RotaMan99

My first intake thought was to just throw the intake filter bhind the front bumper by moving the radiator forward (radiator part already done). Then I was thinking, why not make it a ram air system. I still need to look at the internal support for the bumper but I was thinking of placing a metal rectangle shaped port in the middle of the bumper where the black strip is and it would angle backtoward the rad to a pipe which will bend over to where the air filter usually is and I will build my own sealed box that will use those rectangle K&N filters.

You may not be able to picture it and I will see if I can come up with a picture. So don't stress over how its going to look right now since that isn't the most important thing.

Anyhow, question, why is the stock intake tube so big and over sized for the ports in the TB? Im guessing that if it were the same size as all the ports combined it would in theory simulate a longer intake manifold?

I was thinking of using 3" pipe. I think the last time I measure the stock hose it was 3" but I can't remember. 3" would be tough to get behind the radiator so I was thinking of using to 2.25" OD pipes which would equal the same volume ID as a 3" ID pipe

2 2.25 OD pipes with 3/32 wall which would be a 2.125" ID would be around 28.358 for volume
1 3" ID pipe would be around 28.26 for volume

My main question is, how large should the intake pipe be? Same as the stock pipe or larger since it will be longer? I was thinking about velocity to, so if I got the measurments of the TB ports and got the volume of those and found the right sized pipe for the volume would that work better?

This may be very confusing to read, if so let me know and I will try to reword it.

RotaMan99

Here is a picture of how it might look.

speed_monkey

Its before the throttle body so it doesnt make a difference.

Your drawing looks basically like the stock set up to me. If you really want to see some gains, dump the pos AFM

papiogxl

iTrader: (6)

QFT, Standalone for the win.

Honestly, you won't see much gain out of doing that, just build a standard CAI or even just a box.

adrock3217

Just get the Prelude cold-air intake. Will probably be more effective, and that drop-in doesn't look like a very easy idea.

lupin

iTrader: (3)

+1 for going the standalone route. Just make sure you know people that can help you.

RotaMan99

BTW, This is for a Non Turbo. Not a Turbo which I could see why this would not be worth while.

Its FAR DIFFERENT from the stock air box, I can't even believe you said it looked similar. If I could get rid of the AFM, I would. Obeveously if I placed it in the picture, I still have it and can't get rid of it.

There will be more gain then a standard cai box that most people build which most of the time they build it shitty and doesn't seal right on the hood.

And do what with it? Place the filter in front of the rad like I was originally going to do? The drop in portion would be fairly interesting to build. Some thin sheet metal and a jigsaw will make it happen if I plan on really doing this.

If I had the money I qould go that route but I don't unfortunatly. I would deffinatly be able to put it in my self.

rs1tc

You could save the money you would spend on this intake for standalone. It is a cool idea and I'll give you props for being creative. Or you can do it and prove us wrong. As long as you're having fun I guess thats all that really matters.

speed_monkey

Idk... the stock system has a snorkel like that, and a filter. heh
No matter how much air it can flow, the AFM is still going to be a restriction.


edit- just read it again and I get it now, I thought you were just going to pull air around where the stock snorkel is...
Putting the intake where you are saying might work well actually, the air sure would be nice and cool.

7dust

iTrader: (14)

If its an NA - cut a 3" hole in the side of the support for the radiator near the bottom (right next to the resistor pack for the fuel pump) and route your intake that way.

Done.

86TwinTurbo

should be interesting configuration....that afm tho is going to get really confused on why air is being forced down its throat while the engine is idling and going 80 mph...nothing is acting again the flapper to keep it closed, just vaccum to open it and if now vaccum is not opening it fully and ram air (if in the correct aerodynamic area where I guess positive pressure (forgot either that or negative as pushing in and not pulling out) is opening the flapper and putting more air that it thinking its suck, could there possibly be problems with the air fuel ratio equal u might gain some power in acceleration but might lose some deaccelaration because of a very lean mixture ....then again depending on the surface area of the filter and the material its made of....the air pressure inside the ram set up before the filter might just flow back out the enterance and cause turblence..but ultimately that afm is the restrictive part...only way i see a ram set up being the best is in a carbuator setup that doesnt need a computer to tell it what to do...just throttle open wide and close....or i could be totally off just thoughts before i go to sleep

also on a closing note...basically a turbo is a ram air set up..its forcing (cold) air into the chamber, but the turbo uses a high pressure....i think stock is what 6.9 on an s4?...there is no way u can get that much pressure be of any use to be *forced* into the chamber..ultimately...u cant get more than 100% from an NA unless nitrous oxide or another high potential air/fuel

and not to be mean or anything, I want ur ideas to prove me wrong....because I have an NA and I want it to work haha

RotaMan99

Standalone wont give me the outside air. PLus this will be less then half the cost of a standalone. I have a SAFC2 right now which will work fine.

The Ram air idea I don't know if it will work right with the AFM like you are saying. I also don't know if turbulence will be caused if this will even work, but its a great idea I think that might work. At the very least it will give me 100% outside air.

I guess we will see. I can't say that I will gain anything with the ram idea but in theory i should get some extra power out of it doing 50+ mph?

86TwinTurbo

now only if u could inject freon to give u a cold air brust like the svt ford lightnings

C.A.R

I have been trying to figure out what I am going to do for an aftermarket intake... I am curious as to how this will turn out...
**
I have thought about buying an intake for the 93+ and just rearranging the pipes but cant tell if that would work from just the pictures...
**
I have also thought about researching other MAFs and finding one from another car that is less restrictive that would give the same values (resistance)... Then go to a junk yard, find that MAF, cut the wires and wire the harness and all to my 7... I dont know if that would work or how to go about testing something like that, but it may help in your potential confused MAF situation...
**
I hope it goes good for you and I want to see pics... I would like to know if it works and if you get good gains...

anewconvert

iTrader: (1)

Someone has already done a hotwire maf conversion to work with the stock ECU, but he believes it will only work with an S4. Also its not a simply plug and ply thing. he had to make a board that would invert the signal as a WOT signal would read as an idle signal without.


BC

Evil Aviator

So does the stock intake, which is basically the same thing as your idea except that it has slightly smaller tubing and a different pick-up point. BTW, your design is NOT a ram air intake. A ram air intake uses a divergent duct, not a convergent duct.

Yes, you would absolutely get some extra power out of it if you had an actual ram air system. Let's do the math assuming 100% compression efficiency and no temperature rise:

PSI = (mph)^2 * 0.0000176
PSI = (50mph)^2 * 0.0000176
PSI = 0.044

So at 50mph, you would see about 0.375% bhp increase, which would be about 1/2 bhp on a stock 13B NA.

The AFM isn't very restrictive until very high hp levels in which case you would be using a standalone EMS anyway. The search for a larger MAF is a complete waste of time and money unless you want to run your standalone EMS in mass airflow mode rather than speed-density or alpha-n mode. The only real advantage of mass airflow (AFM and MAF) vs. speed-density is that mass airflow compensates for engine wear.

ericgrau

iTrader: (1)

Amazing, someone else who uses math in these forums. Yeah, ram air intakes don't do squat unless you are going quite fast. In my fluid dynamics class we learned a rule of thumb that says air is "incompressible" below ~200mph. Taking in outside air, however, is still useful for making the air more dense and getting more power that way. They're supposed to be good for about 6HP. That roughly matches my own calculations assuming the air is ~20 degrees colder outside compared to under the hood. Useful info if you replace the stock intake with a cone intake.

easy ways to get HP I know of, biggest first: cat, muffler, VDI, cone intake, Royal Purple, "weight reduction" (just as good as HP): aluminum hood, AAA in place of spare tire, convertible wheels.

86TwinTurbo

aka just keep the maf sensor because in the end...all this extra work for an NA isnt worth it...thats why the NA stays the daily driver and the FD is the weekend car

Delphince

I'd be cautious about using RP in the engine. While their proprietary additives make for an superb film strength and burns with next to no ash (excellent for a rotary engine), Royal Purple is notorious for losing viscocity and thinning out. This isn't so great, especially since a lot of drivers like to run higher weights like the manual calls for.

While I'm a fan of RP products, I personally prefer a Group V polyoester oil like Red Line for rotaries, which can take the temperature abuse of repeatedly flowing through the rotors and oil cooler.

If you continue to use RP and are a spirited driver, I'd send off some samples to Blackstone Labs to make sure that your top-off is keeping up with your VI. If your OMP is disabled, I probably won't run more than 5000 miles on an oil change.