mass air and throttle body

[mlambrecht82]

The C & L is a good buy, it flows better than the stock MAF, by keeping up the air velocity. The 75mm T/B will probably make you loose about 20 HP. The 70mm may be a good idea if you have headers and other exhaust work and are planning to get a blower in the future, otherweise it will slow the air velocity and you will lose horsepower. The ford engineers made these engines and tuned them to the right sizes. If a 70mm t/b gave you 8 hp on a nearly stock 4.6 then the 4.6 would come with a 70mm t/b. Think of it like a river. when the river is narow the current flows fast. When the river widens up it slows the current. Same thing with air flow on an engine. A 75mm t/b may flow a higher CFM but your nearly stock engine doesn't need the higher CFM, so all it does is slow the air velocity, and when it enters the intake manifold you loose all that power. Keep these princepals in mind before you guys mod your cars, the engineers makeing 6 figures designing these engines aren't idiots, so make sure that your engine needs the change you have in mind before you do it.