patman

iTrader: (3)

ok..well..it seems that everyone has a conflicting opinion...and i myself am somewhat biased since i wanna defend my idea. so... im just gonna go ahead and hack a chunk outta my spare hood and fab a scoop on there..in the very front like i said up there somewhere...and see what happens...and if i feel like it maybe i'll put one in back at some point, too.

so..seeing as i have about as much free time as a nympho in a nudist colony, it may be a while, but this will happen sooner or later and i will report my results when i do it.

thanks for all your advice everyone.

Pat

Evil Aviator

Please use some test equipment to see how it works out.

In ideal conditions, you will probably get about 0.15 psi. In less than ideal conditions, you will build a restriction rather than a ram air intake. If you can get 1.5psi boost at 100mph, you should call NASA because your invention would probably be worth millions of dollars.

If you copy that intake, you will get about 10 times as much ram air boost out of your RX-7. Since that Pontiac scoop is totally non-functional as far as ram air boost is concerned, its ram air boost is 0. Therefore, copying it onto your RX-7 will yield 10x0 = 0 ram air boost.

FYI, a "functional ram air scoop" means that it has actual air inlet cutouts as opposed to fake ones (stickers, black paint, etc., made to look like holes), not that it has any ram air boost function.

patman

iTrader: (3)

ok well then why do they put it on there? why do they have a plaque on the side that says v6 ram air? so..yes it seems rahter functional to me.

and someone please tell me what is wrong with my math up there somewhere.

and fyi it is rediculous to surmise that this will be so inefficient as to be a restriction. cmon use a little bit of sense. obviously there will be air peing pushed into the scoop..thats a no brainer. and since the stock intake has to suck the air in... any amount of pressure or flow...whether or not it is sufficieant to build manifold pressure..will make the intake more efficient..and therefore produce (if only slightly) more power.

it is a documented fact that ram air intakes are functional. ever heard of a firebird ram air? those are supposed to build ~20 more hp than stock at speed.
and hell the thing that you sent me about the viper...the guy concluded that he was making 40 hp at 200 mph.

now i cant go 200...and yes its an exponential scale, but if it had 0 effect at 100, then using your own mathematical methods, 0 to any power is 0, so how could it ever make any power? he also said that the viper scoop became noticeably functional at 120...which means that it would in fact increase my top speed.

basically, like i said, i am going to build the damn thing and see. for all you naysayers that means one of two things...either you can have fun laughing at me, or i can have fun laughing at you.

Evil Aviator

Hehehe, I love it when people ask for a technical opinion, and then totally discount it based on advertising hype, urban legend, and wishful thinking.

Warning, don't read these links if you can't handle the truth and would prefer to live in LaLa Land.
http://www.vetteguru.com/ramair/
http://www.amcgltd.com/archives/002681.html

88IntegraLS

For whatever it is worth, I will have a vacuum / boost gauge tapped into my dynamic chamber in a month or two, as well as a sealed air box fed by a duct from my rightmost bumper opening. I will report my data. I'm hoping to eliminate all vacuum in the manifold with ram air; basically, the idea in my mind is to use ram air to overcome the restriction in the manifold, not generate any real boost.

Amur_

Some reading for you:

http://www.gmecca.com/byorc/dtipsaerodynamics.html

Amur_

From our own 2nd Gen archive:

https://www.rx7club.com/showthread.p...threadid=36934



That comment comes from a member whose undergraduate degree is in aeronautical and astronautical engineering.


Go grab your duct tape and get to work!

monkeytown

seems like a good idea...

patman

iTrader: (3)

ok...i reluctanly (and still somewhat skeptically) concede that a ram air scoop will not give me any measurable amount of boost. however, this does not mean that it will not increase performance. as 88integrals says, so shall i do. lol. but really, i have said all along that even if this system does not make boost, it cannot be said that it will not increase power. if i can use the velocity of the air to get more air past the restrictions of the afm and more air thru my filter, which obviously i can do, then i will be a happy guy. basically, if ram air cannot cause boost, it can still increase efficiency by removing any negative pressures caused by restrictions. like he said, if i can get enough air to make my manifold pressure 0, then i will stand to gain a few horsies.

Evil Aviator

It's difficult to decide whether to put a ram air intake in the low-pressure hood vs. a higher-pressure area like the front end or cowl. It comes down to the design, where the high pressure area will probably make it easier for a poorly-designed intake to pick up some air that is already pressurized, while a low pressure area will have a higher velocity that may be better for a well-designed ram air scoop that can decelerate the air more efficiently.

BTW, I'm the person who originally scanned that aerodynamic chart from the Rotary Rocket magazine. Since then, it has appeared in a lot of places over the internet, which I find interesting because that scan is pretty bad, lol.

Oh yeah, and my degrees are in aeronautical science and aviation technology.

Like I said, copy the WS6 scoop and get nothing except maybe colder air. However, make a very well designed scoop with a sealed system and you can shoot for about 0.15psi boost at 100mph. I recommend converting to a standalone EMS so you can get rid of the AFM and monitor your manifold absolute pressure (MAP) and other parameters like the manifold air temperature (MAT).

More links (I have so many links saved to my Favorites that I have trouble finding them sometimes, lol).
http://www.xs4all.nl/~zx11/uk3.htm
http://www.200mph.net/info/mods%20ram%20air.htm
http://www.vararam.com/reality_of_ram_air01.html
http://www.camaro-untoldsecrets.com/...es/rpo_zl2.htm

downwinddave

Have you looked at a NASCAR hood lately? Where is the air intake?
Interesting TV program about Da Judge and Pontiac Firebird wizard Delorian...they put the scoop on cause it looked cool. It was not functional. Urban myth.
Some folks engineer something, others hop on hype!

patman

iTrader: (3)

haha yeah right nascar. the day i start basing my mods on nascar, someone please shoot me in the head. nascar is pathetic. their cars are not engineered to be super fast..they have too many limitations. it isnt really about the car, because nascar cars are all very close to the same. are you tryingto say that because nascar doesnt do it, it isnt worth doing?

and, if you will read all the posts here and the links, you will see that the general consensus is that ram air is not capable of producing any signifigant amount of boost, BUT it is capable of bringing intake pressures up from negative to close to, or just over, 0. this, if engineered correctly, can have an effect of quite a few horses.

Pat

downwinddave

Explain to me again...

The out arrows (vectors) are ? pressure.

The in arrows are ? pressure.

The ram air goes where on the hood?

It looks like the hi pressure is below the bumper and at the cowl in front of the windshield?

Is that correct?

Evil Aviator

My FC's rollcage was designed and built by a NASCAR safety inspector. I will put it up against any Rice rollcage that you can buy from Nopi. To dismiss any and every aspect of NASCAR based solely on a few rules which define the racing class is an odyssey into ignorance.

BTW, the last time I saw a NASCAR up close and personal, it had cowl induction similar to the older model at the top of this link:
http://www.fordfairlane.com/nascarpics.html

... at low speed. However, at high speed, the boost becomes more significant. Also, most of the information on ram air that you have seen so far is with respect to non-turbo engines. When you consider the fact that turbochargers multiply pressure rather than adding it, the ram air benefits are also multiplied in such an application.

Yes, those are just pressure vectors, and I don't know what vehicle speed they represent, but I'm going to guess 55mph because that was generally the target speed in the 1980's. The vectors represent only the pressure points on the car, and do not indicate where the air actually FLOWS. This is why a laminar-type ram air scoop like a NACA duct would not necessarily work well, because you do not know if there is a boundary layer separation somewhere on the hood. It all comes down to placement really, so trial and error may be in order prior to getting good results with a laminar-type scoop.

The closest thing I have to airflow around the car is this CFD rendering. However, it's just an independent computer simulation rather than an official release from Mazda or an actual wind tunnel test, so take that for what it's worth.
http://www.geocities.com/evilaviator/aero

downwinddave

I guess 200 mph for 500 miles cars don't care where they get the air from...

Evil Aviator

Hehehe, did you miss the title of that picture, or do you not know that cowl induction IS a performance enhancer?

patman

iTrader: (3)

ok well the paln is...scoop replacing the front of the hood and the top of the bumper...no that is not an extremely hihg pressure area, because normally the air flow smoothly fron the apex of the front bumper over the hood and so on. however, because the air flows smoothly there, it is at high velocity, and a properly positioned scoop will take advantage of this to consume lots of air.

from there it will go to a pressureization chamber thingy..i dont have the dimesions/shape figured out on this yet, then thru a short pipe and into the filter, afm, etc.

sound good?

well even if it doesnt im gonna do it anyway...

pat

trumper_82072

How did your idea work?
Crazy ideas from a guy no where near as smart as
others-hood scoop off center for straight shortest route,
-two or 3 of above mentioned ideas combined.

patman

iTrader: (3)

i havent done it yet..blew a tranny and a differential mount, and since all i have is one day a week to work with, i havent gotten anywhere yet. I oughtta be able to get something done over thanksgiving or xmas break tho.

Pat

patman

iTrader: (3)

bringing my own thread back from the dead...i have since sold the NA, bought a dead TII, and rebuilt it with all kinds of mods....anyway..im now thinking about this for the TII. I had been thinking about a NACA duct on the fender, like just outside and in front of the stock airbox location, but ive been finding a lot of negative info on NACA ducts, so... I may go for a large vertical scoop in that same place (puppy eater), or a scoop in the brake duct/radiator area...

couple questions..anybody know a lot about NACA ducts??...a friend of mine used to very active in GT racing and he liked that idea...but..i need to know what dimensions would flow enough cfm for me.

also, ive heard that the headlight cover intakes force you to use only 1 headlight...is that true?

pat

Evil Aviator

It's easiest to simply buy a pre-made duct with an outlet sized to your intake pipe. Example:
http://www.racerpartswholesale.com/naca1.htm

Home-made ducts:
http://www.wisil.recumbents.com/wisi.../naca-duct.htm
http://www.rguerra.com/velocity/fina...Structure.html

See the NACA site for all the engineering geek details. Search for "submerged" inlets.
http://naca.larc.nasa.gov

patman

iTrader: (3)

cool thanks evil