I was just wondering if there was a ram air intake available for 2nd gens, or if anyone out there home depoted one themselves. I remember someone saying that they had one on some other post, but couldnt remember which one. I thought about doing one myself, just wanted to see if anyone else had any ideas. i dont wanna do any gay ricer thing sticking a cone out my headlight or anything, something clean. Any ideas?

 

well, a hood scoop will not give you that effect. Here's a pic showing the pressure ares on the RX-7. As you can see the only way to get a ram-air effect would to have some ducting going near the bottom of the car behind the grill. But if you did that it would not be a true ram air since ram air setups are designed not only for forcing air into the engine, but have the shotest/straightest route possible. It would be more of a glorified cold air intake......how ever it would probably produce some gains. Good luck.

 

Man, where the HELL did you come up with that pic? It looks like something that might have been in the FSM, but I know it wasn't. Definitely has a factory look to it.

Also, it seems odd that the entire front end of the car, as well as two-thirds up the hood would be a low pressure zone. And I thought they spent all that time in wind-tunnel testing to make it flow air smoothly across all surfaces of the car. Looks in the pic like there are flow separations all over the place. Am I missing something here?

Ren

 

I think piping could be possible from the stock airbox location to the front of the rad. It wouldn't be very straight, but it would pull in cold air which a lot better than the hot air inside the engine bay. A couple of 1st gens have done this, and it looks pretty cool. This is what Pittdp did to his first gen.

CAI

 

No idea where it came from. Someone on here posted it before and I saved it to my computer.

 

When I first saw that pic here I was amazed at how useless the turbo hood would be and how those fresh air head light replacement would be BUT how much a nicely done cowl hood up to the windsheild would rock!

As for the ram air I have seen lots of cold air feeds but nothing in a way of true ram air. I think theres just to much sheet metal in the way.

 

Why dont you jsut take out one of the ftp lenses and get some dryer piping. that would do some ramming

 

Would enough air get through there to feed the engine? Seems like those aren't big enough to have a sufficient air supply.

 

Well i look at it like this. It flows more than the stock intake so its better than nothing. im not sure but i think ive seen it done before so it might work. I was just making a suggestion

 

That might be a good project for me over X-mas break.

 

I was going to link you guys to some pics of Brian D. Cain's set-up, but this link doesn't seem to be working for me:

http://www.angelfire.com/home/rx7tur...dAirInletDuct/

Does anyone else get an error message from angelfire when clicking that link?

 

Sure do.

 

Recently, I realized that I have access to a machine that can mold plastic... If I make the design I only have to pay for the molding costs, (materials) and the sheet plastic... So this will be relatively cheap to me...

My question? What design do you guys suggest...? I plan on replacing the air box, and fabricating a one piece ram air system... but where? how to route it... etc... any help would be great... thx fellas

 

go out the FTP hole or figure out how to get down and around to the front of the radiator. Might have to utilize a two or three piece thing, but it could prolly be done.

 

How about a ram air from the FTP hole over the support into a replacement top for the stock airbox? Im not sure how much space is actually there between the hood and frame but something the width of the air box wouldnt have to be that tall. Or one fromt he drivers side routed through the sheet metal then over the top of the radiator like the stock snorkle. Maybe even incorperate the stock snorkle? Ive been thinking about this off and on myself.

Ok theres is my misc. ramblings.

 

OK, I saw that diagram on here before and I believe that people are misinterpreting it. At first I couldn't make sense of it (and my undergraduate degree is in aeronautical and astronautical engineering!). But after looking at it, here's what I think it's telling you.

First, the diagram is showing you pressure vectors orthogonal to the surface of the vehicle (perpendicular). This tells me that they measured the pressure exerted on the surface of the car itself. Therefore, as shown in the diagram, the nose of the car will experience relatively high pressure, because it is the first part of the body of the car to encounter relatively still air (not entirely still, but relative to the air flowing around the car, it is still). One thing that can be confusing is the diagram on the lower front air dam. But not really. The fact is that the air flowing past the air dam encounters very little obstruction (maybe the oil cooler, but even that is tilted thereby allowing the air to flow past it rather easily). Therefore, since the air flowing past the lower dam doesn't encounter anything (e.g., sheet metal), very little pressure is experienced on the surface of the vehicle.

Now, here's what's confusing most people, I think. The pressure exerted perpendicularly on the surface of the hood decreases as the air flow moves up over the hood. This is a direct result of the laminar (smooth) characteristics of the air flow. Picture a wing on an airplane. Why does a wing fly? The laminar flow over the top of the wing is flowing very fast (compared to the underside of the wing) and, as a result, the pressure is lower on top of the wing (pressure low on top + pressure high on bottom = wing goes up). Similar things are happening in the diagram. The flow over the hood is smooth and fast, therefore the pressure exerted perpendicularly on the hood, drops as the air speeds up. Thus, the pressure vectors in the diagram decrease in magnitude. as you move over the hood.

Pressure drops further where the hood meets the windshield because an area of stagnation is created. Picture the air flowing up the hood. It hits an obstruction (the bottom of the windshield) and some of the particles stop. More particles back up behind these particles and the air flow slows down. Now, as you get just a little bit higher in the air flow, it remains laminar - imagine the air gently curving from flowing over the hood to flowing over the windshield. But there is still this area of stagnant air very close to the car, where the air is not moving much and, as a result, there is low pressure on the surface of the car.

Now, notice how the pressure increases as you move up the windshield. This is where the laminar flow from the hood encounters the windshield (it doesn't hit the base of the windshield, remember, because of the stagnant air there). But note once again that, as you move over the top of the car, the air becomes laminar again and, as a result, the pressure drops (just like it did over the hood).

Why does the pressure go up again as you move back over the rear glass? Because as the air flows past this point, the laminar flow wants to continue flowing straight back. Therefore, the flow separates from the vehicle and becomes turbulent. The area under this turbulence is lower in pressure and, as a result, the air tends to curve back toward the surface of the vehicle. Thus, the pressure exerted on the surface of the vehicle goes up.

Once again, as you head down the liftgate glass, the flow becomes laminar and the pressure on the surface of the car drops. Until it passes the tail of the vehicle. Once again, the air becomes turbulent and curls down behind the vehicle, striking the rear of the vehicle, thus causing an area of relatively high pressure (this is counterintuitive, I know). Have you ever seen a BMW car carrier? It has the canvas on the sides enclosing the vehicles? Well, it has a "boat tail" cap on the back of the truck to prevent this turbulence at the rear of the truck.

Back to the diagram . . . as the air flowing from underneath the vehicle passes the tail, it also curls up in a turbulent manner, creating pressure on the rear of the vehicle.

Well, that's it folks. What's the bottom line? Well, a hood scoop on an RX-7 is fantastic for collecting all that laminar air flow going over the hood. A great ram air system could be constructed, therefore, by putting a scoop on the hood. Just because the pressure perpendicular to the hood is low (static pressure), the pressure parallel to the hood which results from the speed of the air (dynamic pressure) is very high. Of course, putting such a scoop on the hood would mess up the aerodynamic profile of the diagram .

Good luck,
Dave

 

Dave,

Thanks a LOT!! VERY good article. That clears up a lot. I have a couple of q's, but I'll have to ask later.

Ren

 

OK, ram air is a natural way of supercharging in which air is forced into the manifold and the combustion chamber. Usually this is done through the use of a hood scoop to give the air a straight shot with little in its way. Think of the stock airbox. I can't even count how many bends the air goes through (let's see, one at the snorkel, one at the filter, blah, blah).

The Firebird made use of a low hood scoop down by the headlights to collect the air and send it on it's way. Obviously utilizing a stock TII hood in some fashion isn't really feasible. If you put the filter down in front of the radiator, that will kind of force it through, as the nose sees lots of airflow.

Really, it's not worth the trouble, IMHO. You're on the right track with the cold air part. Bring the filter to the cold air. Not bring the cold air to the filter. In actuality, I don't know how big of a gain you could expect. Heck, ditching the stock air box was about as much as I would focus on the intake.

 

njdave I think you are wrong. the diagram is a graphical representation of the pressure diference of the air as it flows over the body of the car. look at the nose. cut out the bottom just below the side marker light and front to back just behind the side marker. That is the front of an airplane wing! as most people know the airfoil of the wing creats a pressure difference causing lift. The top of the windsheild is also an airfoil.
it only takes 3 psi difference on top of the wings to lift a 747. the diagram is showing you the angle of the lift or drop.
If you will notice also, the very front of the car creates a negative pressure difference slightly forward. This is also due to the arc of the nose. I am currently trying to build a front air dam that lessens this effect while at the same time cutting the frontal area.

Happy flying

 

tweaked,

I'm sorry, but I'm not sure I understand your point. You said I'm wrong, but I don't see what you mean (and I don't think I'm wrong). As mentioned above, I explained (rather crudely) the similarities between the picture and an airfoil. In fact, in college we ran airfoils (and other shapes) through both subsonic, supersonic, and hypersonic windtunnels. For low speed windtunnels and relatively thick airfoils, you get very similar patterns as that shown over the hood of the car in the diagram.

After studying the picture, I am convinced that it represents pressure vectors at specific points along the surface of the vehicle. This pressure is not total pressure, but is static pressure. You get a very similar static pressure representation when you run an air foil in a wind tunnel).

If I got something wrong, let me know.

Dave

 

That's from an issue of rotary rocket magazine back in '85 (I think). It was the preview of the new 2nd gen. Someone scanned the entire magazine in, ads and all. I've got it bookmarked on my other computer. You can search the 1st gen form for it if you like. (don't know why, but that's where it's posted)

 

NJDave,
I think you are right. The best place to put a Ram-air on the car would be about the place where the FTP's are. It makes sense.
The negative pressure on the front lower part could be corrected with a simple chin spoiler or splitter.

 

OK, this is my plan for a ram air that I still havn't gotten all the way finished. Right now I'm waiting on a little bit more $$ to get my front end painted. You can see the chipped part in the pics.

We all know that air flows really easy into the oilcooler area so with that idea I wanted to create a ram air below the airbox.

Similar to http://www.angelfire.com/home/rx7tu...ldAirInletDuct/

(link was down though, i've looked at it alot)
In that link there were pics of a hole being cut out below the stock airbox location and a pipe with a cone filter being inserted into the space infront of the wheel well. I want to place my ram air there and force it up into the engine bay instead of putting the filter down low where rain ect. can get to it fairly easy.



in the above pic you can see that air flows easily.

I have cleared out the space down infront of the wheel well, there is the washer bottle and a sort of filter for air that leaves near the 6 port auctuators. With all that removed I also took out my fog lights. I am planning on fabricating a sort of 'dust pan' ram air but I still will cut out more to the opening below the air box. I have an aftermarket K&N cone filter so There will probably be problems with keeping the stock airbox with this setup.



Ive done 1prototype with the little 'O' hole that is below the box, and both had good results, after hard driving the filter was cold to the touch and the car seemed to have no problems, however after I created a cold air box that would channed air directly from the opening I lost power. Right now I'm planning on using an aluminum sheet and some cardboard for a template whenever I get my front end off.

ugg long

 

Xentrix,
I was also thinking of putting something there where your fog lights are, but that leads directly to the brake rotors to cool them off, so I really didnt wanna mess with that. Well foglights were there on ur car so nothing was going through anyway, so.. But I thought maybe not a good idea to mess with that hole. IMO