Quote:
Originally Posted by JGK95
Greg and Corey,
Won't the 'trumpets' at the back of the intake manifold improve if they are directed at the front? Even if at an angle? I've seen in car mags the BMW v-10 engine with various length trumpets measured to capture a better segment of air.
Thoughts?
Jay K.
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It can't hurt. I was at the Ferrari dealership the other day in their engine assembly room and they were disassembling a 430 engine for a rebuild that is run in the Challenge. The runners extend up into the plenum several inches and have about a ten degree cant on them towards the front of the intake. Ferrari engineers are hardly a group of guys to build a junk manifold.
One thing you have to keep in mind about manifolds is that they do not flow "steady state". The flow is not exactly starting and stopping, but the intensity of flow does increase and decrease a bit. A steady state flow test on a flow bench does not tell the whole story about a manifold. It must be run at the track. I prefer to have a longer runner that uses the 3rd harmonic because the runner will hold more air and will not have a strong need to draw a lot of air from the plenum during the intake stroke. The shorter runner manifolds that rely on the 4th harmonic are more dependant on how quickly air can flow from the plenum into the runner and need to flow at a higher rate, because there is not enough air in the runner to completely fill the cylinder on the intake stroke and air must be drawn from the plenum. Same situation as a single four barrel manifold.