individual runner vs. common plenum intake

[sbc438]

Is anyone familar with the pros and cons of the two differnt intake designs pertaining to V-8 engines in a high performance arena.

Logic would suggest that an individual runner system like a webber set-up would create more low end power through maintaining velocity. Once you reach a "threashold" the inertial energy of the air in a common plenum system may overcome the seperate runners fighting for a common volume of air and surpass the VE of the single runner design (i.e. slight ram effect).

One thing that seems to be a challenge is ballencing the air flow cyclinder to cylinder in a V-8. One would think a single runner design would help ballance the intake flow but at what cost.....?

 

[Majik]

While this has been discussed in several magazines and applications. I will assume we are talking carburation on these manifolds and not EFI. The IR manifold you can tune so each runner is the same length and gets it's own fuel. A common system used to have different length runners and uneven air and fuel distribution. That has been greatly minimized on common intakes today so you don't have to any more keep the middle cylinders rich to prevent the front and rear from going lean. I think it's somewhere are 2% variance on those intakes which far more outweighs trying to set up 4 pairs of webers. The webers can be choked to give power down low or power up high and you can tune the runner length to this. All things considered the engine will make more peak HP with 4 webers vs one holey. In reality they will be pretty close and the webers will never been tuned right. syncronizing 4 webers is a chore in itself. all the jets in those and adjustments you'd spend no less than $500+ on jets and chokes and venturi's trying to get the right tune.