Did some testing today with 15l/minute electric water pump vs Derbi standard mechanical. Electric with reversed flow was almost identical with stock and with normal flow direction it was slightly worse.
Solid: Derbi Mechanical
Dash: Bosch electric pump with reversed flow sucking water out around exhaust duct.
I see electric water pumps on almost every Freetech bikes and with both flow directions. What I’m missing out, is there some track condition gain I won’t see in short dyno runs..?
Having the cold water feeding in under the Exhaust duct is just as wrong as having all the cold water going into the head.
This change was made 2 homologations ago in KZ engines , where the simple but vey inelegant solution was to feed the cold water surrounding the crank , up thru a hose , and into the cylinder
above the top of the Exhaust duct from one side.
The best scenario is to have all the cold water enter the cylinder over the boost port , then run around the bore over the tops of all the transfers - cooling these first.
Then a portion of the return should be directed to a pair of small exit holes on each side under the Exhaust , the remining flow then exits up into the Exhaust side of the head , around the insert and back to the radiator.
This alone is an instant 1 to 1.5 Hp in 50.
Water flow and cooling in general is a very much ignored source of " free " power gains.
Having water flowing around the entire length of the Exhaust duct , where the plugging charge is retained , is super simple , but never done properly as far as I have seen.
These slots in the Exhaust exit surface ( done by hand many years ago in the pit with a battery drill and file ) cools the back of the spigot as well , and reduces the background deto level by around 20% - allowing alot leaner egt level at full power as a result.
This is much easier now with a small 75% exit area and a 6 axis CNC .
Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.
Having the cold water feeding in under the Exhaust duct is just as wrong as having all the cold water going into the head.
This change was made 2 homologations ago in KZ engines , where the simple but vey inelegant solution was to feed the cold water surrounding the crank , up thru a hose , and into the cylinder
above the top of the Exhaust duct from one side.
The best scenario is to have all the cold water enter the cylinder over the boost port , then run around the bore over the tops of all the transfers - cooling these first.
Then a portion of the return should be directed to a pair of small exit holes on each side under the Exhaust , the remining flow then exits up into the Exhaust side of the head , around the insert and back to the radiator.
This alone is an instant 1 to 1.5 Hp in 50.
Water flow and cooling in general is a very much ignored source of " free " power gains.
Having water flowing around the entire length of the Exhaust duct , where the plugging charge is retained , is super simple , but never done properly as far as I have seen.
These slots in the Exhaust exit surface ( done by hand many years ago in the pit with a battery drill and file ) cools the back of the spigot as well , and reduces the background deto level by around 20% - allowing alot leaner egt level at full power as a result.
This is much easier now with a small 75% exit area and a 6 axis CNC .
Wob, if you include the crankcase flow, how would you do it?
The best scenario is to have all the cold water enter the cylinder over the boost port , then run around the bore over the tops of all the transfers - cooling these first.
Then a portion of the return should be directed to a pair of small exit holes on each side under the Exhaust , the remining flow then exits up into the Exhaust side of the head , around the insert and back to the radiator.
This alone is an instant 1 to 1.5 Hp in 50.
Do not know if I really understand. Is there something like this you are thinking of?
No amount of experimentation can ever prove me right; a single experiment can prove me wrong.
Sorry I didnt word my fist description correctly.
If the water is fed initially into the crankcase ( from the front in the Aprilia or the middle as in the TM ) then the main flow from there should be directly up into the cylinder
with a pair of large holes each side of the boost port ( NOT underneath the hot Exhaust duct ) . Another pair of smaller holes should also feed up under the Exhaust port , thus aiding flow around this area separately.
The only exit flow from the cylinder is up into the head directly over the Exhaust port. Thus keeping the water heated up by the Exhaust duct flowing away from the transfers.
This is possible for example in the TM , if the water in the cavity between the case and the gearbox is then also fed forward over the top of the mains ( thus cooling the transfer entry area ) and up
into the cylinder each side of the boost port.
This idea has been applied to old designs , like TZ250/350/750 , where the original flow was completely wrong - but this needs some form of separation plate or gasket between the head and cylinder.
Again , in this case all the flow enters the cylinder thru a new spigot welded in opposite the Exhausts , and all the cold water flows forward across the transfer tops , then exits into the head thru a pair of holes
each side above the Exhausts.
The test was done on a TM by extending the existing water feed hole around to above the boost port. A real 1 Hp free lunch , but not shown in the homologation papers , so probably illegal.
Thus I did the almost as good change , and forced all the cold water away from the Exhaust duct with a hidden manifold inside the cylinder - legal.
Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.
Condyn , I have a stock YZ250 pack from years ago - PM me with your email.
Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.
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