adnoh wrote:
You guys crack me up. Good thing thisis the General BS section. As far as taking it higher it a yes and no. As you raise it it will change the AAML line to which the mm squared is taken for anglearea at T. By taking it higher IF required to increase blown down degree again can be achieved but to high and it will be worse than before. There is some quide lines for blown down related to rest of the porting. A lot depends on where you want to be. For starters you need to determen if there is a need to start the exhaust process sooner and understand the effects of doing so. You can oops here for sure. AS a general quide raiseing the exhaust wil raise the rpm of the power band if you get the rest correct. An example of oops would be raise the port which raises the AAML and not widen that part of the port to not only maintain the correct mm2 but increase itfor the now hiogher rpm to which T is shorter. This is to say the port open in time is less from the higher rpm and decreaesed AAML port area in mm2 and you just rut rued. This would bad if you were running a stock clutch over a one that engaged higher in rpm If you clutch enguages at 4500 or above you would not need set your site on an rpm lower and shift you angle area for the new enguagment rpm or your leaving power on the table. So shift the power curve up starting at 4500or 5000 or even a little higher. If your running your clutch at 7800 than taget that range of 5000 to 7800 and get the angle area for that T. You do this by altering the porting to achieve this result. Even after all the porting if the pipe is not tuned for this there is side effects. Now factor in Compression ratios at that rpm and it will effect the squish velocitys which is a by product of teh new rpm and exhaust port height. Than if you pipe does reach temp and the stuffing effect is out of time the cylinder will start to bleed pressure and loose mixture strenght as a result. Think about this for a second, when we fiqure compression ratio we assume the cylinder is at atmopherioc. This is usally far from the thruth. If the pipe pulse is slow is could be in vacume state or if the the pipe is in tune and on time the cylinder will be in a pressure state before the port closes. This will take our border line CCR to a detonation state via quish velocity for pump gas. Back to to high on the port, pressure loss and charge loss upon closing. on the other side of the stroke if it iopen to soon before combustion is complete you loose power and since the blow down timing is too high you most likly cook the pistons edge right off. Then when the transfers do open they get sucked right out the pipe with out effectivly clearing the cylinder of the spent gases and that will hurt the next now weaker intake charge and it becomes a turd.
Yea I said turd like wet turd I glad this in the BS section. I think I'll pause here and get ready to go ride. No pun intended. Have fun hacking and allowing me to chime in.
Ya what he said!
Today I ported my pipe by drilling eight 1/4 inch holes in the "fat" part of pipe..
It is important not to drill seven as that is not enough and not nine as that would be too much....
Next I'm going to tear the ends off my air filters as the current ends get all dirty and the air just cannot flow through them as well...
"the above written words were derived from foolishness and should only be replicated by those trained in the art of foolery and destructive unhelpful behavior"
Regards
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