What do you all think?

ram air myth

 

I believe it - although my 96 WS.6 has basically the same exhaust as the regular f-car, except for the tips.

I also think it was proven by the CAI kits gaining 20 hp (dyno proven) on the regular lt1 f-cars.

Joe

 

I totally agree with the ram air myth. Most production sports cars ( I don't include Ferrari's, Porsche, Lambos, or other excotics) wont even see speeds above 150. Thats about when the ram air effect may gain you 2 or 3 horse's.
And when the engine can take advantage of air speed around it to provide a ramming affect, its not even worth it, because when your going 160+ your more worried about aerodynamics, and drag caused by a ram air scoop, than adding 10-20hp.

I will say that ram air scoops will help performance for a few reasons.
One, a properly designed system will eliminate alot of the sharp turns the intake air must take to reach the engine that are normally found on a non ram air model.
Two, the majority of the time, the under hood temps of a car are much higher than outside air is. Bringing in cooler air into the engine will inscrease performance almost 100% of the time. So the ram air scoops add a place where cold air induction can be used.
And if your taking your modded Z06 to the track and running 175+ down teh back straight, yes ram air will help you pick up a few horses, but I don't think most people will notice it, especially at 175 plus.
Another thing, it is very hard to test the performance increase of a ram air system, as on a dyno the car is staionary, and even with a huge fan blowing air on the front of the car it still won't simulate accuratley the ram air affect.

So I say, unless you really want the ram air hood (which looks freaking wicked on a black trans am!!), spend your money on another option.

Hunter

 

I was skeptical but my first drive after installing FTRA made me a believer. The car pulls harder and harder the faster you go and the increased pull starts well before reaching triple digit speeds. Throttle response has also improved throughout the rev range (at any speed). Ram air has a mild supercharging effect and you can really feel the power!

 

There's a good example of the calculation of the potential gain, using "velocity head" as the basis, in the "Automotive Math Handbook" by Forbes Aird. He demonstrates that the potential pressure gain is about 1% at 100mph. That means in a stock LT1/LS1, you are looking at about 3HP. However, in a 500HP setup, that's 5HP at 100mph, and since the gain is rpoportional to the square of the speed, that's 10HP at 141mph. Whether that's of value depends on how badly you need that extra 5 or 10HP.

Of course that same "square of the speed" rule means that you are only seeing a potential 3/4HP at 50mph.

It is also apparent that the shape of the 4th Gen Ram Air intake, both the LT1 and the LS1 is far from ideal, and the presence of the baffles and the "tortuous path" they prescribe may well negate all gain.

However, open those baffles up and reshape the ducting, and its a bit more "real".

 

Exactly what injuneer said.

I know how the ram air birds feel, they definatley pull harder than a normal bird, but its not because of the supercharging affect. But as Injuneer said, if you have a 750 hp engine it might matter.

Hunter

 

750 hp? It is well known FTRA is good for a few miles per hour in the quarter.

 

It doesnt RAM air past the filter, I mean there are freaking walls in the hood that block any sort of air flow that would have enough force to ram anything, but it is like cold air once you are moving atleast 25 mph and looks badass, I know its cold air becase I htested it out with datamaster and when I was sitting the air temps started to rise and I started moving and they quickly went down to around the outside temperature. Either is fine I would say ram air looks badass adn gives gains when your moving as well as gives a strait shot to the tb with less heat soak, maybe not so much from the factory since the filter is so covered by the plastic crap, but if money is a concern and you really dont care for a new hood CAI all the way...

 

There certainly isn't much ram-air effect below 100 MPH, but testing on motorcycles by Performance Bikes and Sport Rider have proven that it does exist at higher speeds. Both mags put a variety of bikes on a dyno and ran them up while measuring the airbox pressure, and then did the same with the bikes running around a track at top speed. Well-designed systems using diverging tracts and a large ratio of airbox to cylinder volume showed some not-insignificant gains (I seem to remember that the Hayabusa showed a pressure increase of about 5%), while bikes with poor tract design or small airboxes showed no increase or even a decrease (such as the Suzuki TL1000R).

But, yea, the cold-air effect is certainly what's most noticable at "mortal" speeds.

 

The concept of velocity head demonstrates the pressure increase at the scoop inlet. That pressure increase may not all be "recovered", as a function of the shape of the inlet. But pressure is pressure, and if you have a higher pressure on one side of the baffle, or of the filter element, you will have a higher pressure on the other side of it.

depends

Air temperature doesn't vary with velocity. What you are seeing when you were "sitting" is "heat soak" of the IAT sensing element. When you start moving, the air doesn't cool down, but it removes the heat soak from the sensor and the air box.

Other than totally eliminating the inlet duct, its hard to see how you could get more direct than this.

 

injuneer, thats what I meant by once you get moving it allows cooler air to pass through the hood when moving where as when sitting its not and hot air is being sucked in under the hood, I did see a test on ws6.com that showed the maf sensor reading more air flow at higher speeds in different gears with ram air but it wasnt really proportional to the speed so not sure what it proves.
Have to check out your links later some reason the work computer wont allow my to navigate through links....???

 

What Eric may have alluded to, is that the ram air on a motorcycle has access to 'cleaner' air than full bodied vehicles. This means if the induction system is well designed, IE, a straight path to the TB, but locates the air intake in an area that does not lend itself to high pressure, if won't be an efficient system as a whole. Therefore, the ram effect will not be as effective. AFAIC, like spoilers/wings, most oem ram air placements are designed by stylists, and not engineers. It should be noted, that high pressure translates into low velocity. IOW, you do not want to place the intake opening in a location of high velocity. An excellent reference book would be one authored by Joe Haile, entitled 'Motorcycle Turbocharging, Supercharging & Nitrous Oxide'.

 

As I attempted to explain above, it's one or the other. You won't get both at the same location. They are opposites.

 

edit: I just reread your post, Arnie. Now I get it.

 

As an owner of a 1996 Z28 SS, I believe there is some net advantage to Ram air. Below are some estimates of the effects:

1) On any given Revolution of the engine there is a maximum intake of 175 cubic inches of air consumed (VE=100%)
2) At 60 Miles per hour, the vehicle moves at 1056 inches per second. (5280/60/12)
3) If the opening of the Ram Air is 3 X 8, that is 24 cubic inches of intake potential. (discounting restrictions, etc.)
4) If the vehicle is moving at 60 MPH and the engine RPM is at 1500, then the maximum air intake being pushed through the
plenum is 25,344 cubic inches per second. Wheras the maximum intake is 262,500 cubic inches of air. (<10%)
5) if the vehicle is moving at 60 MPH and the engine RPM is 3000 RPM, then the maximum air intake being pushed through the
plenum is still only 25,344 cubic inches per second. Wheras the maximum intake is 525,000 cubic inches of air. (<4%)
6) The engine does not operate at 100% efficiency, nor does the ram air. In each case, if the VE was low and the
ram air was extremely efficient, then the percentage of ram air would be higher.
7) Conversely, as the RPM rises (I.e lower gears), then the RAM air factor is reduced in relation to the intake demand.


However, this 4-10% ram air effect does offset vacuum that is present when the throttle is light. The effect during acceleration may be enough to generate some additional velocity during the initial foot stomping. In addition, any ram air should increase the velocity inside the intake plenum to some minor degree.

This is not a scientific breakdown and the results are probably even lower than shown. But at 40% VE, light throttle - the ram air may rise upwards of 20% of total air intake.