Engine intake runner length?

  • Thread starter heli-mech
  • Start date
  • #1
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Main Question or Discussion Point

I'm currently adapting a rack of four 36mm carbs to a 1.6L (97.64 ci) 4 cylinder engine. I'm trying to figure out how to calculate the proper intake runner length to use. This is to be a zippy daily driver, not an 1/8th mile drag car. I've found information on "Independant Throttle Bodies" length calculations for fuel injected systems, but this involves a plenum and does not seem relevant. Any help would be much appreciated.:smile:
 

Answers and Replies

  • #2
Danger
Gold Member
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I can't help with any formulae. As a general rule, however, your power band is partially governed by the runner length. Longer means your band is in a higher rpm range.
 
  • #3
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As far as I know the whole secret of side draught carbs are in the fact that they have very short intake manifolds producing power from a very low rpm. range. part of the m3 power is the 6 individual throttle bodies mounted directly on to the engine. Suggest you make the runners as short as possible.
 

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