I was planning on fabbing up a diff intake tube from the air filter to the throttle body to keep that air cooler and give the engine a cleaner look. so is it better to use stainless steel or aluminum to keep the air cooler? or is the plastic the best?

 

something like this? stainless cost a lot more than alum



i'm going to wrap the pipe and run a vinspeed box w/ cold air

 

isn't that bad because the afm is not level?

 

Don't worry too much about keeping the air cooler with respect to piping material. Straight-wall pipes are lousy at transfering heat, especially when the air inside is moving at over 300cfm. Most people use aluminum because it is light and cheap. If you really need to avoid that extra 5degF of absorbed heat (1/2% hp loss), then you can ceramic coat or thermal wrap the pipe. Most of the available plastics will crack and/or melt, but that would be a good option if you have access to a special plastic fabricator who can supply you with the correct bends and material.

Your main concern should be the source of the intake air. Try not to position your inlet so that the hot discharge air from the radiator is sucked into the engine.

Another good area of focus is keeping the amount of bends to a minimum, and avoiding sharp bends or tight-radius bends. However, this would be more of a factor after the turbo (if you have one). Speaking of which, it is easier for people to answer your questions if you list the year and model of your RX-7 in your profile or signature.

Yes, and the sharp bends are not so great for airflow. However, I don't see any major problems with that setup.