The guy who owned my 7 before me took a piece of metal, cut it out in a circular fashion (so that it would sort of resemble the original dinner plate), and left the sides of the intake cylinder/box open. I don't know if there is any actual increase, but it looks kind of cool if you ask me.

 

Actually skin friction is lower on a slightly rough surface than on a perfectly smooth one because of the type of boundary layer that's built up. Your top speed is higher with an unwaxed car. Pressure force dominates over skin friction on cars at high speeds so it would be a VERY small difference.

Off topic, sorry, but just to show that conventional wisdom and intuition isn't always right when it comes to air flow.

 

Way to go longduck,half the fun sometimes on our cars is making something for it
that makes you feel good. thats why i recomended that he relocate the air temp sensor closer to the front of the air pipe where the air is the coolest and do away with the stock air box and run a cone type kn at the end. We all know that our afm
are restrictive, but you can go in and change the tuning inside of them. If we can finally find out how to use a 2nd gen afm and tune it properly that would be great also. I am currently working on a cai for my 84 se and for some of the members 2nd gens. nothing is a waste of time if you enjoy what you are doing. This is how new info is gathered and how people learn to do other mods on their vehicles.
The quest for more air has been around for along time. turbos, superchargers, ram
induction hoods, cai has been very effective on many vehicles, noted that the have
different style t/bodys and maf sensors does not mean we can just give up looking for a functional system for our cars. We have to fabricate tons of stuff on our cars to make them stand above the crowd. Why not brainstorm what will it take to make a very functional cai system that will produce say 7hp to start. Granted my
93 mitsubishi eclipse 2.0 dohc gained 12 hp at the front wheels with injens cai,
proven by dyno. Need to work together to develop something that will work effectively on our cars. I might have an answer on a 2nd gen in bout 2 weeks if everything pans out. If they have a motto that they can make their hondas faster, than we should be able to the same. rx7doctor

 

I use an insulated cold air intake like what is outlined on the tutorial here:

http://maz_tutorials.ten15.net/

It's cheap and it's insulated, so it has to do SOMETHING to lower the intake temps. Also the intake is high enough off the ground that there is no worries about getting bucketfuls of water down the old carby.

 

MY cars painted a nice dark green colour, so on a hot day the hood is too hot to touch - the temperatures under there are quite high in comparison to ambient air temperature.

I built an airbox which I've bolted onto the front right radiator bracket (which I've cut a hole through) where cold air from out in front of the car enters the box, passing thru a cone filter then into the intake. Gaffa tape is my temporary seal heh, until I find something a little more long-lasting. By the way I have no AFM.



Before the CAI I would find the car would be quite sluggish on hot days, and now with it installed it is much more responsive in the heat Only cost me US$2.50 for the steel and about 7 hours with the tin-snips and hacksaw.

 

jesus, 7 hours?!?! doesnt seem worth it

 

Well it was the first time I'd ever worked with metals. Thinking back I could have designed everything before I purchased the metal sheeting so I could have it cut at the yard. Most of the time was spent hacksawing away at it, blunting blades and getting it to be the perfect shape.

It was a good learning experience and I felt it was worth it. Fits perfectly in the space I had, functions as I expected and doesnt look too dodgy hehe.

Most of the galvonised steel was 1mm but for the main load bearing piece I got 1.5mm which takes some serious time to cut. All riveted together and sealed with silicone. Clear perspex panel, easily removable to clean/change filter.

My whole aim was as some have said above, to do something myself, that would satisfy an aim, my aim was to improve performance in the heat, and that was satisfied, and for only $2.50 and a bit of learning and patience on my part, it went pretty well.

That metal pipe that goes through the box was also hammered out of a piece of steel, then solder sealed. Cheap as chips.

 

NO AFM? What did you do to bypass this?

 

its a wonderfull thing called engine management

 

Really? Thanks.

 

I always figured a headlight or hood scoop to a short-ram intake was the best way to cool an engine down while adding power. But that could just be me misunderstanding the ways of the world again.

 

It's an aftermarket ECU and wasnt setup with an AFM - apparently they are fairly restrictive..

At the moment I have just a hole cut through to the space in front of the radiator, but when I get some time I may consider a scoop, however as already noted, there is a noticable improvement in hot weather, so I'm not too fussed.

 

Carbon doesn't dissolve in water. Making hard, jagged particles swirl around in a water suspension among moving engine parts just doesn't seem like a good idea...

 

Thanks for the real reply. I too am trying to get rid of the AFM with out spending alot of money. That is holding my gsl-se back. I have s4 rotors, streetported s4 housings, s4 upper and lower intake with block offs. and the s4 throttlebody with the mod done to it. If I could get rid of the AFM and go from the 710cc injectors to 800-820's I think I would see a huge improvement.

 

Really the only way to get rid of the AFM is to convert to standalone EMS, the stock ECU NEEDS the afm to work, there is really no way around it unfortunatley

 

Ya, this is my problem. I was hoping he found some way to do it.
I really don't want to spend that much more money when I am not sure of the hp increase going EMS would give me.

 

ems basically give you the ability to tune your engine down to the needle thus utilizing hidden horsepower that is restricted by the stock ECU

 

I ghetto rigged my own ram air/cold air intake since they don't sell one for the 12a Rx7's. I know most cold air intakes are all hype, but I noticed a difference after I installed it - then again I also go rid of the secondary butterfly on the carb and removed all the restrictions the air filter canister had. http://www.cardomain.com/id/topgunm2k

 

A CAI will no suck up any water unless the filter is totally submerged in water and if you're that deep, you've got other things to worry about. Reason why it won't suck any in is because your engine will suck up the ligher, less dense substance, in this case, the air. Vacuums do not suck everything up and I doubt your engine's make enough suction to inhale all the water and air where your CAI comes out. Here's a fun experiment for those that may not believe me: take a straw and put a hole in the side. The stick the straw into a glass of water. Now suck in. Any water? Unless you made a tiny hole that almost sealed itself you won't get any. Just nice, less dense air. Mmmm mmmm, gotta love it.

 

you bastard, i was gonna pop in a **** till i looked at your car

 

That has some serious badass style

 

i just finished with bending the aluminum pipe, still have to get mounting brackets fabricated and welded in place. pipe is also 4" diameter, not the restrictive rectangle plastic.

 

Sweet, pics?

 

Someone mentioned that sucking up water will increase carbon buildup. Gregs I think. Actually, water will DECREASE carbon buildup. Water disentegrates carbon when it comes in contact. I've sucked water into a pissed-on motor with carbon knock, and it stops after a few minutes of dipping the brake booster vacuum line in a cup of water. Common on older Chevy small blocks.

 

...sucking up SMALL amounts of water is good, hydrolocking is when the engine takes in ONLY water, which does not compress like air does, and thus destroys an engine