I thought some of you might be interested in this. I thought it was interesting, and learned a bit from it.

http://www.vetteguru.com/ramair/

basically, it states that the concept of ram air at automobile speeds does not exist, hood scoops provide nothing more than cooler air, and 'ram air' is nothing more than a marketing ploy.

 

so tell me why ships sail in the the currents, could it be because more water is flowing and therefore bring more water/fluid with it past a single point than simple stagnant water? Why sit in front of a fan when you're hot? Because more air is flowing by you than would normally occur with stagnant air. You need the air to move away heat, the car needs a higher flow of moving "rammed" air for more intense explosions. If the air is stagnant it will move past the throttle body at one speed, if the air is flowing it will move past the throttle body faster.
Any idea why they put those big ass fans in front of cars when they're on the dyno?
issuez

 

I'm gonna call on this one and I don't even understand all that technical gibberish.

What I Have read over the years is that -most- of the factory designs, especially in the 60s-70s when every car had some sort of intimidating hoodscoop(s) didn't really work because they were too low, stuck in a static 'boundry' layer of air on the car's surface that doesn't flow so well. The exceptions would be the GM cowl induction that took the reverse flow air from the low pressure area at the base of the windshield (that's where the cowl hood that we know originated) and some of the early W30 442 cars that had scoops ducted under the bumper. So yes, many were/are just for looks.

However, look at racecars. Big money racecars. Pro drag cars, leMans-type cars, F1, whatever. Some of the biggest ass scoops you'll ever see. I guess raceteams with millions of dollars invested and on the line just give up aero so they car look intimidating to the competition. More surface area for sponsors' decals, perhaps?

I guess all the 8 second Mustangs better put that headlightt back in, 'cause that air is useless. Just duct it to a rear wheelwell or something. Idiot.

 

Ram air effect? Maybe not. But these are DEFINITELY better flowing intake tracts than having it flowing through some complicated intake tubing. If the air flows better into the engine (AND with less turbulence), it should result in more air in the cylinder, which would equal more HP. So there IS a reason for doing that, just not the reason most people think.

 

Don't know how true the article is, I don't pretend to know enough about fluid dynamics to be able to discredit or credit the guy. My first instinct is to thow the flag up too. After all, ram air seemed to make since to me, and why would all the real race cars have scoops? BUT, it seems that he may have a valid argument. Can anyone come up with some proof one way or the other? I'm still wondering.

 

That was an interesting read. ALthough, I have heard the same idea since the advent of the Ram Air Firebird. Questions I do have are: What constitutes RAm Air to most people? Is the author thinking that Ram Air is trying to achieve actual BOOST in the intake?
Has anyone seen the air route thourgh the Ram Air Firebirds? I heard it's a real torture chamber. Most scoope on the racecars I see are for Cold air just for the engine, the brakes, and various radiators on the car. I don't how many are actually trying to achieve ram air effects for their engine.

 

I beleive that you can get an affective ram air, but not below 100mph. I think it would help a 125+ mph drag car on the big end, but I don't think the added "ram air" effect will make a big difference.

 

So if you dyno a WS6 Ram-air T/A and a non-Ram-air WS6, the one with the "ram-air" gets higher numbers because its seeing colder air only??

-Adam

 

Yeah, I've heard in the past, that the "ram" effect is only about 1-2% HP increase at 100mph. So there may be some ram effect, although VERY little at regular 1/4 mile speeds. Almost all of any HP increase is from providing cooler ambient air to the engine.

Brian

 

A friend from work has shown me some more proof as to why ram air only provides cold air. He looked up some fluid dynamic stuff and found out that the guy is at least partially correct. In fact, the more we read, the more logical it sounded. Other than smoothing out the flow, reducing turbulence, and providing cooler air, I believe the 'ram air' kits don't provide any fraction of 'boost' to N/A cars, therefore one would see just as much performance gain out of a well made cold air setup.

just my .02, I sure would like to see some proof one way or the other, like some hp #'s to contribute to the theory.

 

I do know alot about fluid mechanics and the layer of air that is about 1-2 inches is known as the boundary layer and here is where there is minimal air speed in relation to the air passing over this layer. The ram air effect only comes into play at speeds over 100 MPH as Underpsi stated. This is why you see the Pro-stock, F1, and other race cars using a scoop. Also notice the placement of these scoops in relation to the main body lines of the car. All these scoops are way above the boundary layer of the car's surface so they are receiveing the air that is moving at the same speed as the car thus providing a ram air effect for the engine to digest. On a "street car" (a car driving under 100 MPH) there is no ram effect what so ever only a good source of cold air for the motor. The fans used on a dyno are mainly for simulating the air that would be moving across the car while driving for the intercooler. This does help a ton for a turbo/supercharged car otherwise the guys are just using the fan to push air across the radiator. At one time i actually had a customer purchase a boost gauge to measure the "ram air" his car was producing ( I was laughing my ass off the whole time) and it didn't even move the gauge off of zero at all. What a waste of money that was huh!

 

Over 100 mph? According to the article, that isn't even close to starting the ram air effect. What your saying makes since as far as the air in the boundary layer is moving closer to the speed of the car, but even if the car was going 200 mph, according to this guys theory (which he claims isn't a theory, but a fact), it still wouldn't make any 'ram air' boost.

yes I know that the f1 cars, etc. etc. all use high scoops, but does that mean it provides the 'ram air' affect? obviously everyone thinks so. I don't know. I'd like to see some proof it does, regardless who uses it. Either thier assumptions are untrue about ram air, or this guys idea of fluid dyamics is wrong. So what is it? true or not, ignoring any cool air, non-turbulent air, etc.. etc.. , does anyone have any proof that 'ram air' pressurises the air in the intake?

 

When i was saying over 100MPH that MIGHT help increase the intake pressure 0.01 psi which in an order of magnitude is absolutely undetectable without either an extremely sensitive dyno or pressure sensor. I agree with the guy who wrote the article 100%. The velocity of the air entering the intake however would increase thus allowing more air to enter the combustion chamber. This i feel is the main reason all of the race cars use these scoops. The speed of the air is increasing but that doesn't have to mean that the air in being compressed in the intake. I hope that clears up what i said earlier.

 

so the car gets the cooling effect of driving so it does not over heat.

 

So you agree, Well, I'm glad I'm not the only one. I was watching hot rod TV the other day, they installed a ram air kit, and were assuming they would get a 'ram air' affect on the car, even those obviously haven't looked into it. I think that the majority of hot rodder's out there aren't aware of the non-existence of 'ram air' at auto speeds. It definately shook my way of thinking up some.

 

Or the high dollar race teams use NACA ducts which work with the boundary layer air. Those propeller heads working for NACA in the 40s and 50s knew a thing about airflow.

The problem I have with this guys speach is that I don't recall anyone ever claiming that the ram air systems "pressurized" anything.

 

You mean NASA? like the ducts the roundy-round cars use to cool their brakes?

I agree with the guy totally, I've taken a fluid dynamics class and can attest to it.

Ram air is totally a ploy for manufacturers to sell more cars!

 

No, I think he means NACA.

There was a great article about this in Sport Rider magazine not to long ago. Like car manufactures bike manufacturers have provided some type of "Ram air" on their top of the line bikes. Sport rider took 4-5 bikes with factory ram air and outfitted a highly sensitive pressure sensor in the airbox to measure the pressure of the air charge. What was funny is some of the bike produced a positive air charge around 100 -120 mph and then dropped off as speed increased almost like the fast air rushing past the vents was drawing air out of the air box system. For the most part the bikes saw an air pressure gain that would add 1 -2 % hp above 120 mph.

Now as far as turbo cars go the best example I can think of is Ken Rubeks T-type. Car is a solid mid 8 second performer at high 150's mph. As an experiment they added two Naca ducts in the hood to feed the turbos pressurized air, car responded with a 5 or 6 mph gain if I remember correctly which would probably account for 4-5% increase in power. Now whether this was a direct effect of ram air or just two turbos that were starving for air I don't know.

 

NACA was the father of NASA. It stood for National Advisory Committee on Aeronautics. NASA was created in late 1958 and NACA was disbanded. Those ducts your talking about were designed by NACA engineers for the X plane programs in the 40s and actually do use the boundary layer air to present positive pressure through their ducting.

 

For some real world, before and after results.. I added a Kenne-Bell ram air setup to my car.. Magazine test had dubbed it one of the best flowing designs on the market..

On my car, I lost close to 2 mph.. Tried everything to tune back in the lost power, with no help..When I called Jim Bell, he told me to try it with the hose from the scoop under my grill removed (that told me something right there).. The car ran a little better, with the kits 8" cone sealed to my fender opening.. It ran the same with just the cone without it's fender sealing inclosure.. I was never able to get my full power back, until I reinstalled my stock airbox with the K&N panel filter...

My test concluded that the ram kits they sell Fox Mustangs are a waste of money..

On a side note..The guy I sold the Ram Air kit to, swears his car runs better..He never goes to the drag strip, but he feels his throttle response is better.. I'm glad he's happy..