Author Topic: Variable length intake manifold configuration  (Read 140 times)

Offline msh

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Variable length intake manifold configuration
« on: March 20, 2020, 05:02:45 am »
So, in the near future I'm going to install variable length intake manifold on engine of my golf, VW ABA-like clone, manifold will be from VW AFT engine. I clearly understand how to configure the electrical and software stuff, as it's simple, I expect some problems with the throttle that will come with that manifold, but I'm aware of them. I'm slightly confused what conditions to use to switch over that manifold to torque setting. The original approach, as far as I'm aware, is that long manifold is switched over @ 1k rpm and back to short manifold again @ 4k. But it happened that I got to read VAG SSP 212, about "variable intake on VR engines", different engines and different intakes but principles remain the same, and it says that 1) switchover point @ 1k rpm is solely to keep the variable length mechanism from getting stuck, otherwise it would be rarely operated 2) it would be beneficial to run short intake at medium revs at low and medium load, switching over to long intake at those revs only under heavy load.

Can anyone give some input on necessity of having 1k switchover point in order to keep the mechanism from getting stuck, and about switching over to long intake only under heavy load? :)

Offline gunni

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Re: Variable length intake manifold configuration
« Reply #1 on: March 20, 2020, 12:41:48 pm »
I think you can just tune the switch points as they provide you with the maximum torque production, the sub 1k short runner may be as you describe for it not to get stuck other wise the manifold for about 90% of people would always remain long as many normal people donĀ“t rev high enough to need shorter runners.