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Why a new exhaust manifold?


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  • 2 weeks later...

It's called Computational Fluid Dynamics and is used for gasses and liquids and an important part of tuning correctly:

http://en.wikipedia.org/wiki/Computational_fluid_dynamics

There are many variables, not least of all packaging and emissions regs etc and in short, best power is straight in and straight out with no restrictions but obviously that is not always possible.

Below is something I acquired over the years of studying it and is a reference model to the change in length of inlet and exhaust pipes (on a diesel engine) and the way in which it changes the torque and power characteristics (imaging the curve as the orque curve you see on dyno's to make it easier to understand and where the power/torque is in relation to the rev range).

TDIInletManiModels_zpsd78cc6a6.jpg

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No probs, tons of CFD info, it's mainly about calcs though than making the pictures look alright! (Also when you have up to a 1000 logs on each CFD tests it's time consuming to put them together).

vr6inletmani2-Copy_zps20651a5f.jpg

Lots of inlet and exhaust mani stuff, this was one of the dozens of tests regarding the feeding of the first cylinder in the plenum and the effects on plenum tapers etc

pressurevariations-Copy_zps1d5941f6.jpg

RBPE log VRT exhaust mani

VR6Turbocstlogmanifold2d_zpsccc28e93.jpg

Look pretty more than anything, in short, you'll be amazed at the differences plenum shapes, runner shapes, pipe circumferences etc all make and any bend radii, and contrary to what anyone tells you, my tests show that the standard exhaust, throttle body etc all become massive flow restriction points at anything from a bar of boost plus! (Done 2bar + at this present time)

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