when that question is asked all the replys usually say short for high rpm power and long for torque. nothing really wrong with that statement but it tells you nothing at all really.
how long is too long and how short is too short. it may suprise most that inlet runners are usually too short even if they are thought to be too long. most engine bays cannot accomadate runners long enough to be of any use.
this link is a good summary of how runners affect real performance on a dynoed engine and also on that site they have designed adjustable trumpets to be able to dyno the best out of an engine. the great advantage being that you could find two sweet spots and change between maxium power and maximum torque for different events or driving conditions.
runner length tuning is nothing new. i have an old engine design and tuning book from the 60's that says exactly the same. i built my 45 Weber inlet manifold quite long and still people say it's too long for power and i should go shorter
how long is too long and how short is too short. it may suprise most that inlet runners are usually too short even if they are thought to be too long. most engine bays cannot accomadate runners long enough to be of any use.
this link is a good summary of how runners affect real performance on a dynoed engine and also on that site they have designed adjustable trumpets to be able to dyno the best out of an engine. the great advantage being that you could find two sweet spots and change between maxium power and maximum torque for different events or driving conditions.
runner length tuning is nothing new. i have an old engine design and tuning book from the 60's that says exactly the same. i built my 45 Weber inlet manifold quite long and still people say it's too long for power and i should go shorter
