My GXL had the stock air box when I bought it, I swapped in the K&N and didn't notice any major differences, it certainly didn't give me a bad idle... I would like to have thought it revved quicker but i couldn't vouch for that with any evidence but honestly,I liked the style of the K&N and got some compliments and thats all I expected. On an NA it's up to you, but you won't catch a stock air box on my TII, thats for sure.

and it does seems like everyone's got their panties in a bunch in here....

hehehe butt dyno....hehehe

Edit: and i'll be going back to the stocker airbox for my gxl when it's time comes again.

 

KN air filter on stock airbox is best

 

Pictures please.
I want to fab a cold air intake for my 88 N/A. I'd like to see pictures of what you have made/bought. If it looks getto I won't do it. I want a clean factory look.

 

The performance difference between an OEM filter and a K&N one is basically nothing. It's the airbox that's restrictive, not the filter in it.

 

This all makes me wish that I bought my FC unmolested.

 

Corksport, ARC and Pettit have these for the RX7 but you can make your own. Anything to keep any hot air out.





what bothers me about the filter without the box is that the filter will be surrounded by the radiator, engine and headers/turbo. You want as little hot air as possible. The Stocker is better because the vents in the front end directs the ambient air into the snorkel and your filter.


If you're going to go with a filter, do it the proper way to make sure you're getting the coldest air possible for best performance. I'd use something else besides metal to truly insure no heat gets to the filter though. A nicely vented headlight cover will provide the ambient air (which will be much cooler than the air under the bay) or a custom hybrid front end with special vening to the intake will ensure enough COOLER (edited for those detail ppl.)air gets in there.

Found this link with a nice diagram.
http://www.ggimages.com/rx7/coldbox.html


Have any you felt the difference between a hot summer day and a cold, dry sunny winter day? The difference is there. Feels like it takes off better and pulls harder. Fall and winter are my favorite times of the year, no snow and SOME rain.

 

If you're trying to keep heat out all those intakes are truly awful designs. Not one actually allows ambient air in and keeps engine bay air out. The Corksport one is nothing but a very small cone filter with a ***** skirt, the ARC one is not much better than the stock airbox with the top cut open and the Pettit one is for an FD. All are hideously expensive...

Have you noticed that all of the headlight vents are no bigger than the stock intake duct? They're not nearly big enough for a true performance intake. If you were somehow able to seal one completely to the intake, it'd be a restriction. But since that's impossible, most of the air sucked into the intake will come from somewhere other than the headlight vent.

 

well he asked for designs. I chose the CS one for the CF since it won't conduct as much heat as the metal ones. The ARC one is a generic design but it still gives him an idea on how to close up a box. I know the petttit is for the FD but I was mostly trying to show that anything (like the plate that separates the radiator and the filter) that blocks hot air will work .


How do you figure it would be a restriction? The main argument vs. the stock intake is the restrictions of the stock setup (the snorkel, the box, the intake tube). When you replace it with a filter then the intake will not be getting the same amount of ambient air as before (even if you leave the snorkel in place) so the small headlight vent will help. It won't be ram air, but it will help.

 

I'm sure he wanted good designs...

Sure, but that one still won't do anything useful. It's not doing anything to stop the engine bay air from entering the filter, which is pretty obvious just from looking at it. It doesn't matter what it's made of, the intake temp will be the same as if it wasn't there.

It's not a closed box, it's just a box that holds a filter. It's still sucking 100% engine bay air.

That one doesn't block hot engine bay air either. If it had a rear side that sealed against the inner guard with holes for the intake hoses, then it might work.

Like I said, "If you were somehow able to seal one completely to the intake, it'd be a restriction", simply because it's a very small hole. But you can't do that (unless you remove the entire right headlight assembly) so it's a moot point. The point I was trying to make is that air is being sucked into the intake, and it will take any and all paths it can to get there. The easier the path is, the more air will take that path, and vice versa. The only way to make a cold air intake work properly is to make it much harder for engine bay air to get to the filter than it is for outside air.

There are much better ways to do that; the headlight vents are simply too small. I've got my filter quite well sealed off from the engine bay, and two large holes cut in the sheetmetal beside and in front of the filter allowing air from outside the engine bay in. I've logged temps at the filter and they remain very close to ambient.

 

Not questioning the validity, but where did you find or how did you research this info? I've been experimenting with intake recently, and am curious about such matters.

-Collin

 

so, what's your favorite set-up?

 

Mine!

See the engine bay pic in the link in my sig. All it is is a heat shield that is reasonably well sealed all round to keep engine bay air out and a way for outside air to get in as I described above.

 

Ummmm no.

Just for *****, I like mine the best. Don't even say anything about the AFM. I have experienced no issue at all. Only consistant power instead of "heat soak" power.
http://midnightgray.net/images/cai1.jpg
http://midnightgray.net/images/cai2.jpg
http://midnightgray.net/images/cai3.jpg

NoPistons has some restriction numbers in In-H20. He just did the math to figure it out

I saw on autospeed ( I think is the name of the site), they tested a miata air intake system with a VERY ugly dirty air filter. They put a K&N air filter in and found a difference to small to even think about considering. I'll see if I can find that page again.

 

Details here.

 

Pictures don't work.

 

can i just side with the "stock are box is ugly" group?
idk nor do i care about "no, stock is better........." "no, cone is better" ::billy madison voice here::
seriously, i just dont like when manufacturers go "hey, theres some empty space, quick, put some plastic there before the boss comes >.> <.< >.> <.<"

peace

 

Here's where we set up the HKS filter way back in 1995 (no sheet metal cutting)

 

Still kind of on topic...

What would be a good material for a cold air box, easy to work with minimal heat soak material? I have a buddy who's good with fiberglass - is this a better choice than aluminum or sheet metal? If it works out, I'll post pics. and stuff.

 

I had fabbed my box out of flashing aluminum I bought at Lowes and covered it with insulation material secured by aluminum tape I bought at Black Dragon.

The point I want to emphasise here is that on my stock unmodded N/A there was no noticeable difference between the stock air box and my cone filter with the heat box only. Maybe putting the cone filter outside of the engine bay, either in front of the radiator or perhaps in the wheel well would.

 

I've been told that ABS plastic is a good candidate, though I would like to know what the best material is (within affordability) for making an airbox)

 

my twin apex made my gas mileage go to hell

 

Er, actually pictures work on this PC, sorry Clokker.

 

while this arguement is entertaining, you guys are WAY wrong. it's about pressurized cold air not cold or hot air only...yes cold air helps your engine breathe better but it really doesnt help on performance cars, especially N/A's. THE AIR HAS TO BE ABOVE ATMOSPHERIC PRESSURE, or positive pressure. if the air in the intake supplies positive pressure to the engine you will see a pretty noticeable gain in performance, especially on boosted engines. you simply buy a cheap pressure switch, tape it in various places on the front of the car, wherever the switch is when the switch goes off at the lowest speed is the area that creates the most positive pressure. you simply route the intake as close to this spot as possible. the faster you go when the intake is there, the better your car will pull, kinda like a supercharging effect.
here is a wonderful article that will settle this once and for all.....
http://www.autospeed.com/cms/A_1023/...popularArticle

 

Queue Evil Aviator..

 

electric supercharger??? evidently you didnt read the article....it explains that the air in the intake only adds performance gains if it is positive pressure. meaning don't put your filter in the engine bay and don't cut holes in your ride to let your filter suck in just cold air. but take the time to test for the highest pressure point on the front of the car, then engineer a way to get ayour piping or filter to it.....they even prove that having a stock MAF sensor and stock paper filter have no restrictions on the intake as long as it is routed to a high pressure area.