Any ideas on how to create a true cold air intake system I would like to do it. Any pics?

Thanks

 

i've been thinking about this lately too. twothings i've come up with are to make a ducting going from the air box to the vent in the bumper or to hook up some ducting from your a/c to blow into your air box. iknow it might sound stupid but hey it would work

 

If you really have that Apex FMIC, it should be pretty easy for you to figure out. And you could always get the current Amemiya flush lights with the high beam removed on our passenger side.

 

I am not sure what you mean I do have the FMIC but the thing takes up all the front space I would have to build a ducting sytem. The intercooler is only going to cool the intake air a few degrees.

 

I went to Home Depot, bought two wet/dry vac crevice tools that attach to vac hoses, cut out slits in the bottom of my airbox closest to the passenger side, slid the crevice tools down the slots in between the radiator, and the frame down under the car, and sealed any holes with great stuff. worked great. sucks air in from right under the car, and only costs about 15 dollars

 

I no longer have a stock airbox,

 

Whenever I get some time I'm going to do this. What I'll be doing is making some carbon fiber panels that will bolt onto some 90 degree angle aluminum pieces on the inside to make a box around my K&N filters. In the bottom of the box will be a hole cut out fed by a tube that will snake down under the headlight getting air from the passenger side air duct (touring model). It'll be sealed with rubber gaskets and look pretty nice(theoretically). I just need to take some time off to mix up some epoxy and do it.

 

I am actually interested in the effectiveness of "cold air". Could someone explain to me the theory of putting air into turbos of some 1200F that is ~5F cooler than what you would draw in normally? I understand the idea on an N/A engine as that is the actual air going into the engine. However, I see the final verdict in intake air temp being the efficiency of your intercooler. Perhaps this is what DK was hinting?
Non-"cold air"- 85F air into 1200F turbos, out under pressure at 150F (no idea, but would like some data from research of people with spare time to measure intake temp after turbos!) through intercooler (FMIC) with 75F air to promote equilibrium, into throttle body (warmed with coolant) at 90F and into engine...
"cold air"- 80F air into 1200F turbos, out under pressure at 149.9F through intercooler with 75F, into throttle body at 89.99F and into engine.
It seems to me that by trying to run dryer ducting through an oil cooler duct up to a carbon fiber box to get effectively no power gain is a waste of time and money. Put effort in possibly cooling the intercooler for your superheated charge temps to come down further. I have been working on an efficient system to effectively cool the intercooler with a fine spray of 50/50 mix of alcohol and water on the intercooler as the alcohol's evaporation takes greater heat from the intercooler fins. I am almost positive there are cheaper and better ways to spend your time on do-it-yourself single digit hp mods. I am open to criticism and comment.

Richard

 

I too have been dwelling upon how to do cold air, hiwever, I have it somewhat easier, I have the C-West headlight kit, and the space underneath the headlights is just aching to have K&N's stuffed in there, and air borrowed from the Oil cooler openings. I also have the Apexi Front bumper, so the Oil cooler openings are larger then stock, whick should compensate for the engine taking some of the air from there.

As for the turbos ingesting cold air vs. hot air, here's my theory, and anyone who really knows turbo operation is welcome to confirm/deny my ideas. First off, the turbo compressor housings are aluminum, and if they were 1200 degrees, they would most likely be a puddle of aluminum under the car. Most alloys of aluminum melt in that neighborhood. I would think they are between 200, and 500 degrees. Yes, they are hot, and they do heat up the air, thats what the intercooler is for. Now the theory. Turbochargers are centrifigual compressors, they compress the incoming air by slinging it fast enough that the air "weighs" slightly more then the air in the turbo outlet. This way the air wants to go to the area of lower pressure, the turbo outlet. It accomplishes this by spinning the incoming air to make it dense enough to overcome the preessure in the turbo outlet. Now the bulk of the theory, in order to make hot air, which is less dense heavy enough to overcome the weight (pressure) in the turbo outlet, the turbo(s) have to spin faster than if the inlet air was more dense(cooler) and we all have read that the stockers get unreliable around 14-15+psi. I wonder if the unreliability is related to the shaft speeds for the assembly getting too fast. Also the compressor is being driven by a turbine which also is spinning at the same shaft speed, and the exhaust gases have to overcome the turbine backpressure caused by the same cenfrifigual force that is helping to compress the intake air. So I think if we can provide the turbos with cooler, denser air, we will lower the shafts speeds, which will improve turbo life, lower exhaust manifold pressure, and increase turbo system efficiency, oh, and also give a net gain in HP. I plan on doing the cold air mod soon, just have to get other projects finished. I would love to be able to use an optical tach, and measure compressor rpm's both before and after this mod, however I lack an optical tach. But the pitch (sound) of the turbos might give a smal indicator of the change. Again, this is just theory on my part, any turbo experts please feel free to chime in.
J

 

I'd say the overwhelming majority of the temperature increase in air going through the turbo(s) is caused by the compression, not by heat transfer (metal to air). That's why you want cool, dense air to start with, before putting it into your turbos, regardless of their temperature.

Generally, ~5F cooler air in = ~5F cooler air out.

 

Not too mention that we all know when we have a cooler night our cars run much better and a tad faster. I personaly want to do it to lengthen the life of my Turbos and Engine by not allowing it to breathe the still hot air under the hood.

 

I welcome all of the replies and understand the logic behind what you present. I am not doubting that there is a theoretical improvement in the intake temperature, however, I would like to see some data for comparison to note whether this modification will produce the results that many are claiming. The suggestion of 5F cooler in= 5F cooler out is interesting because with compression being yet another variable to affect temperature, I doubt that the final charge temperature will be a linear improvement. I do not know what the relationship will be, and think some real numbers would help solve the confusion.
I have seen dryer ducting on a 390 rwhp stock sequential FD before and there were no noticable gains (not to mention, it looked hideous).
Yellowbird- I found some problems with the way you described the turbos functioning, but it will take about a 4 page presentation on how the exhaust/turbos/air function together to make a proper arguement, so I will work on that and PM it to you when I get the chance. Realistically, a 5F change in temperature to the turbos will have a miniscule effect on turbo life and overall power gain.
JAMMNN- I would attribute the feel we get on cooler nights to the change in temperature from the intercooler running in cooler ambient air.
Of course all of this info is relative to what mods you have on your car. For example, a pure stock RX-7 with the plastic sufficating the engine is going to benefit from just getting a K&N drop in and allowing more air into the system regardless of temperature. The "Pettit" system will benefit with a dryer duct setup assuming everything else is left stock (especially I/C), but an all out modded FMIC, open K&N filter, vented hood, removed air pump, relocated battery etc... will have very minimal gains in overall intake charge temp if air is pulled in from outside the engine bay due to the fact that the engine bay is more open and allows for greater ventilation. It also depends on whether the car is idling at a stop light or driving down the highway, or is being cooled down between drag runs... just some variables to think about, but I would like to see some numbers to validate the correct thinking here. Thank you for your input and thoughts, and also for keeping it civil.

Richard

 

There was a guy on the forum who posted some pics of a box made from plexi-glass and a couple of K&N filters a couple of months ago. I've had a search but can't find the thread .. anybody remember it??

P'Cola Fd : I've been thinking about the same thing, except why are you planning on using alloy to create the 90 deg? Can you not just make the box 100% from carbon?

How about using a little quick-set glue to hold the panels at 90 deg then lay some carbon mat on the inside and outside of the corners?

 

I created one that costs about 5 bucks to do. It was my first modification and damn what a difference. At highway speed I got 1 lb extra boost, so I know it works. I don't have pics yet but I took the box and cut a hole in the bottom about 3.5 X 5 or something like that. I bought special hose at Home Depot, its a strong 2.5 inch reinforced vynle hose. The stuff is like 5.97 per foot. It takes about 1 foot or so. I removed the black plastic wedge that sits in the opening of the car infront of the radiator (the one on passenger side). and then routed the hose from my intake box and stuck it between the radiator and the chasis of the car. It works real good, brings REAL cold air into the car. The best part is you still get the air from the box the way the factory intended + the extra air from the modifcation.

 

This being a prototype, I want it to be as simple as possible. I also want to be able to take it apart easily.

 

I have something a little different than ZeroBanger's setup.

I have the Pettit Intake system and a 2-1/2" diameter hose placed under the car directly below the 3 K&N filters and 90 degrees out facing the front of the car. The outside air flows up to the filters. Then, I cut a 3" diameter hole in the inner header plastic, just in front of the shocks. My theory is, that the outside air flows past the filters and some excapes out the fender well. It seems to work.