How do people that have ram air hoods and such drive in the rain? Am I missing something here?

 

I believe that most ram/scam air intakes have a baffle that keeps the rain from getting to the filter. JMHO

 

There are two baffles immediately behind the hood openings (at least on the factory and SLP hoods). One is attached to the underside of the hood, pointing down. the other is on the inside of the hood, pointing up. The air bends down 90-degrees, makes a sharp 180-degree turn upwards, throwing any water on the "floor", where it drains out several holes. Then the air has to make another 90-degree bend to reach the air filter panel.

I cut the baffles back a bit, and had no trouble with any water getting past them. Just keep them overlapping slightly. Since my car is now "track only" I cut the baffles out completely, and I have to put a foam plug in the opening even when I'm towing it to keep the rain out.

http://cjcfo.fbody.com/members/injun.../Hoodscoop.jpg

Bubba.... don't believe everything you read on the internet. The article that says "ram air is a scam" has several tech errors in it. Essentially, he is treating is as closed channel flow, and that's not correct. The increase in pressure at the hood openings can easilly be explained and quantified using the principle of "velocity head". Not a lot of gain, and even that small amount is reduced by the hood boundary layer, the inefficiency of the shape of the openings, and losses due to all the bends. Ram Air is not a "scam", its just over-rated. You might want to think about why drag cars have a scoop sticking 18" above the hood. Pressure gains are proportional to the square of the speed.... not much there at 50mph, but at 200mph, the gains are appreciable.

 

I didn't read anything like that...I have been using that term since I bought my SS in 97. I use the term Scam Air, because the air is not rammed, but inducted, just like a CAI. The scoops that sit on the hood of a carbed engine go directly (do not pass go) to the carb or SC which is much more efficient than the circuitous route that e.g. the 97 SLP plenum routes the inducted air.

Of course I know that you know what I'm talking about...I just have a thing about those who continue to call a hood scoop an "ram air system " or CAI a Cold Air Intake"(btw CAI doesn;t mean the air is "cold" either) so I guess I'd say that both terms, to wit: Ram Air and CAI are used quite indiscriminately, but hey this is just my opinion.

For that matter, any vendor who claims that the aftermarket hood scoops or the SLP system "rams/packs" the intake is in effect fooling/scamming those who actully believe that you are getting anything close to a true ram system i.e, a SC or Turbo setup. Kinda like the infamous Tornado.

 

Ramair can happen at high speeds high enough speeds that aerodynamics matter and the scoop hurts enough to about negate the gains, in a street car though they are basically just a ambient air intake as in not heated by being underhood just outdoor air temp. There are a couple of great ones for the b-body the RAISS and SSRI, you guys don't have room for it though. There is one called RAMIT that does have water problems but not rain it mounts the inlet at the air dam and puddles have resulted in a lot of drowned engines and a couple destroyed ones.

 

This is quite battered about, but I don't think everyone is convinced, one way or the other.

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 (in a pretty linear/perfect example):

1) On any given Revolution of the engine there is a maximum intake of 175 cubic inches of air consumed (VE=100%, 350 c.i.)
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 sq 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 (uncompressed). Wheras the maximum intake, at 1,500 RPM (6th gear), is 262,500 cubic inches of air. (<10%)
5) if the vehicle is moving at 60 MPH and the engine RPM is 3000 RPM (3rd gear?), 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. (a minor variable to consider or dismiss)
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 engine vacuum that is present when the throttle is light (15-18" hg). 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 10-20% of total air intake versus vacuum.

I think it has an effect, however it is completely insignificant at low speeds/pressure and minor, at best, during high-speeds. I also think if you are at cruise with very little throttle (60+) , there may be some positive pressure on the air filter, but once you open the throttle, the vacuum is such a tremendous factor, that it is probably negligible.

I also agree that Cold-Air Intake isn't cold at all, but only equal to outside air temperature, AT BEST! Even an intercooler does not reduce temperatures below OAT, it just removes excess heat that was created during compression in the super/turbo charger. However, if you draw in engine cavity air, it is typically about 100 degrees hotter than outside air.

No great answer, but the sure do look cool!

 

That's exactly what I said.

 

Actually to really build pressure even at speed the inlet needs to be small feeding a larger chamber behind, someone did testing with a motorcycle and even with a perfectly shaped box the pressure gain was a couple decimal points of zeros before you hit an actual number. Guys have tested modified stock airboxes on b-bodies vs. the "ramair" setups available and at best the ramair system simply dropped inlet temps to ambient faster with all gains being in the first few feet of track. If ramair really worked at street vehicle speeds they would have seen an increase in MPH but didn't. Don't mistake what I am saying as bashing "ramair" I have the RAISS on my car. I just see it for what it is and that is an effective short coldair system. There is a boot on the TB directly to the MAF and then a scoop is fitted over the maf and then the cone filter goes over the protruding end of the MAF. Here maybe a pic will help http://www.regionofdoomforum.com/Upl...ebe0ae4589a6cf hope that worked. I know it is a mess but it is a 160K salt belt car so pretty is not a concern or even realistic hope, the ricer blue hoses are goodyear himilers and the color was a downside. You can't really see it but there is a piece in front of the radiator to force air up over the core support.