Originally Posted by davidv

The most troubling threads always begin similar to this.

Originally Posted by Hoooper

too bad nobody ever seems to test in motion, since when youre moving the air around the engine is pretty close to exterior temps.

case in point: go take your cold car, go WOT several times while driving for like 5 mins, then feel the intake manifold. its still cold. only when you let the heat from the heads creep up into the intake manifold does it make a difference. with my phenolic spacers, i drive home from work, hit traffic and probly average about 15mph on the way home. when i get there the intake manifold is still cold. if the air in the engine bay was hot when in motion, the intake would be hot after driving even though it didnt transfer through the phenolic. there ARE differences with the heat shield even when moving, but theyre small. you really wouldnt notice unless youre stopped or on a dyno where its obviously not a moving test.

the point: if you have them use them, but if you dont have them it doesnt matter