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I recently discovered something very important and completely by accident.
You know the baffle pipe that is inside of mufflers on cars, motorcyles and whatever. The muffler type that is constructed using many perferated holes, slots or louvers tru-out the length of this baffle pipe tube. These perferations allow flow into some fibreglass packing or into an adjacent silencing chambre like as in turbo mufflers.
While constructing a strait thru style custom muffler it was discovered that I had the wrong baffle pipe I.D. that was just a little bigger then the inlet/outlet pipe I.D. The temporary solution was to slip the inlet/outlet pipes inside the baffle a bit and secure them using hose clamps. The packing chambre was then built around this.
There was a 5% HP gain and on an allready highly refined racing engine! this gain was comparable to if all pipes were the same I.D.
The next logical change was to install an even larger baffle pipe I.D. for even less baffle restriction and using bushings to reinstall the inlet/outlet pipes. The result of this was that the H.P. was now the same as in the beginning as with all pipes of equal I.D. ---????
The hypothesis is now that the boundry layer flow thickness is normally .060 but that it becomes .1 or more thick wile in the turbulent baffle pipe I.D. The idea is to maintain a consistant pipe flow I.D. minus boundry layer thickness which will vary depending on port wall texture.
The real baffling thing in all this was that the flow stream speed apparently needs to maintain a consistant velocity without ever speeding up or slowing down as it does with changes in cross sectional area, and even if those "slow downs" are well intentioned and ment to give less pipe restriction.
You know the baffle pipe that is inside of mufflers on cars, motorcyles and whatever. The muffler type that is constructed using many perferated holes, slots or louvers tru-out the length of this baffle pipe tube. These perferations allow flow into some fibreglass packing or into an adjacent silencing chambre like as in turbo mufflers.
While constructing a strait thru style custom muffler it was discovered that I had the wrong baffle pipe I.D. that was just a little bigger then the inlet/outlet pipe I.D. The temporary solution was to slip the inlet/outlet pipes inside the baffle a bit and secure them using hose clamps. The packing chambre was then built around this.
There was a 5% HP gain and on an allready highly refined racing engine! this gain was comparable to if all pipes were the same I.D.
The next logical change was to install an even larger baffle pipe I.D. for even less baffle restriction and using bushings to reinstall the inlet/outlet pipes. The result of this was that the H.P. was now the same as in the beginning as with all pipes of equal I.D. ---????
The hypothesis is now that the boundry layer flow thickness is normally .060 but that it becomes .1 or more thick wile in the turbulent baffle pipe I.D. The idea is to maintain a consistant pipe flow I.D. minus boundry layer thickness which will vary depending on port wall texture.
The real baffling thing in all this was that the flow stream speed apparently needs to maintain a consistant velocity without ever speeding up or slowing down as it does with changes in cross sectional area, and even if those "slow downs" are well intentioned and ment to give less pipe restriction.
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