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The DISA varies the length of the intake runners. At low rpms the runners need to be longer than they need to be at higher rpms. The idea is to take advantage of air flow dynamics with the intake and cylinder head.
 

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The DISA varies the length of the intake runners. At low rpms the runners need to be longer than they need to be at higher rpms. The idea is to take advantage of air flow dynamics with the intake and cylinder head.
:yikes:, excuse me for being a idiot, but I don't understand nothing you wrote. Please could you break it down into idiot form so I can understand.:hmm:
 

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:yikes:, excuse me for being a idiot, but I don't understand nothing you wrote. Please could you break it down into idiot form so I can understand.:hmm:
The DISA gives you more torque when your engine is at lower RPMs than it otherwise would have. That's what it does.

For a comparison, Hondas don't have this kind of valve and that's why they don't have much pickup until you rev them high.
 

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The DISA gives you more torque when your engine is at lower RPMs than it otherwise would have. That's what it does.

For a comparison, Hondas don't have this kind of valve and that's why they don't have much pickup until you rev them high.
Ohh, I now have an idea of what takes place. Thanks :thumbup:. Correct me if I am wrong it increases the gas to air ratio at low rpm resulting in more torque. Or something like that.
 

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Ohh, I now have an idea of what takes place. Thanks :thumbup:. Correct me if I am wrong it increases the gas to air ratio at low rpm resulting in more torque. Or something like that.
No, it varies the length of the intake runners. The air travels a shorter distance at low RPM (below 4k) then at higher RPM the DISA opens letting the air run a longer combined distance and larger diameter runners, that is better for higher RPMs.

Find more information here, it is not an easy subject neither is BMW solution perfect. When working on a plane that has constant RPM it is easy to fine tune every aspect of the engine operation. On a car that revs from 1000 to 7000 RPM all is a compromise.
 

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No, it varies the length of the intake runners. The air travels a shorter distance at low RPM (below 4k) then at higher RPM the DISA opens letting the air run a longer combined distance and larger diameter runners, that is better for higher RPMs.

Find more information here, it is not an easy subject neither is BMW solution perfect. When working on a plane that has constant RPM it is easy to fine tune every aspect of the engine operation. On a car that revs from 1000 to 7000 RPM all is a compromise.
Wow, now I have been schooled,:clap:, I now have a pretty good idea what it is and how it works :D, thanks for the link. It sure opened my eyes. So the DISA opens causing the high pressure air in the intake runners to run longer because at low rpm the strokes are slower so when the valves re-open for the next stroke it gets the full blast of air kicking up the torque. I am glad they have people like you guys here. I feel like a rocket scientists :D. Thanks again :clap::clap:
 
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