Intake Runner Length

[b20b]

Is there an optimum intake runner length for B series engines producing over 200Hp atfw .Or what would be the best length as a starting point

[rev-tech]

there is a bunch of equasions to work out that kinda stuff.....i know it has a very noticable effect on carbie engines.

have a look in a book called 21st centruy performance......VERY good book.....talk's all about stuff like that

[pgclee]

May i know what have u got internally? 200hp atfw is kinda high...if you're saying just putting a header...with the rite measurement...

[wynode]

Is not intake runner lenght related to your power band or where you want your peak power?

[saxman]

Is not intake runner lenght related to your power band or where you want your peak power?
yes... also has to do wtih fun stuff with valve reversion and other good stuff... I've done intake length tuning on itb set ups... don't know too much on single throttle body ones though

[rev-tech]

if you run like 2 or 3 foot intake runners you can get >100% volumetric efficiency! :D

[Fattony]

Quoted from 21st century performance is that for 10,000rpm the runner legnth needs to be 7 inches from the valve seat, add 1.7 inches on that for every thousand rpm you wish to decrease the value. If you are tuning for peak torque you can soon realise that the runner would need to be very long in order to bring down the value, so its a good rule of thumb that you would want the runners to be aslong as physically possible within the restraints of your engine bay becuase even then you will find that they will prob still be to short, well i suppose it all depends on what sort of power you want to make and at what rpm

[wynode]

must the runners be in a straight line for good mid-low torque?