Skunk2 intake manifold
12-12-2016, 05:51 PM
#221
The basic idea is the intake runner is a tube and the intake pulses set up a series of standing waves, much like waves on a guitar string, or organ pipe.
A standing wave is a series of high and low pressure areas. You tune the intake runner length so the high pressure pulse (the node) of the standing wave corresponds with the valve opening You tune the length for a specific RPM range. A number of people earlier on this thread worked out the calculations, take a look at them, here is link that gives an overview.
It really depends on what RPM range you want a torque peak. Short runners give the resonance peak at higher rpm, and visa versa with longer runners. The F22C runner length is pretty good for an F20, but when they stroked the F22, they should have increased the runner length as well.
Plenum volume calculations are much more trickier and is almost a guesswork as it has so many variables. I made a model in SolidWorks which is basically like a virtual flow bench. But it doesn't do resonance calculations (at least I'm not sure how to do them with SolidWorks), so I just used the standard formulas to get the runner length. Manifold design is a balance between optimal resonances and optimal flow, and there's a lot of trial/error involved because its so complicated.
In any case, most estimates of ideal F22 runner length for a torque peak around 6000 come out to around 8.5", an inch longer than factory, and plenum volume should be around 2-2.5 liters, factory is 1.5.
index
A standing wave is a series of high and low pressure areas. You tune the intake runner length so the high pressure pulse (the node) of the standing wave corresponds with the valve opening You tune the length for a specific RPM range. A number of people earlier on this thread worked out the calculations, take a look at them, here is link that gives an overview.
It really depends on what RPM range you want a torque peak. Short runners give the resonance peak at higher rpm, and visa versa with longer runners. The F22C runner length is pretty good for an F20, but when they stroked the F22, they should have increased the runner length as well.
Plenum volume calculations are much more trickier and is almost a guesswork as it has so many variables. I made a model in SolidWorks which is basically like a virtual flow bench. But it doesn't do resonance calculations (at least I'm not sure how to do them with SolidWorks), so I just used the standard formulas to get the runner length. Manifold design is a balance between optimal resonances and optimal flow, and there's a lot of trial/error involved because its so complicated.
In any case, most estimates of ideal F22 runner length for a torque peak around 6000 come out to around 8.5", an inch longer than factory, and plenum volume should be around 2-2.5 liters, factory is 1.5.
index
12-29-2016, 03:36 PM
#225
Pretty disappointed that Skunk2 didn't design this F intake manifold to be compatible with stock (or aftermarket) s2000 fuel rails. Had they done so they'd have likely made the runners a bit longer too (which would've made their product better for NA).
12-30-2016, 09:33 AM
#226
I agree with you 100% when I seen that, I was glad I did not buy any aftermarket fuel rail but if the gains are there I will forget about it LOL
01-26-2017, 05:40 PM
#229
Registered User
I have one on the way from x performance. Will be doing before and after dyno comparisons don't know how soon but it'll happen. I'll get some pics up soon as I get it hopefully early next week.
The following users liked this post:
wochi (01-27-2017)
01-31-2017, 06:42 PM
#230
