Variable-length intake manifold?

[22Silver]

Just read that the NB's got given the same engine as the NA's, with only a few minor changes.

- Domed pistons for more compression
- solid lifters and stronger cams
- variable intake control system

Apparantly engines can adjust the length of the intake manifold to shorten and narrow at low RPM and lengthen and widen at high RPM for max breathing.
Anyone know how this effect plays out on the part of the intake not inside the engine- such as, the differences in peak performance (in terms of an RPM range) between engines with stock or long, hotside CAI's, and engines with short coldside intakes (like the pod filter on a half intake tube behind the drivers side headlamp)

Also, did I dream it or see it; ITB's with sliding trumpets, adjusting length relative to revs.

[project.r.racing]

was used in 323s and ford lasers from 1990. dunno why it took so long to get into a mx5.

i dont understand you question in relation to the hot/cold intakes.




sound like a engine related question for the engine related section.

[22Silver]

Basically me question relating to hot and cold side intakes is:
When people put short intakes on (so they can sit the open element pod filter at the drivers headlamp), what effect does this have on performance?
I understand that intake length is important and not just some random length that fits the engine bay, so wouldn't shortening the black intake pipe have some effect on performance?

[NitroDann]

All of the quickest cars in the states running an n/a BP run a 21" long 2.5" pipe to a pod filter on the cold side of the engine bay or over the radiator. 949 did the dyno testing and this works.

Dann