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ITBS with plenum over it... why?

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Have a friend with a BMW 2002, its in having throttle bodies fitted, and both his mechanic and the rolling road are recommending fitting some kind of plenum. 

He's running a fairly wild schrick cam, more compression, and what looks like quite short trumpets..


They're saying -  you'll get colder air, more low end torque, and it's because of the cam. 




I thought:

ITBS idle better with lairy cams because the pulses don't interfere with other cylinders, like they would with a plenum

Top end you have less restriction?

And where the torque is is more a function of the tract length than anything else, as dave walker proved with his article where he did multiple runs with different inlet lengths. 

Plenum will dial down the glorious induction hammer.


His rolling road date is next week, and i'm saying to him that if i wanted to move the torque around i would be experimenting with different trumpet lengths. 

There is LOADS of space in front of the trumpets, like a foot, and the trumpets look about 60mm. 







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