18 mpg in the summer avg 20 degree Celsius.

When the thermometer dips down below 0 degrees Celsius I notice the mpg runs in the 13-16 mpg range.

I will always be convinced no matter what someone says. More air equals more fuel. Colder air also takes more fuel.

From what i read in most places the dakotas with a 4.7 usually run in the 20 mpg range.

As for vacumn i have no idea.