IntakeManifold runner lengths..

[onelowciv]

thinking back, tha days of working on my motorcycle, i was told that tha longer tha runner length between tha carb and engine would produce more torque at lower end.. tha shorter it was, more HP at tha top end.. now im building a d16z6 with plans on boost(vortech SC). my question is would runner length matter when your under pressure? anyone ever experiment with different lengths?

[onelowciv]

anyone? opinions & thoughts would be greatly appreciated!!

[Zinc]

you said it all

short is horsepower, long is torque!

[kommon_sense]

horsepower and torque are not 2 seperate things. hp is *DIRECTLY* derived from torque.

hp = tq * rpm / 5252

So without torque, there is no hp.

shorter runners push the powerband higher up into the rpm range but really sacrifice low end and midrange. So you end up with a bad torque curve which results in a peaky hp graph.

And yes, runner length will still matter because you have to get that turbo to spool. I would suggest going longer to have a good low end and midrange as well as a responsive turbo.

[Zinc]

Well i didn't know all that!

Actually i did. It doesn't change my answer, i just wasn't being specific.

Long runners = good at low to medium-low air velocity (want more torque?)
Short runners = good at medium high to high air velocity (revy engine?)

[onelowciv]

appreciate tha opinions! altho im still in tha same boat.. i chink imma play around n make my own intake mani. will see what tha dyno has to say about it all..

[Zinc]

Cool
Well i know the sc from jackson racing comes with a manifold with really short runners. That might be because of where its placed.