An interesting concept, why then do larger bore race exhausts/headers provide more power? Surely the larger bore exhaust runs at lower pressure than a narrow bore one on the same engine?
hummm... thats a tough one.youd be right about the lower pressure. I thought it is only the muffler at the end which has a larger bore, with the rest of the system at the standard factory thickness. most likely wrong though. as I say I know little about engines. on the other hand, having a wider pipe would be providing more space for the gases to escape into meaning less energy needed for it to be forced out of the cylinder when preparing for its next cycle. that would mean wasting less kinetic energy generated by combustion in the cyclinders at the opposite point of the stroke cycle- thus increasing the efficiency and power transfered to the driveshaft due to the lower resistance the piston encounters on the upstroke. as an example, when operating a hand powered tyre pump, its much easier to push the piston when its not attached to the tire, but also... if you were blowing it into somebodies mouth who was sucking in at the moment you pumped it, although it would be into a sealed space( the lungs instead of the tyre) the vacuum created by sucking would be lowering the pressure in the space which would have the same result as there being nothing attached... the gas would be expelled out of the pump faster. whether its more room for the gas to escape in to, or a narrower pipe at a higher pressure forcing the gas out, I think both would give a similar outcome by increasing efficiency in different ways.
Does that make sense? I know f all too but my guess was a fatter exhaust created a lower pressure (similar to your bike pump vacuum example) to increase the flow of exhaust gasses from combustion chamber increasing gas speed within the combustion chamber hence aiding the intake of fresh fuel. Probably complete bollocks though...
Kinetic energy in gases? Ek=1/2.m.v^2 m is mass, and since the gas has little weight there'd be negligible kinetic energy? I can't recall all the formuli relaying to the mechanics of the i.c. engine, but I'd imagine fluid dynamics would be more applicable to the design of exhaust systems. Think Venturis and 2-stroke pulse tuned exhausts drawing the spent gases from the combustion chamber. PS If the exhaust bore is too large there'd be little to no back pressure; resulting in burnt valves. Think we need the advice of a qualified mechanic?
by kinetic energy i meant the energy changed from the combustion into the movement of the driveshaft and mechanisms. I agree totally with your p.s and also the need for a mechanic.... in fact lets make it a race engine engineer lol.
Half wrapped mine now, two words of advice- 1- wear kind sleeved top and well fitting gloves (glass fibres itch like fk) 2- invest in many more steel zip tie thingi's, you only get 5 with the pack I ordered and on a v4 I estimate at least 14 are needed. Looks good IMO and will look trick when on the bike come Saturday evening/Sunday
We used to use heat wrap on the ZX6R headers, during a hot race meetig the bike would start to run a little on the hot side. We found that by wrapping the headers we reduced the running temp as less heat was being transferred from the headers to the radiator.
Has cost me £27.97 to do the full system on mine (had to but two packs of wrap (2mm x50mm x10m) And an extra set of 5 steel ties. Put it on after a good soak in water, has been two days since I did the first bit dry and still itching like crazy!! Looks sweet IMO though and exhaust was touchable after a run out
