Why did Ford go from the alum intake on the 99 5.4 to the plastic one used from 2000 - 2003? Are there any differences in flow, did they do it to quiet the engine down, can they be swapped out, were there any performance gains? Thanks for your help in advance

 

My guess is Ford's reasoning is the plastic ones are slightly lighter and cheaper.

I think they can be swapped with the metal ones, but i doubt if you would see any performance increase. Certainly not enough to justify the time & cost of making the swap.

 

runners are longer on the aluminum style, they are a bit noisier, last longer but weigh few grams more. ford mostly went to them cause cost of aluminum went up i beleive

 

The "plastic" version also does not absorb as much heat as the aluminum, resulting in a slightly cooler intake charge. The intake on my '95 Ranger 4.0 was plastic.

 

plastic is an insulator meaning is hold heat but doesnt conduct it as well so while the intial intake charge is less once it does get hot under cruising temperatures the intake temps will rise because it doesnt decipate heat as well as an aluminum. aluminums heat up and cool down quicker and actually have lower intake temperatures because of all the casting ridges that create air turbulance helping the air fuel mixture the passing air cools the runners down.

 

Thanks for the help. I'm buying a 99' Expy and was curious if there was any performance gains from changing to plastic. You all have saved me money and time. I had a 98 Expy before and that motor was on the quiet side, but this 99' I'm picking up has alot more engine noise (guess its the P.I. heads) that give it a bit more noise. I love how much more power the 99 has compaired to my old 98'. Again, thanks everyone

 

I've designed my own cold air intake that only costs around 60 bucks if your interested in making your own. This one places the filter in front of the front left tire, where colder moving air will be forced into it.

 

were refering to intake manifolds...

 

Ah, manifolds. Didn't read the word manifold anywhere... got confused.