Whats good to look for when buying a cold air intake ? i.e. kind of material[[ for a 92 civic cx ]]
If it's the stock engine, don't waste your $ buying one. It's an 8-valve economy engine that is good for nothing but gas mileage. A CAI will only hurt your already horrible powerband. I put an intake on my '94 CX, and not only did it hurt performance at low rpms, but it also killed my gas mileage as well. It barely makes enough power to move from a stop, as it is. Shifting the powerband to the mid to high rpms only makes things worse. But as for materials; carbon fiber or aluminum are the best to look for. The aluminum dissipates heat much better than steel, so the air going through the intake will be cooler. The cooler the air, the more dense it is. The more dense the air, more air molecules that will be pumped in to the engine at the same flow rate. Carbon fiber also doesn't absorb heat nearly as much as steel, so it won't heat up from the hot engine/engine bay, as a steel intake will. But honestly, on a stock engine (or lightly modded one), the specifics of the intake aren't going to make a noticeable difference. You'd be talking about 1-2hp at the higher rpms, where most people don't take the car to on a regular basis. So in this case, if you do actually decide to get an aftermarket intake, just get a cheap knock-off brand OKorder one. An even better choice would be to buy a KN drop-in filter with your stock intake/air box.
AEM is a leader, and perhaps your best bet. I'd go with a polished chrome finish since it will reflect more radiant heat than any of the powder coated models. It's important to thermally isolate the intake from as much conductive heat (coming from the throttle body), and from radiant/convective heat coming off the engine as possible. A cooler CAI pipe means a denser air-fuel mixture.more horsepower. Check out OUTLAW ENGINEERING's website for their thermoblock spacers that have proven to add HP by insulating the CAI from the throttle body.
Most CAIs are made of polished or anodized aluminum as it is the best material for dissipating heat before it can affect the air traveling through the intake. Even more importantly than the material of the CAI, you need to check how the intake fits into your vehicle. ensure that the intake you are buying has room between itself and other engine components that conduct heat. Also it is a good idea to purchase improved intake manifold gaskets, throttle body gaskets and throttle body spacers to prevent heat from transfering from your intake manifold, by way of the engine, onto your throttle body and then onto your intake. Good luck and happy tuning.
