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The reason for a IR manifold is driveability, you can run a big cam to make HP and still get it to idle smooth. It helps smooth out the TQ curve, low rpms the cylinders are not trying to pull the breath out of another cylinder and massive airflow at high rpms.

I think it could be fast, driveable and look awesome if done right



For some reason I am thinking that if it had all those advantages it wouldn't have been abandoned over 30 years ago.

If you go to Hilborn's or Kinsler's websites you will see many variations of Small block IR fuel injection systems. Typical throttle bore sizes are way bigger than any available carburator. 2 7/16" - 2 5/8" are common and they can be as big as 3". At least with F.I. the pulseing that goes on in an IR arrangement doesn't disrupt fuel delivery like it does in carburetors. The bottom line is that the reason they quit using IR manifolds back in the day is because everyone that put a plenom on top of their IR manifold went faster.


In theory, there is no difference between theory and practice. In practice, there is.